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Sample records for antenna complexes protect

  1. Antenna complexes protect Photosystem I from Photoinhibition

    Directory of Open Access Journals (Sweden)

    Hienerwadel Rainer

    2009-06-01

    Full Text Available Abstract Background Photosystems are composed of two moieties, a reaction center and a peripheral antenna system. In photosynthetic eukaryotes the latter system is composed of proteins belonging to Lhc family. An increasing set of evidences demonstrated how these polypeptides play a relevant physiological function in both light harvesting and photoprotection. Despite the sequence similarity between antenna proteins associated with the two Photosystems, present knowledge on their physiological role is mostly limited to complexes associated to Photosystem II. Results In this work we analyzed the physiological role of Photosystem I antenna system in Arabidopsis thaliana both in vivo and in vitro. Plants depleted in individual antenna polypeptides showed a reduced capacity for photoprotection and an increased production of reactive oxygen species upon high light exposure. In vitro experiments on isolated complexes confirmed that depletion of antenna proteins reduced the resistance of isolated Photosystem I particles to high light and that the antenna is effective in photoprotection only upon the interaction with the core complex. Conclusion We show that antenna proteins play a dual role in Arabidopsis thaliana Photosystem I photoprotection: first, a Photosystem I with an intact antenna system is more resistant to high light because of a reduced production of reactive oxygen species and, second, antenna chlorophyll-proteins are the first target of high light damages. When photoprotection mechanisms become insufficient, the antenna chlorophyll proteins act as fuses: LHCI chlorophylls are degraded while the reaction center photochemical activity is maintained. Differences with respect to photoprotection strategy in Photosystem II, where the reaction center is the first target of photoinhibition, are discussed.

  2. Planetary protection for Europa radar sounder antenna

    Science.gov (United States)

    Aaron, Kim M.; Moussessian, Alina; Newlin, Laura E.; Willis, Paul B.; Chen, Fei; Harcke, Leif J.; Chapin, Elaine; Jun, Insoo; Gim, Yonggyu; McEachen, Michael; Allen, Scotty; Kirchner, Donald; Blankenship, Donald

    2016-05-01

    The potential for habitability puts stringent requirements on planetary protection for a mission to Europa. A long-wavelength radar sounder with a large antenna is one of the proposed instruments for a future Europa mission. The size and construction of radar sounding antennas make the usual methods of meeting planetary protection requirements challenging. This paper discusses a viable planetary protection scheme for an antenna optimized for Europa radar sounding. The preferred methodology for this antenna is exposure to 100 kGy (10 Mrad) in water of gamma radiation using a Cobalt-60 source for both bulk and surface sterilization and exposure to vapor hydrogen peroxide for surface treatment for possible recontamination due to subsequent handling. For the boom-supported antenna design, selected tests were performed to confirm the suitability of these treatment methods. A portion of a coilable boom residual from an earlier mission was irradiated and its deployment repeatability confirmed with no degradation. Elasticity was measured of several fiberglass samples using a four-point bending test to confirm that there was no degradation due to radiation exposure. Vapor hydrogen peroxide treatment was applied to the silver-coated braid used as the antenna radiating element as it was the material most likely to be susceptible to oxidative attack under the treatment conditions. There was no discernable effect. These tests confirm that the radar sounding antenna for a Europa mission should be able tolerate the proposed sterilization methods.

  3. Designing hydrophobic sheet protected Eu(III)-tetracycline complex using long chain unsaturated fatty acid: Efficient ‘antenna effect’ in aqueous medium

    Energy Technology Data Exchange (ETDEWEB)

    Samanta, Swarna Kamal; Sanyal, Sagarika; Samanta, Sugata; Ghosh, Sanjib, E-mail: pchemsg@gmail.com

    2015-04-15

    We have designed a novel ternary system consisting of Tetracycline hydrochloride (TC), Eu(III) and unsaturated long chain fatty acid (Oleic acid, α-Linolenic acid) in aqueous buffer at physiological pH of 7.2. The systems exhibit highly efficient ‘antenna effect’ of Eu(III) compared to that observed in the binary system of TC and Eu(III) [Eu{sub 3}TC]. Transients of Eu(III) emission in aqueous buffer and D{sub 2}O buffer show that the number of water molecules, coordinated directly to the Eu(III) ion, decreases from 12 in Eu{sub 3}TC to 2 in the ternary system using oleic acid. The micelle formed by the bent conformation of the unsaturated oleic acid provides a hydrophobic sheet on all sides of Eu{sub 3}TC complex protecting Eu(III) from interacting with O–H oscillator. The simple biocompatible system could be used for imaging purpose, and biomedical assay. - Highlights: • A ternary system containing a ligand, oleic acid and Eu(III) has been developed. • The system exhibits enhanced ‘antenna effect’ in aqueous medium at pH=7.2. • This may help design a useful biosensor/imaging technique using Eu(III)

  4. Designing hydrophobic sheet protected Eu(III)-tetracycline complex using long chain unsaturated fatty acid: Efficient ‘antenna effect’ in aqueous medium

    International Nuclear Information System (INIS)

    We have designed a novel ternary system consisting of Tetracycline hydrochloride (TC), Eu(III) and unsaturated long chain fatty acid (Oleic acid, α-Linolenic acid) in aqueous buffer at physiological pH of 7.2. The systems exhibit highly efficient ‘antenna effect’ of Eu(III) compared to that observed in the binary system of TC and Eu(III) [Eu3TC]. Transients of Eu(III) emission in aqueous buffer and D2O buffer show that the number of water molecules, coordinated directly to the Eu(III) ion, decreases from 12 in Eu3TC to 2 in the ternary system using oleic acid. The micelle formed by the bent conformation of the unsaturated oleic acid provides a hydrophobic sheet on all sides of Eu3TC complex protecting Eu(III) from interacting with O–H oscillator. The simple biocompatible system could be used for imaging purpose, and biomedical assay. - Highlights: • A ternary system containing a ligand, oleic acid and Eu(III) has been developed. • The system exhibits enhanced ‘antenna effect’ in aqueous medium at pH=7.2. • This may help design a useful biosensor/imaging technique using Eu(III)

  5. Antenna Miniaturization in Complex Electromagnetic Environments

    DEFF Research Database (Denmark)

    Zhang, Jiaying

    . Moreover, the modified Wheeler cap method for measurements of small antennas in complex environments is further developed. A cable-free impedance and gain measurement technique for electrically small antennas is also proposed. The electromagnetic model of this technique is derived by using the spherical...... wave expansion, and it is valid for arbitrary electrically small AUT at arbitrary distances between the probe and AUT. The whole measurement setup is modeled by the cascade of three coupled multipleort networks. The electromagnetic model, the simulation results, and the obtained measurement results...

  6. Heterometallic antenna-reactor complexes for photocatalysis.

    Science.gov (United States)

    Swearer, Dayne F; Zhao, Hangqi; Zhou, Linan; Zhang, Chao; Robatjazi, Hossein; Martirez, John Mark P; Krauter, Caroline M; Yazdi, Sadegh; McClain, Michael J; Ringe, Emilie; Carter, Emily A; Nordlander, Peter; Halas, Naomi J

    2016-08-01

    Metallic nanoparticles with strong optically resonant properties behave as nanoscale optical antennas, and have recently shown extraordinary promise as light-driven catalysts. Traditionally, however, heterogeneous catalysis has relied upon weakly light-absorbing metals such as Pd, Pt, Ru, or Rh to lower the activation energy for chemical reactions. Here we show that coupling a plasmonic nanoantenna directly to catalytic nanoparticles enables the light-induced generation of hot carriers within the catalyst nanoparticles, transforming the entire complex into an efficient light-controlled reactive catalyst. In Pd-decorated Al nanocrystals, photocatalytic hydrogen desorption closely follows the antenna-induced local absorption cross-section of the Pd islands, and a supralinear power dependence strongly suggests that hot-carrier-induced desorption occurs at the Pd island surface. When acetylene is present along with hydrogen, the selectivity for photocatalytic ethylene production relative to ethane is strongly enhanced, approaching 40:1. These observations indicate that antenna-reactor complexes may greatly expand possibilities for developing designer photocatalytic substrates.

  7. Heterometallic antenna-reactor complexes for photocatalysis.

    Science.gov (United States)

    Swearer, Dayne F; Zhao, Hangqi; Zhou, Linan; Zhang, Chao; Robatjazi, Hossein; Martirez, John Mark P; Krauter, Caroline M; Yazdi, Sadegh; McClain, Michael J; Ringe, Emilie; Carter, Emily A; Nordlander, Peter; Halas, Naomi J

    2016-08-01

    Metallic nanoparticles with strong optically resonant properties behave as nanoscale optical antennas, and have recently shown extraordinary promise as light-driven catalysts. Traditionally, however, heterogeneous catalysis has relied upon weakly light-absorbing metals such as Pd, Pt, Ru, or Rh to lower the activation energy for chemical reactions. Here we show that coupling a plasmonic nanoantenna directly to catalytic nanoparticles enables the light-induced generation of hot carriers within the catalyst nanoparticles, transforming the entire complex into an efficient light-controlled reactive catalyst. In Pd-decorated Al nanocrystals, photocatalytic hydrogen desorption closely follows the antenna-induced local absorption cross-section of the Pd islands, and a supralinear power dependence strongly suggests that hot-carrier-induced desorption occurs at the Pd island surface. When acetylene is present along with hydrogen, the selectivity for photocatalytic ethylene production relative to ethane is strongly enhanced, approaching 40:1. These observations indicate that antenna-reactor complexes may greatly expand possibilities for developing designer photocatalytic substrates. PMID:27444015

  8. Evidence for a cysteine-mediated mechanism of excitation energy regulation in a photosynthetic antenna complex.

    Science.gov (United States)

    Orf, Gregory S; Saer, Rafael G; Niedzwiedzki, Dariusz M; Zhang, Hao; McIntosh, Chelsea L; Schultz, Jason W; Mirica, Liviu M; Blankenship, Robert E

    2016-08-01

    Light-harvesting antenna complexes not only aid in the capture of solar energy for photosynthesis, but regulate the quantity of transferred energy as well. Light-harvesting regulation is important for protecting reaction center complexes from overexcitation, generation of reactive oxygen species, and metabolic overload. Usually, this regulation is controlled by the association of light-harvesting antennas with accessory quenchers such as carotenoids. One antenna complex, the Fenna-Matthews-Olson (FMO) antenna protein from green sulfur bacteria, completely lacks carotenoids and other known accessory quenchers. Nonetheless, the FMO protein is able to quench energy transfer in aerobic conditions effectively, indicating a previously unidentified type of regulatory mechanism. Through de novo sequencing MS, chemical modification, and mutagenesis, we have pinpointed the source of the quenching action to cysteine residues (Cys49 and Cys353) situated near two low-energy bacteriochlorophylls in the FMO protein from Chlorobaculum tepidum Removal of these cysteines (particularly removal of the completely conserved Cys353) through N-ethylmaleimide modification or mutagenesis to alanine abolishes the aerobic quenching effect. Electrochemical analysis and electron paramagnetic resonance spectra suggest that in aerobic conditions the cysteine thiols are converted to thiyl radicals which then are capable of quenching bacteriochlorophyll excited states through electron transfer photochemistry. This simple mechanism has implications for the design of bio-inspired light-harvesting antennas and the redesign of natural photosynthetic systems. PMID:27335466

  9. Photon-blockade as protection in photosynthesis Antenna with cyclic structures

    CERN Document Server

    Dong, Hui; Yi, Zhenhuan; Agarwal, Girish S; Scully, Marlan O

    2016-01-01

    Excess energy absorbed by the light-harvesting antennas could be potentially harmful to the photosynthesis complexes. The biological system has developed various mechanisms, e.g. non-photon chemical quenching, to prevent these damages by dissipating energy into the surrounding environment. In additional to this well-known mechanism, we hypothesise a new protection mechanism of suppressing the probability of double excitation in photosynthesis system, where pigment-protein complexes form cyclic structures with dipole-dipole interaction between adjacent chlorophylls. We also demonstrate robustness of the photon blockade against the disorder in the ring structures. The photon blockade can explain the recent observation on the suppression of simultaneous emission of two photons in natural photosynthetic antennas.

  10. Towards quantification of vibronic coupling in photosynthetic antenna complexes

    Energy Technology Data Exchange (ETDEWEB)

    Singh, V. P.; Westberg, M.; Wang, C.; Gellen, T.; Engel, G. S., E-mail: gsengel@uchicago.edu [Department of Chemistry, The James Franck Institute and The Institute for Biophysical Dynamics, The University of Chicago, Chicago, Illinois 60637 (United States); Dahlberg, P. D. [Graduate Program in the Biophysical Sciences, The James Franck Institute and The Institute for Biophysical Dynamics, The University of Chicago, Chicago, Illinois 60637 (United States); Gardiner, A. T.; Cogdell, R. J. [Department of Botany, Institute of Molecular Cell and Systems Biology, University of Glasgow, Glasgow, Scotland (United Kingdom)

    2015-06-07

    Photosynthetic antenna complexes harvest sunlight and efficiently transport energy to the reaction center where charge separation powers biochemical energy storage. The discovery of existence of long lived quantum coherence during energy transfer has sparked the discussion on the role of quantum coherence on the energy transfer efficiency. Early works assigned observed coherences to electronic states, and theoretical studies showed that electronic coherences could affect energy transfer efficiency—by either enhancing or suppressing transfer. However, the nature of coherences has been fiercely debated as coherences only report the energy gap between the states that generate coherence signals. Recent works have suggested that either the coherences observed in photosynthetic antenna complexes arise from vibrational wave packets on the ground state or, alternatively, coherences arise from mixed electronic and vibrational states. Understanding origin of coherences is important for designing molecules for efficient light harvesting. Here, we give a direct experimental observation from a mutant of LH2, which does not have B800 chromophores, to distinguish between electronic, vibrational, and vibronic coherence. We also present a minimal theoretical model to characterize the coherences both in the two limiting cases of purely vibrational and purely electronic coherence as well as in the intermediate, vibronic regime.

  11. Towards quantification of vibronic coupling in photosynthetic antenna complexes

    Science.gov (United States)

    Singh, V. P.; Westberg, M.; Wang, C.; Dahlberg, P. D.; Gellen, T.; Gardiner, A. T.; Cogdell, R. J.

    2015-01-01

    Photosynthetic antenna complexes harvest sunlight and efficiently transport energy to the reaction center where charge separation powers biochemical energy storage. The discovery of existence of long lived quantum coherence during energy transfer has sparked the discussion on the role of quantum coherence on the energy transfer efficiency. Early works assigned observed coherences to electronic states, and theoretical studies showed that electronic coherences could affect energy transfer efficiency—by either enhancing or suppressing transfer. However, the nature of coherences has been fiercely debated as coherences only report the energy gap between the states that generate coherence signals. Recent works have suggested that either the coherences observed in photosynthetic antenna complexes arise from vibrational wave packets on the ground state or, alternatively, coherences arise from mixed electronic and vibrational states. Understanding origin of coherences is important for designing molecules for efficient light harvesting. Here, we give a direct experimental observation from a mutant of LH2, which does not have B800 chromophores, to distinguish between electronic, vibrational, and vibronic coherence. We also present a minimal theoretical model to characterize the coherences both in the two limiting cases of purely vibrational and purely electronic coherence as well as in the intermediate, vibronic regime. PMID:26049466

  12. Biohybrid photosynthetic antenna complexes for enhanced light-harvesting.

    Science.gov (United States)

    Springer, Joseph W; Parkes-Loach, Pamela S; Reddy, Kanumuri Ramesh; Krayer, Michael; Jiao, Jieying; Lee, Gregory M; Niedzwiedzki, Dariusz M; Harris, Michelle A; Kirmaier, Christine; Bocian, David F; Lindsey, Jonathan S; Holten, Dewey; Loach, Paul A

    2012-03-14

    Biohybrid antenna systems have been constructed that contain synthetic chromophores attached to 31mer analogues of the bacterial photosynthetic core light-harvesting (LH1) β-polypeptide. The peptides are engineered with a Cys site for bioconjugation with maleimide-terminated chromophores, which include synthetic bacteriochlorins (BC1, BC2) with strong near-infrared absorption and commercial dyes Oregon green (OGR) and rhodamine red (RR) with strong absorption in the blue-green to yellow-orange regions. The peptides place the Cys 14 (or 6) residues before a native His site that binds bacteriochlorophyll a (BChl-a) and, like the native LH proteins, have high helical content as probed by single-reflection IR spectroscopy. The His residue associates with BChl-a as in the native LH1 β-polypeptide to form dimeric ββ-subunit complexes [31mer(-14Cys)X/BChl](2), where X is one of the synthetic chromophores. The native-like BChl-a dimer has Q(y) absorption at 820 nm and serves as the acceptor for energy from light absorbed by the appended synthetic chromophore. The energy-transfer characteristics of biohybrid complexes have been characterized by steady-state and time-resolved fluorescence and absorption measurements. The quantum yields of energy transfer from a synthetic chromophore located 14 residues from the BChl-coordinating His site are as follows: OGR (0.30) BChl](n) are accompanied by a bathochromic shift of the Q(y) absorption of the BChl-a oligomer as far as the 850-nm position found in cyclic native photosynthetic LH2 complexes. Room-temperature stabilized oligomeric biohybrids have energy-transfer quantum yields comparable to those of the dimeric subunit complexes as follows: OGR (0.20) self-assembly characteristics of the native antenna complexes, offer enhanced coverage of the solar spectrum, and illustrate a versatile paradigm for the construction of artificial LH systems. PMID:22375881

  13. Directional antenna array (DAA) for communications, control, and data link protection

    Science.gov (United States)

    Molchanov, Pavlo A.; Contarino, Vincent M.

    2013-06-01

    A next generation of Smart antennas with point-to-point communication and jam, spoof protection capability by verification of spatial position is offered. A directional antenna array (DAA) with narrow irradiation beam provides counter terrorism protection for communications, data link, control and GPS. Communications are "invisible" to guided missiles because of 20 dB smaller irradiation outside the beam and spatial separation. This solution can be implemented with current technology. Directional antennas have higher gain and can be multi-frequency or have wide frequency band in contrast to phase antenna arrays. This multi-directional antenna array provides a multi-functional communication network and simultaneously can be used for command control, data link and GPS.

  14. In situ high-resolution structure of the baseplate antenna complex in Chlorobaculum tepidum

    DEFF Research Database (Denmark)

    Nielsen, Jakob Toudahl; Kulminskaya, Natalia V.; Bjerring, Morten;

    2016-01-01

    Photosynthetic antenna systems enable organisms harvesting light and transfer the energy to the photosynthetic reaction centre, where the conversion to chemical energy takes place. One of the most complex antenna systems, the chlorosome, found in the photosynthetic green sulfur bacterium Chloroba...

  15. Low complexity transmit antenna selection with power balancing in OFDM systems

    KAUST Repository

    Park, Kihong

    2010-10-01

    In this paper, we consider multi-carrier systems with multiple transmit antennas under the power balancing constraint, which is defined as the constraint that the power on each antenna should be limited under a certain level due to the linearity of the power amplifier of the RF chain. Applying transmit antenna selection and fixed-power variable-rate transmission per subcarrier as a function of channel variations, we propose an implementation-friendly antenna selection method which offers a reduced complexity in comparison with the optimal antenna selection scheme. More specifically, in order to solve the subcarrier imbalance across the antennas, we operate a two-step reallocation procedure to minimize the loss of spectral efficiency. We also provide an analytic lower bound on the spectral efficiency for the proposed scheme. From selected numerical results, we show that our suboptimal scheme offers almost the same spectral efficiency as the optimal one. © 2010 IEEE.

  16. Photoprotection Mechanism of Light-Harvesting Antenna Complex from Purple Bacteria.

    Science.gov (United States)

    Kosumi, Daisuke; Horibe, Tomoko; Sugisaki, Mitsuru; Cogdell, Richard J; Hashimoto, Hideki

    2016-02-11

    Photosynthetic light-harvesting apparatus efficiently capture sunlight and transfer the energy to reaction centers, while they safely dissipate excess energy to surrounding environments for a protection of their organisms. In this study, we performed pump-probe spectroscopic measurements with a temporal window ranging from femtosecond to submillisecond on the purple bacterial antenna complex LH2 from Rhodobacter sphaeroides 2.4.1 to clarify its photoprotection functions. The observed excited state dynamics in the time range from subnanosecond to microsecond exhibits that the triplet-triplet excitation energy transfer from bacteriochlorophyll a to carotenoid takes place with a time constant of 16.7 ns. Furthermore, ultrafast spectroscopic data suggests that a molecular assembly of bacteriochlorophyll a in LH2 efficiently suppresses a generation of triple bacteriochlorophyll a.

  17. New theoretical analysis method for the phase center in the Fresnel region of complex structure antennas

    Institute of Scientific and Technical Information of China (English)

    Nian Feng; Wang Wei

    2008-01-01

    A finite domain time difference (FDTD) and second-derivative combined method is proposed for the evaluation of phase center in the Fresnel region of complex structure millimeter antennas.This method adopts FDTD's near to far field transformation to obtain the fields in Fresnel region and then applies the second-derivative method to calculate the phase center.The adoption of FDTD efficiently overcomes the difficulties arising from the existing calculation methods' requirements for the radiation analytical formula of some complex antennas,which makes the existing second-derivative method more applicable in engineering.Also,FDTD increases the precision owing to the superposition field calculation from its extrapolation.The correctness of this proposed method is certified with typical examples and the phase center in the Fresnel region of a microwave radiometry calibration corrugate horn antenna is evaluated with the key features.

  18. Low-Complexity MMSE Precoding for Coordinated Multipoint with Per-Antenna Power Constraint

    DEFF Research Database (Denmark)

    Kim, Tae Min; Sun, Fan; Paulraj, Arogyaswami

    2013-01-01

    We propose a low-complexity minimum mean square error (MMSE) transmit filter design for the coordinated beamforming (CB) in the coordinated multipoint (CoMP) under the practical per-antenna power constraint (PAPC). The proposed design is based on the non-linear Gauss-Seidel type algorithm in which...

  19. Structure, Function and Reconstitution of Antenna Complexes of Green Photosynthetic Bacteria

    Energy Technology Data Exchange (ETDEWEB)

    Blankenship, Robert E.

    2005-06-10

    Most chlorophyll-type pigments in a photosynthetic organism function as an antenna, absorbing light and transferring excitations to a photochemical reaction center where energy storage takes place by a series of chemical reactions. The green photosynthetic bacteria are characterized by large antenna complexes known as chlorosomes, in which pigment-pigment interactions are of dominant importance. The overall objective of this project is to determine the mechanisms of excitation transfer and regulation of this unique antenna system, including how it is integrated into the rest of the photosynthetic energy transduction apparatus. Techniques that are being used in this research include biochemical analysis, spectroscopy, microscopy, X-ray structural studies, and reconstitution from purified components. Our recent results indicate that the chlorosome baseplate structure, which is the membrane attachment site for the chlorosome to the membrane, is a unique pigment-protein that contains large amounts of carotenoids and small amounts of bacteriochlorophyll a. Reconstitution of directed energy transfer in chlorosomes will be carried out using purified baseplates and oligomeric pigments. The integral membrane B808-866 antenna complex from Chloroflexus aurantiacus and the Fenna-Matthews-Olson protein-reaction center complex from green sulfur bacteria will be characterized by spectroscopic and structural techniques.

  20. Nonphotochemical Hole-Burning Studies of Energy Transfer Dynamics in Antenna Complexes of Photosynthetic Bacteria

    Energy Technology Data Exchange (ETDEWEB)

    Satoshi Matsuzaki

    2002-08-01

    This thesis contains the candidate's original work on excitonic structure and energy transfer dynamics of two bacterial antenna complexes as studied using spectral hole-burning spectroscopy. The general introduction is divided into two chapters (1 and 2). Chapter 1 provides background material on photosynthesis and bacterial antenna complexes with emphasis on the two bacterial antenna systems related to the thesis research. Chapter 2 reviews the underlying principles and mechanism of persistent nonphotochemical hole-burning (NPHB) spectroscopy. Relevant energy transfer theories are also discussed. Chapters 3 and 4 are papers by the candidate that have been published. Chapter 3 describes the application of NPHB spectroscopy to the Fenna-Matthews-Olson (FMO) complex from the green sulfur bacterium Prosthecochloris aestuarii; emphasis is on determination of the low energy vibrational structure that is important for understanding the energy transfer process associated within three lowest energy Qy-states of the complex. The results are compared with those obtained earlier on the FMO complex from Chlorobium tepidum. In Chapter 4, the energy transfer dynamics of the B800 molecules of intact LH2 and B800-deficient LH2 complexes of the purple bacterium Rhodopseudomonas acidophila are compared. New insights on the additional decay channel of the B800 ring of bacteriochlorophyll a (BChl a) molecules are provided. General conclusions are given in Chapter 5.

  1. Evolutionary complexity for protection of critical assets.

    Energy Technology Data Exchange (ETDEWEB)

    Battaile, Corbett Chandler; Chandross, Michael Evan

    2005-01-01

    This report summarizes the work performed as part of a one-year LDRD project, 'Evolutionary Complexity for Protection of Critical Assets.' A brief introduction is given to the topics of genetic algorithms and genetic programming, followed by a discussion of relevant results obtained during the project's research, and finally the conclusions drawn from those results. The focus is on using genetic programming to evolve solutions for relatively simple algebraic equations as a prototype application for evolving complexity in computer codes. The results were obtained using the lil-gp genetic program, a C code for evolving solutions to user-defined problems and functions. These results suggest that genetic programs are not well-suited to evolving complexity for critical asset protection because they cannot efficiently evolve solutions to complex problems, and introduce unacceptable performance penalties into solutions for simple ones.

  2. Self-trapped excitons in circular cacteriochlorophyll antenna complexes

    International Nuclear Information System (INIS)

    Fluorescence line narrowing and hole-burning spectroscopic studies of excitons in the LH2 pigment-protein complex, which is a part of the light harvesting system of purple bacteria, are combined with straightforward numerical simulations of the emission spectra based on exciton polaron model. The analysis provides evidence for self-trapping of all the excitons, except the lowest one

  3. On Improving the Performance of Nonphotochemical Quenching in CP29 Light-Harvesting Antenna Complex

    OpenAIRE

    Berman, Gennady P.; Nesterov, Alexander I; Sayre, Richard T.; Still, Susanne

    2015-01-01

    We model and simulate the performance of charge-transfer in nonphotochemical quenching (NPQ) in the CP29 light-harvesting antenna-complex associated with photosystem II (PSII). The model consists of five discrete excitonic energy states and two sinks, responsible for the potentially damaging processes and charge-transfer channels, respectively. We demonstrate that by varying (i) the parameters of the chlorophyll-based dimer, (ii) the resonant properties of the protein-solvent environment inte...

  4. Novel type of red-shifted chlorophyll a antenna complex from Chromera velia: II. Biochemistry and spectroscopy.

    Science.gov (United States)

    Bína, David; Gardian, Zdenko; Herbstová, Miroslava; Kotabová, Eva; Koník, Peter; Litvín, Radek; Prášil, Ondřej; Tichý, Josef; Vácha, František

    2014-06-01

    A novel chlorophyll a containing pigment-protein complex expressed by cells of Chromera velia adapted to growth under red/far-red illumination [1]. Purification of the complex was achieved by means of anion-exchange chromatography and gel-filtration. The antenna is shown to be an aggregate of ~20kDa proteins of the light-harvesting complex (LHC) family, unstable in the isolated form. The complex possesses an absorption maximum at 705nm at room temperature in addition to the main chlorophyll a maximum at 677nm producing the major emission band at 714nm at room temperature. The far-red absorption is shown to be the property of the isolated aggregate in the intact form and lost upon dissociation. The purified complex was further characterized by circular dichroism spectroscopy and fluorescence spectroscopy. This work thus identified the third different class of antenna complex in C. velia after the recently described FCP-like and LHCr-like antennas. Possible candidates for red antennas are identified in other taxonomic groups, such as eustigmatophytes and the relevance of the present results to other known examples of red-shifted antenna from other organisms is discussed. This work appears to be the first successful isolation of a chlorophyll a-based far-red antenna complex absorbing above 700nm unrelated to LHCI.

  5. Nonphotochemical Hole-Burning Studies of Energy Transfer Dynamics in Antenna Complexes of Photosynthetic Bacteria

    Energy Technology Data Exchange (ETDEWEB)

    Satoshi Matsuzaki

    2002-06-27

    This thesis contains the candidate's original work on excitonic structure and energy transfer dynamics of two bacterial antenna complexes as studied using spectral hole-burning spectroscopy. The general introduction is divided into two chapters (1 and 2). Chapter 1 provides background material on photosynthesis and bacterial antenna complexes with emphasis on the two bacterial antenna systems related to the thesis research. Chapter 2 reviews the underlying principles and mechanism of persistent nonphotochemical hole-burning (NPHB) spectroscopy. Relevant energy transfer theories are also discussed. Chapters 3 and 4 are papers by the candidate that have been published. Chapter 3 describes the application of NPHB spectroscopy to the Fenna-Matthews-Olson (FMO) complex from the green sulfur bacterium Prosthecochloris aestuarii; emphasis is on determination of the low energy vibrational structure that is important for understanding the energy transfer process associated within three lowest energy Q{sub y}-states of the complex. The results are compared with those obtained earlier on the FMO complex from Chlorobium tepidum. In Chapter 4, the energy transfer dynamics of the B800 molecules of intact LH2 and B800-deficient LH2 complexes of the purple bacterium Rhodopseudomonas acidophila are compared. New insights on the additional decay channel of the B800 ring of bacteriochlorophyll{sub a} (BChl{sub a}) molecules are provided. General conclusions are given in Chapter 5. A version of the hole spectrum simulation program written by the candidate for the FMO complex study (Chapter 3) is included as an appendix. The references for each chapter are given at the end of each chapter.

  6. Infrared Line Emission in the Interacting Region of Arp 244 (the Antennae) Colliding Molecular Cloud Complexes ?

    CERN Document Server

    Liang, M C; Lo, K Y; Kim, D C

    2001-01-01

    We report velocity-resolved spectroscopy of infrared hydrogen recombination lines in the interacting region of the Antennae galaxies (NGC 4038/4039). It generally has been assumed that the active star formation found there is due to the interaction of the disks of the two galaxies and \\citet{lee01} have observed two molecular cloud complexes, separated in velocity by $\\sim$100 km s$^{-1}$, in the southern part of this region. Our measurements imply that the two cloud complexes are moving away from each other. This result poses interesting questions about the physical mechanisms leading to starbursts in Arp 244 and other interacting galaxies.

  7. On the reflectivity of complex mesh surfaces. [of space-deployable reflector antennas

    Science.gov (United States)

    Imbriale, William A.; Galindo-Israel, Victor; Rahmat-Samii, Yahya

    1991-01-01

    Poorer than expected surface reflectivity was observed in an early Tracking and Data Relay Satellite System antenna utilizing a tricot mesh weave. This poor reflectivity was determined to be caused by inadequate electrical contact at wire crossover points. A proper mathematical and numerical approach to assess the impact of wire junctions on reflectivity performance is developed. A mathematical method is presented for computing the surface reflectivity of complex mesh configurations like those on unfurlable-type spacecraft antennas. The method is based on the Floquet mode expansion to establish an integral equation for mesh wire currents. The equation is solved using the method of moments with triangular basis functions. It is observed that it is necessary to give special attention to the junction treatment among different branches of the mesh configurations. A vector junction current approach that resulted in satisfactory solutions for the current is described. The results of numerical simulations are compared against measured data and excellent agreement is observed.

  8. Strong antenna-enhanced fluorescence of a single light-harvesting complex shows photon antibunching.

    Science.gov (United States)

    Wientjes, Emilie; Renger, Jan; Curto, Alberto G; Cogdell, Richard; van Hulst, Niek F

    2014-06-23

    The nature of the highly efficient energy transfer in photosynthetic light-harvesting complexes is a subject of intense research. Unfortunately, the low fluorescence efficiency and limited photostability hampers the study of individual light-harvesting complexes at ambient conditions. Here we demonstrate an over 500-fold fluorescence enhancement of light-harvesting complex 2 (LH2) at the single-molecule level by coupling to a gold nanoantenna. The resonant antenna produces an excitation enhancement of circa 100 times and a fluorescence lifetime shortening to ~20 ps. The radiative rate enhancement results in a 5.5-fold-improved fluorescence quantum efficiency. Exploiting the unique brightness, we have recorded the first photon antibunching of a single light-harvesting complex under ambient conditions, showing that the 27 bacteriochlorophylls coordinated by LH2 act as a non-classical single-photon emitter. The presented bright antenna-enhanced LH2 emission is a highly promising system to study energy transfer and the role of quantum coherence at the level of single complexes.

  9. Low-Complexity Transmit Antenna Selection in Large-Scale Spatial Modulation Systems

    Directory of Open Access Journals (Sweden)

    Peng Wei

    2015-01-01

    Full Text Available Transmit antenna selection (TAS is an efficient way for improving the system performance of spatial modulation (SM systems. However, in the case of large-scale multiple-input multiple-output (MIMO configuration, the computational complexity of TAS in large-scale SM will be extremely high, which prohibits the application of TAS-SM in a real large-scale MIMO system for future 5G wireless communications. For solving this problem, in this paper, two novel low-complexity TAS schemes, named as norm-angle guided subset division (NAG-SD and threshold-based NAG-SD ones, are proposed to offer a better tradeoff between computational complexity and system performance. Simulation results show that the proposed schemes can achieve better performance than traditional TAS schemes, while effectively reducing the computational complexity in large-scale spatial modulation systems.

  10. Application of the modified Wheeler cap method for radiation efficiency measurement of balanced electrically small antennas in complex environment

    DEFF Research Database (Denmark)

    Zhang, Jiaying; Pivnenko, Sergey; Breinbjerg, Olav

    2010-01-01

    In this paper, application of a modified Wheeler cap method for the radiation efficiency measurement of balanced electrically small antennas is presented. It is shown that the limitations on the cavity dimension can be overcome and thus measurement in a large cavity is possible. The cavity loss...... is investigated, and a modified radiation efficiency formula that includes the cavity loss is introduced. Moreover, a modification of the technique is proposed that involves the antenna working complex environment inside the Wheeler Cap and thus makes possible measurement of an antenna close to a hand or head...

  11. A New Family of Low-Complexity STBCs for Four Transmit Antennas

    KAUST Repository

    Ismail, Amr

    2012-12-29

    Space-Time Block Codes (STBCs) suffer from a prohibitively high decoding complexity unless the low-complexity decodability property is taken into consideration in the STBC design. For this purpose, several families of STBCs that involve a reduced decoding complexity have been proposed, notably the multi-group decodable and the fast decodable (FD) codes. Recently, a new family of codes that combines both of these families namely the fast group decodable (FGD) codes was proposed. In this paper, we propose a new construction scheme for rate-1 FGD codes for 2^a transmit antennas. The proposed scheme is then applied to the case of four transmit antennas and we show that the new rate-1 FGD code has the lowest worst-case decoding complexity among existing comparable STBCs. The coding gain of the new rate-1 code is optimized through constellation stretching and proved to be constant irrespective of the underlying QAM constellation prior to normalization. Next, we propose a new rate-2 FD STBC by multiplexing two of our rate-1 codes by the means of a unitary matrix. Also a compromise between rate and complexity is obtained through puncturing our rate-2 FD code giving rise to a new rate-3/2 FD code. The proposed codes are compared to existing codes in the literature and simulation results show that our rate-3/2 code has a lower average decoding complexity while our rate-2 code maintains its lower average decoding complexity in the low SNR region. If a time-out sphere decoder is employed, our proposed codes outperform existing codes at high SNR region thanks to their lower worst-case decoding complexity.

  12. Light and Heat Induced Denaturation of Photosystem Ⅱ Core Antenna Complex CP47

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    Light and heat induced denaturation of CP47, the core antenna complex of photosystem Ⅱ purified from spinach, were investigated using absorption and circular dichroism spectra.Light caused the destruction of chlorophyll a and excitonic interaction of chlorophyll a in CP47, while the protein secondary structure was not apparently changed.Heat induced the destruction of protein secondary structure and excitonic interaction of chlorophyll a, but the chlorophyll a molecule was not damaged.The results suggest that both the chlorophyll a molecular structure and the protein native conformation are necessary for excitonic interaction of chlorophyll a and the energy transfer function of the chlorophyll a binding protein.

  13. Theoretical prediction of spectral and optical properties of bacteriochlorophylls in thermally disordered LH2 antenna complexes

    CERN Document Server

    Janosi, L; Kosztin, I; Damjanovic, Ana; Janosi, Lorant; Kosztin, Ioan

    2006-01-01

    A general approach for calculating spectral and optical properties of pigment-protein complexes of known atomic structure is presented. The method, that combines molecular dynamics simulations, quantum chemistry calculations and statistical mechanical modeling, is demonstrated by calculating the absorption and circular dichroism spectra of the B800-B850 BChls of the LH2 antenna complex from Rs. molischianum at room temperature. The calculated spectra are found to be in good agreement with the available experimental results. The calculations reveal that the broadening of the B800 band is mainly caused by the interactions with the polar protein environment, while the broadening of the B850 band is due to the excitonic interactions. Since it contains no fitting parameters, in principle, the proposed method can be used to predict optical spectra of arbitrary pigment-protein complexes of known structure.

  14. Large/Complex Antenna Performance Validation for Spaceborne Radar/Radiometeric Instruments

    Science.gov (United States)

    Focardi, Paolo; Harrell, Jefferson; Vacchione, Joseph

    2013-01-01

    Over the past decade, Earth observing missions which employ spaceborne combined radar & radiometric instruments have been developed and implemented. These instruments include the use of large and complex deployable antennas whose radiation characteristics need to be accurately determined over 4 pisteradians. Given the size and complexity of these antennas, the performance of the flight units cannot be readily measured. In addition, the radiation performance is impacted by the presence of the instrument's service platform which cannot easily be included in any measurement campaign. In order to meet the system performance knowledge requirements, a two pronged approach has been employed. The first is to use modeling tools to characterize the system and the second is to build a scale model of the system and use RF measurements to validate the results of the modeling tools. This paper demonstrates the resulting level of agreement between scale model and numerical modeling for two recent missions: (1) the earlier Aquarius instrument currently in Earth orbit and (2) the upcoming Soil Moisture Active Passive (SMAP) mission. The results from two modeling approaches, Ansoft's High Frequency Structure Simulator (HFSS) and TICRA's General RF Applications Software Package (GRASP), were compared with measurements of approximately 1/10th scale models of the Aquarius and SMAP systems. Generally good agreement was found between the three methods but each approach had its shortcomings as will be detailed in this paper.

  15. Antennas in inhomogeneous media

    CERN Document Server

    Galejs, Janis; Fock, V A; Wait, J R

    2013-01-01

    Antennas in Inhomogeneous Media details the methods of analyzing antennas in such inhomogeneous media. The title covers the complex geometrical configurations along with its variational formulations. The coverage of the text includes various conditions the antennas are subjected to, such as antennas in the interface between two media; antennas in compressible isotropic plasma; and linear antennas in a magnetoionic medium. The selection also covers insulated loops in lossy media; slot antennas with a stratified dielectric or isotropic plasma layers; and cavity-backed slot antennas. The book wil

  16. In situ high-resolution structure of the baseplate antenna complex in Chlorobaculum tepidum.

    Science.gov (United States)

    Nielsen, Jakob Toudahl; Kulminskaya, Natalia V; Bjerring, Morten; Linnanto, Juha M; Rätsep, Margus; Pedersen, Marie Østergaard; Lambrev, Petar H; Dorogi, Márta; Garab, Győző; Thomsen, Karen; Jegerschöld, Caroline; Frigaard, Niels-Ulrik; Lindahl, Martin; Nielsen, Niels Chr

    2016-01-01

    Photosynthetic antenna systems enable organisms harvesting light and transfer the energy to the photosynthetic reaction centre, where the conversion to chemical energy takes place. One of the most complex antenna systems, the chlorosome, found in the photosynthetic green sulfur bacterium Chlorobaculum (Cba.) tepidum contains a baseplate, which is a scaffolding super-structure, formed by the protein CsmA and bacteriochlorophyll a. Here we present the first high-resolution structure of the CsmA baseplate using intact fully functional, light-harvesting organelles from Cba. tepidum, following a hybrid approach combining five complementary methods: solid-state NMR spectroscopy, cryo-electron microscopy, isotropic and anisotropic circular dichroism and linear dichroism. The structure calculation was facilitated through development of new software, GASyCS for efficient geometry optimization of highly symmetric oligomeric structures. We show that the baseplate is composed of rods of repeated dimers of the strongly amphipathic CsmA with pigments sandwiched within the dimer at the hydrophobic side of the helix. PMID:27534696

  17. In situ high-resolution structure of the baseplate antenna complex in Chlorobaculum tepidum

    Science.gov (United States)

    Nielsen, Jakob Toudahl; Kulminskaya, Natalia V.; Bjerring, Morten; Linnanto, Juha M.; Rätsep, Margus; Pedersen, Marie Østergaard; Lambrev, Petar H.; Dorogi, Márta; Garab, Győző; Thomsen, Karen; Jegerschöld, Caroline; Frigaard, Niels-Ulrik; Lindahl, Martin; Nielsen, Niels Chr.

    2016-08-01

    Photosynthetic antenna systems enable organisms harvesting light and transfer the energy to the photosynthetic reaction centre, where the conversion to chemical energy takes place. One of the most complex antenna systems, the chlorosome, found in the photosynthetic green sulfur bacterium Chlorobaculum (Cba.) tepidum contains a baseplate, which is a scaffolding super-structure, formed by the protein CsmA and bacteriochlorophyll a. Here we present the first high-resolution structure of the CsmA baseplate using intact fully functional, light-harvesting organelles from Cba. tepidum, following a hybrid approach combining five complementary methods: solid-state NMR spectroscopy, cryo-electron microscopy, isotropic and anisotropic circular dichroism and linear dichroism. The structure calculation was facilitated through development of new software, GASyCS for efficient geometry optimization of highly symmetric oligomeric structures. We show that the baseplate is composed of rods of repeated dimers of the strongly amphipathic CsmA with pigments sandwiched within the dimer at the hydrophobic side of the helix.

  18. Complex Protection of Vertical Stainless Steel Tanks

    OpenAIRE

    Fakhrislamov Radik Zakievich

    2014-01-01

    The authors consider the problem of fail-safe oil and oil products storage in stainless steel tanks and present the patented tank inner side protection technology. The latter provides process, ecological and fire safety and reducing soil evaporation of oil products, which is a specific problem. The above-mentioned technology includes corrosion protection and heat insulation protection providing increase of cover durability and RVS service life in general. The offered technological protection ...

  19. On improving the performance of nonphotochemical quenching in CP29 light-harvesting antenna complex

    Science.gov (United States)

    Berman, Gennady P.; Nesterov, Alexander I.; Sayre, Richard T.; Still, Susanne

    2016-03-01

    We model and simulate the performance of charge-transfer in nonphotochemical quenching (NPQ) in the CP29 light-harvesting antenna-complex associated with photosystem II (PSII). The model consists of five discrete excitonic energy states and two sinks, responsible for the potentially damaging processes and charge-transfer channels, respectively. We demonstrate that by varying (i) the parameters of the chlorophyll-based dimer, (ii) the resonant properties of the protein-solvent environment interaction, and (iii) the energy transfer rates to the sinks, one can significantly improve the performance of the NPQ. Our analysis suggests strategies for improving the performance of the NPQ in response to environmental changes, and may stimulate experimental verification.

  20. On Improving the Performance of Nonphotochemical Quenching in CP29 Light-Harvesting Antenna Complex

    CERN Document Server

    Berman, Gennady P; Sayre, Richard T; Still, Susanne

    2015-01-01

    We model and simulate the performance of charge-transfer in nonphotochemical quenching (NPQ) in the CP29 light-harvesting antenna-complex associated with photosystem II (PSII). The model consists of five discrete excitonic energy states and two sinks, responsible for the potentially damaging processes and charge-transfer channels, respectively. We demonstrate that by varying (i) the parameters of the chlorophyll-based dimer, (ii) the resonant properties of the protein-solvent environment interaction, and (iii) the energy transfer rates to the sinks, one can significantly improve the performance of the NPQ. Our analysis suggests strategies for improving the performance of the NPQ in response to environmental changes, and may stimulate experimental verification.

  1. Complex Protection of Vertical Stainless Steel Tanks

    Directory of Open Access Journals (Sweden)

    Fakhrislamov Radik Zakievich

    2014-03-01

    Full Text Available The authors consider the problem of fail-safe oil and oil products storage in stainless steel tanks and present the patented tank inner side protection technology. The latter provides process, ecological and fire safety and reducing soil evaporation of oil products, which is a specific problem. The above-mentioned technology includes corrosion protection and heat insulation protection providing increase of cover durability and RVS service life in general. The offered technological protection scheme is a collaboration of the author, Steel Paint GmbH firm and JSC “Koksokhimmontazhproyekt”. PU foam unicomponent materials of Steel Paint GmbH firm provide the protection of tank inner side and cover.

  2. Evaluation of Concrete Consolidation: DSS-35 Antenna Reinforced Concrete Pedestal, Canberra Deep Space Communications Complex, Australia

    Science.gov (United States)

    Saldua, B. P.; Dodge, E. C.; Kolf, P. R.; Olson, C. A.

    2016-02-01

    Antenna structures for the Deep Space Network track spacecraft that are millions of miles away. Therefore, these structures have tight specifications for translation, rotation, and differential settlement. This article presents several nondestructive test methods that were used to evaluate, locate, and repair imperfections in the reinforced concrete pedestal that supports the DSS-35 antenna structure. These methods include: (1) impulse response (IR), (2) ultrasonic shear-wave tomography (MIRA), and (3) ground-penetrating radar (GPR).

  3. The challenge of characterizing an inefficient antenna field for health protection purposes

    Science.gov (United States)

    Lundquist, Marjorie

    2006-03-01

    Growing evidence that the electromagnetic field around electrical wires is harmful to human health prompted a 1990s National Academy of Sciences study of power-frequency (50-60 Hz) fields; results for power-frequency fields were negative but data suggested that fields from transients may be hazardous.^1 Transients represent high frequencies that can reach into the radiofrequency (RF) range. What instrument can be used to measure an RF field around electric wires carrying RF current? Such an RF field is that of an inefficient antenna, which lacks the pure far-field region characteristic of an efficient antenna field for which standard RF measuring instruments are calibrated, making it impossible to obtain a properly calibrated measurement with such instruments. The magnetic induction current dB/dt is explored as an alternative way to characterize the inefficient antenna RF field sheathing electric wires carrying RF due to poor power quality (e.g., switching transients) or to utility use of power line carrier^2 or of FCC-approved broadband on power lines. ^1National Research Council, Possible Health Effects of Exposure to Residential Electric and Magnetic Fields, Washington, DC: National Academy Press, 1997. ^2M. Vignati & L. Giuliani, Environ. Health Perspect. 105(Suppl 6):1565-1568(1997).

  4. The spherical helical antenna

    OpenAIRE

    Cardoso, J. Christopher

    1992-01-01

    The spherical helical antenna is investigated as a new variation of the conventional helical antenna. The spherical helix is a wire antenna in a helix shape that is wound over a spherical surface instead of the standard cylindrical one. Analysis of this structure requires numerical methods and experimental measurements because its complex geometry makes it very difficult to develop analytic expressions for its radiation characteristics. The wire antenna code ESP, based on the method of ...

  5. Knowledge Protection and Input Complexity Arising from Open Innovation

    DEFF Research Database (Denmark)

    Peeters, Thijs; Sofka, Wolfgang

    Controlling unique knowledge is of increasing importance to firms. Therefore, firms use knowledge protection mechanisms to prevent competitors from imitating their knowledge. We study the effects of the complexity of knowledge inputs that arises from open innovation on the importance of two widely...... used protection mechanisms: patents and trademarks. We argue that this complexity makes the threat of imitation less predictable, and thus makes knowledge protection more important. By analyzing survey data of 938 German firms, we find that patents are more important for firms in industries with higher...

  6. Study of high speed complex number algorithms. [for determining antenna for field radiation patterns

    Science.gov (United States)

    Heisler, R.

    1981-01-01

    A method of evaluating the radiation integral on the curved surface of a reflecting antenna is presented. A three dimensional Fourier transform approach is used to generate a two dimensional radiation cross-section along a planer cut at any angle phi through the far field pattern. Salient to the method is an algorithm for evaluating a subset of the total three dimensional discrete Fourier transform results. The subset elements are selectively evaluated to yield data along a geometric plane of constant. The algorithm is extremely efficient so that computation of the induced surface currents via the physical optics approximation dominates the computer time required to compute a radiation pattern. Application to paraboloid reflectors with off-focus feeds in presented, but the method is easily extended to offset antenna systems and reflectors of arbitrary shapes. Numerical results were computed for both gain and phase and are compared with other published work.

  7. Structural characterization of the B800-850 and B875 light-harvesting antenna complexes from Rhodobacter sphaeroides by electron microscopy

    NARCIS (Netherlands)

    Boonstra, Arjen F.; Visschers, Ronald W.; Calkoen, Florentine; Grondelle, Rienk van; Bruggen, Ernst F.J. van; Boekema, Egbert J.

    1993-01-01

    The structure and aggregation behavior of B800-850 (LHII) and B875 (LHI) antenna complexes of Rhodobacter sphaeroides were studied by electron microscopy. Single molecular projections (top views and side views) of isolated particles were analyzed. The B800-850 complexes, isolated as 150 kDa particle

  8. Effects of pH on the peripheral light-harvesting antenna complex for Rhodopseudomonas palustris

    Institute of Scientific and Technical Information of China (English)

    FENG Juan; LI XueFeng; LIU Yan

    2008-01-01

    In this work steady-state absorption spectroscopy, circular dichroism spectroscopy and sub-micro-second time-resolved absorption spectroscopy were used to investigate the effect of pH on the struc-tures and functions of LH2 complex for Rhodopseudomonas palustris. The results revealed that: (1) B800 Bchla was gradually transformed to free pigments absorbing around 760 nm on the minutes timescale upon the induction of strong acidic pH, and subsequently there disappeared the CD signal for Qy band of B800 in the absence of B800. In addition, Carotenoids changed with the similar tendency to B850 BChl. (2) The introduction of strong basic pH gave rise to no significant changes for B800 Bchla, while B850 BChla experienced remarkable spectral blue-shift from 852 to 837 nm. Similar phe-nomenon was seen for the CD signal for Qy band of B850. Carotenoids displayed strong and pH-independent CD signals in the visible range. (3) In the case of both physiological and basic pH, broad and asymmetrical positive Tn←T1 transient absorption appeared following the pulsed photo-excitation of Car at 532 nm. By contrast, the featureless and weak positive signal was observed on the sub-microsecond timescale in the acidic pH environment. The aforementioned experimental results indicated that acidic pH-induced removal of B800 Bchla prevented the generation of the caro-tenoid triplet state (3Car*), which is known to be essential for the photo-protection function. Neverthe-less, carotenoids can still perform this important physiological role under the basic pH condition, where the spectral blue shift of B850 exerts little effect on the overall structure of the cyclic aggregate, therefore favoring the formation of carotenoid triplet state.

  9. Smart antennas

    CERN Document Server

    Godara, Lal Chand

    2004-01-01

    INTRODUCTION Antenna GainPhased Array AntennaPower Pattern Beam Steering Degree of Freedom Optimal AntennaAdaptive AntennaSmart AntennaSummary NARROWBAND PROCESSINGSignal Model Conventional BeamformerNull Steering BeamformerOptimal BeamformerOptimization Using Reference SignalBeam Space Processing Effect of ErrorsNotation and AbbreviationsReferencesADAPTIVE PROCESSINGSample Matrix Inversion AlgorithmUnconstrained Least Mean Squares AlgorithmNormalized Least Mean Squares AlgorithmConstrained

  10. Multiband Antennas for SDR Applications

    Directory of Open Access Journals (Sweden)

    E. Surducan

    2009-01-01

    Full Text Available We present multiband antennas configurations for SDR applications. Using a composite folded dipole structure as starting point, we derived more complex antenna configurations to support multiple communication protocols for mobile application with linear and circular polarizations. Prototypes as single antenna with circular polarization, tunable single antenna with PIN diode and MIMO systems with three and four antennas, all derivatives of the same basic structure, were produced in an iterative fashion until the desired parameters were achieved. These antennas are suitable for microstrip circuit realizations and can be included in the printed circuit board (PCB of the device, or used as stand alone. The shapes and measurement results are presented throughout the paper. From the illustrated graphs it can be seen that the stand-alone antennas exhibit positive gain for all the frequency bands of interest while the separation between antennas, for the multiple-input multiple-output (MIMO case, is better than 15 dB.

  11. Zeaxanthin Radical Cation Formation in Minor Light-Harvesting Complexes of Higher Plant Antenna

    Energy Technology Data Exchange (ETDEWEB)

    Avenson, Thomas H.; Ahn, Tae Kyu; Zigmantas, Donatas; Niyogi, Krishna K.; Li, Zhirong; Ballottari, Matteo; Bassi, Roberto; Fleming, Graham R.

    2008-01-31

    Previous work on intact thylakoid membranes showed that transient formation of a zeaxanthin radical cation was correlated with regulation of photosynthetic light-harvesting via energy-dependent quenching. A molecular mechanism for such quenching was proposed to involve charge transfer within a chlorophyll-zeaxanthin heterodimer. Using near infrared (880-1100 nm) transient absorption spectroscopy, we demonstrate that carotenoid (mainly zeaxanthin) radical cation generation occurs solely in isolated minor light-harvesting complexes that bind zeaxanthin, consistent with the engagement of charge transfer quenching therein. We estimated that less than 0.5percent of the isolated minor complexes undergo charge transfer quenching in vitro, whereas the fraction of minor complexes estimated to be engaged in charge transfer quenching in isolated thylakoids was more than 80 times higher. We conclude that minor complexes which bind zeaxanthin are sites of charge transfer quenching in vivo and that they can assume Non-quenching and Quenching conformations, the equilibrium LHC(N)<--> LHC(Q) of which is modulated by the transthylakoid pH gradient, the PsbS protein, and protein-protein interactions.

  12. Automated imitating-measuring complex for designing and measuring characteristics of phased antenna arrays

    OpenAIRE

    Usin, V.; Markov, V.; Pomazanov, S.; Usina, A.; Filonenko, A.

    2011-01-01

    This article considers design principles, structure and technical characteristics of automated imitating-measuring complex, contains variants of its hardware and software implementation for selecting APD, tolerance justification, estimation of manufacturing errors’ influence, discrete nature of control and mutual influence of radiating elements on PAA parameters.

  13. Nanometer arrays of functional light harvesting antenna complexes by nanoimprint lithography and host-guest interactions

    NARCIS (Netherlands)

    Escalante, Maryana; Zhao, Yiping; Ludden, Manon J.W.; Vermeij, Rolf; Olsen, John D.; Berenschot, Erwin; Hunter, C. Neil; Huskens, Jurriaan; Subramaniam, Vinod; Otto, Cees

    2008-01-01

    We show an approach based on a combination of site-directed mutagenesis, NIL and multivalent host−guest interactions for the realization of engineered ordered functional arrays of purified components of the photosynthetic system, the membrane-bound LH2 complex. In addition to micrometer-scale patter

  14. Taxonomic distribution and origins of the extended LHC (light-harvesting complex antenna protein superfamily

    Directory of Open Access Journals (Sweden)

    Brinkmann Henner

    2010-07-01

    Full Text Available Abstract Background The extended light-harvesting complex (LHC protein superfamily is a centerpiece of eukaryotic photosynthesis, comprising the LHC family and several families involved in photoprotection, like the LHC-like and the photosystem II subunit S (PSBS. The evolution of this complex superfamily has long remained elusive, partially due to previously missing families. Results In this study we present a meticulous search for LHC-like sequences in public genome and expressed sequence tag databases covering twelve representative photosynthetic eukaryotes from the three primary lineages of plants (Plantae: glaucophytes, red algae and green plants (Viridiplantae. By introducing a coherent classification of the different protein families based on both, hidden Markov model analyses and structural predictions, numerous new LHC-like sequences were identified and several new families were described, including the red lineage chlorophyll a/b-binding-like protein (RedCAP family from red algae and diatoms. The test of alternative topologies of sequences of the highly conserved chlorophyll-binding core structure of LHC and PSBS proteins significantly supports the independent origins of LHC and PSBS families via two unrelated internal gene duplication events. This result was confirmed by the application of cluster likelihood mapping. Conclusions The independent evolution of LHC and PSBS families is supported by strong phylogenetic evidence. In addition, a possible origin of LHC and PSBS families from different homologous members of the stress-enhanced protein subfamily, a diverse and anciently paralogous group of two-helix proteins, seems likely. The new hypothesis for the evolution of the extended LHC protein superfamily proposed here is in agreement with the character evolution analysis that incorporates the distribution of families and subfamilies across taxonomic lineages. Intriguingly, stress-enhanced proteins, which are universally found in the

  15. Luminescent europium and terbium complexes of dipyridoquinoxaline and dipyridophenazine ligands as photosensitizing antennae: structures and biological perspectives.

    Science.gov (United States)

    Dasari, Srikanth; Patra, Ashis K

    2015-12-14

    The europium(III) and terbium(III) complexes, namely [Eu(dpq)(DMF)2(NO3)3] (1), [Eu(dppz)2(NO3)3] (2), [Tb(dpq)(DMF)2Cl3] (3), and [Tb(dppz)(DMF)2Cl3] (4), where dipyrido[3,2-d:2',3'-f]quinoxaline (dpq in 1 and 3), dipyrido[3,2-a:2',3'-c]phenazine (dppz in 2 and 4) and N,N'-dimethylformamide (DMF) have been isolated, characterized from their physicochemical data, luminescence studies and their interaction with DNA, serum albumin protein and photo-induced DNA cleavage activity are studied. The X-ray crystal structures of complexes 1-4 show discrete mononuclear Ln(3+)-based structures. The Eu(3+) in [Eu(dpq)(DMF)2(NO3)3] (1) and [Eu(dppz)2(NO3)3] (2) as [Eu(dppz)2(NO3)3]·dppz (2a) adopts a ten-coordinated bicapped dodecahedron structure with a bidentate N,N-donor dpq ligand, two DMF and three NO3(-) anions in 1 and two bidentate N,N-donor dppz ligands and three NO3(-) anions in 2. Complexes 3 and 4 show a seven-coordinated mono-capped octahedron structure where Tb(3+) contains bidentate dpq/dppz ligands, two DMF and three Cl(-) anions. The complexes are highly luminescent in nature indicating efficient photo-excited energy transfer from the dpq/dppz antenna to Ln(3+) to generate long-lived emissive excited states for characteristic f → f transitions. The time-resolved luminescence spectra of complexes 1-4 show typical narrow emission bands attributed to the (5)D0 → (7)F(J) and (5)D4 → (7)F(J) f-f transitions of Eu(3+) and Tb(3+) ions respectively. The number of inner-sphere water molecules (q) was determined from luminescence lifetime measurements in H2O and D2O confirming ligand-exchange reactions with water in solution. The complexes display significant binding propensity to the CT-DNA giving binding constant values in the range of 1.0 × 10(4)-6.1 × 10(4) M(-1) in the order 2, 4 (dppz) > 1, 3 (dpq). DNA binding data suggest DNA groove binding with the partial intercalation nature of the complexes. All the complexes also show binding propensity (K(BSA)

  16. Adaptive antennas and receivers

    CERN Document Server

    Weiner, Melvin M

    2005-01-01

    In our modern age of remote sensing, wireless communication, and the nearly endless list of other antenna-based applications, complex problems require increasingly sophisticated solutions. Conventional antenna systems are no longer suited to high-noise or low-signal applications such as intrusion detection. Detailing highly effective approaches to non-Gaussian weak signal detection, Adaptive Antennas and Receivers provides an authoritative introduction to state-of-the-art research on the modeling, testing, and application of these technologies.Edited by innovative researcher and eminent expert

  17. RNA protects a nucleoprotein complex against radiation damage.

    Science.gov (United States)

    Bury, Charles S; McGeehan, John E; Antson, Alfred A; Carmichael, Ian; Gerstel, Markus; Shevtsov, Mikhail B; Garman, Elspeth F

    2016-05-01

    Radiation damage during macromolecular X-ray crystallographic data collection is still the main impediment for many macromolecular structure determinations. Even when an eventual model results from the crystallographic pipeline, the manifestations of radiation-induced structural and conformation changes, the so-called specific damage, within crystalline macromolecules can lead to false interpretations of biological mechanisms. Although this has been well characterized within protein crystals, far less is known about specific damage effects within the larger class of nucleoprotein complexes. Here, a methodology has been developed whereby per-atom density changes could be quantified with increasing dose over a wide (1.3-25.0 MGy) range and at higher resolution (1.98 Å) than the previous systematic specific damage study on a protein-DNA complex. Specific damage manifestations were determined within the large trp RNA-binding attenuation protein (TRAP) bound to a single-stranded RNA that forms a belt around the protein. Over a large dose range, the RNA was found to be far less susceptible to radiation-induced chemical changes than the protein. The availability of two TRAP molecules in the asymmetric unit, of which only one contained bound RNA, allowed a controlled investigation into the exact role of RNA binding in protein specific damage susceptibility. The 11-fold symmetry within each TRAP ring permitted statistically significant analysis of the Glu and Asp damage patterns, with RNA binding unexpectedly being observed to protect these otherwise highly sensitive residues within the 11 RNA-binding pockets distributed around the outside of the protein molecule. Additionally, the method enabled a quantification of the reduction in radiation-induced Lys and Phe disordering upon RNA binding directly from the electron density. PMID:27139628

  18. Plasma antennas

    CERN Document Server

    Anderson, Theodore

    2011-01-01

    The plasma antenna is an emerging technology that partially or fully utilizes ionized gas as the conducting medium instead of metal to create an antenna. The key advantages of plasma antennas are that they are highly reconfigurable and can be turned on and off. The disadvantage is that the plasma antennas require energy to be ionized. This unique resource provides you with a solid understanding of the efficient design and prototype development of plasma antennas, helping you to meet the challenge of reducing the power required to ionize the gas at various plasma densities. You also find thorou

  19. Reconfigurable antenna pattern verification

    Science.gov (United States)

    Drexler, Jerome P. (Inventor); Becker, Robert C. (Inventor); Meyers, David W. (Inventor); Muldoon, Kelly P. (Inventor)

    2013-01-01

    A method of verifying programmable antenna configurations is disclosed. The method comprises selecting a desired antenna configuration from a plurality of antenna configuration patterns, with the selected antenna configuration forming at least one reconfigurable antenna from reconfigurable antenna array elements. The method validates the formation of the selected antenna configuration to determine antenna performance of the at least one reconfigurable antenna.

  20. Complex genetic interactions govern the temporal effects of Antennapedia on antenna-to-leg transformations in Drosophila melanogaster

    Indian Academy of Sciences (India)

    Ian Dworkin; Wendy Lee; Fiona Mccloskey; Ellen Larsen

    2007-08-01

    The putative regulatory relationships between Antennapedia (Antp), spalt major (salm) and homothorax (hth) are tested with regard to the sensitive period of antenna-to-leg transformations. Although Antp expression repressed hth as predicted, contrary to expectations, hth did not show increased repression at higher Antp doses, whereas salm, a gene downstream of hth, did show such a dose response. Loss of hth allowed antenna-to-leg transformations but the relative timing of proximal–distal transformations was reversed, relative to transformations induced by ectopic Antp. Finally, overexpression of Hth was only partially able to rescue transformations induced by ectopic Antp. These results indicate that there may be additional molecules involved in antenna/leg identity and that spatial, temporal and dosage relationships are more subtle than suspected and must be part of a robust understanding of molecular network behaviour involved in determining appendage identity in Drosophila melanogaster.

  1. Superior Light-Harvesting Heteroleptic Ruthenium(II) Complexes with Electron-Donating Antennas for High Performance Dye-Sensitized Solar Cells.

    Science.gov (United States)

    Chen, Wang-Chao; Kong, Fan-Tai; Li, Zhao-Qian; Pan, Jia-Hong; Liu, Xue-Peng; Guo, Fu-Ling; Zhou, Li; Huang, Yang; Yu, Ting; Dai, Song-Yuan

    2016-08-01

    Three heteroleptic polypyridyl ruthenium complexes, RC-41, RC-42, and RC-43, with efficient electron-donating antennas in the ancillary ligands were designed, synthesized, and characterized as sensitizers for dye-sensitized solar cell. All the RC dye sensitizers showed remarkable light-harvesting capacity and broadened absorption range. Significantly, RC-43 obtained the lower energy metal-ligand charge transfer (MLCT) band peaked at 557 nm with a high molar extinction coefficient of 27 400 M(-1) cm(-1). In conjunction with TiO2 photoanode of submicrospheres and iodide-based electrolytes, the DSSCs sensitizing with the RC sensitizers, achieved impressively high short-circuit current density (19.04 mA cm(-2) for RC-41, 19.83 mA cm(-2) for RC-42, and 20.21 mA cm(-2) for RC-43) and power conversion efficiency (10.07% for RC-41, 10.52% for RC-42, and 10.78% for RC-43). The superior performances of RC dye sensitizers were attributed to the enhanced light-harvesting capacity and incident-photon-to-current efficiency (IPCE) caused by the introduction of electron-donating antennas in the ancillary ligands. The interfacial charge recombination/regeneration kinetics and electron lifetime were further evaluated by the electrochemical impedance spectroscopy (EIS) and transient absorption spectroscopy (TAS). These data decisively revealed the dependences on the photovoltaic performance of ruthenium sensitizers incorporating electron-donating antennas. PMID:27409513

  2. Superior Light-Harvesting Heteroleptic Ruthenium(II) Complexes with Electron-Donating Antennas for High Performance Dye-Sensitized Solar Cells.

    Science.gov (United States)

    Chen, Wang-Chao; Kong, Fan-Tai; Li, Zhao-Qian; Pan, Jia-Hong; Liu, Xue-Peng; Guo, Fu-Ling; Zhou, Li; Huang, Yang; Yu, Ting; Dai, Song-Yuan

    2016-08-01

    Three heteroleptic polypyridyl ruthenium complexes, RC-41, RC-42, and RC-43, with efficient electron-donating antennas in the ancillary ligands were designed, synthesized, and characterized as sensitizers for dye-sensitized solar cell. All the RC dye sensitizers showed remarkable light-harvesting capacity and broadened absorption range. Significantly, RC-43 obtained the lower energy metal-ligand charge transfer (MLCT) band peaked at 557 nm with a high molar extinction coefficient of 27 400 M(-1) cm(-1). In conjunction with TiO2 photoanode of submicrospheres and iodide-based electrolytes, the DSSCs sensitizing with the RC sensitizers, achieved impressively high short-circuit current density (19.04 mA cm(-2) for RC-41, 19.83 mA cm(-2) for RC-42, and 20.21 mA cm(-2) for RC-43) and power conversion efficiency (10.07% for RC-41, 10.52% for RC-42, and 10.78% for RC-43). The superior performances of RC dye sensitizers were attributed to the enhanced light-harvesting capacity and incident-photon-to-current efficiency (IPCE) caused by the introduction of electron-donating antennas in the ancillary ligands. The interfacial charge recombination/regeneration kinetics and electron lifetime were further evaluated by the electrochemical impedance spectroscopy (EIS) and transient absorption spectroscopy (TAS). These data decisively revealed the dependences on the photovoltaic performance of ruthenium sensitizers incorporating electron-donating antennas.

  3. Reconfigurable antennas

    CERN Document Server

    Bernhard, Jennifer

    2007-01-01

    This lecture explores the emerging area of reconfigurable antennas from basic concepts that provide insight into fundamental design approaches to advanced techniques and examples that offer important new capabilities for next-generation applications. Antennas are necessary and critical components of communication and radar systems, but sometimes their inability to adjust to new operating scenarios can limit system performance. Making antennas reconfigurable so that their behavior can adapt with changing system requirements or environmental conditions can ameliorate or eliminate these restricti

  4. Microstrip Antenna

    OpenAIRE

    Anuj Mehta

    2015-01-01

    Abstract This article presents an overview of the microstrip patch antenna and its design techniques. Basically a microstrip patch antenna comprises of a trace of copper or any other metal of any geometry on one side of a standard printed circuit board substrate with other side grounded. The antenna is fed using various feeding techniques like coaxial strip line aperture coupling or proximity coupling techniques. The working principle and the radiation mechanism have also been described. The ...

  5. Antenna toolkit

    CERN Document Server

    Carr, Joseph

    2006-01-01

    Joe Carr has provided radio amateurs and short-wave listeners with the definitive design guide for sending and receiving radio signals with Antenna Toolkit 2nd edition.Together with the powerful suite of CD software, the reader will have a complete solution for constructing or using an antenna - bar the actual hardware! The software provides a simple Windows-based aid to carrying out the design calculations at the heart of successful antenna design. All the user needs to do is select the antenna type and set the frequency - a much more fun and less error prone method than using a con

  6. Use of single-molecule spectroscopy to tackle fundamental problems in biochemistry: using studies on purple bacterial antenna complexes as an example.

    Science.gov (United States)

    Cogdell, Richard J; Köhler, Jürgen

    2009-08-13

    Optical single-molecule techniques can be used in two modes to investigate fundamental questions in biochemistry, namely single-molecule detection and single-molecule spectroscopy. This review provides an overview of how single-molecule spectroscopy can be used to gain detailed information on the electronic structure of purple bacterial antenna complexes and to draw conclusions about the underlying physical structure. This information can be used to understand the energy-transfer reactions that are responsible for the earliest reactions in photosynthesis.

  7. Antenna Calibration and Measurement Equipment

    Science.gov (United States)

    Rochblatt, David J.; Cortes, Manuel Vazquez

    2012-01-01

    A document describes the Antenna Calibration & Measurement Equipment (ACME) system that will provide the Deep Space Network (DSN) with instrumentation enabling a trained RF engineer at each complex to perform antenna calibration measurements and to generate antenna calibration data. This data includes continuous-scan auto-bore-based data acquisition with all-sky data gathering in support of 4th order pointing model generation requirements. Other data includes antenna subreflector focus, system noise temperature and tipping curves, antenna efficiency, reports system linearity, and instrument calibration. The ACME system design is based on the on-the-fly (OTF) mapping technique and architecture. ACME has contributed to the improved RF performance of the DSN by approximately a factor of two. It improved the pointing performances of the DSN antennas and productivity of its personnel and calibration engineers.

  8. Fluorescence-excitation and emission spectra from LH2 antenna complexes of Rhodopseudomonas acidophila as a function of the sample preparation conditions.

    Science.gov (United States)

    Kunz, Ralf; Timpmann, Kõu; Southall, June; Cogdell, Richard J; Köhler, Jürgen; Freiberg, Arvi

    2013-10-10

    The high sensitivity of optical spectra of pigment-protein complexes to temperature and pressure is well known. In the present study, we have demonstrated the significant influence of the environments commonly used in bulk and single-molecule spectroscopic studies at low temperatures on the LH2 photosynthetic antenna complex from Rhodopseudomonas acidophila. A transfer of this LH2 complex from a bulk-buffer solution into a spin-coated polymer film results in a 189 cm(-1) blue shift of the B850 excitonic absorption band at 5 K. Within the molecular exciton model, the origin of this shift could be disentangled into three parts, namely to an increase of the local site energies, a contraction of the exciton band, and a decrease of the displacement energy.

  9. Simultaneous Measurement of Antenna Gain and Complex Permittivity of Liquid in Near-Field Region Using Weighted Regression

    Science.gov (United States)

    Ishii, Nozomu; Shiga, Hiroki; Ikarashi, Naoto; Sato, Ken-Ichi; Hamada, Lira; Watanabe, Soichi

    As a technique for calibrating electric-field probes used in standardized SAR (Specific Absorption Rate) assessment, we have studied the technique using the Friis transmission formula in the tissue-equivalent liquid. It is difficult to measure power transmission between two reference antennas in the far-field region due to large attenuation in the liquid. This means that the conventional Friis transmission formula cannot be applied to our measurement so that we developed an extension of this formula that is valid in the near-field region. In this paper, the method of weighted least squares is introduced to reduce the effect of the noise in the measurement system when the gain of the antenna operated in the liquid is determined by the curve-fitting technique. And we examine how to choose the fitting range to reduce the uncertainty of the estimated gain.

  10. Complex permittivity measurements during high temperature recycling of space shuttle antenna window and dielectric heat shield materials

    Science.gov (United States)

    Bassett, H. L.; Bomar, S. H., Jr.

    1973-01-01

    The research performed and the data obtained on candidate space shuttle antenna window and heat shield materials are presented. The measurement technique employs a free-space focused beam microwave bridge for obtaining RF transmission data, and a device which rotates a sample holder which is heated on one side by natural gas-air flames. The surface temperature of each sample is monitored by IR pyrometry; embedded and rear surface thermocouples are also used in obtaining temperature data. The surface of the sample undergoing test is subjected to approximately the same temperature/time profile that occurs at a proposed antenna position on the space shuttle as it re-enters. The samples are cycled through ten of these temperature profiles to determine the recycling effects. Very little change was noted in the materials due to the recycling.

  11. Radiation protection program at an accelerator facility complex

    International Nuclear Information System (INIS)

    Broad aspects of Radiation Protection Program at the Tyco Healthcare/Mallinckrodt Inc. will be presented with emphasis on Occupational dose, Public dose and ALARA program. Regulatory requirements, compliance and radio nuclides of concern for external exposure and internal contamination will be discussed. The facility is subject to in depth annual inspections by the Nuclear Regulatory Commission (NRC) to ensure compliance with regulations and operating license requirements. The facility is required to have an emergency contingency plan in place. A simulated emergency drill scenario is witnessed and graded by the NRC and state inspectors, with full participation by the fire department and the local hospital. Radiation Safety Officer (RSO) is in charge of all radiological aspects of the facility, and reports to the plant manager directly. The RSO or any of his staff has the authority to stop a job if there is a radiological concern. The Radiation protection organization interfaces with Production, QA and Engineering and ensures there is no conflict with Industrial Safety, OSHA and FDA requirements. Any employee has the right to call the regulatory officials if he/she has a concern. Operational aspects of Radiation protection program such as radiological survey, contamination control and limits, air sample survey, radio active waste processing and record retention requirements are per plant procedures and regulatory requirements. Shielding and administrative requirements for designing a modification to an existing design or a new lab/hot cell is subject to in-depth review and approval by Radiation Safety Committee. Each department has a Dose Reduction Subcommittee which meets periodically to discuss if any changes in procedures or facility can be made to decrease the dose. The subcommittee also trends the dose to ensure it is trending downward. Even though 99Mo/99mTC generators are manufactured at the facility, majority of the dose is from cyclotron maintenance. Total

  12. Research on Electromagnetic Pulse Protection Technology for Antenna Port of Comunication Equipment%通信设备天线端口电磁脉冲防护技术研究

    Institute of Scientific and Technical Information of China (English)

    颜克文; 阮成礼; 梁源; 何昕

    2012-01-01

    天线是通信装备最重要的组成部分之一,是接收和发射电磁波信号的"门户",文章研究了短波通信设备天线在强电磁脉冲辐射下的实验方法和耦合效应,并验证了射频前端电磁脉冲防护模块的重要性,提出了天线端口电磁脉冲防护的措施。%Antenna is one of the most important compenent in comunication equipment,which is the door that receive and emit Electromagnetic signal,this paper researched the experimental method and coupling when antenna of short-wave communication equipment was exposed to strong electromagnetic pulse,and the importance of protection module is proved which play an important role in impairing strong energy from antenna.At last,measures of protection about antenna port of communication system in strong electricmagnitude pulse environment.

  13. Fence-sitters Protect Cooperation in Complex Networks

    CERN Document Server

    Zhang, Yichao; Bertelle, Cyrille; Zhou, Shi; Wang, Wenting

    2014-01-01

    Evolutionary game theory is one of the key paradigms behind many scientific disciplines from science to engineering. In complex networks, because of the difficulty of formulating the replicator dynamics, most of previous studies are confined to a numerical level. In this paper, we introduce a vectorial formulation to derive three classes of individuals' payoff analytically. The three classes are pure cooperators, pure defectors, and fence-sitters. Here, fence-sitters are the individuals who change their strategies at least once in the strategy evolutionary process. As a general approach, our vectorial formalization can be applied to all the two-strategies games. To clarify the function of the fence-sitters, we define a parameter, payoff memory, as the number of rounds that the individuals' payoffs are aggregated. We observe that the payoff memory can control the fence-sitters' effects and the level of cooperation efficiently. Our results indicate that the fence-sitters' role is nontrivial in the complex topol...

  14. [Protective properties of avermectine complex and plant growth regulators].

    Science.gov (United States)

    Iamborko, N A; Pindrus, A A

    2009-01-01

    Antimutagen properties of avermectine complex of Avercom synthesized by Streptomyces avermitilis UCM Ac-2161, and growth regulators of plants (GRP) of bioagrostim-extra, ivin and emistim-C have been revealed in experiments with test-cultures of Salmonella typhimurium TA 100, TA 98. Avercom and plant growth regulators neutralize by toxication 27-48% and mutagen action of pesticides on soil microbial associations by 19.0-30.0%.

  15. Circularly polarized antennas

    CERN Document Server

    Gao, Steven; Zhu, Fuguo

    2013-01-01

    This book presents a comprehensive insight into the design techniques for different types of CP antenna elements and arrays In this book, the authors address a broad range of topics on circularly polarized (CP) antennas. Firstly, it introduces to the reader basic principles, design techniques and characteristics of various types of CP antennas, such as CP patch antennas, CP helix antennas, quadrifilar helix antennas (QHA), printed quadrifilar helix antennas (PQHA), spiral antenna, CP slot antennas, CP dielectric resonator antennas, loop antennas, crossed dipoles, monopoles and CP horns. Adva

  16. Diamond dipole active antenna

    OpenAIRE

    Bubnov, I. N.; Falkovych, I. S.; Gridin, A. A.; Stanislavsky, A. A.; Reznik, A. P.

    2015-01-01

    Advantages of the diamond dipole antenna as an active antenna are presented. Such an antenna is like an inverted bow-tie antenna, but the former has some advantages over the ordinary bow-tie antenna. It is shown that the diamond dipole antenna may be an effective element of a new antenna array for low-frequency radio astronomy as well as a communication antenna.

  17. Antenna reconfiguration using metasurfaces

    OpenAIRE

    Zhu, H; Cheung, WSW; Yuk, TI

    2014-01-01

    The paper describes the designs of a frequency-reconfigurable, polarization reconfigurable and pattern reconfigurable antennas using metasurfaces (MS). The frequency-reconfigurable and polarization reconfigurable antennas are composed of a simple circular patch antenna or slot antenna as the source antenna and a circular MS with the same diameter, with both source antenna and MS implemented using planar technology. The pattern reconfigurable antenna is composed of a circular patch antenna as ...

  18. A Fast Adaptive Receive Antenna Selection Method in MIMO System

    Directory of Open Access Journals (Sweden)

    Chaowei Wang

    2013-01-01

    Full Text Available Antenna selection has been regarded as an effective method to acquire the diversity benefits of multiple antennas while potentially reduce hardware costs. This paper focuses on receive antenna selection. According to the proportion between the numbers of total receive antennas and selected antennas and the influence of each antenna on system capacity, we propose a fast adaptive antenna selection algorithm for wireless multiple-input multiple-output (MIMO systems. Mathematical analysis and numerical results show that our algorithm significantly reduces the computational complexity and memory requirement and achieves considerable system capacity gain compared with the optimal selection technique in the same time.

  19. Covalent lanthanide(III) macrocyclic complexes: the bonding nature and optical properties of a promising single antenna molecule.

    Science.gov (United States)

    Rabanal-León, Walter A; Páez-Hernández, Dayán; Arratia-Pérez, Ramiro

    2014-12-21

    The present work is focused on the elucidation of the electronic structure, bonding nature and optical properties of a series of low symmetry (C2) coordination compounds of type [Ln(III)HAM](3+), where "Ln(III)" are the trivalent lanthanide ions: La(3+), Ce(3+), Eu(3+) and Lu(3+), while "HAM" is the neutral six-nitrogen donor macrocyclic ligand [C22N6H26]. This systematic study has been performed in the framework of the Relativistic Density Functional Theory (R-DFT) and also using a multi-reference approach via the Complete Active Space (CAS) wavefunction treatment with the aim of analyzing their ground state and excited state electronic structures as well as electronic correlation. Furthermore, the use of the energy decomposition scheme proposed by Morokuma-Ziegler and the electron localization function (ELF) allows us to characterize the bonding between the lanthanide ions and the macrocyclic ligand, obtaining as a result a dative-covalent interaction. Due to a great deal of lanthanide optical properties and their technological applications, the absorption spectra of this set of coordination compounds were calculated using the time-dependent density functional theory (TD-DFT), where the presence of the intense Ligand to Metal Charge Transfer (LMCT) bands in the ultraviolet and visible region and the inherent f-f electronic transitions in the Near-Infra Red (NIR) region for some lanthanide ions allow us to propose these systems as "single antenna molecules" with potential applications in NIR technologies.

  20. Strong antenna-enhanced fluorescence of a single light-harvesting complex shows photon anti-bunching

    NARCIS (Netherlands)

    Wientjes, E.; Renger, J.; Curto, A.G.; Cogdell, R.; Hulst, van N.F.

    2014-01-01

    The nature of the highly efficient energy transfer in photosynthetic light-harvesting complexes is a subject of intense research. Unfortunately, the low fluorescence efficiency and limited photostability hampers the study of individual light-harvesting complexes at ambient conditions. Here we demons

  1. A New Low-Complexity Decodable Rate-5/4 STBC for Four Transmit Antennas with Nonvanishing Determinants

    CERN Document Server

    Ismail, Amr; Sari, Hikmet

    2012-01-01

    The use of Space-Time Block Codes (STBCs) increases significantly the optimal detection complexity at the receiver unless the low-complexity decodability property is taken into consideration in the STBC design. In this paper we propose a new low-complexity decodable rate-5/4 full-diversity 4 x 4 STBC. We provide an analytical proof that the proposed code has the Non-Vanishing-Determinant (NVD) property, a property that can be exploited through the use of adaptive modulation which changes the transmission rate according to the wireless channel quality. We compare the proposed code to the best existing low-complexity decodable rate-5/4 full-diversity 4 x 4 STBC in terms of performance over quasi-static Rayleigh fading channels, worst- case complexity, average complexity, and Peak-to-Average Power Ratio (PAPR). Our code is found to provide better performance, lower average decoding complexity, and lower PAPR at the expense of a slight increase in worst-case decoding complexity.

  2. An estimation of directivity characteristics of antenna elements in antenna array with counting of signal conjugate components

    OpenAIRE

    Kopiievska, V. S.; Slyusar, Vadym I.

    2011-01-01

    In this article a two-stage digital processing of N-OFDM signals test sources for measurement of directivity characteristics (DC) of antenna elements in digital antenna array (DAA) with counting of complex conjugate components are presented.

  3. Coupling of metal-based light-harvesting antennas and electron-donor subunits: Trinuclear Ruthenium(II) complexes containing tetrathiafulvalene-substituted polypyridine ligands

    DEFF Research Database (Denmark)

    Campagna, Sebastiano; Serroni, Scolastica; Puntoriero, Fausto;

    2002-01-01

    +) (4,4'-Mebpy = 4,4'-dimethyl-2,2'-bipyridine) and [{(bpy)(2)Ru(mu-2,3-dpp)}(2)Ru(bpy)](6+). The absorption spectra and redox behavior of all the new metal compounds can be interpreted by a multicomponent approach, in which specific absorption features and redox processes can be assigned to specific......Three new tetrathiafulvalene-substituted 2,2'-bipyridine ligands, cis-bpy-TTF1, trans-bpy-TTF1, and cis-bpy-TTF2 have been prepared and characterized. X-ray analysis of trans-bpy-TTF1, is also reported. Such ligands have been used to prepare two new trinuclear Ru-II complexes, namely, [{(bpy)(2)Ru...... as light-harvesting antennas and the tetrathiafulvalene electron donors can induce charge separation. The absorption spectra, redox behavior, and luminescence properties (both at room temperature in acetonitrile and at 77 K in a rigid matrix of butyronitrile) of the trinuclear metal complexes have been...

  4. UWB planar antenna technology

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Recent developments of the ultra-wideband(UWB)planar antennas are reviewed,where the progress in UWB plate monopole antennas,UWB printed monopole antennas and the UWB printed slot antennas is introduced and compared.In addition,the UWB printed antennas with the band-notched functions are also presented.

  5. Major histocompatibility complex-controlled protective influences on experimental autoimmune encephalomyelitis are peptide specific

    DEFF Research Database (Denmark)

    Issazadeh-Navikas, Shohreh; Kjellén, P; Olsson, T;

    1997-01-01

    The myelin basic protein (MBP) peptide 63-88-induced experimental autoimmune encephalomyelitis (EAE) and its associated T cell cytokine profile are influenced by the rat major histocompatibility complex (MHC). There is an allele-specific protective influence of the MHC class I region, whereas...

  6. Engrailed protects mouse midbrain dopaminergic neurons against mitochondrial complex I insults

    OpenAIRE

    Alvarez-Fischer, Daniel; Fuchs, Julia; Castagner, François; Stettler, Olivier; Massiani-Beaudoin, Olivia; Moya, Kenneth L.; Bouillot, Colette; Wolfgang H Oertel; Lombès, Anne; Faigle, Wolfgang; Joshi, Rajiv L.; Hartmann, Andreas; Prochiantz, Alain

    2011-01-01

    Abstract Mice heterozygous for homeobox gene Engrailed-1 display progressive loss of mesencephalic dopaminergic (mDA) neurons. We report that exogenous Engrailed-1 and Engrailed-2 (collectively Engrailed) protect mDA neurons from 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), a mitochondrial complex I toxin used to model PD in animals. Engrailed enhances the translation of nuclear-encoded mRNAs for two key complex I subunits, Ndufs1 and Ndufs3, and increases complex I activit...

  7. A directive pulse antenna

    OpenAIRE

    Titov, A.N.; Titov, A. A.

    2003-01-01

    Using quite general concepts as guidance in the design of an antenna for short pulse transmission and reception, a new type of horn-antenna has been devised. A certain variety of experimental data obtained by the antenna are presented.

  8. In situ solid-state NMR spectroscopy of protein in heterogeneous membranes: the baseplate antenna complex of Chlorobaculum tepidum.

    Science.gov (United States)

    Kulminskaya, Natalia V; Pedersen, Marie Ø; Bjerring, Morten; Underhaug, Jarl; Miller, Mette; Frigaard, Niels-Ulrik; Nielsen, Jakob T; Nielsen, Niels Chr

    2012-07-01

    A clever combination: an in situ solid-state NMR analysis of CsmA proteins in the heterogeneous environment of the photoreceptor of Chlorobaculum tepidum is reported. Using different combinations of 2D and 3D solid-state NMR spectra, 90 % of the CsmA resonances are assigned and provide on the basis of chemical shift data information about the structure and conformation of CsmA in the CsmA-bacteriochlorophyll a complex.

  9. Modeling of optical spectra of the light-harvesting CP29 antenna complex of photosystem II--part II.

    Science.gov (United States)

    Feng, Ximao; Kell, Adam; Pieper, Jörg; Jankowiak, Ryszard

    2013-06-01

    Until recently, it was believed that the CP29 protein from higher plant photosystem II (PSII) contains 8 chlorophylls (Chl's) per complex (Ahn et al. Science 2008, 320, 794-797; Bassi et al. Proc. Natl. Acad. Sci. U.S.A. 1999, 96, 10056-10061) in contrast to the 13 Chl's revealed by the recent X-ray structure (Pan et al. Nat. Struct. Mol. Biol. 2011, 18, 309-315). This disagreement presents a constraint on the interpretation of the underlying electronic structure of this complex. To shed more light on the interpretation of various experimental optical spectra discussed in the accompanying paper (part I, DOI 10.1021/jp4004328 ), we report here calculated low-temperature (5 K) absorption, fluorescence, hole-burned (HB), and 300 K circular dichroism (CD) spectra for CP29 complexes with a different number of pigments. We focus on excitonic structure and the nature of the low-energy state using modeling based on the X-ray structure of CP29 and Redfield theory. We show that the lowest energy state is mostly contributed to by a612, a611, and a615 Chl's. We suggest that in the previously studied CP29 complexes from spinach (Pieper et al. Photochem. Photobiol.2000, 71, 574-589) two Chl's could have been lost during the preparation/purification procedure, but it is unlikely that the spinach CP29 protein contains only eight Chl's, as suggested by the sequence homology-based study (Bassi et al. Proc. Natl. Acad. Sci. U.S.A.1999, 96, 10056-10061). The likely Chl's missing in wild-type (WT) CP29 complexes studied previously (Pieper et al. Photochem. Photobiol. 2000, 71, 574-589) include a615 and b607. This is why the nonresonant HB spectra shown in that reference were ~1 nm blue-shifted with the low-energy state mostly localized on about one Chl a (i.e., a612) molecule. Pigment composition of CP29 is discussed in the context of light-harvesting and excitation energy transfer.

  10. Terminal Antenna Design

    OpenAIRE

    Skrivervik, A. K.; Zurcher, J. F.

    2008-01-01

    This paper introduces first some general considerations about antenna miniaturization and multi-band terminal antenna design. These general design principles are then illustrated on some practical applications.

  11. Terahertz antenna electronic chopper

    Energy Technology Data Exchange (ETDEWEB)

    Sterczewski, L. A., E-mail: lukasz.sterczewski@pwr.edu.pl; Grzelczak, M. P.; Plinski, E. F. [Department of Electronics, Wroclaw University of Technology, 27 Wybrzeze Wyspianskiego St., 50-370 Wroclaw (Poland)

    2016-01-15

    In this paper, we present an electronic circuit used to bias a photoconductive antenna that generates terahertz radiation. The working principles and the design process for the device are discussed in detail. The noise and shape of the wave measurements for a built device are considered. Furthermore, their impact on a terahertz pulse and its spectra is also examined. The proposed implementation is simple to build, robust and offers a real improvement over THz instrumentation due to the frequency tuning. Additionally, it provides for galvanic isolation and ESD protection.

  12. Loaded antenna in half lossy space base on HDGA

    Institute of Scientific and Technical Information of China (English)

    SUN Guo-xi; YIN Jun-xun

    2005-01-01

    Antenna loads can modify the current distribution on the wires, thus improving antenna characteristics in the process. However, it is difficult to calculate appropriate loads of antenna near the ground because in half lossy space there are inherent situational complexities. This paper optimizes loads of antenna near the ground base using a half-determined genetic algorithm. The numerical results show the HDGA has a quicker convergent speed and a better convergent value than the SGA.

  13. Microencapsulation of aspartame by double emulsion followed by complex coacervation to provide protection and prolong sweetness.

    Science.gov (United States)

    Rocha-Selmi, Glaucia A; Bozza, Fernanda T; Thomazini, Marcelo; Bolini, Helena M A; Fávaro-Trindade, Carmen S

    2013-08-15

    The objective of this work was to microencapsulate aspartame by double emulsion followed by complex coacervation, aiming to protect it and control its release. Six treatments were prepared using sunflower oil to prepare the primary emulsion and gelatin and gum Arabic as the wall materials. The microcapsules were evaluated structurally with respect to their sorption isotherms and release into water (36°C and 80°C). The microcapsules were multinucleated, not very water-soluble or hygroscopic and showed reduced rates of equilibrium moisture content and release at both temperatures. FTIR confirmed complexation between the wall materials and the intact nature of aspartame. The results indicated it was possible to encapsulate aspartame with the techniques employed and that these protected the sweetener even at 80°C. The reduced solubility and low release rates indicated the enormous potential of the vehicle developed in controlling the release of the aspartame into the food, thus prolonging its sweetness.

  14. Curved spiral antennas for underwater biological applications

    Science.gov (United States)

    Llamas, Ruben

    We developed curved spiral antennas for use in underwater (freshwater) communications. Specifically, these antennas will be integrated in so-called mussel backpacks. Backpacks are compact electronics that incorporate sensors and a small radio that operate around 300 MHz. Researchers attach these backpacks in their freshwater mussel related research. The antennas must be small, lightweight, and form-fit the mussel. Additionally, since the mussel orientation is unknown, the antennas must have broad radiation patterns. Further, the electromagnetic environment changes significantly as the mussels burrow into the river bottom. Broadband antennas, such a spiral antennas, will perform better in this instance. While spiral antennas are well established, there has been little work on their performance in freshwater. Additionally, there has been some work on curved spiral antennas, but this work focused on curving in one dimension, namely curving around a cylinder. In this thesis we develop spiral antennas that curve in two dimensions in order to conform the contour of a mussel's shell. Our research has three components, namely (a) an investigation of the relevant theoretical underpinning of spiral antennas, (b) extensive computer simulations using state-of-the art computational electromagnetics (CEM) simulation software, and (c) experimental validation. The experimental validation was performed in a large tank in a laboratory setting. We also validated some designs in a pool (~300,000 liters of water and ~410 squared-meter dive pool) with the aid of a certified diver. To use CEM software and perform successful antenna-related experiments require careful attention to many details. The mathematical description of radiation from an antenna, antenna input impedance and so on, is inherently complex. Engineers often make simplifying assumptions such as assuming no reflections, or an isotropic propagation environment, or operation in the antenna far field, and so on. This makes

  15. Femtosecond and hole-burning studies of B800`s excitation energy relaxation dynamics in the LH2 antenna complex of Rhodopseudomonas acidophila (strain 10050)

    Energy Technology Data Exchange (ETDEWEB)

    Wu, H.M.; Savikhin, S.; Reddy, N.R.S.; Jankowiak, R.; Struve, W.S.; Small, G.J. [Ames Lab., IA (United States)]|[Iowa State Univ., Ames, IA (United States); Cogdell, R.J. [Univ. of Glasgow (United Kingdom)

    1996-07-18

    One- and two-color pump/probe femtosecond and hole-burning data are reported for the isolated B800-850 (LH2) antenna complex of Rhodopseudomonas acidophila (strain 10050). The two-color profiles are interpretable in terms of essentially monophasic B800{yields}B850 energy transfer with kinetics ranging from 1.6 to 1.1 ps between 19 and 130 K for excitation at or to the red of the B800 absorption maximum. The B800 zero-phonon hole profiles obtained at 4.2 K with burn frequencies located near or to the red of this maximum yielded a transfer time of 1.8 ps. B800 hole-burning data (4.2 K) are also reported for chromatophores at ambient pressure and pressures of 270 and 375 MPa. At ambient pressure the B800-B850 energy gap is 950 cm{sup -1}, while at 270 and 375 MPa it is close to 1000 and 1050 cm{sup -1}, respectively. However, no dependence of the B800{yields}B850 transfer time on pressure was observed. The resilience of the transfer rate to pressure-induced changes in the energy gap and the weak temperature dependence of the rate are consistent with the model that has the spectral overlap (of Foerster theory) provided by the B800 fluorescence origin band and weak vibronic absorption bands of B850. However, both the time domain and hole-burning data establish that there is an additional relaxation channel for B800, which is observed when excitation is located to the blue of the B800 absorption maximum. 40 refs., 11 figs., 6 tabs.

  16. Radiation of planar stripline ultra-wideband antenna for WPAN systems

    OpenAIRE

    Garbaruk, M.

    2007-01-01

    The paper presents results of design and computer simulation of planar monopole pulse ultra-wideband (UWB) antenna for WPAN applications. A complex approach to design of UWB antennas was used. Problem of radiation of UWB signals by the antenna was discussed. Electric fields radiated by the antenna for chosen directions were calculated and shown.

  17. Antenna systems research

    OpenAIRE

    Keen, Keith Malcolm

    1999-01-01

    This thesis is an overview of a number of investigations on antenna systems and related subjects over a period of 28 years, which has resulted in 44 publications in the technical literature, one current patent, and an M.Sc. thesis. The investigations have been grouped into 7 categories: - Log periodic antennas, - Antenna performance measurement techniques, - Spacecraft Antenna Systems, - Satcom Terminal Antennas, - Transmission lines and baluns, - High Radar Cross Secti...

  18. A True Metasurface Antenna

    OpenAIRE

    Mohamed El Badawe; Almoneef, Thamer S.; Omar M. Ramahi

    2016-01-01

    We present a true metasurface antenna based on electrically-small resonators. The resonators are placed on a flat surface and connected to one feed point using corporate feed. Unlike conventional array antennas where the distance between adjacent antennas is half wavelength to reduce mutual coupling between adjacent antennas, here the distance between the radiating elements is electrically very small to affect good impedance matching of each resonator to its feed. A metasurface antenna measur...

  19. Computational Investigation of Microstrip Antennas in Plasma Environment

    CERN Document Server

    Vyas, Hardik; Gupta, Sanjeev

    2016-01-01

    Microstrip antennas are extensively used in spacecraft systems and other applications where they encounter a plasma environment. A detailed computational investigation of change in antenna radiation properties in the presence of plasma has been presented in this paper. The study shows antenna properties such as the resonant frequency, return loss, radiation properties and the different characteristics of the antenna changes when it is surrounded by plasma. Particular focus of the work is to understand the causes behind these changes by correlating the complex propagation constant in the plasma medium, field distribution on the patch and effective dielectric of the antenna substrate with antenna parameter variations. The study also provides important insights to explore the possibilities of designing tunable microstrip antenna where the substrate can be replaced with plasma and important antenna characteristics can be controlled by varying the plasma density.

  20. Plasma antennas: dynamically configurable antennas for communications

    International Nuclear Information System (INIS)

    In recent years, the rapid growth in both communications and radar systems has led to a concomitant growth in the possible applications and requirements of antennas. These new requirements include compactness and conformality, rapid reconfigurability for directionality and frequency agility. For military applications, antennas should also allow low absolute or out-of-band radar cross-section and facilitate low probability of intercept communications. Investigations have recently begun worldwide on the use of ionised gases or plasmas as the conducting medium in antennas that could satisfy these requirements. Such plasma antennas may even offer a viable alternative to metal in existing applications when overall technical requirements are considered. A recent patent for ground penetrating radar claims the invention of a plasma antenna for the transmission of pulses shorter than 100 ns in which it is claimed that current ringing is avoided and signal processing simplified compared with a metal antenna. A recent US ONR tender has been issued for the design and construction of a compact and rapidly reconfigurable antenna for dynamic signal reception over the frequency range 1 - 45 GHz based on plasma antennas. Recent basic physics experiments at ANU have demonstrated that plasma antennas can attain adequate efficiency, predictable radiation patterns and low base-band noise for HF and VHF communications. In this paper we describe the theory of the low frequency plasma antenna and present a few experimental results

  1. Effects of acid pH and urea on the spectral properties of the LHII antenna complex from the photosynthetic bacterium Ectothiorhodospira sp.

    Science.gov (United States)

    Buche, A; Ramirez, J M; Picorel, R

    2000-06-01

    The aim of this study was to investigate the spectral modifications of the LHII antenna complex from the purple bacterium Ectothiorhodospira sp. upon acid pH titration both in the presence and absence of urea. A blue shift specifically and reversibly affected the B850 band around pH 5.5-6.0 suggesting that a histidine residue most probably participated in the in vivo absorption red shifting mechanism. This transition was observed in the presence and absence of urea. Under strong chaotropic conditions, a second transition occurred around pH 2.0, affecting the B800 band irreversibly and the B850 reversibly. Under these conditions a blue shift from 856 to 842 nm occurred and a new and strong circular dichroism signal from the new 842 nm band was observed. Reverting to the original experimental conditions induced a red shift of the B850 band up to 856 nm but the circular dichroism signal remained mostly unaffected. Under the same experimental conditions, i.e. pH 2.1 in the presence of urea, part of the B800 band was irreversibly destroyed with concomitant appearance of a band around 770 nm due to monomeric bacteriochlorophyll from the disrupted B800. Furthermore, Gaussian deconvolution and second derivative of the reverted spectra at pH 8.0 after strong-acid treatment indicated that the new B850 band was actually composed of two bands centered at 843 and 858 nm. We ascribed the 858 nm band to bacteriochlorophylls that underwent reversible spectral shift and the 843 nm band to oligomeric bacteriopheophytin formed from a part of the B850 bacteriochlorophyll. This new oligomer would be responsible for the observed strong and mostly conservative circular dichroism signal. The presence of bacteriopheophytin in the reverted samples was definitively demonstrated by HPLC pigment analysis. The pheophytinization process progressed as the pH decreased below 2.1, and at a certain point (i.e. pH 1.5) all bacteriochlorophylls, including those from the B800 band, became converted to

  2. MDP: A Deinococcus Mn2+-Decapeptide Complex Protects Mice from Ionizing Radiation

    Science.gov (United States)

    Smith, Joan T.; Gaidamakova, Elena K.; Matrosova, Vera Y.; Grichenko, Olga; Knollmann-Ritschel, Barbara; Daly, Michael J.; Kiang, Juliann G.

    2016-01-01

    The radioprotective capacity of a rationally-designed Mn2+-decapeptide complex (MDP), based on Mn antioxidants in the bacterium Deinococcus radiodurans, was investigated in a mouse model of radiation injury. MDP was previously reported to be extraordinarily radioprotective of proteins in the setting of vaccine development. The peptide-component (DEHGTAVMLK) of MDP applied here was selected from a group of synthetic peptides screened in vitro for their ability to protect cultured human cells and purified enzymes from extreme damage caused by ionizing radiation (IR). We show that the peptides accumulated in Jurkat T-cells and protected them from 100 Gy. MDP preserved the activity of T4 DNA ligase exposed to 60,000 Gy. In vivo, MDP was nontoxic and protected B6D2F1/J (female) mice from acute radiation syndrome. All irradiated mice treated with MDP survived exposure to 9.5 Gy (LD70/30) in comparison to the untreated mice, which displayed 63% lethality after 30 days. Our results show that MDP provides early protection of white blood cells, and attenuates IR-induced damage to bone marrow and hematopoietic stem cells via G-CSF and GM-CSF modulation. Moreover, MDP mediated the immunomodulation of several cytokine concentrations in serum including G-CSF, GM-CSF, IL-3 and IL-10 during early recovery. Our results present the necessary prelude for future efforts towards clinical application of MDP as a promising IR countermeasure. Further investigation of MDP as a pre-exposure prophylactic and post-exposure therapeutic in radiotherapy and radiation emergencies is warranted. PMID:27500529

  3. Cross resonant optical antenna.

    Science.gov (United States)

    Biagioni, P; Huang, J S; Duò, L; Finazzi, M; Hecht, B

    2009-06-26

    We propose a novel cross resonant optical antenna consisting of two perpendicular nanosized gold dipole antennas with a common feed gap. We demonstrate that the cross antenna is able to convert propagating fields of any polarization state into correspondingly polarized, localized, and enhanced fields and vice versa. The cross antenna structure therefore opens the road towards the control of light-matter interactions based on polarized light as well as the analysis of polarized fields on the nanometer scale.

  4. Wide Coverage Antennas

    OpenAIRE

    Zackrisson, Jan

    2007-01-01

    Small satellites require small and lightweight antennas for telemetry and command function as well as for downlinking of data. We have during the last thirty years developed a large suite of wide coverage antennas. The basic radiator designs used are quadrifilar helices, waveguides, horns and patch excited cups (PEC) depending on frequency range, coverage requirements and application. The antenna designs range from L-band up to Ka-band frequencies. Typical coverages for the antennas are from ...

  5. Experimental demonstration of superdirective dielectric antenna

    Energy Technology Data Exchange (ETDEWEB)

    Krasnok, Alexander E.; Filonov, Dmitry S.; Belov, Pavel A. [National Research University of Information Technologies, Mechanics and Optics (ITMO), St. Petersburg 197101 (Russian Federation); Simovski, Constantin R. [National Research University of Information Technologies, Mechanics and Optics (ITMO), St. Petersburg 197101 (Russian Federation); Aalto University, School of Electric and Electronic Engineering, Aalto FI76000 (Finland); Kivshar, Yuri S. [National Research University of Information Technologies, Mechanics and Optics (ITMO), St. Petersburg 197101 (Russian Federation); Nonlinear Physics Center, Research School of Physics and Engineering, Australian National University, Canberra ACT 0200 (Australia)

    2014-03-31

    We propose and demonstrate experimentally a simple approach for achieving superdirectivity of emitted radiation for electrically small antennas based on a spherical dielectric resonator with a notch excited by a dipole source. Superdirectivity is achieved without using complex antenna arrays and for a wide range of frequencies. We also demonstrate the steering effect for a subwavelength displacement of the source. Finally, unlike previously known superdirective antennas, our design has significantly smaller losses, at the operation frequency radiation efficiency attains 80%, and matching holds in the 3%-wide frequency band without any special matching technique.

  6. Wideband Circularly Polarized Dielectric Rod Antenna

    OpenAIRE

    Min Guo; Ji-Jun Yan; Shun-Shi Zhong; Zhu Sun

    2012-01-01

    A new dielectric rod antenna (DRA) is introduced to produce circular polarization (CP) over a wide frequency band without a complex feed network. Along with the simulated results, measured results of the antenna prototype are presented, showing a 3 dB axial ratio (AR) CP bandwidth of 17.7%. The radiation characteristics of the fabricated antenna are also demonstrated showing the measured gain of better than 6.2 dBi. Moreover, the measured impedance bandwidth (VSWR ≤2) reaches 20.1%, from 8.75...

  7. Retrodirective Antenna Array Using High Frequency Offset

    Directory of Open Access Journals (Sweden)

    P. Sindler

    2012-12-01

    Full Text Available The paper deals with the design of a simple retrodirective antenna array exhibiting by high frequency offset between received and transmitted wave. Analysis of the beam pointing error using antenna array model developed in MATLAB is described. The frequencies of transmitted wave and received wave are chosen on the basis of this analysis. Then a suitable structure for further design is determined and particular blocks of complete retrodirective antenna array are briefly described and their measured parameters are presented. Relatively high frequency offset between received and transmitted wave makes it possible to use frequency filters for received and transmitted signal separation which led to significant reduction of the circuit complexity.

  8. Modern methods of analysis and computation of antenna radomes

    OpenAIRE

    Kozakoff, Dennis J.

    1999-01-01

    A radome, an acronym coined from radar dome, is a structure placed over an antenna that protects the antenna from its physical environment. Ideally, the radome is radio-frequency (RF) transparent and does not degrade the electrical performance of the en-closed antenna. Today, radomes find wide applications in ground, maritime, aircraft, and missile electronic systems (Fig. 1).Very early methods of radome evaluation were cumbersome, relying on the use of a nomograph (1, 2). With the advent of ...

  9. Optimal antenna spacings in interferometric SAR

    Science.gov (United States)

    Xiao, Shu; Munson, David C., Jr.

    2000-08-01

    In practice, a synthetic aperture radar (SAR) reconstructs the complex reflectivity function of a scene, modulated by phase terms that capture 3-D imaging geometry. INSAR (interferometric SAR) attempts to obtain the geometric information by interfering two images (from two antennas) to cancel the same scene reflectivity and recover the scene topography transduced by the image-phase data. This approach, however, leads to a phase-unwrapping problem, which causes ambiguities in estimates of elevation. The phase-unwrapping problem can be solved in a pointwise fashion by using more than two antennas. This approach can effectively prevent error propagation which occurs in traditional phase-unwrapping algorithms. In this work, we study the optimal antenna spacings for pointwise terrain height estimation. In particular, we start from the maximum likelihood estimates of the phase using neighborhood pixels collected by any pair of antennas. The phase estimation noise is approximated as Gaussian with variance prescribed by the Cramer-Rao lower bound on the phase estimate. The ambiguous terrain height derived from any pair of antennas is modeled by a periodic waveform with each period having an approximately Gaussian shape. For multiple pairs of antennas, the corresponding functions describing the ambiguous elevation have different periods, which acts to help resolve the ambiguity. We derive and analyze the ML estimate of elevation at each scene point using multiple pairs of antennas. For the three-antenna case, by analyzing the tradeoff between cycle errors and measurement errors, a closed-form formula approximating the mean squared error (MSE) of the estimated terrain height is derived as a function of antenna spacing. By minimizing the MSE, we determine the optimal antenna spacing. The algorithm is tested with simulated data.

  10. The mathematical model of antenna and antenna-radome system

    OpenAIRE

    Knyazeva, L. V.; Artishev, A. I.

    2003-01-01

    Methods, algorithms and programs for calculation by computer of the characteristics of the antenna and the antenna-radome system (ARS) are developed. The type of antenna considered is the phased antenna array (PAA) or the cophase antenna with a mechanical beam control (an antenna array - AA). Radome shape is spherical, quasi-conic or flattened ellipsoid. Radome shell is multilayer ( N≥1), same-thickness, or special profile. Errors in the manufacture of the antenna are taken into account. Prog...

  11. Argonaute 2 complexes selectively protect the circulating microRNAs in cell-secreted microvesicles.

    Directory of Open Access Journals (Sweden)

    Limin Li

    Full Text Available Cell-secreted miRNAs are highly stable and can serve as biomarkers for various diseases and signaling molecules in intercellular communication. The mechanism underlying the stability of circulating miRNAs, however, remains incompletely understood. Here we show that Argonaute 2 (Ago2 complexes and microvesicles (MVs provide specific and non-specific protection for miRNA in cell-secreted MVs, respectively. First, the resistance of MV-encapsulated miRNAs to RNaseA was both depended on intact vesicular structure of MVs and protease-sensitive. Second, an immunoprecipitation assay using a probe complementary to human miR-16, a miRNA primarily located in the MVs and showed a strong, protease-sensitive resistance to RNaseA, identified Ago2 as a major miR-16-associated protein. Compared with protein-free miR-16, Ago2-associated miR-16 was resistant to RNaseA in a dose- and time-dependent fashion. Third, when the miR-16/Ago2 complex was disrupted by trypaflavine, the resistance of miR-16 to RNaseA was decreased. In contrast, when the association of miR-16 with the Ago2 complexes was increased during cell apoptosis, although the total amount of miR-16 and Ago2 remained unchanged, the resistance of miR-16 to RNaseA in the MVs was enhanced. A similar correlation between the increase of miR-223/Ago2 association and the resistance of miR-223 against RNaseA was observed during all trans retinoic acid (ATRA-induced cell differentiation of promyelocytic HL60 cells. In conclusion, the association of miRNAs with Ago2 complexes, an event that is linked to cell functional status, plays a critical role in stabilizing the circulating miRNAs in cell-secreted MVs.

  12. Energizing the light harvesting antenna: Insight from CP29.

    Science.gov (United States)

    Ioannidis, Nikolaos E; Papadatos, Sotiris; Daskalakis, Vangelis

    2016-10-01

    How do plants cope with excess light energy? Crop health and stress tolerance are governed by molecular photoprotective mechanisms. Protective exciton quenching in plants is activated by membrane energization, via unclear conformational changes in proteins called antennas. Here we show that pH and salt gradients stimulate the response of such an antenna under low and high energization by all-atom Molecular Dynamics Simulations. Novel insight establishes that helix-5 (H5) conformation in CP29 from spinach is regulated by chemiosmotic factors. This is selectively correlated with the chl-614 macrocycle deformation and interactions with nearby pigments, that could suggest a role in plant photoprotection. Adding to the significance of our findings, H5 domain is conserved among five antennas (LHCB1-5). These results suggest that light harvesting complexes of Photosystem II, one of the most abundant proteins on earth, can sense chemiosmotic gradients via their H5 domains in an upgraded role from a solar detector to also a chemiosmotic sensor.

  13. submitter Radiation Protection Studies for CERN LINAC4/SPL Accelerator Complex

    CERN Document Server

    Mauro, Egidio; Silari, Marco

    2009-01-01

    CERN is presently designing a new chain of accelerators to replace the present Proton Synchrotron (PS) complex: a 160 MeV room-temperature H$^-$ linac (Linac4) to replace the present 50 MeV proton linac injector, a 3.5 GeV Superconducting Proton Linac (SPL) to replace the 1.4 GeV PS booster (PSB) and a 50 GeV synchrotron (named PS2) to replace the 26 GeV PS. Linac4 has been funded and the civil engineering work started in October 2008, whilst the SPL is in an advanced stage of design. Beyond injecting into the future 50 GeV PS, the ultimate goal of the SPL is to generate a 4 MW beam for the production of intense neutrino beams. The radiation protection design is driven by the latter requirement. This thesis summarizes the radiation protection studies conducted for Linac4. FLUKA Monte Carlo simulations, complemented by analytical estimates, were performed 1) to evaluate the propagation of neutrons through the waveguide, ventilation and cable ducts placed along the accelerator, 2) to estimate the radiological i...

  14. Complex adenovirus-vectored vaccine protects guinea pigs from three strains of Marburg virus challenges

    International Nuclear Information System (INIS)

    The Marburg virus (MARV), an African filovirus closely related to the Ebola virus, causes a deadly hemorrhagic fever in humans, with up to 90% mortality. Currently, treatment of disease is only supportive, and no vaccines are available to prevent spread of MARV infections. In order to address this need, we have developed and characterized a novel recombinant vaccine that utilizes a single complex adenovirus-vectored vaccine (cAdVax) to overexpress a MARV glycoprotein (GP) fusion protein derived from the Musoke and Ci67 strains of MARV. Vaccination with the cAdVaxM(fus) vaccine led to efficient production of MARV-specific antibodies in both mice and guinea pigs. Significantly, guinea pigs vaccinated with at least 5 x 107 pfu of cAdVaxM(fus) vaccine were 100% protected against lethal challenges by the Musoke, Ci67 and Ravn strains of MARV, making it a vaccine with trivalent protective efficacy. Therefore, the cAdVaxM(fus) vaccine serves as a promising vaccine candidate to prevent and contain multi-strain infections by MARV

  15. Morphological characterisation of complex powder used for protective coatings for geothermal plant components

    Science.gov (United States)

    Csaki, I.; Karlsdottir, S. N.; Buzaianu, A.; Serghiuta, S.; Popescu, G.; Motoiu, V. A.; Ragnarstottir, K. R.; Guðlaugsson, S.

    2016-06-01

    This paper aims to review the morphological characteristics, microstructures, physical and chemical properties of two complex composite powders: Ni18Cr5Si2B and Ni21Cr11Al2.5Y. These powders will be used as an option for coating geothermal turbine blades to prevent corrosion. The corrosion process in the steam turbine results in damages being recognized as the leading cause of reduced availability in geothermal power plants and is depends on temperature, mechanical and vaporous carryover of impurities and water treatment. Thermal spraying is a suitable technique for coating layers with wear and corrosion resistance. Therefore this technique could be successfully used in geothermal applications for obtaining coatings layers from new complex composite powders protecting the turbine blades from corrosions and good control of steam chemistry. The composite powders were investigated using X-ray diffraction and electronic microscopy to provide detailed information about composites morphological modifications. The results obtained after morphological evaluation are encouraging for using these composite powders as an option for coating geothermal components using thermal spraying technique.

  16. Hot tips on hot tips: technical problems with percutaneous insertion of a microwave antenna through rigid tissue

    International Nuclear Information System (INIS)

    We report an instance of microwave antenna breakage upon insertion through rigid costal cartilage and tip dislodgement during withdrawal of the antenna. Furthermore, we highlight antenna incompatibility with certain coaxial needles. Given the complexity and fragility of microwave antennas, it is not recommended to insert them through rigid tissue such as cartilage or calcified pleural plaques.

  17. Prediction and Protection of Radio Antenna Electromagnetic Radiation With High-power Medium-short Wave%大功率中短波广播天线电磁辐射的预测与防护

    Institute of Scientific and Technical Information of China (English)

    唐章宏; 王群; 冀志江; 施楣梧

    2014-01-01

    随着城镇密集度越来越高,大功率电磁辐射设备如大功率中短波天线不可避免的与建筑越来越近,因而对室内的电磁环境污染逐步加剧。电磁辐射造成的危害通常包括对人体健康的危害(健康效应)和干扰其他电磁设备而造成严重后果(电磁干扰)。针对大功率中短波天线造成的电磁环境污染问题,提出一套远场条件下电磁辐射的预测方法并成功预测了一个典型大功率中短波天线群附近的拟建项目区域的电磁环境,在此基础上,提出有效的针对拟建项目的电磁防护方案。%As the population density becomes higher in cities and towns, electromagnetic radiation equip-ment with high-power, such as high-power medium-short wave antenna are more close to buildings which results in intensified pollution to the indoor electromagnetic environment. The harm caused by the electromagnetic radiation usually includes harm to human health (health effect) and interfering to other electromagnetic devices and cause serious consequences (electromagnetic interference). This paper proposes a set of far field electromagnetic radiation prediction method against electromagnetic envi-ronmental pollution problems caused by the high-power medium-short wave antenna and successfully pre-dicted the electromagnetic environment of a typical superpower shortwave antenna group which is close to a planned building. Based on this, effective electromagnetic protection program is proposed for planned buildings.

  18. 大功率中短波广播天线电磁辐射的预测与防护%Prediction and Protection of Radio Antenna Electromagnetic Radiation With High-power Medium-short Wave

    Institute of Scientific and Technical Information of China (English)

    唐章宏; 王群; 冀志江; 施楣梧

    2014-01-01

    As the population density becomes higher in cities and towns, electromagnetic radiation equip-ment with high-power, such as high-power medium-short wave antenna are more close to buildings which results in intensified pollution to the indoor electromagnetic environment. The harm caused by the electromagnetic radiation usually includes harm to human health (health effect) and interfering to other electromagnetic devices and cause serious consequences (electromagnetic interference). This paper proposes a set of far field electromagnetic radiation prediction method against electromagnetic envi-ronmental pollution problems caused by the high-power medium-short wave antenna and successfully pre-dicted the electromagnetic environment of a typical superpower shortwave antenna group which is close to a planned building. Based on this, effective electromagnetic protection program is proposed for planned buildings.%随着城镇密集度越来越高,大功率电磁辐射设备如大功率中短波天线不可避免的与建筑越来越近,因而对室内的电磁环境污染逐步加剧。电磁辐射造成的危害通常包括对人体健康的危害(健康效应)和干扰其他电磁设备而造成严重后果(电磁干扰)。针对大功率中短波天线造成的电磁环境污染问题,提出一套远场条件下电磁辐射的预测方法并成功预测了一个典型大功率中短波天线群附近的拟建项目区域的电磁环境,在此基础上,提出有效的针对拟建项目的电磁防护方案。

  19. Using the Antenna Effect as a Spectroscopic Tool; Photophysics and Solution Thermodynamics of the Model Luminescent Hydroxypyridonate Complex [EuIII(3,4,3-LI(1,2-HOPO))]-

    Energy Technology Data Exchange (ETDEWEB)

    Abergel, Rebecca J.; D' Aleo, Anthony; Ng Pak Leung, Clara; Shuh, David; Raymond, Kenneth

    2009-11-20

    While widely used in bioassays, the spectrofluorimetric method described here uses the antenna effect as a tool to probe the thermodynamic parameters of ligands that sensitize lanthanide luminescence. The Eu3+ coordination chemistry, solution thermodynamic stability and photophysical properties of the spermine-based hydroxypyridonate octadentate chelator 3,4,3-LI(1,2-HOPO) are reported. The complex [EuIII(3,4,3-LI(1,2-HOPO))]- luminesces with a long lifetime (805 mu s) and a quantum yield of 7.0percent in aqueous solution, at pH 7.4. These remarkable optical properties were exploited to determine the high (and proton-independent) stability of the complex (log beta 110 = 20.2(2)) and to define the influence of the ligand scaffold on the stability and photophysical properties.

  20. Calculating the Lightning Protection System Downconductors' Grounding Resistance at Launch Complex 39B, Kennedy Space Center

    Science.gov (United States)

    Mata, Carlos T.; Mata, Angel G.

    2012-01-01

    A new Lightning Protection System (LPS) was designed and built at Launch Complex 39B (LC39B), at the Kennedy Space Center (KSC), Florida, which consists of a catenary wire system (at a height of about 181 meters above ground level) supported by three insulators installed atop three towers in a triangular configuration. Nine downconductors (each about 250 meters long) are connected to the catenary wire system. Each downconductor is connected to a 7.62-meter-radius circular counterpoise conductor with six equally spaced, 6-meter-long vertical grounding rods. Grounding requirements at LC39B call for all underground and aboveground metallic piping, enclosures, raceways, and cable trays, within 7.62 meters of the counterpoise, to be bonded to the counterpoise, which results in a complex interconnected grounding system, given the many metallic piping, raceways, and cable trays that run in multiple directions around LC39B. The complexity of this grounding system makes the fall-of-potential method, which uses multiple metallic rods or stakes, unsuitable for measuring the grounding impedances of the downconductors. To calculate the grounding impedance of the downconductors, an Earth Ground Clamp (EGC) (a stakeless device for measuring grounding impedance) and an Alternative Transient Program (ATP) model of the LPS are used. The EGC is used to measure the loop impedance plus the grounding impedance of each downconductor, and the ATP model is used to calculate the loop impedance of each downconductor circuit. The grounding resistance of the downconductors is then calculated by subtracting the ATP calculated loop impedances from the EGC measurements.

  1. A hemispherically scanning X/Ka band mirror antenna

    Science.gov (United States)

    Hollenbeck, Kurt; Kesler, Oren

    1987-02-01

    Texas Instruments, under contract to Naval Surface Weapons Center (NSWC), have delivered the first proof of concept, prototype X and Ka band Mirror Scanning Antenna to the Navy. This antenna is a candidate for the Navy's new generation of ship self defense weapon systems and culminates over two years of work by Texas Instruments' Antenna Department. Several unique operational features are offered by the Mirror Scanning Antenna. These features include full hemispherical scan coverage, simultaneous X and Ka band dual plane monopulse tracking, rapid scan rates, variable scan modes, high Ka band power handling ability, and an integral weather-tight protective radome.

  2. 基于复数电压分布的波导缝隙天线的改进设计%An improved design method of slotted waveguide antennas based on complex voltage distribution

    Institute of Scientific and Technical Information of China (English)

    石力; 邓云凯

    2011-01-01

    This paper proposes an improved design method of slotted waveguide antennas. Since Elliott's design method for slotted waveguide antennas applies only to the case with real voltage distribution it is incapable of designing slotted waveguide antennas with arbitrary radiation pattern. The improved design method presented and is extends its applications to case of the complex voltage distribution including the effects of mutual coupling. The comparison of results derived by the improved method and the commercial software Ansoft HFSS shows that, the method is accurate and effective.%针对波导缝隙阵列,提出了一种基于复数电压分布的改进的波导缝隙阵列天线的设计方法.针对Elliot对于波导缝隙阵列的设计只适用于实数的电压分布,从而不能设计出有任意形状的方向图的天线的问题,对此方法进行了改进,将其扩展到了任意的复数电压分布,并且考虑了缝隙之间互耦的影响.最后,利用改进的方法设计了一个有16个缝隙的端馈线阵方向图,与商业软件Ansoft HFSS的仿真结果比较,证明了方法的有效性.

  3. A True Metasurface Antenna

    Science.gov (United States)

    Badawe, Mohamed El; Almoneef, Thamer S.; Ramahi, Omar M.

    2016-01-01

    We present a true metasurface antenna based on electrically-small resonators. The resonators are placed on a flat surface and connected to one feed point using corporate feed. Unlike conventional array antennas where the distance between adjacent antennas is half wavelength to reduce mutual coupling between adjacent antennas, here the distance between the radiating elements is electrically very small to affect good impedance matching of each resonator to its feed. A metasurface antenna measuring 1.2λ × 1.2λ and designed to operate at 3 GHz achieved a gain of 12 dBi. A prototype was fabricated and tested showing good agreement between numerical simulations and experimental results. Through numerical simulation, we show that the metasurface antenna has the ability to provide beam steering by phasing all the resonators appropriately.

  4. Antenna subset selection at multi-antenna relay with adaptive modulation

    KAUST Repository

    Choi, Seyeong

    2011-06-01

    In this paper, we proposed several antenna selection schemes for cooperative diversity systems with adaptive transmission. The proposed schemes were based on dual-hop relaying where a relay with multiple-antenna capabilities at reception and transmission is deployed between the source and the destination nodes. We analyzed the performance of the proposed schemes by quantifying the average spectral efficiency and the outage probability. We also investigated the trade-off of performance and complexity by comparing the average number of active antennas, path estimations, and signal-to-noise ratio comparisons of the different proposed schemes. Copyright © 2011 John Wiley & Sons, Ltd.

  5. A curl antenna

    OpenAIRE

    Nakano, Hisamatsu; Okuzawa, Shigeru; Ohishi, Katsumi; Mimaki, Hiroaki; Yamauchi, Junji

    1993-01-01

    A radiation element, designated as a curl antenna, is proposed for a circularly polarized antenna. The radiation characteristics of the curl are numerically analyzed. The gain is approximately 8.4 dB, and the 3-dB axial ratio criterion is 6.7%. Two aspects of curl array antennas are also presented: a decoupling factor between two curls and a circular array antenna consisting of 168 curls. Calculations show how the decoupling factor depends on the relative rotation angle of the two curls. The ...

  6. MASTER TELEVISION ANTENNA SYSTEM.

    Science.gov (United States)

    Rhode Island State Dept. of Education, Providence.

    SPECIFICATIONS FOR THE FURNISHING AND INSTALLATION OF TELEVISION MASTER ANTENNA SYSTEMS FOR SECONDARY AND ELEMENTARY SCHOOLS ARE GIVEN. CONTRACTOR REQUIREMENTS, EQUIPMENT, PERFORMANCE STANDARDS, AND FUNCTIONS ARE DESCRIBED. (MS)

  7. Fast Adaptive Beamforming with Smart Antenna for Radio Frequency Repeater

    Directory of Open Access Journals (Sweden)

    Wang Chaoqun

    2016-01-01

    Full Text Available We present a fast adaptive beamforming null algorithm with smart antenna for Radio Frequency Repeater (RFR. The smart antenna system is realized by a Direction Of Arrival (DOA Estimator, whose output is used by an adaptive beamforming algorithm to shape a suitable radiation pattern of the equivalent antenna; so that the co-channel interference due to retransmitting antenna can be reduced. The proposed adaptive beamforming algorithm, which has been proved by formulaic analysis and simulation, has a lower computation complexity yet better performance.

  8. Canine Distemper Virus (CDV) immune-stimulating complexes (iscoms), but not measles virus iscoms, protect dogs against CDV infection.

    NARCIS (Netherlands)

    P. de Vries (Petra); F.G.C.M. Uytdehaag (Fons); A.D.M.E. Osterhaus (Ab)

    1988-01-01

    textabstractThe potential of immune-stimulating complexes (iscoms), a novel form of antigenic presentation, for the induction of protective immunity against morbillivirus infection was shown by immunizing dogs with canine distemper virus (CDV) iscoms, which contained the fusion (F) protein and a min

  9. Substrate integrated antennas and arrays

    CERN Document Server

    Cheng, Yu Jian

    2015-01-01

    Substrate Integrated Antennas and Arrays provides a single source for cutting-edge information on substrate integrated circuits (SICs), substrate integrated waveguide (SIW) feeding networks, SIW slot array antennas, SIC traveling-wave antennas, SIW feeding antennas, SIW monopulse antennas, and SIW multibeam antennas. Inspired by the author's extensive research, this comprehensive book:Describes a revolutionary SIC-based antenna technique with the potential to replace existing antenna technologiesExamines theoretical and experimental results connected to electrical and mechanical performanceExp

  10. Directional borehole antenna - Theory

    International Nuclear Information System (INIS)

    A directional antenna has been developed for the borehole radar constructed during phase 2 of the Stripa project. The new antenna can determine the azimuth of a strong reflector with an accuracy of about 3 degrees as confirmed during experiments in Stripa, although the ratio of borehole diameter to wavelength is small, about 0.03. The antenna synthesizes the effect of a loop antenna rotating in the borehole from four signals measured in turn by a stationary antenna. These signals are also used to calculate an electric dipole signal and a check sum which is used to examine the function of the system. The theory of directional antennas is reviewed and used to design an antenna consisting of four parallel wires. The radiation pattern of this antenna is calculated using transmission line theory with due regard to polarization, which is of fundamental importance for the analysis of directional data. In particular the multipole expansion of the field is calculated to describe the antenna radiation pattern. Various sources of error, e.g. the effect of the borehole, are discussed and the methods of calibrating the antenna are reviewed. The ambiguity inherent in a loop antenna can be removed by taking the phase of the signal into account. Typical reflectors in rock, e.g. fracture zones an tunnels, may be modelled as simple geometrical structures. The corresponding analysis is described and exemplified on measurements from Stripa. Radar data is nowadays usually analyzed directly on the computer screen using the program RADINTER developed within the Stripa project. An algorithm for automatic estimation of the parameters of a reflector have been tested with some success. The relation between measured radar data and external coordinates as determined by rotational indicators is finally expressed in terms of Euler angles. (au)

  11. Milestones in Broadcasting: Antennas.

    Science.gov (United States)

    Media in Education and Development, 1985

    1985-01-01

    Briefly describes the development of antennas in the prebroadcast era (elevated antenna, selectivity to prevent interference between stations, birth of diplex, directional properties, support structures), as well as technological developments used in long-, medium-, and short-wave broadcasting, VHF/FM and television broadcasting, and satellite…

  12. MEMS Tunable Antennas

    DEFF Research Database (Denmark)

    Barrio, Samantha Caporal Del; Morris, Art; Pedersen, Gert Frølund

    2014-01-01

    Addressing low frequency bands is challenging on small platforms. Tunability is a promising solution to cover the bandwidth required for 4G mobile communication. The work presents two designs and shows that for comparable efficiency and bandwidth, the tunable antenna occupies half the volume...... required by the wide-band antenna....

  13. Experiments with Dipole Antennas

    Science.gov (United States)

    Kraftmakher, Yaakov

    2009-01-01

    Employment of a data-acquisition system for data collection and calculations makes experiments with antennas more convenient and less time consuming. The determined directional patterns of the dipole antennas of different lengths are in reasonable agreement with theory. The enhancement of the signal by using a reflector is demonstrated, and a…

  14. mm-wave antenna

    Science.gov (United States)

    Muhs, H. P.

    1985-07-01

    The present low profile seeker front end's slotted waveguide antenna was primarily developed to investigate the feasibility of the application of standard manufacturing techniques to mm-wave hardware. A dual plane monopulse comparator was constructed to mate with the antenna via integrated packaging techniques. The comparator was fabricated by CAD/CAM milling operations.

  15. Entropy and Fractal Antennas

    OpenAIRE

    Emanuel Guariglia

    2016-01-01

    The entropies of Shannon, Rényi and Kolmogorov are analyzed and compared together with their main properties. The entropy of some particular antennas with a pre-fractal shape, also called fractal antennas, is studied. In particular, their entropy is linked with the fractal geometrical shape and the physical performance.

  16. Annular Planar Monopole Antennas

    OpenAIRE

    Chen, Z. N.; Ammann, Max; Chia, W.Y. W.; See, T.S. P.

    2002-01-01

    A type of annular planar monopole antenna is presented. The impedance and radiation characteristics of the monopole with different holes and feed gaps are experimentally examined. The measured results demonstrate that the proposed antenna is capable of providing significantly broad impedance bandwidth with acceptable radiation performance.

  17. Printed Triband Terminal Antenna

    OpenAIRE

    JOHN, MATTHIAS; Ammann, Max; Farrell, R.

    2005-01-01

    This paper presents a printed triple-band multibranch monopole for use in modern wireless systems. The antenna is designed to operate in three bands which cover virtually all wireless channels. Parameters of the antenna geometry are varied and the effects of these variations on the impedance bandwidth are shown.

  18. Protective efficacy of a Pasteurella haemolytica Serotype A2 outer membrane protein polysaccharide (OMP-PS) complex vaccine in sheep

    International Nuclear Information System (INIS)

    The aim is to study the immunogenicity of the crude and purified OMP-PS complex in conventional sheep and to determine the possible contribution of this candidate antigen to Pasteurella vaccines. This allows improvements of the existing vaccines for an effective control of pneumonic pasteurellosis in small ruminants. The trial has indicated that the purified preparation of OMP-PS complex vaccine was most successful in enhancing the serological response. The complex was immunogenic in adult sheet, with induction of humoral anticapsular antibody in the IHA test and with OMP in immunoblotting. The sera from adult sheep immunized with OMP-PS passively protected mice against A2 challenge. The study has demonstrated that immunity and protection in sheep are not confined to vaccination with live organisms, and that the OMP-PS can act as very effective vaccines in mice and sheep

  19. Handbook of antenna technologies

    CERN Document Server

    Liu, Duixian; Nakano, Hisamatsu; Qing, Xianming; Zwick, Thomas

    2016-01-01

    The Handbook of Antenna Technologies aims to present the rapid development of antenna technologies, particularly in the past two decades, and also showcasing the newly developed technologies and the latest applications. The handbook will provide readers with the comprehensive updated reference information covering theory, modeling and optimization methods, design and measurement, new electromagnetic materials, and applications of antennas. The handbook will widely cover not only all key antenna design issues but also fundamentals, issues related to antennas (transmission, propagation, feeding structure, materials, fabrication, measurement, system, and unique design challenges in specific applications). This handbook will benefit the readers as a full and quick technical reference with a high-level historic review of technology, detailed technical descriptions and the latest practical applications.

  20. Aircraft radar antennas

    Science.gov (United States)

    Schrank, Helmut E.

    1987-04-01

    Many changes have taken place in airborne radar antennas since their beginnings over forty years ago. A brief historical review of the advances in technology is presented, from mechanically scanned reflectors to modern multiple function phased arrays. However, emphasis is not on history but on the state-of-the-art technology and trends for future airborne radar systems. The status of rotating surveillance antennas is illustrated by the AN/APY-1 Airborne Warning and Control System (AWACS) slotted waveguide array, which achieved a significant breakthrough in sidelobe suppression. Gimballed flat plate arrays in nose radomes are typified by the AN/APG-66 (F-16) antenna. Multifunction phased arrays are presented by the Electronically Agile Radar (EAR) antenna, which has achieved significant advances in performance versatility and reliability. Trends toward active aperture, adaptive, and digital beamforming arrays are briefly discussed. Antennas for future aircraft radar systems must provide multiple functions in less aperture space, and must perform more reliably.

  1. Performance Study of Screen-Printed Textile Antennas after Repeated Washing

    Directory of Open Access Journals (Sweden)

    Kazani I.

    2014-06-01

    Full Text Available The stability of wearable textile antennas after 20 reference washing cycles was evaluated by measuring the reflection coefficient of different antenna prototypes. The prototypes’ conductive parts were screen-printed on several textile substrates using two different silver-based conductive inks. The necessity of coating the antennas with a thermoplastic polyurethane (TPU coating was investigated by comparing coated with uncoated antennas. It is shown that covering the antennas with the TPU layer not only protects the screen-printed conductive area but also prevents delamination of the multilayered textile fabric substrates, making the antennas washable for up to 20 cycles. Furthermore, it is proven that coating is not necessary for maintaining antenna operation and this up to 20 washing cycles. However, connector detachment caused by friction during the washing process was the main problem of antenna performance degradation. Hence, other flexible, durable methods should be developed for establishing a stable electrical connection.

  2. RF MEMS Based Reconfigurable Antennas

    Science.gov (United States)

    Simons, Rainee N.

    2004-01-01

    The presentation will first of all address the advantages of RF MEMS circuit in antenna applications and also the need for electronically reconfigurable antennas. Next, discuss some of the recent examples of RF MEMS based reconfigurable microstrip antennas. Finally, conclude the talk with a summary of MEMS antenna performance.

  3. SAR antenna calibration techniques

    Science.gov (United States)

    Carver, K. R.; Newell, A. C.

    1978-01-01

    Calibration of SAR antennas requires a measurement of gain, elevation and azimuth pattern shape, boresight error, cross-polarization levels, and phase vs. angle and frequency. For spaceborne SAR antennas of SEASAT size operating at C-band or higher, some of these measurements can become extremely difficult using conventional far-field antenna test ranges. Near-field scanning techniques offer an alternative approach and for C-band or X-band SARs, give much improved accuracy and precision as compared to that obtainable with a far-field approach.

  4. Optimisation of Microstrip Antenna

    Directory of Open Access Journals (Sweden)

    H. El Hamchary

    1996-04-01

    Full Text Available When choosing the most appropriate microstrip antenna configuration for particular applications, the kind of excitation of the radiating element is an essential factor that requires careful considerations. For controlling the distribution of energy of the linear or planar array of elements and for coupling energy to the individual elements, a wide variety of feed mechanisms are available. In this paper, the coaxial antenna feeding is assumed and the best (optimised feeding is found. Then, antenna characteristics such as radiation pattern, return loss, input impedance, and VSWR are obtained.

  5. Tunable Liquid Dielectric Antenna

    Directory of Open Access Journals (Sweden)

    Kamal Raj Singh Rajoriya

    2012-06-01

    Full Text Available This paper presents on modified the dielectric properties of liquid with varying salinity that was based on monopole structure. Dielectric resonator antennas (DRAs can be made with a wide range of materials and allow many excitation methods [2]. Pure water does not work at high frequency (> 1 GHz but increase in the salinity of water modifies the dielectric properties of water. Here proposed antenna shows that when the salinity increases in form of molar solution, the antenna was tuned at different frequency with increases return loss.

  6. Principles of planar near-field antenna measurements

    CERN Document Server

    Gregson, Stuart; Parini, Clive

    2007-01-01

    This single volume provides a comprehensive introduction and explanation of both the theory and practice of 'Planar Near-Field Antenna Measurement' from its basic postulates and assumptions, to the intricacies of its deployment in complex and demanding measurement scenarios.

  7. Antennas from theory to practice

    CERN Document Server

    Huang, Yi

    2008-01-01

    Practical, concise and complete reference for the basics of modern antenna design Antennas: from Theory to Practice discusses the basics of modern antenna design and theory. Developed specifically for engineers and designers who work with radio communications, radar and RF engineering, this book offers practical and hands-on treatment of antenna theory and techniques, and provides its readers the skills to analyse, design and measure various antennas. Key features: Provides thorough coverage on the basics of transmission lines, radio waves and propag

  8. Department of Energy Nuclear Material Protection, Control, and Accounting Program at the Mangyshlak Atomic Energy Complex, Aktau, Republic of Kazakhstan

    International Nuclear Information System (INIS)

    As part of the Cooperative Threat Reduction Nuclear Material Protection, Control, and Accounting (MPC and A) Program, the US Department of Energy and Mangyshlak Atomic Energy Complex (MAEC), Aktau, Republic of Kazakstan have cooperated to enhance existing MAEC MPC and A features at the BN-350 liquid-metal fast-breeder reactor. This paper describes the methodology of the enhancement activities and provides representative examples of the MPC and A augmentation implemented at the MAEC

  9. Antenna Beam Pattern Modulation with Lattice Reduction Aided Detection

    OpenAIRE

    Ramirez-Gutierrez, R; Zhang, LX; Elmirghani, J

    2015-01-01

    This paper introduces a novel transmission design for antenna beam pattern modulation (ABPM) with a low complexity decoding method. The concept of ABPM was first presented with the optimal maximum likelihood (ML) decoding. However, an ML detector may not be viable for practical systems when the constellation size or the number of antennas is large such as in massive multiple input multiple output (MIMO) systems. Linear detectors, on the other hand, have lower complexity but inferior performan...

  10. Nonlinear plasmonic antennas

    Directory of Open Access Journals (Sweden)

    Shakeeb Bin Hasan

    2014-12-01

    Full Text Available Contrary to traditional optical elements, plasmonic antennas made from nanostructured metals permit the localization of electromagnetic fields on length scales much smaller than the wavelength of light. This results in huge amplitudes for the electromagnetic field close to the antenna being conducive for the observation of nonlinear effects already at moderate pump powers. Thus, these antennas exhibit a promising potential to achieve optical frequency conversion and all-optical control of light at the nano-scale. This opens unprecedented opportunities for ultrafast nonlinear spectroscopy, sensing devices, on-chip optical frequency conversion, nonlinear optical metamaterials, and novel photon sources. Here, we review some of the recent advances in exploiting the potential of plasmonic antennas to realize robust nonlinear applications.

  11. Fractal multiband patch antenna

    OpenAIRE

    Borja, C.; Puente Baliarda, Carles; Romeu Robert, Jordi; Anguera Pros, Jaume

    2000-01-01

    The multiband behaviour of the Sierpinski patch antenna is described in this paper. Experimental results show that the self similarity properties of the fractal shape are translated into its electromagnetic behaviour. Peer Reviewed

  12. Spaceborne distributed SAR antenna

    Science.gov (United States)

    Mckenna, D. B.

    1984-01-01

    The MSAR c-band array panel was developed and tested. Each element of the antenna system is discussed individually as well as collectively. Textual descriptions together with test data are both used to enable a clear understanding of the antenna system performance. In general, test data has confirmed or exceeded expectations. Of particular note is the excellent cross polarization achieved with a field cancelling geometry.

  13. Intelsat VI antenna system

    Science.gov (United States)

    Caulfield, M. F.; Lane, S. O.; Taormina, F. A.

    The antenna system design of a series of five new communications satellites known as Intelsat VI is described in detail. Each satellite will utilize 50 transponders operating in the C and K band portions of the frequency spectrum. The transponders are interconnectible using either static switch matrices or a network which provides satellite switched time division multiple access capability. The antenna coverages, characteristics, and special design features are shown and discussed.

  14. MLS airborne antenna research

    Science.gov (United States)

    Yu, C. L.; Burnside, W. D.

    1975-01-01

    The geometrical theory of diffraction was used to analyze the elevation plane pattern of on-aircraft antennas. The radiation patterns for basic elements (infinitesimal dipole, circumferential and axial slot) mounted on fuselage of various aircrafts with or without radome included were calculated and compared well with experimental results. Error phase plots were also presented. The effects of radiation patterns and error phase plots on the polarization selection for the MLS airborne antenna are discussed.

  15. Wideband Circularly Polarized Dielectric Rod Antenna

    Directory of Open Access Journals (Sweden)

    Min Guo

    2012-01-01

    Full Text Available A new dielectric rod antenna (DRA is introduced to produce circular polarization (CP over a wide frequency band without a complex feed network. Along with the simulated results, measured results of the antenna prototype are presented, showing a 3 dB axial ratio (AR CP bandwidth of 17.7%. The radiation characteristics of the fabricated antenna are also demonstrated showing the measured gain of better than 6.2 dBi. Moreover, the measured impedance bandwidth (VSWR ≤2 reaches 20.1%, from 8.75 GHz to 10.7 GHz, while the CP beamwidth (AR ≤3 dB at the central frequency is measured over 120°.

  16. A ribonucleoprotein complex protects the interleukin-6 mRNA from degradation by distinct herpesviral endonucleases.

    Directory of Open Access Journals (Sweden)

    Mandy Muller

    2015-05-01

    Full Text Available During lytic Kaposi's sarcoma-associated herpesvirus (KSHV infection, the viral endonuclease SOX promotes widespread degradation of cytoplasmic messenger RNA (mRNA. However, select mRNAs escape SOX-induced cleavage and remain robustly expressed. Prominent among these is interleukin-6 (IL-6, a growth factor important for survival of KSHV infected B cells. IL-6 escape is notable because it contains a sequence within its 3' untranslated region (UTR that can confer protection when transferred to a SOX-targeted mRNA, and thus overrides the endonuclease targeting mechanism. Here, we pursued how this protective RNA element functions to maintain mRNA stability. Using affinity purification and mass spectrometry, we identified a set of proteins that associate specifically with the protective element. Although multiple proteins contributed to the escape mechanism, depletion of nucleolin (NCL most severely impacted protection. NCL was re-localized out of the nucleolus during lytic KSHV infection, and its presence in the cytoplasm was required for protection. After loading onto the IL-6 3' UTR, NCL differentially bound to the translation initiation factor eIF4H. Disrupting this interaction, or depleting eIF4H, reinstated SOX targeting of the RNA, suggesting that interactions between proteins bound to distant regions of the mRNA are important for escape. Finally, we found that the IL-6 3' UTR was also protected against mRNA degradation by the vhs endonuclease encoded by herpes simplex virus, despite the fact that its mechanism of mRNA targeting is distinct from SOX. These findings highlight how a multitude of RNA-protein interactions can impact endonuclease targeting, and identify new features underlying the regulation of the IL-6 mRNA.

  17. A ribonucleoprotein complex protects the interleukin-6 mRNA from degradation by distinct herpesviral endonucleases.

    Science.gov (United States)

    Muller, Mandy; Hutin, Stephanie; Marigold, Oliver; Li, Kathy H; Burlingame, Al; Glaunsinger, Britt A

    2015-05-01

    During lytic Kaposi's sarcoma-associated herpesvirus (KSHV) infection, the viral endonuclease SOX promotes widespread degradation of cytoplasmic messenger RNA (mRNA). However, select mRNAs escape SOX-induced cleavage and remain robustly expressed. Prominent among these is interleukin-6 (IL-6), a growth factor important for survival of KSHV infected B cells. IL-6 escape is notable because it contains a sequence within its 3' untranslated region (UTR) that can confer protection when transferred to a SOX-targeted mRNA, and thus overrides the endonuclease targeting mechanism. Here, we pursued how this protective RNA element functions to maintain mRNA stability. Using affinity purification and mass spectrometry, we identified a set of proteins that associate specifically with the protective element. Although multiple proteins contributed to the escape mechanism, depletion of nucleolin (NCL) most severely impacted protection. NCL was re-localized out of the nucleolus during lytic KSHV infection, and its presence in the cytoplasm was required for protection. After loading onto the IL-6 3' UTR, NCL differentially bound to the translation initiation factor eIF4H. Disrupting this interaction, or depleting eIF4H, reinstated SOX targeting of the RNA, suggesting that interactions between proteins bound to distant regions of the mRNA are important for escape. Finally, we found that the IL-6 3' UTR was also protected against mRNA degradation by the vhs endonuclease encoded by herpes simplex virus, despite the fact that its mechanism of mRNA targeting is distinct from SOX. These findings highlight how a multitude of RNA-protein interactions can impact endonuclease targeting, and identify new features underlying the regulation of the IL-6 mRNA. PMID:25965334

  18. GROUP TRANSMIT ANTENNA SELECTION BASED ON GIS TECHNOLOGY FOR V-BLAST SYSTEM

    Institute of Scientific and Technical Information of China (English)

    Zhang Xiaoge; Xu Chengqi

    2008-01-01

    The conventional transmit antenna selection for Vertical Bell Laboratories Layered Space Time (V-BLAST) system is very complex because it needs to compute the inverse of channel matrices time after time. In this paper, a new group transmit antenna selection scheme for V-BLAST system is proposed. The 1st group transmit antennas are decided according to a certain selection criterion among the available antennas. Then, with Group Interference Suppression (GIS) technology, the interferences of the transmit symbols from the selected antennas can be suppressed. Finally, the 2nd group transmit antennas are decided among the residual available antennas. Simulations show that its performance is lower than that of the conventional selection scheme. However, the new selection scheme has lower complexity than the conventional one.

  19. Optical phased arrays with evanescently-coupled antennas

    Science.gov (United States)

    Sun, Jie; Watts, Michael R; Yaacobi, Ami; Timurdogan, Erman

    2015-03-24

    An optical phased array formed of a large number of nanophotonic antenna elements can be used to project complex images into the far field. These nanophotonic phased arrays, including the nanophotonic antenna elements and waveguides, can be formed on a single chip of silicon using complementary metal-oxide-semiconductor (CMOS) processes. Directional couplers evanescently couple light from the waveguides to the nanophotonic antenna elements, which emit the light as beams with phases and amplitudes selected so that the emitted beams interfere in the far field to produce the desired pattern. In some cases, each antenna in the phased array may be optically coupled to a corresponding variable delay line, such as a thermo-optically tuned waveguide or a liquid-filled cell, which can be used to vary the phase of the antenna's output (and the resulting far-field interference pattern).

  20. Reconfigurable Antenna Assisted Intrusion Detection in Wireless Networks

    OpenAIRE

    Prathaban Mookiah; Walsh, John M.; Rachel Greenstadt; Dandekar, Kapil R.

    2013-01-01

    Intrusion detection is a challenging problem in wireless networks due to the broadcast nature of the wireless medium. Physical layer information is increasingly used to protect these vulnerable networks. Meanwhile, reconfigurable antennas are gradually finding their way into wireless devices due to their ability to improve data throughput. In this paper, the capabilities of reconfigurable antennas are used to devise an intrusion detection scheme that operates at the physical layer. The detect...

  1. Two-photon excited fluorescence from higher electronic states of chlorophylls in photosynthetic antenna complexes a new approach to detect strong excitonic chlorophyll a/b coupling

    CERN Document Server

    Leupold, D; Ehlert, J; Irrgang, K D; Renger, G; Lokstein, H

    2002-01-01

    Stepwise two-photon excitation of chlorophyll a and b in the higher plant main light-harvesting complex (LHC II) and the minor complex CP29 (as well as in organic solution) with 100-fs pulses in the Q/sub y/ region results in a weak blue fluorescence. The dependence of the spectral shape of the blue fluorescence on excitation wavelength offers a new approach to elucidate the long-standing problem of the origin of spectral "chlorophyll forms" in pigment-protein complexes, in particular the characterization of chlorophyll a/b-heterodimers. As a first result we present evidence for the existence of strong chlorophyll a/b-interactions (excitonically coupled transitions at 650 and 680 nm) in LHC II at ambient temperature. In comparison with LHC II, the experiments with CP29 provide further evidence that the lowest energy chlorophyll a transition (at ~680 nm) is not excitonically coupled to chlorophyll b. (22 refs).

  2. SANTANA- Smart Antenna Terminal Design

    OpenAIRE

    Liu, Ying

    2006-01-01

    This project is embedded in SANTANA (Smart Antenna Terminal) project. The project goal is to design a Ka-band circularly polarized antenna radiator for the receiver SANTANA system. The research work focuses on two types of circularly polarized antennas: aperture-coupled patch antenna and CPW-fed patch antenna. A two steps design process is used. Firstly, only the antennas and their feed structure are designed and optimized. Secondly, a via-transition to connect to a MMIC layer is added. When ...

  3. Implementation of a complex of measures to fulfill the planetary protection requirements of the ExoMars-2016 mission

    Science.gov (United States)

    Khamidullina, Natalia; Novikova, Nataliya; Deshevaya, Elena; Orlov, Oleg; Guridov, Alexander; Zakharenko, Dmitry; Zaytseva, Olga

    2016-07-01

    The major purpose of the planetary protection program in the ExoMars-2016 mission is to forestall Mars contamination by terrestrial microorganisms. Since Martian descent module is not intended for biological experiments, ExoMars-2016 mission falls under COSPAR category IVa. Within the joint project co-sponsored by ESA and Roscosmos the European side holds full responsibility for ensuring a prescribed level of SC microbiological purity, while the Russian side is charged with compliance of the launch services provided on Baikonur technical complex with the planetary protection requirements that is, specifically, prevention of SC recontamination. To this end, a complex of measures was executed to control microbial contamination of cosmodrome facilities on the prescribed level which included: - regular decontamination of clean rooms using an effective disinfectant and impulse ultraviolet radiation that created favorable conditions for reliable functioning of the ESA clean tent, - replacement of airline filters in the Thermal Conditioning Unit (TCU) air duct for SC conditioning with pure air. The results of microbiological tests performed in the period of 2015 - 2016 lead to the conclusion that the Baikonur clean rooms (ISO class 8), TCU air ducts and Air Thermal Control System (ATCS) at launch site are ready for the launch campaign and that the Russian side fulfilled the planetary protection requirements of the ExoMars-2016 mission.

  4. Development of horn antenna mixer array with internal local oscillator module for microwave imaging diagnostics

    Energy Technology Data Exchange (ETDEWEB)

    Kuwahara, D., E-mail: dkuwahar@cc.tuat.ac.jp [Department of Mechanical Systems Engineering, Tokyo University of Agriculture and Technology, Koganei, Tokyo 184-8588 (Japan); Ito, N. [Department of Intelligent System Engineering, Ube National College of Technology, Ube, Yamaguchi 755-8555 (Japan); Nagayama, Y. [Department of Helical Plasma Research, National Institute for Fusion Science, Toki, Gifu 509-5292 (Japan); Yoshinaga, T. [Department of Applied Physics, National Defense Academy, Yokosuka, Kanagawa 239-0811 (Japan); Yamaguchi, S. [Department of Pure and Applied Physics, Kansai University, Suita, Osaka 564-8680 (Japan); Yoshikawa, M.; Kohagura, J. [Graduate School of Pure and Applied Science, University of Tsukuba, Tsukuba, Ibaraki 305-8577 (Japan); Sugito, S. [Equipment Development Center, Institute for Molecular Science, Okazaki, Aichi 444-8585 (Japan); Kogi, Y. [Department of Information Electronics, Fukuoka Institute of Technology, Fukuoka, Fukuoka 811-0295 (Japan); Mase, A. [Art, Science and Technology Center for Cooperative Research, Kyusyu University, Kasuga, Fukuoka 816-8580 (Japan)

    2014-11-15

    A new antenna array is proposed in order to improve the sensitivity and complexity of microwave imaging diagnostics systems such as a microwave imaging reflectometry, a microwave imaging interferometer, and an electron cyclotron emission imaging. The antenna array consists of five elements: a horn antenna, a waveguide-to-microstrip line transition, a mixer, a local oscillation (LO) module, and an intermediate frequency amplifier. By using an LO module, the LO optics can be removed, and the supplied LO power to each element can be equalized. We report details of the antenna array and characteristics of a prototype antenna array.

  5. Development of horn antenna mixer array with internal local oscillator module for microwave imaging diagnostics.

    Science.gov (United States)

    Kuwahara, D; Ito, N; Nagayama, Y; Yoshinaga, T; Yamaguchi, S; Yoshikawa, M; Kohagura, J; Sugito, S; Kogi, Y; Mase, A

    2014-11-01

    A new antenna array is proposed in order to improve the sensitivity and complexity of microwave imaging diagnostics systems such as a microwave imaging reflectometry, a microwave imaging interferometer, and an electron cyclotron emission imaging. The antenna array consists of five elements: a horn antenna, a waveguide-to-microstrip line transition, a mixer, a local oscillation (LO) module, and an intermediate frequency amplifier. By using an LO module, the LO optics can be removed, and the supplied LO power to each element can be equalized. We report details of the antenna array and characteristics of a prototype antenna array.

  6. Preliminary experimental study of the antenna module for Alfven wave excitation system in TCABR Tokamak

    International Nuclear Information System (INIS)

    The results of the initial experimental studies of the Alfven wave antenna module, which is destined to be a part of the advanced antenna system of TCABR tokamak, are presented. The tests were carried out in a specially constructed vacuum chamber and included the measurement of antenna electrical parameters and testing of the power diagnostic tools. The complex impedances and inductive mutual coupling of antenna loops were measured and results were compared with theoretical calculations. The tests have shown that the parameters of the antenna module have values according to the design. (author)

  7. Development of horn antenna mixer array with internal local oscillator module for microwave imaging diagnostics.

    Science.gov (United States)

    Kuwahara, D; Ito, N; Nagayama, Y; Yoshinaga, T; Yamaguchi, S; Yoshikawa, M; Kohagura, J; Sugito, S; Kogi, Y; Mase, A

    2014-11-01

    A new antenna array is proposed in order to improve the sensitivity and complexity of microwave imaging diagnostics systems such as a microwave imaging reflectometry, a microwave imaging interferometer, and an electron cyclotron emission imaging. The antenna array consists of five elements: a horn antenna, a waveguide-to-microstrip line transition, a mixer, a local oscillation (LO) module, and an intermediate frequency amplifier. By using an LO module, the LO optics can be removed, and the supplied LO power to each element can be equalized. We report details of the antenna array and characteristics of a prototype antenna array. PMID:25430218

  8. Zero-forcing beamforming with receiver antenna selection in downlink multi-antenna multi-user system*

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    A study on the zero-forcing beamforming (ZFBF) scheme with antenna selection at user terminals in downlink multi-antenna multi-user systems is presented. Simulation results show that the proposed ZFBF scheme with receiver antenna selection (ZFBF-AS) achieves considerable throughput improvement over the ZFBF scheme with single receiver antenna. The results also show that, with multi-user diversity, the ZFBF-AS scheme approaches the throughput performance of the ZFBF scheme using all receiver antennas (ZFBF-WO-AS) when the base station adopts semi-orthogonal user selection (SUS) algorithm, and achieves larger throughput when the base station adopts the Round-robin scheduling algorithm. Compared with ZFBF-WO-AS, the proposed ZFBF-AS scheme can reduce the cost of user equipments and the channel state information requirement at the transmitter (CSIT) as well as the multiuser scheduling complexity at the transmitter.

  9. Assessment of Spatial Unevenness of Road Accidents Severity as Instrument of Preventive Protection from Emergency Situations in Road Complex

    Science.gov (United States)

    Petrov, A.; Petrova, D.

    2016-08-01

    Emergency situations in road complex are road traffic accidents (RA) with severe consequences. These are incidents connected with the death and injury of large number of people. The most common reasons for this are the collision of three or more cars, the collision of buses with trains at railroad crossings, the fall of the buses in the mountain gorge, and other similar cases. Is it possible to predict such events? How to build a preventive protection against such emergencies? We have to understand that emergencies in a road complex are qualitative expression of the quantitative processes that characterize the general state of road safety in the region. In this regard, at the level of state monitoring of emergency situations it is important to understand in general - in which region the situation is more complicated and in which is more favorable. This knowledge helps to more efficiently reallocate resources intended to solve the problems of road safety provision. The consequence of this is improvement of the quality of preventive protection from the emergencies in the road complex. The article presents quantitative values of severity of accidents in the Russian Federation regions and the Pareto chart distribution of cumulates of the accident severity for the Russian Federation. On the basis of the complex assessment of the spatial non-uniformity of the accident severity results it offers two important recommendations, implementation of which will alleviate the issue of formation of emergency situations in the road of the Russian Federation on the basis of the complex assessment of the spatial nonuniformity of the accident severity results.

  10. First two ALMA antennas successfully linked

    Science.gov (United States)

    2009-05-01

    a millionth of a second between equipment located many kilometers apart. The extreme environment where the ALMA observatory is located, with its strong winds, high altitude, and wide range of temperatures, just adds to the complexity of the observatory and to the fascinating engineering challenges we face", comments Richard Murowinski, ALMA Project Engineer. The astronomical target in this scientific milestone was the planet Mars. The astronomers measured the distinctive "fringes" -- a regular pattern of alternating strong and weak signals -- detected by the interferometer as the planet moved across the sky. The hardware used in this successful first test included two 12-metre diameter ALMA antennas as well as the complex series of electronic processing components needed to combine the signals. Such pairs of antennas are the basic building blocks of imaging systems that enable radio telescopes to deliver pictures that approach or even exceed the resolving power of visible light telescopes. Each antenna is combined electronically with every other antenna to form a multitude of antenna pairs. Each pair contributes unique information that is used to build a highly detailed image of the astronomical object under observation. When completed in early in the next decade, ALMA's 66 antennas will provide over a thousand such antenna pairings, with distances between antennas up to 16 kilometres. This will enable ALMA to see with a sharpness surpassing that of the best space telescopes, and to complement ground-based optical interferometers such as the ESO Very Large Telescope Interferometer (VLTI). "We are on target to do the first interferometry tests at the 5000-metre high-altitude site by the end of this year, and by the end of 2011 we plan to have at least 16 antennas working together as a single giant telescope," said Thijs de Graauw, ALMA Director. Notes for editors ALMA is a revolutionary astronomical telescope, comprising an array of 66 giant 12-metre and 7-metre

  11. [The health protection of Italian workers abroad: complex and varied but still guaranteed].

    Science.gov (United States)

    Di Lorenzo, Luigi; Corfiati, Marisa; Cassano, Filippo

    2011-01-01

    The employment contracts for Italian working abroad are legally different. So many national laws, European Union (EU) directives and regulations should be applied concerning health and safety at work. This paper is aimed to clarify these features, focusing on their impact on workers' health surveillance. For originally transnational contracts the law applicable is chosen by the parties but in compliance with minimum standards of workers' health protection. An authorization by Italian Labour Minister is also needed for employment in non-EU countries requiring minimum protection conditions. Italian legislation is applied to temporary work abroad. Long-lasting or permanent abroad transfer is regulated as originally transnational work. Workers posted in a EU country should receive the same protection ensured by laws, regulations, collective agreements or arbitrations to resident workers. Health surveillance of workers hired or transferred to work abroad is performed by a occupational physician (OP) operating in the foreign country. Temporary abroad workers undergo health surveillance by the Italian OP. The workplace inspection could be conducted by the OP through audiovisual electronic systems, reserving the on-site visit to particular situations. The host employer is responsible for health surveillance of posted workers entrusted to a local OP. PMID:23393830

  12. Electrochemically Programmable Plasmonic Antennas.

    Science.gov (United States)

    Dong, Shi; Zhang, Kai; Yu, Zhiping; Fan, Jonathan A

    2016-07-26

    Plasmonic antennas are building blocks in advanced nano-optical systems due to their ability to tailor optical response based on their geometry. We propose an electrochemical approach to program the optical properties of dipole antennas in a scalable, fast, and energy-efficient manner. These antennas comprise two arms, one serving as an anode and the other a cathode, separated by a solid electrolyte. As a voltage is applied between the antenna arms, a conductive filament either grows or dissolves within the electrolyte, modifying the antenna load. We probe the dynamics of stochastic filament formation and their effects on plasmonic mode programming using a combination of three-dimensional optical and electronic simulations. In particular, we identify device operation regimes in which the charge-transfer plasmon mode can be programmed to be "on" or "off." We also identify, unexpectedly, a strong correlation between DC filament resistance and charge-transfer plasmon mode frequency that is insensitive to the detailed filament morphology. We envision that the scalability of our electrochemical platform can generalize to large-area reconfigurable metamaterials and metasurfaces for on-chip and free-space applications.

  13. Imaging antenna arrays

    Science.gov (United States)

    Rutledge, D. B.; Muha, M. S.

    1982-01-01

    Many millimeter and far-infrared imaging systems are limited in sensitivity and speed because they depend on a single scanned element. Because of recent advances in planar detectors such as Schottky diodes, superconducting tunnel junctions, and microbolometers, an attractive approach to this problem is a planar antenna array with integrated detectors. A planar line antenna array and optical system for imaging has been developed. The significant advances are a 'reverse-microscope' optical configuration and a modified bow-tie antenna design. In the 'reverse-microscope' configuration, a lens is attached to the bottom of the substrate containing the antennas. Imaging is done through the substrate. This configuration eliminates the troublesome effects of substrate surface waves. The substrate lens has only a single refracting surface, making possible a virtually aplanatic system, with little spherical aberration or coma. The array is characterized by an optical transfer function that is easily measured. An array with 19 dB crosstalk levels between adjacent antennas has been tested and it was found that the array captured 50 percent of the available power. This imaging system was diffraction limited.

  14. Technologies and Applications of Microwave Photonic Antennas

    OpenAIRE

    Y. Yashchyshyn; Chizh, A.; Malyshev, S.; Modelski, J

    2010-01-01

    This paper describes the development of microwave photonic antennas concepts and their applications. The experimental study of the transmitting and receiving photonic antenna are shown. The transmitting photonic antenna consists of photodiode integrated with microstrip E-shaped patch antenna, and receiving photonic antenna consists of laser diode integrated directly with the Vivaldi antenna.

  15. Membrane attachment is key to protecting transducin GTPase activating complex from intracellular proteolysis in photoreceptors

    OpenAIRE

    Gospe, Sidney M.; Sheila A Baker; Kessler, Christopher; Brucato, Martha F.; Winter, Joan R.; Burns, Marie E; Arshavsky, Vadim Y.

    2011-01-01

    The members of the R7 RGS protein sub-family are versatile regulators of G protein signaling throughout the nervous system. Recent studies indicate that they are often found in complexes with membrane anchor proteins which serve as versatile modulators of their activity, intracellular targeting and stability. One striking example is the interplay between the membrane anchor R9AP and the RGS9-1·Gβ5 GTPase activating complex responsible for the rapid inactivation of the G protein transducin in ...

  16. PASS spacecraft antenna technology assessment

    Science.gov (United States)

    Freeland, R. E.

    1990-09-01

    The purpose was to generate estimates of mechanical performance for the classes of spacecraft antenna under construction for application to the Personal Access Satellite System (PASS). These performance data are needed for the support of trade studies involving antenna system development. The classes of antenna considered included: (1) rigid non-deployable antenna structures; (2) mechanical deployable antenna concepts; (3) inflatable deployable antenna concepts; and (4) mesh deployable antenna concepts. The estimates of mechanical performance are presented in terms of structural weight and cost as a function of the reflector size. Estimates of aperture surface precision are presented for a few discrete antenna sizes. The range of reflector size is 1 to 4 meters for non-deployable structures and 2 to 8 meters for deployable structures. The range of reflector surface precision is lambda/30 to lambda/50 for 20 and 30 GHz, respectively.

  17. Hemispheric ultra-wideband antenna.

    Energy Technology Data Exchange (ETDEWEB)

    Brocato, Robert Wesley

    2006-04-01

    This report begins with a review of reduced size ultra-wideband (UWB) antennas and the peculiar problems that arise when building a UWB antenna. It then gives a description of a new type of UWB antenna that resolves these problems. This antenna, dubbed the hemispheric conical antenna, is similar to a conventional conical antenna in that it uses the same inverted conical conductor over a ground plane, but it also uses a hemispheric dielectric fill in between the conductive cone and the ground plane. The dielectric material creates a fundamentally new antenna which is reduced in size and much more rugged than a standard UWB conical antenna. The creation of finite-difference time domain (FDTD) software tools in spherical coordinates, as described in SAND2004-6577, enabled this technological advance.

  18. Dual polarization flat plate antenna

    Science.gov (United States)

    Kelly, Kenneth C.

    Rectangular waveguides with radiating slots are used in groups to form planar array microwave antennas with large apertures and small depth. Such flat plate antennas are widely used on spacecraft and aircraft. Typically, flat plate antennas provide fixed linear polarization. The present paper describes a new flat plate antenna which produces two coincident beams that are distinguished by their orthogonal linear polarizations. The antenna has two ports, one for each of the coicident beams. Completely external to the antenna, connecting a simple network to those terminal ports enables the antenna to provide right circular polarization from one port and left from the other. A different external network enables the antenna to have arbitrarily adjustable polarizations.

  19. Dielectric covered microstrip patch antennas

    Science.gov (United States)

    Sharpe, Lisa M.

    1988-11-01

    Microstrip antennas have many properties that make them suitable for airborne and satellite communications systems. These antennas are low in cost and lightweight. For these reasons, Rome Air Development Center is interested in verifying and augmenting existing design models for these antennas. The theory and results are presented for modeling microstrip antennas that are covered with a sheet of dielectric material. There are several reasons for designing a microstrip antenna covered with a dielectric material. This configuration would allow the modeling of antennas with an integrated radome. A cover layer could possibly be used to support a polarizer; to mount additional antenna elements on top of the cover layer to provide bandwidth enhancements; or to be used as a dual frequency antenna.

  20. An immune stimulating complex (iscom) subunit rabies vaccine protects dogs and mice against street rabies challenge.

    NARCIS (Netherlands)

    M. Fekadu; J.H. Schaddock; J. Ekströ m; A.D.M.E. Osterhaus (Ab); D.W. Sanderlin; B. Sundquist; B. Morein (Bror)

    1992-01-01

    textabstractDogs and mice were immunized with either a rabies glycoprotein subunit vaccine incorporated into an immune stimulating complex (ISCOM) or a commercial human diploid cell vaccine (HDCV) prepared from a Pitman Moore (PM) rabies vaccine strain. Pre-exposure vaccination of mice with two intr

  1. Selective transformations of complex molecules are enabled by aptameric protective groups

    NARCIS (Netherlands)

    Bastian, Andreas A.; Marcozzi, Alessio; Herrmann, Andreas

    2012-01-01

    Emerging trends in drug discovery are prompting a renewed interest in natural products as a source of chemical diversity and lead structures. However, owing to the structural complexity of many natural compounds, the synthesis of derivatives is not easily realized. Here, we demonstrate a conceptuall

  2. Backfire antennas with dipole elements

    DEFF Research Database (Denmark)

    Nielsen, Erik Dragø; Pontoppidan, Knud

    1970-01-01

    A method is set up for a theoretical investigation of arbitrary backfire antennas based upon dipole structures. The mutual impedance between the dipole elements of the antenna is taken into account, and the field radiated due to a surface wave reflector of finite extent is determined by calculating...... the surface current distribution on the reflector plate. Numerical results obtained for Yagi backfire antennas and short-backfire antennas using this theory are compared with experimental results....

  3. Galileo satellite antenna modeling

    Science.gov (United States)

    Steigenberger, Peter; Dach, Rolf; Prange, Lars; Montenbruck, Oliver

    2015-04-01

    The space segment of the European satellite navigation system Galileo currently consists of six satellites. Four of them belong to the first generation of In-Orbit Validation (IOV) satellites whereas the other two are Full Operational Capability (FOC) satellites. High-precision geodetic applications require detailed knowledge about the actual phase center of the satellite and receiver antenna. The deviation of this actual phase center from a well-defined reference point is described by phase center offsets (PCOs) and phase center variations (PCVs). Unfortunately, no public information is available about the Galileo satellite antenna PCOs and PCVs, neither for the IOV, nor the FOC satellites. Therefore, conventional values for the IOV satellite antenna PCOs have been adopted for the Multi-GNSS experiment (MGEX) of the International GNSS Service (IGS). The effect of the PCVs is currently neglected and no PCOs for the FOC satellites are available yet. To overcome this deficiency in GNSS observation modeling, satellite antenna PCOs and PCVs are estimated for the Galileo IOV satellites based on global GNSS tracking data of the MGEX network and additional stations of the legacy IGS network. Two completely independent solutions are computed with the Bernese and Napeos software packages. The PCO and PCV values of the individual satellites are analyzed and the availability of two different solutions allows for an accuracy assessment. The FOC satellites are built by a different manufacturer and are also equipped with another type of antenna panel compared to the IOV satellites. Signal transmission of the first FOC satellite has started in December 2014 and activation of the second satellite is expected for early 2015. Based on the available observations PCO estimates and, optionally PCVs of the FOC satellites will be presented as well. Finally, the impact of the new antenna model on the precision and accuracy of the Galileo orbit determination is analyzed.

  4. Frequency Reconfigurable Hybrid Slot Antenna Using PIN Diodes

    Science.gov (United States)

    Yang, Xiaolin; Sheng, Lili; Lin, Jiancheng; Chen, Gang

    2015-11-01

    This paper introduces a frequency reconfigurable hybrid slot antenna fed by coplanar waveguide (CPW) without complex bias network and DC blocking capacitor chips. In order to add reconfigurablility to the antenna, the PIN diodes are equipped in the slots. The antenna is capable of frequency switching at six different frequency bands between 1.7 GHz to 2.5 GHz, which can be used in multiradio wireless systems, such as DCS-1800, PCS1900, UMTS, Wibro and Bluetooth bands. The simulated and measured return loss, peak gain, together with the radiation patterns are presented and compared. Especially, the radiation patterns are stable at different frequency.

  5. RESEARCH ON INDOOR ELECTROMAGNETIC RADIATION FIELD OF MULTIPLE ANTENNA SYSTEM

    Institute of Scientific and Technical Information of China (English)

    Ma Li; Lu Yanhui; Zou Peng; Zhou Xiaoping

    2012-01-01

    The complexity of the indoor environment brings great challenges to predict the electromagnetic radiation field of multiple antenna systems.Based on the Finite Difference Time Domain (FDTD) algorithm,using the mobile phone shielding device as the multiple antenna systems example,the mobile phone shielding device's indoor electromagnetic radiation field is researched by measurment method and simulation method.The effectivity of prediction method is verified by comparing the prediciton results with the measurment results.About 80% of the error can be controlled less than ±4 dB.The quantitative research has certain guiding significance to the prediction of the multiple antenna systems radio wave propagation.

  6. Hybrid Maritime Satellite Communication Antenna

    DEFF Research Database (Denmark)

    Smith, Thomas Gunst

    is incorporated in a parabolic FSS reflector antenna that is investigated by full-wave analysis tools, and the antenna shows performance comparable to conventional reflector antennas within its frequency band of operation. A planar prototype FSS is manufactured and measured with particular attention to the impact...

  7. China's Largest Radio Antenna System

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    @@ After three-and-half-year efforts, the National Astronomical Observatories at CAS (NAOC) has constructed two arrays of radio antennae: a 50m antenna at Miyun Station in Beijing and a 40m antenna in Kunming, capital of southwest China's Yunnan Province.

  8. Printed MIMO antenna engineering

    CERN Document Server

    Sharawi, Mohammad S

    2014-01-01

    Wireless communications has made a huge leap during the past two decades. The multiple-input-multiple-output (MIMO) technology was proposed in the 1990's as a viable solution that can overcome the data rate limit experienced by single-input-single-output (SISO) systems. This resource is focused on printed MIMO antenna system design. Printed antennas are widely used in mobile and handheld terminals due to their conformity with the device, low cost, good integration within the device elements and mechanical parts, as well as ease of fabrication.A perfect design companion for practicing engineers

  9. Hyperbolic thermal antenna

    CERN Document Server

    Barbillon, Grégory; Biehs, Svend-Age; Ben-Abdallah, Philippe

    2016-01-01

    A thermal antenna is an electromagnetic source which emits in its surrounding, a spatially coherent field in the infrared frequency range. Usually, its emission pattern changes with the wavelength so that the heat flux it radiates is weakly directive. Here, we show that a class of hyperbolic materials, possesses a Brewster angle which is weakly dependent on the wavelength, so that they can radiate like a true thermal antenna with a highly directional heat flux. The realization of these sources could open a new avenue in the field of thermal management in far-field regime.

  10. The Antennae Galaxies

    OpenAIRE

    Karl, Simon

    2012-01-01

    The Antennae galaxies (NGC 4038/39) are the nearest and best-studied major merger of two gas-rich spirals in the local Universe. They are named after the characteristic pair of tidal tails that protrude out of their main galactic disks. Due to their proximity the Antennae are extremely well sampled by modern high-resolution observations over an enormous wavelength range, from radio to X-ray. This allows for a comprehensive multiwavelength approach to the present-day morpholo...

  11. Furlable spacecraft antenna development

    Science.gov (United States)

    Oliver, R. E.; Wilson, A. H.

    1972-01-01

    The development of large furlable spacecraft antennas using conical main reflectors is described. Two basic antenna configurations which utilize conical main reflectors have been conceived and are under development. In the conical-Gregorian configuration each ray experiences two reflections in traveling from the feed center to the aperture plane. In the Quadreflex (four reflection) configuration, each ray experiences four reflections, one at each of two subreflector surfaces and two at the main conical reflector surface. The RF gain measurements obtained from 6-ft and 30-in. models of the conical-Gregorian and Quadreflex concepts respectively were sufficiently encouraging to warrant further development of the concepts.

  12. Non-standard antennas

    CERN Document Server

    Le Chevalier, Francois; Staraj, Robert

    2013-01-01

    This book aims at describing the wide variety of new technologies and concepts of non-standard antenna systems - reconfigurable, integrated, terahertz, deformable, ultra-wideband, using metamaterials, or MEMS,  etc, and how they open the way to a wide range of applications, from personal security and communications to multifunction radars and towed sonars, or satellite navigation systems, with space-time diversity on transmit and receive. A reference book for designers  in this lively scientific community linking antenna experts and signal processing engineers.

  13. Aperture optical antennas

    CERN Document Server

    Wenger, Jerome

    2014-01-01

    This contribution reviews the studies on subwavelength aperture antennas in the optical regime, paying attention to both the fundamental investigations and the applications. Section 2 reports on the enhancement of light-matter interaction using three main types of aperture antennas: single subwavelength aperture, single aperture surrounded by shallow surface corrugations, and subwavelength aperture arrays. A large fraction of nanoaperture applications is devoted to the field of biophotonics to improve molecular sensing, which are reviewed in Section 3. Lastly, the applications towards nano-optics (sources, detectors and filters) are discussed in Section 4.

  14. Antennas fundamentals, design, measurement

    CERN Document Server

    Long, Maurice

    2009-01-01

    This comprehensive revision (3rd Edition) is a senior undergraduate or first-year graduate level textbook on antenna fundamentals, design, performance analysis, and measurements. In addition to its use as a formal course textbook, the book's pragmatic style and emphasis on the fundamentals make it especially useful to engineering professionals who need to grasp the essence of the subject quickly but without being mired in unnecessary detail. This new edition was prepared for a first year graduate course at Southern Polytechnic State University in Georgia. It provides broad coverage of antenna

  15. Wireless Distributed Antenna MIMO

    DEFF Research Database (Denmark)

    2015-01-01

    The present disclosure relates to system applications of multicore optical fibers. One embodiment relates to a base transceiver station for a wireless telecommunication system comprising a plurality of antenna units arranged in a MIMO configuration and adapted for transmission and/or reception of...... radio-frequency signals, an optical transmitter in the form of an electro-optic conversion unit for each of said plurality of antenna units, each electro-optic conversion unit adapted for converting an RF signal into an optical signal, a plurality of a single core optical fibers for guiding the optical...

  16. Square Planar Monopole Antenna

    OpenAIRE

    Ammann, Max

    1999-01-01

    A planar monopole may be realised by replacing the wire element of a conventional monopole with a planar element. In this case, the planar element which is square, is located above a groundplane and fed using an SMA connector as illustrated. The square monopole has a simple geometry and a smaller bandwidth compared to the circular-disc monopole. However, it is still a broadband antenna with a typical impedance bandwidth of 75 % at S band. This broadband antenna shows a constant radiation patt...

  17. Cattle with increased severity of bovine respiratory disease complex exhibit decreased capacity to protect against histone cytotoxicity.

    Science.gov (United States)

    Matera, J A; Wilson, B K; Hernandez Gifford, J A; Step, D L; Krehbiel, C R; Gifford, C A

    2015-04-01

    Bovine respiratory disease complex (BRDC) is the leading cause of morbidity and mortality in feedlot cattle. Significant inflammation and lesions are often observed in lungs of infected cattle. During acute inflammatory responses, histones contribute to mortality in rodents and humans and serum proteins can protect against histone-induced cytotoxicity. We hypothesized that cattle experiencing chronic or fatal cases of BRDC have reduced ability to protect against cytotoxic effects of histones. Serum samples were collected from 66 bull calves at the time of normal feedlot processing procedures. Animals were retrospectively assigned to groups consisting of calves never treated for BRDC (control [CONT]; n = 10), calves treated with antimicrobials once for BRDC (1T; n = 16), calves treated twice for BRDC (2T; n = 13), calves treated 3 times for BRDC (3T; n = 14), or calves treated 4 times for BRDC (4T; n = 13). Samples were also collected each time animals received antimicrobial treatment; animals within a group were further sorted by calves that recovered and calves that died to test histone cytotoxicity. Bovine kidney cells were cultured in duplicate in 96-well plates and exposed to 0 or 50 μg/mL of total histones for 18 h with 1% serum from each animal. Cell viability was assessed by the addition of resazurin for 6 h followed by fluorescent quantification. Fluorescent values from serum alone were subtracted from values obtained for histone treatment for each animal. Serum from CONT, 1T, and 2T at initial processing all exhibited a similar (P > 0.10) response to histone treatment with fluorescent values of -312 ± 557, -1,059 ± 441, and -975 ± 489, respectively. However, 3T and 4T demonstrated an impaired capacity (P < 0.05) to protect against histones (-2,778 ± 471 and -3,026 ± 489) at initial processing when compared to the other groups. When sorted by mortality within group, calves that were treated twice and recovered (-847 ± 331) demonstrated a greater (P

  18. Modern Design of Resonant Edge-Slot Array Antennas

    Science.gov (United States)

    Gosselin, R. B.

    2006-01-01

    Resonant edge-slot (slotted-waveguide) array antennas can now be designed very accurately following a modern computational approach like that followed for some other microwave components. This modern approach makes it possible to design superior antennas at lower cost than was previously possible. Heretofore, the physical and engineering knowledge of resonant edge-slot array antennas had remained immature since they were introduced during World War II. This is because despite their mechanical simplicity, high reliability, and potential for operation with high efficiency, the electromagnetic behavior of resonant edge-slot antennas is very complex. Because engineering design formulas and curves for such antennas are not available in the open literature, designers have been forced to implement iterative processes of fabricating and testing multiple prototypes to derive design databases, each unique for a specific combination of operating frequency and set of waveguide tube dimensions. The expensive, time-consuming nature of these processes has inhibited the use of resonant edge-slot antennas. The present modern approach reduces costs by making it unnecessary to build and test multiple prototypes. As an additional benefit, this approach affords a capability to design an array of slots having different dimensions to taper the antenna illumination to reduce the amplitudes of unwanted side lobes. The heart of the modern approach is the use of the latest commercially available microwave-design software, which implements finite-element models of electromagnetic fields in and around waveguides, antenna elements, and similar components. Instead of building and testing prototypes, one builds a database and constructs design curves from the results of computational simulations for sets of design parameters. The figure shows a resonant edge-slot antenna designed following this approach. Intended for use as part of a radiometer operating at a frequency of 10.7 GHz, this antenna

  19. Ellagic acid protects against arsenic toxicity in isolated rat mitochondria possibly through the maintaining of complex II.

    Science.gov (United States)

    Keshtzar, E; Khodayar, M J; Javadipour, M; Ghaffari, M A; Bolduc, D L; Rezaei, M

    2016-10-01

    Chronic arsenic exposure has been linked to many health problems including diabetes and cancer. In the present study, we assessed the protective effect of ellagic acid (EA) against toxicity induced by arsenic in isolated rat liver mitochondria. Reactive oxygen species (ROS) and mitochondrial membrane potential decline were assayed using dichlorofluorescein diacetate and rhodamine 123, respectively, and dehydrogenase activity obtained by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide conversion assay. Arsenic increased ROS levels and mitochondrial dysfunction, which led to a reduction in mitochondrial total dehydrogenase activity. Mitochondria pretreated with EA exposed to arsenic at various concentrations led to a reversal of ROS production and mitochondrial damage. Our results showed that mitochondria were significantly affected when exposed to arsenic, which resulted in excessive ROS production and mitochondrial membrane disruption. Pretreatment with EA, reduced ROS amounts, mitochondrial damage, and restored total dehydrogenase activity specifically associated with mitochondrial complex II. EA protective characteristics may be accomplished particularly throughout the mitochondrial maintenance either directly by its antioxidant property or indirectly through its maintaining of complex II. These findings also suggest a potential role for EA in treating or preventing mitochondria associated disorders.

  20. Design and Analysis of HJ-1-C Satellite SAR Antenna

    OpenAIRE

    Zheng Shi-kun; Ji You-zhi; Cui Zhao-yun; Fang Yong-gang; Zhou Li-ping

    2014-01-01

    With truss deployable mesh parabolic reflector, the HJ-1-C SAR antenna has complex structure and multiple steps during the deployed processing. The design of the antenna is difficult in terms of deployed reliability and electrical performance. This paper makes intensive research on system, structure and electrical design, and the analysis of mechanical and thermal performance in the actual space conditions is also presented. The successful deploying in orbit and high image quality of the HJ-1...

  1. Hybrid Deployable Foam Antennas and Reflectors

    Science.gov (United States)

    Rivellini, Tommaso; Willis, Paul; Hodges, Richard; Spitz, Suzanne

    2006-01-01

    Hybrid deployable radio antennas and reflectors of a proposed type would feature rigid narrower apertures plus wider adjoining apertures comprising reflective surfaces supported by open-cell polymeric foam structures (see figure). The open-cell foam structure of such an antenna would be compressed for compact stowage during transport. To initiate deployment of the antenna, the foam structure would simply be released from its stowage mechanical restraint. The elasticity of the foam would drive the expansion of the foam structure to its full size and shape. There are several alternatives for fabricating a reflective surface supported by a polymeric foam structure. One approach would be to coat the foam with a metal. Another approach would be to attach a metal film or a metal-coated polymeric membrane to the foam. Yet another approach would be to attach a metal mesh to the foam. The hybrid antenna design and deployment concept as proposed offers significant advantages over other concepts for deployable antennas: 1) In the unlikely event of failure to deploy, the rigid narrow portion of the antenna would still function, providing a minimum level of assured performance. In contrast, most other concepts for deploying a large antenna from compact stowage are of an "all or nothing" nature: the antenna is not useful at all until and unless it is fully deployed. 2) Stowage and deployment would not depend on complex mechanisms or actuators, nor would it involve the use of inflatable structures. Therefore, relative to antennas deployed by use of mechanisms, actuators, or inflation systems, this antenna could be lighter, cheaper, amenable to stowage in a smaller volume, and more reliable. An open-cell polymeric (e.g., polyurethane) foam offers several advantages for use as a compressible/expandable structural material to support a large antenna or reflector aperture. A few of these advantages are the following: 3) The open cellular structure is amenable to compression to a very

  2. Hole burning with pressure and electric field: A window on the electronic structure and energy transfer dynamics of bacterial antenna complexes

    Energy Technology Data Exchange (ETDEWEB)

    Wu, H.M.

    1999-02-12

    Light-harvesting (LH) complexes of cyclic (C{sub n}) symmetry from photosynthetic bacteria are studied using absorption and high pressure- and Stark-hole burning spectroscopies. The B800 absorption band of LH2 is inhomogeneously broadened while the B850 band of LH2 and the B875 band of the LH1 complex exhibit significant homogeneous broadening due to ultra-fast inter-exciton level relaxation. The B800{r_arrow}B850 energy transfer rate of ({approximately}2 ps){sup {minus}1} as determined by hole burning and femtosecond pump-probe spectroscopies, is weakly dependent on pressure and temperature, both of which significantly affect the B800-B850 energy gap. The resilience is theoretically explained in terms of a modified Foerster theory with the spectral overlap provided by the B800 fluorescence origin band and weak vibronic absorption bands of B850. Possible explanations for the additional sub-picosecond relaxation channel of B800 observed with excitation on the blue side of B800 are given. Data from pressure and temperature dependent studies show that the B800 and B850 bacteriochlorophyll a (BChl a) molecules are weakly and strongly excitonically coupled, respectively, which is consistent with the X-ray structure of LH2. The B875 BChl a molecules are also strongly coupled. It is concluded that electron-exchange, in addition to electrostatic interactions, is important for understanding the strong coupling of the B850 and B875 rings. The large linear pressure shifts of {approximately}{minus}0.6 cm{sup {minus}1}/MPa associated with B850 and B875 can serve as important benchmarks for electronic structure calculations.

  3. Functions that Protect Escherichia coli from Tightly Bound DNA-Protein Complexes Created by Mutant EcoRII Methyltransferase.

    Directory of Open Access Journals (Sweden)

    Morgan L Henderson

    Full Text Available Expression of mutant EcoRII methyltransferase protein (M.EcoRII-C186A in Escherichia coli leads to tightly bound DNA-protein complexes (TBCs, located sporadically on the chromosome rather than in tandem arrays. The mechanisms behind the lethality induced by such sporadic TBCs are not well studied, nor is it clear whether very tight binding but non-covalent complexes are processed in the same way as covalent DNA-protein crosslinks (DPCs. Using 2D gel electrophoresis, we found that TBCs induced by M.EcoRII-C186A block replication forks in vivo. Specific bubble molecules were detected as spots on the 2D gel, only when M.EcoRII-C186A was induced, and a mutation that eliminates a specific EcoRII methylation site led to disappearance of the corresponding spot. We also performed a candidate gene screen for mutants that are hypersensitive to TBCs induced by M.EcoRII-C186A. We found several gene products necessary for protection against these TBCs that are known to also protect against DPCs induced with wild-type M.EcoRII (after 5-azacytidine incorporation: RecA, RecBC, RecG, RuvABC, UvrD, FtsK, XerCD and SsrA (tmRNA. In contrast, the RecFOR pathway and Rep helicase are needed for protection against TBCs but not DPCs induced by M.EcoRII. We propose that stalled fork processing by RecFOR and RecA promotes release of tightly bound (but non-covalent blocking proteins, perhaps by licensing Rep helicase-driven dissociation of the blocking M.EcoRII-C186A. Our studies also argued against the involvement of several proteins that might be expected to protect against TBCs. We took the opportunity to directly compare the sensitivity of all tested mutants to two quinolone antibiotics, which target bacterial type II topoisomerases and induce a unique form of DPC. We uncovered rep, ftsK and xerCD as novel quinolone hypersensitive mutants, and also obtained evidence against the involvement of a number of functions that might be expected to protect against quinolones.

  4. Functions that Protect Escherichia coli from Tightly Bound DNA-Protein Complexes Created by Mutant EcoRII Methyltransferase.

    Science.gov (United States)

    Henderson, Morgan L; Kreuzer, Kenneth N

    2015-01-01

    Expression of mutant EcoRII methyltransferase protein (M.EcoRII-C186A) in Escherichia coli leads to tightly bound DNA-protein complexes (TBCs), located sporadically on the chromosome rather than in tandem arrays. The mechanisms behind the lethality induced by such sporadic TBCs are not well studied, nor is it clear whether very tight binding but non-covalent complexes are processed in the same way as covalent DNA-protein crosslinks (DPCs). Using 2D gel electrophoresis, we found that TBCs induced by M.EcoRII-C186A block replication forks in vivo. Specific bubble molecules were detected as spots on the 2D gel, only when M.EcoRII-C186A was induced, and a mutation that eliminates a specific EcoRII methylation site led to disappearance of the corresponding spot. We also performed a candidate gene screen for mutants that are hypersensitive to TBCs induced by M.EcoRII-C186A. We found several gene products necessary for protection against these TBCs that are known to also protect against DPCs induced with wild-type M.EcoRII (after 5-azacytidine incorporation): RecA, RecBC, RecG, RuvABC, UvrD, FtsK, XerCD and SsrA (tmRNA). In contrast, the RecFOR pathway and Rep helicase are needed for protection against TBCs but not DPCs induced by M.EcoRII. We propose that stalled fork processing by RecFOR and RecA promotes release of tightly bound (but non-covalent) blocking proteins, perhaps by licensing Rep helicase-driven dissociation of the blocking M.EcoRII-C186A. Our studies also argued against the involvement of several proteins that might be expected to protect against TBCs. We took the opportunity to directly compare the sensitivity of all tested mutants to two quinolone antibiotics, which target bacterial type II topoisomerases and induce a unique form of DPC. We uncovered rep, ftsK and xerCD as novel quinolone hypersensitive mutants, and also obtained evidence against the involvement of a number of functions that might be expected to protect against quinolones. PMID:25993347

  5. Nitric Oxide Induces Cardiac Protection by Preventing Extracellular Matrix Degradation through the Complex Caveolin-3/EMMPRIN in Cardiac Myocytes.

    Science.gov (United States)

    Cuadrado, Irene; Castejon, Borja; Martin, Ana M; Saura, Marta; Reventun-Torralba, Paula; Zamorano, Jose Luis; Zaragoza, Carlos

    2016-01-01

    Inhibition of Extracellular Matrix degradation by nitric oxide (NO) induces cardiac protection against coronary ischemia/reperfusion (IR). Glycosylation of Extracellular Matrix Metalloproteinase Inducer (EMMPRIN) stimulates enzymatic activation of matrix metalloproteinases (MMPs) in the heart, although the mechanisms leading to EMMPRIN glycosylation are poorly understood. We sought to determine if NO may induce cardiac protection by preventing glycosylation of EMMPRIN in a mouse model of IR. Here we found that Caveolin-3 binds to low glycosylated EMMPRIN (LG-EMMPRIN) in cardiac cells and in the hearts of healthy mice, whereas IR disrupted the complex in nitric oxide synthase 2 (NOS2) knockout (KO) mice. By contrast, the binding was partially restored when mice were fed with an NO donor (DEA-NO) in the drinking water, showing a significant reduction on infarct size (NOS2KO: 34.6±5 vs NOS2KO+DEA-NO: 20.7±9), in expression of matrix metalloproteinases, and cardiac performance was improved (left ventricular ejection fraction (LVEF). NOS2KO: 31±4 vs NOS2KO+DEA-NO: 46±6). The role of Caveolin-3/EMMPRIN in NO-mediated cardiac protection was further assayed in Caveolin-3 KO mice, showing no significant improvement on infarct size (Caveolin-3 KO: 34.8±3 vs Caveolin-3 KO+DEA-NO:33.7±5), or in the expression of MMPs, suggesting that stabilization of the complex Caveolin-3/LG-EMMPRIN may play a significant role in the cardioprotective effect of NO against IR. PMID:27649573

  6. Evolutionary optimization of optical antennas

    CERN Document Server

    Feichtner, Thorsten; Kiunke, Markus; Hecht, Bert

    2012-01-01

    The design of nano-antennas is so far mainly inspired by radio-frequency technology. However, material properties and experimental settings need to be reconsidered at optical frequencies, which entails the need for alternative optimal antenna designs. Here a checkerboard-type, initially random array of gold cubes is subjected to evolutionary optimization. To illustrate the power of the approach we demonstrate that by optimizing the near-field intensity enhancement the evolutionary algorithm finds a new antenna geometry, essentially a split-ring/two-wire antenna hybrid which surpasses by far the performance of a conventional gap antenna by shifting the n=1 split-ring resonance into the optical regime.

  7. Antenna theory analysis and design

    CERN Document Server

    Balanis, Constantine A

    2005-01-01

    The discipline of antenna theory has experienced vast technological changes. In response, Constantine Balanis has updated his classic text, Antenna Theory, offering the most recent look at all the necessary topics. New material includes smart antennas and fractal antennas, along with the latest applications in wireless communications. Multimedia material on an accompanying CD presents PowerPoint viewgraphs of lecture notes, interactive review questions, Java animations and applets, and MATLAB features. Like the previous editions, Antenna Theory, Third Edition meets the needs of e

  8. Community Antenna Television (CATV).

    Science.gov (United States)

    Federal Communications Commission, Washington, DC.

    The number of households hooked up to cable television or community antenna television (CATV) is expanding rapidly, and Federal Communications Commission (FCC) has been developing regulations since 1962 to guide the growth of the industry. By 1965 the FCC had claimed jurisdiction over all CATV systems in the U. S. This jurisdiction was challenged…

  9. Frequency scanning microstrip antennas

    DEFF Research Database (Denmark)

    Danielsen, Magnus; Jørgensen, Rolf

    1979-01-01

    The principles of using radiating microstrip resonators as elements in a frequency scanning antenna array are described. The resonators are cascade-coupled. This gives a scan of the main lobe due to the phase-shift in the resonator in addition to that created by the transmission line phase...

  10. Passive Microwave Components and Antennas

    DEFF Research Database (Denmark)

    State-of-the-art microwave systems always require higher performance and lower cost microwave components. Constantly growing demands and performance requirements of industrial and scientific applications often make employing traditionally designed components impractical. For that reason, the design...... and development process remains a great challenge today. This problem motivated intensive research efforts in microwave design and technology, which is responsible for a great number of recently appeared alternative approaches to analysis and design of microwave components and antennas. This book highlights...... techniques. Modelling and computations in electromagnetics is a quite fast-growing research area. The recent interest in this field is caused by the increased demand for designing complex microwave components, modeling electromagnetic materials, and rapid increase in computational power for calculation...

  11. Design of an Airborne Complex-structural Wideband Flush-mounted Antenna%一种可齐平安装的机载复合结构宽带天线的设计

    Institute of Scientific and Technical Information of China (English)

    陈爱新; 姜铁华; 苏东林; 魏文轩; 张艳君; 闫伟

    2011-01-01

    In this paper, a wideband ultra-high frequency (UHF) antenna which can be flush-mounted is designed. The antenna is composed of three parts: the cavity-backed discone antenna, the short-circuited structure between the top plate of the discone and ground, and the multi-plate antenna. These parts respectively generate medium, Iow and high resonance frequencies, thus widening the bandwidth of antenna efficiently. The influences of primary structural parameters on the resonance frequencies and impendence bandwidth are analyzed, then the optimal values are given, and the prototype with optimal parameters is fabricated. The measurement results show that the impedance bandwidth of VSWR≤2. 5 achieves 65%,covering a frequency range from 430 MHz to 845 MHz, and the antenna has omni-directional patterns. Meanwhile, the antenna has very Iow profile; the overall height of it is less than one tenth of the largest operating wavelength of the antenna. This antenna has great potential in practical applications to aircrafts and vessels where flush-mounted antennas are required.%设计了一种可齐平安装的宽带超高频(UHF)天线.该天线由含有背腔结构的盘锥天线、盘锥顶盘与地板之间的短路结构、以及多板天线3个部分复合而成.这3个部分分别在频率的中端、低端和高端产生3个邻近的独立谐振点,从而有效地展宽了天线的工作带宽.分析了天线各主要结构参数对谐振频点和阻抗带宽的影响,给出了这些参数的最优值,并据此制作了天线样机.测试结果表明,设计的天线在430~845 MHz的频带内,驻波比小于2.5.相对带宽为65%,辐射方向图水平全向.同时,该天线具有低剖面结构,整体高度小于最大工作波长的十分之一,在要求齐平安装的飞机和舰船等平台上具有广泛的应用前景.

  12. Kinetic modeling of exciton migration in photosynthetic systems. 2. Simulations of excitation dynamics in two-dimensional photosystem I core antenna/reaction center complexes.

    Science.gov (United States)

    Trinkunas, G; Holzwarth, A R

    1994-02-01

    Kinetic modeling of the exciton migration in the cyanobacterial photosystem I core complex from Synechococcus sp. was performed by an exact solution of the Pauli master equation for exciton motion. A square two-dimensional 10 x 10 pigment lattice and a Förster dipole-dipole coupling between chromophores was assumed. We calculated decay-associated spectra and lifetimes and compared them to the corresponding experimental data from picosecond fluorescence and transient absorption obtained by global analysis. Seven spectral chlorophyll(Chl) forms, identical in shape but shifted in their absorption maximums, were used to describe the non-homogeneous broadening of the PS I-100 particle absorption spectrum. The optimized Chl lattice arrangement best reproducing the experimental decay-associated spectra as well as the steady-state fluorescence spectrum indicated the long-wavelength-absorbing Chls forming a cluster in the corner of the lattice with the reaction center (RC) placed apart at a distance of two lattice constants. The variable parameters, i.e., the charge separation rate in the RC and the lattice constant a, were found to be optimal at kRC = 2.3 ps-1 and a = 1.14 nm, respectively. The surprising conclusions of the simulations is that Chls with absorption maxima as long a 724 nm have to be taken into account to describe the time-resolved spectra of this PS I particle properly. The dependencies of the exciton decay in the model PS I particle on the excitation wavelength and on the temperature are discussed. We also show that the excited state decay of similar PS I particles that lack the long-wavelength absorbing Chls is nearly mono-exponential. Various critical factors that limit the general reliability of the conclusions of such simulations are discussed in detail. PMID:8161695

  13. Protective Effects of Vitamin E against Oxidative Damage Induced by Aβ1-40Cu(Ⅱ) Complexes

    Institute of Scientific and Technical Information of China (English)

    Xueling DAI; Yaxuan SUN; Zhaofeng JIANG

    2007-01-01

    β-amyloid peptide (Aβ) is considered to be responsible for the formation of senile plaques,which is the hallmark of Alzheimer's disease (AD). Oxidative stress, manifested by protein oxidation and lipid peroxidation, among other alterations, is a characteristic of AD brain. A growing body of evidence has been presented in support of Aβ1-40 forming an oligomeric complex that binds copper at a CuZn superoxide dismutase-like binding site. Aβ1-40Cu(Ⅱ) complexes generate neurotoxic hydrogen peroxide (H2O2) from O2 via Cu2+ reduction, though the precise reaction mechanism is unclear. Thc toxicity of Aβ1-40 or the Aβ1-40Cu(Ⅱ)complexes to cultured primary cortical neurons was partially attenuated when (+)-α-tocopherol (vitamin E)as free radical antioxidant was added at a concentration of 100 μM. The data derived from lactate dehydrogenase (LDH) release and the formation of H2O2 confirmed the results from the MTT assay. These findings indicate that copper binding to Aβ1-40 can give rise to greater production of H2O2, which leads to a breakdown in the integrity of the plasma membrane and subsequent neuronal death. Groups treated with vitamin E exhibited much slighter damage, suggesting that vitamin E plays a key role in protecting neuronal cells from dysfunction or death.

  14. The Uve1 endonuclease is regulated by the white collar complex to protect cryptococcus neoformans from UV damage.

    Directory of Open Access Journals (Sweden)

    Surbhi Verma

    Full Text Available The pathogenic fungus Cryptococcus neoformans uses the Bwc1-Bwc2 photoreceptor complex to regulate mating in response to light, virulence and ultraviolet radiation tolerance. How the complex controls these functions is unclear. Here, we identify and characterize a gene in Cryptococcus, UVE1, whose mutation leads to a UV hypersensitive phenotype. The homologous gene in fission yeast Schizosaccharomyces pombe encodes an apurinic/apyrimidinic endonuclease acting in the UVDE-dependent excision repair (UVER pathway. C. neoformans UVE1 complements a S. pombe uvde knockout strain. UVE1 is photoregulated in a Bwc1-dependent manner in Cryptococcus, and in Neurospora crassa and Phycomyces blakesleeanus that are species that represent two other major lineages in the fungi. Overexpression of UVE1 in bwc1 mutants rescues their UV sensitivity phenotype and gel mobility shift experiments show binding of Bwc2 to the UVE1 promoter, indicating that UVE1 is a direct downstream target for the Bwc1-Bwc2 complex. Uve1-GFP fusions localize to the mitochondria. Repair of UV-induced damage to the mitochondria is delayed in the uve1 mutant strain. Thus, in C. neoformans UVE1 is a key gene regulated in response to light that is responsible for tolerance to UV stress for protection of the mitochondrial genome.

  15. FAILURE CORRECTION OF LINEAR ARRAY ANTENNA WITH MULTIPLE NULL PLACEMENT USING CUCKOO SEARCH ALGORITHM

    OpenAIRE

    Muralidaran, R.; A. Vallavaraj; Hemant Patidar; Mahanti, G. K.

    2014-01-01

    The influence of evolutionary algorithms enhanced its scope of getting its existence in almost every complex optimization problems. In this paper, cuckoo search algorithm, an algorithm based on the brood parasite behavior along with Levy weights has been proposed for the radiation pattern correction of a linear array of isotropic antennas with uniform spacing when failed with more than one antenna element. Even though deterioration produced by the failure of antenna elements results in variou...

  16. Protection of metal artefacts with the formation of metal-oxalates complexes by Beauveria bassiana.

    Directory of Open Access Journals (Sweden)

    Edith eJoseph

    2012-01-01

    Full Text Available Several fungi present high tolerance to toxic metals and some are able to transform metals into metal-oxalate complexes. In this study, the ability of Beauveria bassiana to produce copper oxalates was evaluated in vitro. Growth performance was tested on various copper-containing media. B. bassiana proved highly resistant to copper, tolerating concentrations of up to 20 g.L-1, and precipitating copper oxalates on all media tested. Chromatographic analyses showed that this species produced oxalic acid as sole metal chelator. The production of metal-oxalates can be used in the restoration and conservation of archaeological and modern metal artefacts. The production of copper-oxalates was confirmed directly using metallic pieces (both archaeological and modern. The conversion of corrosion products into copper oxalates was demonstrated as well. In order to assess whether the capability of B. bassiana to produce metal-oxalates could be applied to other metals, iron and silver were tested as well. Iron appears to be directly sequestered in the wall of the fungal hyphae forming oxalates and probably goethite. However, the formation of a homogeneous layer on the object is not yet optimal. Silver nitrate was extracellularly reduced into nanoparticles of elemental silver by an unknown mechanism. The production of copper oxalates is immediately applicable for the conservation of copper-based artefacts. For iron and silver this is not yet the case. However, the vast ability of B. bassiana to transform toxic metals using different immobilization mechanisms seems to offer considerable possibilities for industrial applications, such as the bioremediation of contaminated soils or the green synthesis of chemicals.

  17. Protection of Metal Artifacts with the Formation of Metal-Oxalates Complexes by Beauveria bassiana.

    Science.gov (United States)

    Joseph, Edith; Cario, Sylvie; Simon, Anaële; Wörle, Marie; Mazzeo, Rocco; Junier, Pilar; Job, Daniel

    2011-01-01

    Several fungi present high tolerance to toxic metals and some are able to transform metals into metal-oxalate complexes. In this study, the ability of Beauveria bassiana to produce copper oxalates was evaluated. Growth performance was tested on various copper-containing media. B. bassiana proved highly resistant to copper, tolerating concentrations of up to 20 g L(-1), and precipitating copper oxalates on all media tested. Chromatographic analyses showed that this species produced oxalic acid as sole metal chelator. The production of metal-oxalates can be used in the restoration and conservation of archeological and modern metal artifacts. The production of copper oxalates was confirmed directly using metallic pieces (both archeological and modern). The conversion of corrosion products into copper oxalates was demonstrated as well. In order to assess whether the capability of B. bassiana to produce metal-oxalates could be applied to other metals, iron and silver were tested as well. Iron appears to be directly sequestered in the wall of the fungal hyphae forming oxalates. However, the formation of a homogeneous layer on the object is not yet optimal. On silver, a co-precipitation of copper and silver oxalates occurred. As this greenish patina would not be acceptable on silver objects, silver reduction was explored as a tarnishing remediation. First experiments showed the transformation of silver nitrate into nanoparticles of elemental silver by an unknown extracellular mechanism. The production of copper oxalates is immediately applicable for the conservation of copper-based artifacts. For iron and silver this is not yet the case. However, the vast ability of B. bassiana to transform toxic metals using different immobilization mechanisms seems to offer considerable possibilities for industrial applications, such as the bioremediation of contaminated soils or the green synthesis of chemicals. PMID:22291684

  18. 47 CFR 80.863 - Antenna system.

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false Antenna system. 80.863 Section 80.863... Antenna system. (a) An antenna system must be installed which is as nondirectional and as efficient as is... construction of the required antenna must insure operation in time of emergency. (b) If the required antenna...

  19. 47 CFR 80.866 - Spare antenna.

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false Spare antenna. 80.866 Section 80.866... Spare antenna. A spare transmitting antenna completely assembled for immediate erection must be provided. If the installed transmitting antenna is suspended between supports, this spare antenna must be...

  20. Analysis and design of plasma monopole antenna

    OpenAIRE

    Wei, Li; Jinghui, Qiu; Ying, Suo

    2009-01-01

    Two kinds of plasma monopole antennas are simulated and analyzed in this article. For different radius, reflection coefficient, radiation pattern and radiation efficiency of a cylindrical plasma monopole antenna are calculated respectively. According to actual situation, a conical plasma monopole antenna with different cone angle is simulated. Impedance and radiation characteristics of the plasma antenna are similar to the metal monopole antenna.

  1. Major histocompatibility complex class I molecules protect motor neurons from astrocyte-induced toxicity in amyotrophic lateral sclerosis.

    Science.gov (United States)

    Song, SungWon; Miranda, Carlos J; Braun, Lyndsey; Meyer, Kathrin; Frakes, Ashley E; Ferraiuolo, Laura; Likhite, Shibi; Bevan, Adam K; Foust, Kevin D; McConnell, Michael J; Walker, Christopher M; Kaspar, Brian K

    2016-04-01

    Astrocytes isolated from individuals with amyotrophic lateral sclerosis (ALS) are toxic to motor neurons (MNs) and play a non-cell autonomous role in disease pathogenesis. The mechanisms underlying the susceptibility of MNs to cell death remain unclear. Here we report that astrocytes derived from either mice bearing mutations in genes associated with ALS or human subjects with ALS reduce the expression of major histocompatibility complex class I (MHCI) molecules on MNs; reduced MHCI expression makes these MNs susceptible to astrocyte-induced cell death. Increasing MHCI expression on MNs increases survival and motor performance in a mouse model of ALS and protects MNs against astrocyte toxicity. Overexpression of a single MHCI molecule, HLA-F, protects human MNs from ALS astrocyte-mediated toxicity, whereas knockdown of its receptor, the killer cell immunoglobulin-like receptor KIR3DL2, on human astrocytes results in enhanced MN death. Thus, our data indicate that, in ALS, loss of MHCI expression on MNs renders them more vulnerable to astrocyte-mediated toxicity. PMID:26928464

  2. About negative influence of complex tests on sites on biosphere and about necessity of suffered citizens protection

    International Nuclear Information System (INIS)

    Population living nearby of Kapustin Yar and atomic Azgir sites belonging to Russia and situated in West Kazakhstan and Atyrau oblasts more than half of the century is suffering from nuclear, rocket and other tests. There were 45 nuclear explosions carried out on these sites, 24,000 missiles were launched, and 177 different weapons samples were tested. In the result of these complex tests significant part of the region territory was polluted with products of nuclear explosions, heavy metals, toxic elements and the great damage to health of people is inflicted. In number of districts of the region there is crisis ecological situation: significantly growth of number of diseases and mortality of people, especial in infancy age; decrease of birth-rate; increasing of birth of children with abnormals. However suffered citizens of the region socially does not protected yet. So far there is not corresponding laws of Republic of Kazakhstan on social protection of population suffered because of nuclear, missile, and other weapons tests on Kapustin Yar and Azgir sites

  3. Complexity

    CERN Document Server

    Gershenson, Carlos

    2011-01-01

    The term complexity derives etymologically from the Latin plexus, which means interwoven. Intuitively, this implies that something complex is composed by elements that are difficult to separate. This difficulty arises from the relevant interactions that take place between components. This lack of separability is at odds with the classical scientific method - which has been used since the times of Galileo, Newton, Descartes, and Laplace - and has also influenced philosophy and engineering. In recent decades, the scientific study of complexity and complex systems has proposed a paradigm shift in science and philosophy, proposing novel methods that take into account relevant interactions.

  4. Omnidirectional Circularly Polarized Antennas – a Small Antenna Perspective

    OpenAIRE

    Narbudowicz, Adam; Ammann, Max

    2015-01-01

    The paper discusses recent developments and challenges in the design of small omnidirectionalcircularly-polarized (CP) antennas. Although omnidirectional CP coverage is easily achievable usingantenna arrays, it is just recently that small and low-cost antennas delivered this functionality.The paper addresses practical design problems for these antennas, not reported in previous publications.This includes selection of the omnidirectional plane relative to the ground plane and measurement chall...

  5. Numerical analysis of patch antenna as antenna array element

    OpenAIRE

    Kizimenko, V.; Bobkov, Y

    2009-01-01

    The patch antennas as antenna array element can be modeling by finite element method (programs Microwave Office, Ansoft HFSS and other). But this method need to use fast computer with memory large size. In this work the authors make an attempt to use thin wire integral equation method for patch antenna analysis. The results of modeling by proposed method are compared with the same of modeling by finite elements method and experimental results.

  6. MULTILAYER MICROSTRIP ANTENNA QUALITY FACTOR OPTIMIZATION FOR BANDWIDTH ENHANCEMENT

    Directory of Open Access Journals (Sweden)

    M.C. SRIVASTAVA

    2012-12-01

    Full Text Available The impedance bandwidth, one of the important characteristics of microstrip patch antennas, can be significantly improved by using a multilayer dielectric configuration. In this paper the focus is on bandwidth enhancement technique of a multilayer patch antenna for X-band applications. In order to enhance the bandwidth, antenna losses are contained by controlling those quality factors which can have a significant impact on the bandwidth for a given permittivity and thickness of the substrate. This has been achieved by conformal transformation of the multidielectric microstrip antenna. For the ease of analysis Wheelers transformation is used to map the complex permittivity of a multilayer substrate to a single layer. Method of Moments and Finite Difference Time Domain approaches are used for the computation of results.

  7. Design and Analysis of HJ-1-C Satellite SAR Antenna

    Directory of Open Access Journals (Sweden)

    Zheng Shi-kun

    2014-06-01

    Full Text Available With truss deployable mesh parabolic reflector, the HJ-1-C SAR antenna has complex structure and multiple steps during the deployed processing. The design of the antenna is difficult in terms of deployed reliability and electrical performance. This paper makes intensive research on system, structure and electrical design, and the analysis of mechanical and thermal performance in the actual space conditions is also presented. The successful deploying in orbit and high image quality of the HJ-1-C satellite indicate that the mechanical, electronic, thermal and reliability design of the antenna satisfy the project requirement, and these research provides valuable experience for the design of the centralized mesh parabolic SAR antenna.

  8. Measurement of rf voltages on the plasma-touching surfaces of ICRF antennas

    International Nuclear Information System (INIS)

    Measurements of the rf voltages on Faraday shields and protection bumpers have been made for several loop antennas, including the mock-up antenna and Al for JET, the original antenna for Tore Supra, the present ASDEX-U antenna, and the folded waveguide. The loop antennas show voltages that scale to ∼12 kV for a maximum input voltage of 30 kV with 0/0 phasing. The voltages are dramatically reduced for 0/π phasing. These voltages are significant in that they can substantially increase the rf sheath potential beyond the levels associated with the simple electromagnetic field linkage from the current straps that results in plasma heating. In this paper, we investigate and measure the source of these voltages, their scaling with antenna impedance, and the differences between the loop arrays

  9. Microsecond switchable thermal antenna

    Energy Technology Data Exchange (ETDEWEB)

    Ben-Abdallah, Philippe, E-mail: pba@institutoptique.fr; Benisty, Henri; Besbes, Mondher [Laboratoire Charles Fabry, UMR 8501, Institut d' Optique, CNRS, Université Paris-Sud 11, 2, Avenue Augustin Fresnel, 91127 Palaiseau Cedex (France)

    2014-07-21

    We propose a thermal antenna that can be actively switched on and off at the microsecond scale by means of a phase transition of a metal-insulator material, the vanadium dioxide (VO{sub 2}). This thermal source is made of a periodically patterned tunable VO{sub 2} nanolayer, which support a surface phonon-polariton in the infrared range in their crystalline phase. Using electrodes properly registered with respect to the pattern, the VO{sub 2} phase transition can be locally triggered by ohmic heating so that the surface phonon-polariton can be diffracted by the induced grating, producing a highly directional thermal emission. Conversely, when heating less, the VO{sub 2} layers cool down below the transition temperature, the surface phonon-polariton cannot be diffracted anymore so that thermal emission is inhibited. This switchable antenna could find broad applications in the domain of active thermal coatings or in those of infrared spectroscopy and sensing.

  10. Antennas on circular cylinders

    DEFF Research Database (Denmark)

    Knudsen, H. L.

    1959-01-01

    antenna in a circular cylinder. By a procedure similar to the one used by Silver and Saunders, expressions have been derived for the field radiated from an arbitrary surface current distribution on a cylinder surface coaxial with a perfectly conducting cylinder. The cases where the space between the two......On the basis of the results obtained by Silver and Saunders [4] for the field radiated from an arbitrary slot in a perfectly conducting circular cylinder, expressions have been derived for the field radiated by a narrow helical slot, with an arbitrary aperture field distribution, in a circular...... cylindrical surfaces have the sane characteristic constants and different constants are treated separately. Extensive numerical computations of the field radiated from the slot antennas described here are being carried out, but no numerical results are yet available...

  11. Antenna structure with distributed strip

    Science.gov (United States)

    Rodenbeck, Christopher T.

    2008-03-18

    An antenna comprises electrical conductors arranged to form a radiating element including a folded line configuration and a distributed strip configuration, where the radiating element is in proximity to a ground conductor. The folded line and the distributed strip can be electrically interconnected and substantially coplanar. The ground conductor can be spaced from, and coplanar to, the radiating element, or can alternatively lie in a plane set at an angle to the radiating element. Embodiments of the antenna include conductor patterns formed on a printed wiring board, having a ground plane, spacedly adjacent to and coplanar with the radiating element. Other embodiments of the antenna comprise a ground plane and radiating element on opposed sides of a printed wiring board. Other embodiments of the antenna comprise conductors that can be arranged as free standing "foils". Other embodiments include antennas that are encapsulated into a package containing the antenna.

  12. Microstrip antenna theory and design

    Science.gov (United States)

    James, J. R.; Hall, P. S.; Wood, C.

    Microstrip is the name given to a type of open waveguiding structure which is now commonly used in present-day electronics, not only as a transmission line but for circuit components such as filters, couplers, and resonators. The idea of using microstrip to construct antennas is a much more recent development. The purpose of this monograph is to present the reader with an appreciation of useful antenna design approaches and the overall state-of-the art situation. Flat-plate antenna techniques and constraints on performance are considered along with microstrip design equations and data, the radiation mechanism of an open-circuit microstrip termination and the resulting design implications, the basic methods of calculation and design of patch antennas, and linear array techniques. Attention is also given to techniques and design limitations in two-dimensional arrays, circular polarization techniques, manufacturing and operational problems of microstrip antennas, recent advances in microstrip antenna analysis, and possible future developments.

  13. A Compact UWB Diversity Antenna

    Directory of Open Access Journals (Sweden)

    Hui Zhao

    2014-01-01

    Full Text Available A compact printed ultrawideband (UWB diversity antenna with a size of 30 mm × 36 mm operating at a frequency range of 3.1–10.6 GHz is proposed. The antenna is composed of two semielliptical monopoles fed by two microstrip lines. Two semicircular slots, two rectangular slots, and one stub are introduced in the ground plane to adjust the impedance bandwidth of the antenna and improve the isolation between two feeding ports. The simulated and measured results show that impedance bandwidth of the proposed antenna can cover the whole UWB band with a good isolation of < −15 dB. The radiation patterns, peak antenna gain, and envelope correlation coefficient are also measured and discussed. The measured results show that the proposed antenna can be a good candidate for some portable MIMO/diversity UWB applications.

  14. A distributed array antenna system

    Science.gov (United States)

    Shaw, R.; Kovitz, J.

    1986-01-01

    The Space Station communication system will use microwave frequency radio links to carry digitized information from sender to receiver. The ability of the antenna system to meet stringent requirements on coverage zones, multiple users, and reliability will play an important part in the overall multiple access communication system. This paper will describe the configuration of a multibeam conformal phased array antenna and the individual microwave integrated components incoporated into this antenna system.

  15. Broadband Loaded Cylindrical Monopole Antenna

    OpenAIRE

    Boucher, Solene; Sharaiha, Ala; Potier, Patrick

    2013-01-01

    Ahstract-A broadband printed monopole antenna based on the variation of the conductivity along its length is proposed .. The result indicates that a non-monotonous repartition provides interesting performances in terms of impedance bandwidth but also concerning antenna gain. The achievement of the method is demonstrated through its application, using the carbon fibers to perform this conductivity variation. Monopole antenna presents a large impedance bandwidth of 123% with an interesting gain...

  16. Spiral Microstrip Antenna with Resistance

    Science.gov (United States)

    Shively, David G. (Inventor)

    1998-01-01

    A spiral microstrip antenna having resistor elements embedded in each of the spiral arms is provided. The antenna is constructed using a conductive back plane as a base. The back plane supports a dielectric slab having a thickness between one-sixteenth and one-quarter of an inch. A square spiral, having either two or four arms, is attached to the dielectric slab. Each arm of the spiral has resistor elements thereby dissipating an excess energy not already emitted through radiation. The entire configuration provides a thin, flat, high gain, wide bandwidth antenna which requires no underlying cavity. The configuration allows the antenna to be mounted conformably on an aircraft surface.

  17. UWB Directive Triangular Patch Antenna

    Directory of Open Access Journals (Sweden)

    A. C. Lepage

    2008-01-01

    Full Text Available Compact directive UWB antennas are presented in this paper. We propose an optimization of the F-probe fed triangular patch antenna. The new design achieves an impedance bandwidth of 69% (3–6.15 GHz and presents good radiation characteristics over the whole impedance bandwidth. The average gain is 6.1 dB. A time-domain study has been performed to characterize the antenna behavior in case a UWB pulse is used. Finally, we propose an alternative solution to facilitate the manufacturing process using metallized foam technology. It also improves the robustness of the antenna as well as reducing its cost.

  18. Antenna arrays a computational approach

    CERN Document Server

    Haupt, Randy L

    2010-01-01

    This book covers a wide range of antenna array topics that are becoming increasingly important in wireless applications, particularly in design and computer modeling. Signal processing and numerical modeling algorithms are explored, and MATLAB computer codes are provided for many of the design examples. Pictures of antenna arrays and components provided by industry and government sources are presented with explanations of how they work. Antenna Arrays is a valuable reference for practicing engineers and scientists in wireless communications, radar, and remote sensing, and an excellent textbook for advanced antenna courses.

  19. A FLOSS Tool for Antenna Radiation Patterns

    CERN Document Server

    Yannopoulou, Nikolitsa

    2010-01-01

    This paper briefly highlights the features of the software tool [RadPat4W], named after Radiation Patterns for Windows but also compatible with the [Wine] environment of Linux. The tool is a stand-alone part of a freeware suite that is based on an alternative exposition of fundamental Antenna Theory and is under active development for many years now. Nevertheless, [RadPat4W] source code has been now released as FLOSS Free Libre Open Source Software and thus it may be freely used, copied, modified or redistributed, individually or cooperatively, by the interested user to suit her/his personal needs for reliable antenna applications from the simplest to the more complex.

  20. Modified antenna for orthogonally polarised fields

    OpenAIRE

    Prudyus, Ivan N.; Zakharia, Y. A.; Storozh, V. G.; Mankovsky, S. V.

    2005-01-01

    A compact wideband antenna for transmission and receiving of orthogonally polarized electromagnetic fields is proposed. Results of electrodynamic antenna structure analysis are considered. Main antenna properties by results of experimental investigation are presented.

  1. Ultrawideband method of feeding a dipole antenna

    OpenAIRE

    Bakhrakh, Lev D.; Los', V. F.; Shamanov, A. N.

    2003-01-01

    An antenna-feeder device is considered, in which a new way of antenna excitation is implemented. An example is presented of its use with a dipole antenna for the radiation of super-short pulse signals.

  2. Antenna system for measuring electromagnetic field parameters

    OpenAIRE

    Ilnitskiy, Ludvig Ya.; Shcherbyna, Olga A.

    2014-01-01

    A functional block diagram of the general-purpose antenna system for measuring electromagnetic wave parameters has been presented. Theoretical relationships forming a basis of the antenna system structure are described, and the antenna operation principle is presented.

  3. Design aspects of commercial satellite antennas

    Science.gov (United States)

    Lang, K. C.; Taormina, F. A.

    General design considerations for commercial satellite antennas are reviewed, and design factors of shaped beam reflector antennas are described, including shaped beam efficiency, flat-topping and boundary matching, and analysis by Fourier transforms. Attention is then given to the design of the Telesat Anik 17/Westar/Palapa communications antenna, the Comstar I communications antenna, the SBS communications antenna, and Intelsat IV A communications antenna.

  4. Ultra wideband antennas design, methodologies, and performance

    CERN Document Server

    Galvan-Tejada, Giselle M; Jardón Aguilar, Hildeberto

    2015-01-01

    Ultra Wideband Antennas: Design, Methodologies, and Performance presents the current state of the art of ultra wideband (UWB) antennas, from theory specific for these radiators to guidelines for the design of omnidirectional and directional UWB antennas. Offering a comprehensive overview of the latest UWB antenna research and development, this book:Discusses the developed theory for UWB antennas in frequency and time domainsDelivers a brief exposition of numerical methods for electromagnetics oriented to antennasDescribes solid-planar equivalen

  5. Broadband Corrugated Square-Shaped Monopole Antenna

    OpenAIRE

    S. D. Ahirwar; C. Sairam

    2011-01-01

    Design and development of a corrugated square-shaped monopole antenna is presented with measured results. The operational bandwidth of the antenna is 300 MHz–3000 MHz. The antenna is derived from a square-shaped planar monopole antenna. This basic square-shaped radiating element is corrugated in its lateral dimension. This corrugation reduces the lateral dimension of the antenna by 60%. Electrical performance of this antenna is better than its parent counterpart. This paper presents design an...

  6. UWB and SWB Planar Antenna Technology

    OpenAIRE

    Zhong, Shun-Shi

    2010-01-01

    The recent progress in the development of UWB planar antenna technology has been reviewed. Some types of UWB metal-plate monopole antennas, UWB printed monopole antennas and UWB printed slot antennas are presented. The comparison results of indicate that the UWB printed monopole antennas can realize relatively smaller dimensions, and that the UWB printed slot antennas can achieve relatively higher gain. Finally, some realization manners of the band-notch function of UWB printed monopole anten...

  7. Governance of Protected Areas in West Africa - The case of the W-Arly-Pendjari (WAP) Complex in Benin and Burkina Faso

    OpenAIRE

    Konrad, Tillmann

    2015-01-01

    Protected areas are the central strategy for preserving biodiversity in the face of overexploitation and global change. To ensure their long-term survival, however, these areas may not be regarded as last havens of wilderness, but as complex social-ecological systems. Modern approaches of protected area (PA) management support this view by balancing conservation and development issues in a sustainable way and adapted to the local context. However, success of these strategies in achieving thei...

  8. Cu(II)-disulfide complexes with superoxide dismutase- and catalase-like activities protect mitochondria and whole cells against oxidative stress.

    Science.gov (United States)

    Aliaga, Margarita E; Sandoval-Acuña, Cristián; López-Alarcón, Camilo; Fuentes, Jocelyn; Speisky, Hernan

    2014-10-01

    Mitochondria are a major subcellular site of superoxide (O2(-)) formation. Conditions leading to an uncontrolled production, accumulation and/or conversion of O2(-) into hydrogen peroxide result in an increment in the intramitochondrial oxidative tone which, ultimately leads to the loss of cell viability. Recently, we reported on the ability of a series of Cu(II)-disulfide complexes to act simultaneously as SOD- and catalase-like molecules. In the present study, we addressed the potential of such compounds to protect mitochondria and cells against the oxidative stress and the cytolytic damage induced by diclofenac. Exposure of Caco-2 cells to diclofenac (250µM, 20min) led to a near 80% inhibition of mitochondrial complex I activity and almost doubled the rate of mitochondrial O2(-) production (assessed by Mitosox). A comparable increment was seen in whole cells when the oxidative tone was assessed through the largely hydrogen peroxide-dependent dichlorofluorescein (DCFH) oxidation. The increment in mitochondrial O2(-) production was totally and concentration-dependently prevented by the addition of the complexes formed between Cu(II) and the disulfides of glutathione, homocysteine, or a-dehydro-lipoic acid (20µM each); comparatively, the Cu(II)-cystine complex exerted a weaker protection. A comparable protection pattern was seen at the whole cell level, as these complexes were also effective in preventing the increment in DCFH oxidation. The mitochondrial and whole cell antioxidant protection also translated into a full protection against the cytolytic effects of diclofenac (45min). Results from the present study indicate that the here-tested Cu(II)-disulfides complexes are able to effectively protect cells against the oxidative and the lytic effects of O2(-)-overproducing mitochondria, suggesting a potential for these type of compounds to act as SOD- and catalase-like molecules under oxidative-stress conditions. Supported by FONDECYT #1110018. PMID:26461399

  9. Antenna modeling considerations for accurate SAR calculations in human phantoms in close proximity to GSM cellular base station antennas.

    Science.gov (United States)

    van Wyk, Marnus J; Bingle, Marianne; Meyer, Frans J C

    2005-09-01

    International bodies such as International Commission on Non-Ionizing Radiation Protection (ICNIRP) and the Institute for Electrical and Electronic Engineering (IEEE) make provision for human exposure assessment based on SAR calculations (or measurements) and basic restrictions. In the case of base station exposure this is mostly applicable to occupational exposure scenarios in the very near field of these antennas where the conservative reference level criteria could be unnecessarily restrictive. This study presents a variety of critical aspects that need to be considered when calculating SAR in a human body close to a mobile phone base station antenna. A hybrid FEM/MoM technique is proposed as a suitable numerical method to obtain accurate results. The verification of the FEM/MoM implementation has been presented in a previous publication; the focus of this study is an investigation into the detail that must be included in a numerical model of the antenna, to accurately represent the real-world scenario. This is accomplished by comparing numerical results to measurements for a generic GSM base station antenna and appropriate, representative canonical and human phantoms. The results show that it is critical to take the disturbance effect of the human phantom (a large conductive body) on the base station antenna into account when the antenna-phantom spacing is less than 300 mm. For these small spacings, the antenna structure must be modeled in detail. The conclusion is that it is feasible to calculate, using the proposed techniques and methodology, accurate occupational compliance zones around base station antennas based on a SAR profile and basic restriction guidelines. PMID:15931680

  10. Human-derived physiological heat shock protein 27 complex protects brain after focal cerebral ischemia in mice.

    Directory of Open Access Journals (Sweden)

    Shinichiro Teramoto

    Full Text Available Although challenging, neuroprotective therapies for ischemic stroke remain an interesting strategy for countering ischemic injury and suppressing brain tissue damage. Among potential neuroprotective molecules, heat shock protein 27 (HSP27 is a strong cell death suppressor. To assess the neuroprotective effects of HSP27 in a mouse model of transient middle cerebral artery occlusion, we purified a "physiological" HSP27 (hHSP27 from normal human lymphocytes. hHSP27 differed from recombinant HSP27 in that it formed dimeric, tetrameric, and multimeric complexes, was phosphorylated, and contained small amounts of αβ-crystallin and HSP20. Mice received intravenous injections of hHSP27 following focal cerebral ischemia. Infarct volume, neurological deficit scores, physiological parameters, and immunohistochemical analyses were evaluated 24 h after reperfusion. Intravenous injections of hHSP27 1 h after reperfusion significantly reduced infarct size and improved neurological deficits. Injected hHSP27 was localized in neurons on the ischemic side of the brain. hHSP27 suppressed neuronal cell death resulting from cytochrome c-mediated caspase activation, oxidative stress, and inflammatory responses. Recombinant HSP27 (rHSP27, which was artificially expressed and purified from Escherichia coli, and dephosphorylated hHSP27 did not have brain protective effects, suggesting that the phosphorylation of hHSP27 may be important for neuroprotection after ischemic insults. The present study suggests that hHSP27 with posttranslational modifications provided neuroprotection against ischemia/reperfusion injury and that the protection was mediated through the inhibition of apoptosis, oxidative stress, and inflammation. Intravenously injected human HSP27 should be explored for the treatment of acute ischemic strokes.

  11. Could structural similarity of specific domains between animal globins and plant antenna proteins provide hints important for the photoprotection mechanism?

    Science.gov (United States)

    Ioannidis, Nikolaos E; Kotzabasis, Kiriakos

    2015-01-01

    Non photochemical quenching is a fundamental mechanism in photosynthesis, which protects plants against excess excitation energy and is of crucial importance for their survival and fitness. In the last decades hundreds of papers have appeared that describe the role of antenna regulation in protection or the so called qE response. However, the exact quenching site is still obscure. Previously overlooked features of the antenna may provide hints towards the elucidation of its functionality and of the quenching mechanism. Recently it was demonstrated that the catalytic domain of human myoglobin that binds the pigment (i.e. heme) is similar in structure to the domain of the light harvesting complex II of pea that binds Chl a 614 (former known as b3). In addition, it is well accepted that conformational changes of the chlorophyll macrocycle result in reversible changes of fluorescence (the lowest fluorescence corresponds to non planar macrocycle). Here we put forward a hypothesis regarding the molecular mechanism that leads to the formation of a quenching center inside the antenna proteins. Our main suggestion is that a conformational change of helix H5 (known also as helix D) forces conformational changes in the macrocycle of Chl a 614 is implicated in the ΔA535 absorbance change and quenching during photoprotective qE. The specific features (some of them similar to those of heme domain of globins) of the b3 domain account for these traits. The model predicts that antenna proteins having b3 pigments (i.e. LHCII, CP29, CP26) can act as potential quenchers.

  12. Alcator C-Mod ion cyclotron antenna performance

    International Nuclear Information System (INIS)

    Ion cyclotron range of frequency (ICRF) heating is expected to be an important auxiliary heating source for ITER and fusion reactors. One of the keys to successful ICRF heating is the antenna performance and a number of issues can limit the antenna performance including poor voltage and power handling, impurity production, strong RF plasma edge interactions, poor RF coupling, and localized heating of the antenna structure. High power density antenna operation, with all metal protection tiles and plasma facing components (PFC), present significant challenges to ICRF antenna operation. High performance plasmas can be achieved with all metal PFC's after boronization. In Ohmic H-mode discharges, the plasma performance degradation occurs at a rate 3-4 times slower than RF heated discharges with the similar input energy (discharge integrated). The erosion process also appears to be accelerated for weaker single pass absorption heating scenario, D(3He) on C-Mod. The C-Mod H minority single pass absorption is stronger and is similar to that expected in ITER implying similar RF induced erosion in ITER as on C-Mod. Since Faraday screen-less antenna operation has a number of advantages; the J antenna was operated without a Faraday screen. The voltage and power handling were unaffected by the screen removal. However, the heating effectiveness was 15-20% less and the influx of Cu was identified as the likely cause of the decreased performance. On C-Mod, high density discharges can yield neutral pressures at which antenna operation is prohibited. This neutral pressure limit may be related to phenomena associated with antenna ELM (edge localized mode) interactions. Experiments showed that multipactor can cause a glow discharge at neutral pressures two orders of magnitude below the Paschen breakdown limit. In the presence of a 0.1 T B-field, measurements on the C-Mod antennas showed the presence of a glow discharge at a neutral pressure similar to the observed operational neutral

  13. Antennas - Our electronic eyes and ears

    Science.gov (United States)

    Kraus, John D.

    1989-01-01

    Although the number of antenna types is vast, all antenna properties may be characterized in terms of the same basic parameters of radiation pattern, impedance, radar cross-section, and temperature. A comprehensive introduction is presented to antenna configurations; these encompass, among antennas constructed of wire or tubing, such wideband and circularly polarized types as helices, linear conductors, and loops. Sheet-conductor antenna families include reflectors, waveguides, and slotted antennas. Nonconducting dielectric antennas are lenses, polyrods, and slabs. Antenna array types range over 'driven', parasitic, and adaptive configurations. 'Two half-wavelength' and 'four half-wavelength' element arrays are also discussed.

  14. ICRF antenna coupling theory for a cylindrically stratified plasma

    International Nuclear Information System (INIS)

    Antenna coupling to a cyclindrical plasma is examined for the ion cyclotron range of frequencies (ICRF). A variety of antenna configurations are modelled such as a partial-turn loop, Nagoya coils, an aperture antenna, and arrays of coils. A procedure that utilizes the induction theorem is presented which replaces a general coil configuration with an equivalent representation in terms of sinusoidal current sheets. This transformation reduces the three dimensional antenna boundary value problem to that of one dimension (r, the radial coordinate) with the spatial variation in the other directions represented by complex exponentials (exp (in phi + ik/sub z/z)). As constructed, the transformation is directly applicable to axisymmetric geometries where the plasma parameters are only functions of radius. The radial variation of the plasma parameters such as the local density and temperature are approximated by a stratified model. As the number of strata are increased, the step-wise model is shown to converge to the continuous case. The plasma response is modelled by a local equivalent dielectric tensor. In the context of this model antenna-plasma coupling characteristics are compared for the various ICRF antennas

  15. Antenna array geometry optimization for a passive coherent localisation system

    Science.gov (United States)

    Knott, Peter; Kuschel, Heiner; O'Hagan, Daniel

    2012-11-01

    Passive Coherent Localisation (PCL), also known as Passive Radar, making use of RF sources of opportunity such as Radio or TV Broadcasting Stations, Cellular Phone Network Base Stations, etc. is an advancing technology for covert operation because no active radar transmitter is required. It is also an attractive addition to existing active radar stations because it has the potential to discover low-flying and low-observable targets. The CORA (Covert Radar) experimental passive radar system currently developed at Fraunhofer-FHR features a multi-channel digital radar receiver and a circular antenna array with separate elements for the VHF- and the UHF-range and is used to exploit alternatively Digital Audio (DAB) or Video Broadcasting (DVB-T) signals. For an extension of the system, a wideband antenna array is being designed for which a new discone antenna element has been developed covering the full DVB-T frequency range. The present paper describes the outline of the system and the numerical modelling and optimisation methods applied to solve the complex task of antenna array design: Electromagnetic full wave analysis is required for the parametric design of the antenna elements while combinatorial optimization methods are applied to find the best array positions and excitation coefficients for a regular omni-directional antenna performance. The different steps are combined in an iterative loop until the optimum array layout is found. Simulation and experimental results for the current system will be shown.

  16. Radar transponder antenna pattern analysis for the space shuttle

    Science.gov (United States)

    Radcliff, Roger

    1989-01-01

    In order to improve tracking capability, radar transponder antennas will soon be mounted on the Shuttle solid rocket boosters (SRB). These four antennas, each being identical cavity-backed helices operating at 5.765 GHz, will be mounted near the top of the SRB's, adjacent to the intertank portion of the external tank. The purpose is to calculate the roll-plane pattern (the plane perpendicular to the SRB axes and containing the antennas) in the presence of this complex electromagnetic environment. The large electrical size of this problem mandates an optical (asymptotic) approach. Development of a specific code for this application is beyond the scope of a summer fellowship; thus a general purpose code, the Numerical Electromagnetics Code - Basic Scattering Code, was chosen as the computational tool. This code is based on the modern Geometrical Theory of Diffraction, and allows computation of scattering of bodies composed of canonical problems such as plates and elliptic cylinders. Apertures mounted on a curved surface (the SRB) cannot be accomplished by the code, so an antenna model consisting of wires excited by a method of moments current input was devised that approximated the actual performance of the antennas. The improvised antenna model matched well with measurements taken at the MSFC range. The SRB's, the external tank, and the shuttle nose were modeled as circular cylinders, and the code was able to produce what is thought to be a reasonable roll-plane pattern.

  17. Patch antenna terahertz photodetectors

    Energy Technology Data Exchange (ETDEWEB)

    Palaferri, D.; Todorov, Y., E-mail: yanko.todorov@univ-paris-diderot.fr; Chen, Y. N.; Madeo, J.; Vasanelli, A.; Sirtori, C. [Laboratoire Matériaux et Phénomènes Quantiques, Université Paris Diderot, Sorbonne Paris Cité, CNRS-UMS 7162, 75013 Paris (France); Li, L. H.; Davies, A. G.; Linfield, E. H. [School of Electronic and Electrical Engineering, University of Leeds, Leeds LS2 9JT (United Kingdom)

    2015-04-20

    We report on the implementation of 5 THz quantum well photodetector exploiting a patch antenna cavity array. The benefit of our plasmonic architecture on the detector performance is assessed by comparing it with detectors made using the same quantum well absorbing region, but processed into a standard 45° polished facet mesa. Our results demonstrate a clear improvement in responsivity, polarization insensitivity, and background limited performance. Peak detectivities in excess of 5 × 10{sup 12} cmHz{sup 1/2}/W have been obtained, a value comparable with that of the best cryogenic cooled bolometers.

  18. Ultra wide band antennas

    CERN Document Server

    Begaud, Xavier

    2013-01-01

    Ultra Wide Band Technology (UWB) has reached a level of maturity that allows us to offer wireless links with either high or low data rates. These wireless links are frequently associated with a location capability for which ultimate accuracy varies with the inverse of the frequency bandwidth. Using time or frequency domain waveforms, they are currently the subject of international standards facilitating their commercial implementation. Drawing up a complete state of the art, Ultra Wide Band Antennas is aimed at students, engineers and researchers and presents a summary of internationally recog

  19. Coupling between minimum scattering antennas

    DEFF Research Database (Denmark)

    Andersen, J.; Lessow, H; Schjær-Jacobsen, Hans

    1974-01-01

    Coupling between minimum scattering antennas (MSA's) is investigated by the coupling theory developed by Wasylkiwskyj and Kahn. Only rotationally symmetric power patterns are considered, and graphs of relative mutual impedance are presented as a function of distance and pattern parameters. Crossed......-dipoles and helices are considered in order to establish a correspondence with simple antenna structures....

  20. Mobile Phone Antenna Performance 2016

    DEFF Research Database (Denmark)

    Pedersen, Gert F.

    2016-01-01

    This study investigates the antenna performance of a number of mobile phones widely used in the Nordic Countries. The study is supported by the Nordic Council of Ministers. The antenna performance of the phones is vital for the phones ability to ensure radio coverage in low signal situations. The...

  1. Broadband antenna with frequency scanning

    Directory of Open Access Journals (Sweden)

    A. A. Shekaturin

    2014-06-01

    Full Text Available Relevance of this study. The main advantage of frequency scanning is simplicity of implementation. At this point, multifunctional usage of microwave modules is an urgent task, as well as their maximum simpler and cheaper. Antenna design and operation. The study is aimed at providing electric antenna with frequency scanning. It was based on the log-periodic antenna due to its wideband and negotiation capability over the entire operating frequency range. For this distribution line is bent in an arc of a circle in a plane blade while vibrators are arranged along the radius. Computer modeling of antennas with frequency scanning. Modeled with a non-mechanical motion antenna beam emitters representing system for receiving a radio frequency signal on mobile objects calculated for 1.8 GHz ... 4.2 GHz. The simulation was performed in a software environment for numerical modeling of electromagnetic «Feko 5.5». Analysis of the interaction of radiation is based on the method of moments. Findings. The result of this work is to propose a new design of the antenna with a frequency scanning method as agreed in a wide frequency range. In the studied technical solution provided by the rotation of NAM in the frequency range, and the matching of the antenna to the feed line is maintained. Application of this type of antennas on the proposed technical solution in communication systems will improve the communication reliability by maintaining coordination in the frequency range

  2. Slot-Coupled Barbel Antenna

    DEFF Research Database (Denmark)

    Jørgensen, Kasper Lüthje; Jakobsen, Kaj Bjarne

    2016-01-01

    A novel slot-coupled barbel antenna is designed and analyzed. A sensitivity analysis performed in order to improve the bandwidth, while the center frequency is kept constant.......A novel slot-coupled barbel antenna is designed and analyzed. A sensitivity analysis performed in order to improve the bandwidth, while the center frequency is kept constant....

  3. Antennas for light and plasmons

    NARCIS (Netherlands)

    Dikken, Dirk Jan Willem

    2015-01-01

    Antennas have been used for over a century as emitters, scatterers and receivers of electromagnetic waves. All wireless communication devices, such as radio, mobile phones and satellite communication are strongly dependent on the capability of an antenna to localize propagating electromagnetic waves

  4. Graphene-antenna sandwich photodetector.

    Science.gov (United States)

    Fang, Zheyu; Liu, Zheng; Wang, Yumin; Ajayan, Pulickel M; Nordlander, Peter; Halas, Naomi J

    2012-07-11

    Nanoscale antennas sandwiched between two graphene monolayers yield a photodetector that efficiently converts visible and near-infrared photons into electrons with an 800% enhancement of the photocurrent relative to the antennaless graphene device. The antenna contributes to the photocurrent in two ways: by the transfer of hot electrons generated in the antenna structure upon plasmon decay, as well as by direct plasmon-enhanced excitation of intrinsic graphene electrons due to the antenna near field. This results in a graphene-based photodetector achieving up to 20% internal quantum efficiency in the visible and near-infrared regions of the spectrum. This device can serve as a model for merging the light-harvesting characteristics of optical frequency antennas with the highly attractive transport properties of graphene in new optoelectronic devices. PMID:22703522

  5. DEA deformed stretchable patch antenna

    International Nuclear Information System (INIS)

    A stretchable patch antenna (SPA) whose frequency is tuned by a planar dielectric elastomer actuator (DEA) is presented in this paper. This mechanically reconfigurable antenna system has a configuration resembling a pre-stretched silicone belt. Part of the belt is embedded with a layer of conductive liquid metal to form the patch antenna. Part of the belt is sandwiched between conductive electrodes to form the DEA. Electrical activation of the DEA results in a contraction of the patch antenna, and as a result, in a variation of its resonance frequency. Design and fabrication steps of this system are presented. Measurement results for deformation, resonance frequency variation and efficiency of the patch antenna are also presented. (paper)

  6. Optical antennas as nanoscale resonators

    CERN Document Server

    Agio, Mario

    2011-01-01

    Recent progress in nanotechnology has enabled us to fabricate subwavelength architectures that function as antennas for improving the exchange of optical energy with nanoscale matter. We describe the main features of optical antennas for enhancing quantum emitters and review designs that increase the spontaneous emission rate by orders of magnitude from the ultraviolet up to the near-infrared spectral range. To further explore how optical antennas may lead to unprecedented regimes of light-matter interaction, we draw a relationship between metal nanoparticles, radio-wave antennas and optical resonators. Our analysis points out how optical antennas may function as nanoscale resonators and how these may offer unique opportunities with respect to state-of-the-art microcavities.

  7. Optical antennas as nanoscale resonators.

    Science.gov (United States)

    Agio, Mario

    2012-02-01

    Recent progress in nanotechnology has enabled us to fabricate sub-wavelength architectures that function as antennas for improving the exchange of optical energy with nanoscale matter. We describe the main features of optical antennas for enhancing quantum emitters and review the designs that increase the spontaneous emission rate by orders of magnitude from the ultraviolet up to the near-infrared spectral range. To further explore how optical antennas may lead to unprecedented regimes of light-matter interactions, we draw a relationship between metal nanoparticles, radio-wave antennas and optical resonators. Our analysis points out how optical antennas may function as nanoscale resonators and how these may offer unique opportunities with respect to state-of-the-art microcavities.

  8. Transcatheter Microwave Antenna

    Science.gov (United States)

    Arndt, Dickey G. (Inventor); Carl, James R. (Inventor); Ngo, Phong (Inventor); Raffoul, George W. (Inventor)

    2001-01-01

    A method, simulation, and apparatus are provided that are highly suitable for treatment of benign prostatic hyperplasia (BPH). A catheter is disclosed that includes a small diameter disk loaded monopole antenna surrounded by fusion material having a high heat of fusion and a melting point preferably at or near body temperature. Microwaves from the antenna heat prostatic tissue to promote necrosing of the prostatic tissue that relieves the pressure of the prostatic tissue against the urethra as the body reabsorbs the necrosed or dead tissue. The fusion material keeps the urethra cool by means of the heat of fusion of the fusion material. This prevents damage to the urethra while the prostatic tissue is necrosed. A computer simulation is provided that can be used to predict the resulting temperature profile produced in the prostatic tissue. By changing the various control features of the catheter and method of applying microwave energy a temperature profile can be predicted and produced that is similar to the temperature profile desired for the particular patient.

  9. On Antenna-Architectures for Sensitive Radiometry to Support Oceanography

    Science.gov (United States)

    Van't Klooster, Cornelis; Cappellin, Cecilia; Pontoppidan, Knud; Heighwood Nielsen, Per; Skou, Niels; Ivashina, Marianna; Iupikov, Oleg; Ihle, Alexander

    The presentation discusses different antenna architectures supporting radiometric tasks for oceanographic observations. With Aquarius and SMOS in orbit with their associated resolution and revisit capability in L-band, further enhancements are of interest. Following studies into desirable resolution and frequency band interests for oceanographic applications (ref: Microwat - an ESA study, see also https://www.ghrsst.org/ ), breaking through and desirable requirements have been derived. Investigations into potential antenna architectural realisations have been initiated. Included are radiometer sensor (read:antenna) scenarios, based on conical scanning, interferometric 1D and pushbroom coverage. A wide coverage is available from the first two architectures, and a very good sensitivity is available with the pushbroom scenario. There are a couple of interesting aspects, related to polarimetry capabilities, resolution, sensitivity, etc. The pushbroom architecture, at cost of some complexity offers a very good sensitivity with interesting antenna architecture solutions to offer breaking through capabilities, in particular concerning the sensitivity requirements, in combination with polarimetric capabilities. Coverage comes with some infrastructural antenna complexity, with the needs and creativity for a deployable antenna configuration. Following initial considerations for all three antenna configurations at overview level, the push-broom scenario is presented with more details. Interesting aspects include ongoing technology developments in other related fields with refined results to come would enable to consider antenna architectures are used in which focal plane arrays find a combination with shaped reflector assemblies. With processing capabilities further enhanced - with ongoing developments underway in other sectors as radio astronomers can confirm - one would be able to further improve and refine sensitivity aspects in combination with polarimetric capabilities

  10. Scattering-matrix arc detection on the JET ITER-like ICRH antenna

    Energy Technology Data Exchange (ETDEWEB)

    Becoulet, A. [CEA, Cadarache, France; Vrancken, M. [ERM-KMS, Association EURATOM-Belgian State, Brussels, Belgium; Dumortier, P. [ERM-KMS, Association EURATOM-Belgian State, Brussels, Belgium; Durodie, F. [ERM-KMS, Association EURATOM-Belgian State, Brussels, Belgium; Evrard, M. [ERM-KMS, Association EURATOM-Belgian State, Brussels, Belgium; Huygen, S. [ERM-KMS, Association EURATOM-Belgian State, Brussels, Belgium; Lerche, E. [ERM-KMS, Association EURATOM-Belgian State, Brussels, Belgium; Van Eester, D. [ERM-KMS, Association EURATOM-Belgian State, Brussels, Belgium; Vervier, M. [ERM-KMS, Association EURATOM-Belgian State, Brussels, Belgium; Argouarch, A. [CEA-Cadarache, St. Paul lex Durance, France; Blackman, T. [EURATOM / UKAEA, Abingdon, UK; Graham, M. [EURATOM / UKAEA, Abingdon, UK; Jacquet, P. [EURATOM / UKAEA, Abingdon, UK; Kaye, A. [EURATOM / UKAEA, Abingdon, UK; Nightingale, M. [EURATOM / UKAEA, Abingdon, UK; Goulding, Richard Howell [ORNL

    2009-06-01

    Operating Ion Cyclotron Resonance Heating (ICRH) antennas at high power density puts them at risk of arcing which reduces the coupled power to the plasma because the perturbed impedance match triggers the Voltage Standing Wave Ratio (VWSR) based generator trip system but even worse might damage the antenna beyond repair because of the the arc s localised energy deposition. New antennas are designed to operate in a load tolerant way which creates low impedance zones that are especially at risk since the existing VSWR protection systems are less sensitive to arcs in these areas. To protect these low impedance areas, a new arc protection system referred as Scattering Matrix Arc Detection (SMAD) was proposed. This paper describes the basic operating principle and implementation in hard- and software for the JET ITER-Like Antenna (ILA), with testbed and preliminary JET commissioning results.

  11. Thermal Loss in High-Q Antennas

    DEFF Research Database (Denmark)

    Barrio, Samantha Caporal Del; Bahramzy, Pevand; Svendsen, Simon;

    2014-01-01

    Tunable antennas are very promising for future generations of mobile communications, where antennas are required to cover a wide range operating bands. This letter aims at characterizing the loss mechanism of tunable antennas. Tunable antennas typically exhibit a high Quality factor (Q), which can...

  12. Metamaterial antennas: the most successful metamaterial technology?

    DEFF Research Database (Denmark)

    Breinbjerg, Olav

    2015-01-01

    The Thomson Reuters Web of Science™ lists more than 1500 journal articles related to metamaterial antennas from 2001 to 2015; this paper overviews some major objectives of such antennas.......The Thomson Reuters Web of Science™ lists more than 1500 journal articles related to metamaterial antennas from 2001 to 2015; this paper overviews some major objectives of such antennas....

  13. 47 CFR 95.51 - Antenna height.

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false Antenna height. 95.51 Section 95.51... SERVICES General Mobile Radio Service (GMRS) § 95.51 Antenna height. (a) Certain antenna structures used in... this chapter. (b) The antenna for a small base station or for a small control station must not be...

  14. Microstrip antenna on tunable substrate

    Science.gov (United States)

    Jose, K. A.; Varadan, Vijay K.; Varadan, Vasundara V.; Mohanan, P.

    1995-05-01

    The tunable patch antenna configurations are becoming popular and attractive in many aspects. This was mainly due to the advent of ferrite thin film technology and tunable substrate materials. The integration of monolithic microwave circuits and antennas are becoming easy today. In the development of magnetic tuning of microstrip patch on ferrite substrate is presented by Rainville and Harackewiez. Radiation characteristics of such antennas are presented by Pozer. Band width and radiation characteristics of such tunable antennas are measured and compared. Usually the substrate losses are considered in the analysis and metallization losses are assumed to be ideal. The analysis of magnetic tunable radiator including metallization and ferrite substrate losses are presented. However, all such tuning and integration of circuits and antennas are mainly on ferrite substrate due to magnetic tuning. Recently, Varadan et al. established that the BaxSr1-xTiO3 series ferroelectric materials such as Barium Strontium Titanate (BST) are well suited for microwave phase shifter applications. It could be possible to change the dielectric constant of these materials more than 50% depending on the BST composition, by changing the applied bias voltage. Also, the porosity of BST can be controlled during processing to produce dielectric constants in the range of 15 to 1500, with some trade off in tunability. In this paper, we are presenting the possibility of designing a microstrip patch antenna on such tunable substrate. Such antennas are having the major advantage of electronic tunability and compact size.

  15. Group Delay of High Q Antennas

    DEFF Research Database (Denmark)

    Bahramzy, Pevand; Pedersen, Gert Frølund

    2013-01-01

    become an issue, when working with high Q antennas, because of the steep phase shift over the frequency. In this paper, it is measured how large group delay variations can become, when going from a low Q antenna to a high Q antenna. The group delay of a low Q antenna is shown to be around 1.3 ns, whereas...... a high Q antenna has group delay of around 22 ns. It is due to this huge group delay variation characteristics of high Q antennas, that signal distortion might occur in the radio system with high Q antennas....

  16. Thin magnetic conductor substrate for placement-immune, electrically-small antennas.

    Energy Technology Data Exchange (ETDEWEB)

    Eubanks, Travis Wayne; McDonald, Jacob J.; Loui, Hung

    2011-09-01

    An antenna is considered to be placement-immune when the antenna operates effectively regardless of where it is placed. By building antennas on magnetic conductor materials, the radiated fields will be positively reinforced in the desired radiation direction instead of being negatively affected by the environment. Although this idea has been discussed thoroughly in theoretical research, the difficulty in building thin magnetic conductor materials necessary for in-phase field reflections prevents this technology from becoming more widespread. This project's purpose is to build and measure an electrically-small antenna on a new type of non-metallic, thin magnetic conductor. This problem has not been previously addressed because non-metallic, thin magnetic conductor materials have not yet been discovered. This work proposed the creation of an artificial magnetic conductor (AMC) with in-phase field reflections without using internal electric conductors, the placement of an electrically-small antenna on this magnetic conductor, and the development of a transmit-receive system that utilizes the substrate and electrically-small antenna. By not using internal electric conductors to create the AMC, the substrate thickness can be minimized. The electrically-small antenna will demonstrate the substrate's ability to make an antenna placement immune, and the transmit-receive system combines both the antenna and the substrate while adding a third layer of system complexity to demonstrate the complete idea.

  17. Sulforaphane induces cell cycle arrest by protecting RB-E2F-1 complex in epithelial ovarian cancer cells

    Directory of Open Access Journals (Sweden)

    Morris Robert

    2010-03-01

    Full Text Available Abstract Background Sulforaphane (SFN, an isothiocyanate phytochemical present predominantly in cruciferous vegetables such as brussels sprout and broccoli, is considered a promising chemo-preventive agent against cancer. In-vitro exposure to SFN appears to result in the induction of apoptosis and cell-cycle arrest in a variety of tumor types. However, the molecular mechanisms leading to the inhibition of cell cycle progression by SFN are poorly understood in epithelial ovarian cancer cells (EOC. The aim of this study is to understand the signaling mechanisms through which SFN influences the cell growth and proliferation in EOC. Results SFN at concentrations of 5 - 20 μM induced a dose-dependent suppression of growth in cell lines MDAH 2774 and SkOV-3 with an IC50 of ~8 μM after a 3 day exposure. Combination treatment with chemotherapeutic agent, paclitaxel, resulted in additive growth suppression. SFN at ~8 μM decreased growth by 40% and 20% on day 1 in MDAH 2774 and SkOV-3, respectively. Cells treated with cytotoxic concentrations of SFN have reduced cell migration and increased apoptotic cell death via an increase in Bak/Bcl-2 ratio and cleavage of procaspase-9 and poly (ADP-ribose-polymerase (PARP. Gene expression profile analysis of cell cycle regulated proteins demonstrated increased levels of tumor suppressor retinoblastoma protein (RB and decreased levels of E2F-1 transcription factor. SFN treatment resulted in G1 cell cycle arrest through down modulation of RB phosphorylation and by protecting the RB-E2F-1 complex. Conclusions SFN induces growth arrest and apoptosis in EOC cells. Inhibition of retinoblastoma (RB phosphorylation and reduction in levels of free E2F-1 appear to play an important role in EOC growth arrest.

  18. Antenna Coupling in Multi Active Multi Passive Port Topologies

    DEFF Research Database (Denmark)

    Alrabadi, Osama; Pedersen, Gert Frølund

    2012-01-01

    The electromagnetic (EM) coupling between pairs of antennas in a system comprised of μ active RF ports and M passive ones is expressed under arbitrary complex terminations by obtaining the effective transfer function between the active ports using Mason's rule. Unlike a previous approach where the...

  19. The histone-fold complex MHF is remodeled by FANCM to recognize branched DNA and protect genome stability

    OpenAIRE

    Fox, David; Yan, Zhijiang; Ling, Chen; Zhao, Ye; Lee, Duck-Yeon; Fukagawa, Tatsuo; Yang, Wei; Wang, Weidong

    2014-01-01

    Histone-fold proteins typically assemble in multiprotein complexes to bind duplex DNA. However, one histone-fold complex, MHF, associates with Fanconi anemia (FA) protein FANCM to form a branched DNA remodeling complex that senses and repairs stalled replication forks and activates FA DNA damage response network. How the FANCM-MHF complex recognizes branched DNA is unclear. Here, we solved the crystal structure of MHF and its complex with the MHF-interaction domain (referred to as MID) of FAN...

  20. Minimum Q Electrically Small Antennas

    DEFF Research Database (Denmark)

    Kim, O. S.

    2012-01-01

    Theoretically, the minimum radiation quality factor Q of an isolated resonance can be achieved in a spherical electrically small antenna by combining TM1m and TE1m spherical modes, provided that the stored energy in the antenna spherical volume is totally suppressed. Using closed-form expressions...... for the stored energies obtained through the vector spherical wave theory, it is shown that a magnetic-coated metal core reduces the internal stored energy of both TM1m and TE1m modes simultaneously, so that a self-resonant antenna with the Q approaching the fundamental minimum is created. Numerical results...

  1. Microstrip and printed antenna design

    CERN Document Server

    Bancroft, Randy

    2009-01-01

    The approach in this book is historical and practical. It covers abasic designsa in more detail than other microstrip antenna books that tend to skip important electrical properties and implementation aspects of these types of antennas. Examples include: quarter-wave patch, quarter by quarter patch, detailed design method for rectangular circularly polarized patch, the use of the TM11 (linear and broadside CP), TM21 (monopole CP pattern) and TM02 (monopole linear) circular patch modes in designs, dual-band antenna designs which allow for independent dual-band frequencies. Limits on broadband m

  2. Measurement of mobile antenna systems

    CERN Document Server

    Arai, Hiroyuki

    2012-01-01

    If you're involved with the design, installation or maintenance of mobile antenna systems, this thoroughly revised and updated edition of a classic Artech book offers you the most current and comprehensive coverage of all the mandatory measurement techniques you need for your work in the field. This Second Edition presents critical new material in key areas, including radiation efficiency measurement, mobile phone usage position, and MIMO (multiple-input/multiple-output) antennas.This unique resource provides in-depth examinations of all relevant mobile antenna measurement theories, along with

  3. Miniaturization of Spherical Magnetodielectric Antennas

    DEFF Research Database (Denmark)

    Hansen, Troels Vejle

    ; Arbitrary order of the spherical wave, arbitrary radius of the spherical antenna, as well as arbitrarily large core permeability and/or permittivity, given an inversely proportional frequency variation of the imaginary part(s) and an arbitrary dispersion of the real part(s) - thus describing both lossless...... to the antenna designer. Closed-form expressions for the relative mode excitation have been derived yielding self-resonant or circular polarized operation. Furthermore, an even lower Q is attainable when combining the two dipole modes. For example for a specific self-resonant dual-dipole antenna, a magnetic core...

  4. Moths smell with their antennae

    Science.gov (United States)

    Spencer, Thomas; Ballard, Matthew; Alexeev, Alexander; Hu, David

    2015-11-01

    Moths are reported to smell each other from over 6 miles away, locating each other with just 200 airborne molecules. In this study, we investigate how the structure of the antennae influences particle capture. We measure the branching patterns of over 40 species of moths, across two orders of magnitude in weight. We find that moth antennae have 3 levels of hierarchy, with dimensions on each level scaling with body size. We perform lattice-Boltzman simulations to determine optimal flow patterns around antennae branches allowing for capture of small particles.

  5. DUAL BAND MONOPOLE ANTENNA DESIGN

    Directory of Open Access Journals (Sweden)

    P. Jithu

    2013-06-01

    Full Text Available The WLAN and Bluetooth applications become popular in mobile devices, integrating GSM and ISM bands operation in one compact antenna, can reduce the size of mobile devices. Recently, lot many investigations are carried out in designing a dual band antennas with operating frequencies in GSM band and in ISM band for mobile devices. Printed monopoles are under this investigation. In this paper, dual-band printed monopoles are presented to operate at GSM band i.e. 900 MHz and ISM band i.e. 2.4 GHz. We intend to observe the antenna characteristics on the network analyzer and verify the theoretical results with the practical ones.

  6. Absorption Efficiency of Receiving Antennas

    DEFF Research Database (Denmark)

    Andersen, Jørgen Bach; Frandsen, Aksel

    2005-01-01

    A receiving antenna with a matched load will always scatter some power. This paper sets an upper and a lower bound on the absorption efficiency (absorbed power over sum of absorbed and scattered powers), which lies between 0 and 100% depending on the directivities of the antenna and scatter...... patterns. It can approach 100% as closely as desired, although in practice this may not be an attractive solution. An example with a small endfire array of dipoles shows an efficiency of 93%. Several examples of small conical horn antennas are also given, and they all have absorption efficiencies less than...

  7. EHF SATCOM monopulse antenna

    Science.gov (United States)

    Thomas, D.

    The author describes a coaxial dual-band monopulse feed design specifically tailored to the EHF (extremely high-frequency/SATCOM frequency bands. The device utilizes low-loss waveguide circuits throughout and employs a corrugated feed horn that provides symmetrical primary patterns with steeply tapered skirts. The dimensions in the horn throat/coaxial section were empirically adjusted for good primary patterns in the 45-GHz band. Fortuitously, this also provided good primary performance in the 21-GHz band. In the autotrack mode, the phase and amplitude of the error channel are compared with those of the data channel to obtain tracking error magnitude and sense. The feed and test antenna geometries are described. Measured performance demonstrating nominal efficiencies in the 55 percent-60 percent range, along with good pattern, phase, and impedance match, is presented.

  8. Metal Patch Antenna

    Science.gov (United States)

    Chamberlain, Neil F. (Inventor); Hodges, Richard E. (Inventor); Zawadzki, Mark S. (Inventor)

    2012-01-01

    Disclosed herein is a patch antenna comprises a planar conductive patch attached to a ground plane by a support member, and a probe connector in electrical communication with the conductive patch arranged to conduct electromagnetic energy to or from the conductive patch, wherein the conductive patch is disposed essentially parallel to the ground plane and is separated from the ground plane by a spacing distance; wherein the support member comprises a plurality of sides disposed about a central axis oriented perpendicular to the conductive patch and the ground plane; wherein the conductive patch is solely supported above the ground plane by the support member; and wherein the support member provides electrical communication between the planer conductive patch and the ground plane.

  9. Wideband Antennas for Modern Radar Systems

    OpenAIRE

    Ren, Yu-Jiun; Lai, Chieh-Ping

    2010-01-01

    In this chapter, the basics of the antenna and phased array are reviewed and different wideband antennas for modern radar systems are presented. The concepts of the radome and frequency selective surface are also reviewed. The main contents include important parameters of the antenna, and theory and design consideration of the array antenna. Various wideband antennas are introduced and their performances are demonstrated, including: (1) for the phased array radar, the slotted waveguide array ...

  10. Electrically floating, near vertical incidence, skywave antenna

    Science.gov (United States)

    Anderson, Allen A.; Kaser, Timothy G.; Tremblay, Paul A.; Mays, Belva L.

    2014-07-08

    An Electrically Floating, Near Vertical Incidence, Skywave (NVIS) Antenna comprising an antenna element, a floating ground element, and a grounding element. At least part of said floating ground element is positioned between said antenna element and said grounding element. The antenna is separated from the floating ground element and the grounding element by one or more electrical insulators. The floating ground element is separated from said antenna and said grounding element by one or more electrical insulators.

  11. Bacteria Foraging Algorithm in Antenna Design

    OpenAIRE

    Biswa Binayak Mangaraj; Manas Ranjan Jena; Saumendra Kumar Mohanty

    2016-01-01

    A simple design procedure to realize an optimum antenna using bacteria foraging algorithm (BFA) is proposed in this paper. The first antenna considered is imaginary. This antenna is optimized using the BFA along with a suitable fitness function formulated by considering some performance parameters and their best values. To justify the optimum design approach, one 12-element Yagi-Uda antenna is considered for an experiment. The optimized result of this antenna obtained using the optimization a...

  12. Major histocompatibility complex class I-associated vaccine protection from simian immunodeficiency virus-infected peripheral blood cells

    OpenAIRE

    1994-01-01

    To evaluate the effectiveness of vaccine protection from infected cells from another individual of the same species, vaccinated rhesus macaques (Macaca mulatta) were challenged with peripheral blood mononuclear cells from another animal diagnosed with acquired immune deficiency syndrome (AIDS). Half of the simian immunodeficiency virus (SIV)- vaccinated animals challenged were protected, whereas unprotected vaccinates progressed as rapidly to AIDS. Protection was unrelated to either total ant...

  13. Development of an antenna structure for a deployable offset antenna

    Science.gov (United States)

    Herbig, H.; Tauber, W.; Vorbrugg, H.

    1986-02-01

    An unfurlable spacecraft antenna is described. The antenna consists of a central hub, ribs being radially arranged around the hub, and a mesh which produces the parabolic reflector surface shape. The hub and the ribs are made of CFRP. For the stowed and deployed reflector configuration the CFRP-components were analyzed and optimized under dynamical and dimensional stability aspects. The analytical results and the development of the CFRP components are presented.

  14. Transmit antenna selection based on shadowing side information

    KAUST Repository

    Yilmaz, Ferkan

    2011-05-01

    In this paper, we propose a new transmit antenna selection scheme based on shadowing side information. In the proposed scheme, single transmit antenna which has the highest shadowing coefficient is selected. By the proposed technique, usage of the feedback channel and channel estimation complexity at the receiver can be reduced. We consider independent but not identically distributed Generalized-K composite fading model, which is a general composite fading & shadowing channel model for wireless environments. Exact closed-form outage probability, moment generating function and symbol error probability expressions are derived. In addition, theoretical performance results are validated by Monte Carlo simulations. © 2011 IEEE.

  15. Series-Fed Microstrip Array Antenna with Circular Polarization

    OpenAIRE

    Tuan-Yung Han

    2012-01-01

    This study proposes a novel 2 × 2 array antenna design with broadband and circularly-polarized (CP) operation. The proposed design uses a simple series-fed network to increase the CP bandwidth without requiring one-by-one adjustment of each array element or a complex feed network. Selecting the appropriate spacing between each array element allows the proposed array antenna to generate CP radiation with a low axial ratio. Experimental results based on a prototype show that this 2 × 2 microstr...

  16. Coupled-oscillator based active-array antennas

    CERN Document Server

    Pogorzelski, Ronald J

    2012-01-01

    Describing an innovative approach to phased-array control in antenna design This book explores in detail phased-array antennas that use coupled-oscillator arrays, an arrangement featuring a remarkably simple beam steering control system and a major reduction in complexity compared with traditional methods of phased-array control. It brings together in one convenient, self-contained volume the many salient research results obtained over the past ten to fifteen years in laboratories around the world, including the California Institute of Technology's Jet Propulsion Laboratory.

  17. On chip plasmonic monopole nano-antennas and circuits.

    Science.gov (United States)

    Adato, Ronen; Yanik, Ahmet A; Altug, Hatice

    2011-12-14

    Analogues of many radio frequency (RF) antenna designs such as the half-wave dipole and Yagi-Uda have been successfully adapted to the optical frequency regime, opening the door for important advances in biosensing, photodetection, and emitter control. Examples of monopole antennas, however, are conspicuously rare given the element's extensive use in RF applications. Monopole antennas are attractive as they represent an easy to engineer, compact geometry and are well isolated from interference due the ground plane. Typically, however, the need to orient the antenna element perpendicular to a semi-infinite ground plane requires a three-dimensional structure and is incompatible with chip-based fabrication techniques. We propose and demonstrate here for the first time that monopole antenna elements can be fashioned out of single element nanoparticles fabricated in conventional planar geometries by using a small nanorod as a wire reflector. The structure offers a compact geometry and the reflector element provides a measure of isolation analogous to the RF counterpart. This isolation persists in the conductive coupling regime, allowing multiple monopoles to be combined into a single nanoparticle, yet still operate independently. This contrasts with several previous studies that observed dramatic variations in the spectral response of conductively coupled particles. We are able to account for these effects by modeling the system using circuit equations from standard RF antenna theory. Our model accurately describes this behavior as well as the detailed resonance tuning of the structure. As a specific practical application, the monopole resonances are precisely tuned to desired protein absorption bands, thereby enhancing their spectroscopic signatures. Furthermore, the accurate modeling of conductive coupling and demonstrated electronic isolation should be of general interest to the design of complex plasmonic circuits incorporating multiple antennas and other current

  18. The new 34-meter antenna

    Science.gov (United States)

    Pompa, M. F.

    1986-01-01

    The new 34-m high efficiency Azimuth - Elevation antenna configuration, including its features, dynamic characteristics and performance at 8.4-GHz frequencies is described. The current-technology features of this antenna produce a highly reliable configuration by incorporation of a main wheel and track azimuth support, central pintle pivot bearing, close tolerance surface panels and all-welded construction. Also described are basic drive controls that, as slaved to three automatic microprocessors, provide accurate and safe control of the antenna's steering tasks. At this time antenna installations are completed at Goldstone and Canberra and have operationally supported the Voyager - Uranus encounter. A third installation is being constructed currently in Madrid and is scheduled for completion in late 1986.

  19. Circularly-Polarized Microstrip Antenna

    Science.gov (United States)

    Stanton, P. H.

    1985-01-01

    Microstrip construction compact for mobile applications. Circularly polarized microstrip antenna made of concentric cylindrical layers of conductive and dielectric materials. Coaxial cable feedlines connected to horizontal and vertical subelements from inside. Vertical subelement acts as ground for horizontal subelement.

  20. Dipoles, unintentional antennas and EMC

    Directory of Open Access Journals (Sweden)

    Berend Danker

    2008-01-01

    Full Text Available Radiated emissions from equipment commonly originate from electronic circuits that act as electric dipoles created by the signal voltage between the signal conductors or as magnetic dipoles formed by the signal current flowing in a loop. Direct emission is mostly small, but circuits often couple to long conductors or large wiring loops which act as antennas and are efficient radiators. A comparable situation exists when short dipole antennas or small wiring loops receive ambient noise (susceptibility. Usually the amplitude of noise sources or the susceptibility of circuits is an invariable. The dipole strength increases with the distance between the conductors and the area. Shielding and proper grounding decreases the interaction via unintentional antennas. Short-circuiting and the insertion of lossy ferrite cores reduce the efficiency of unintentional antennas.

  1. Inflatable Antennas Support Emergency Communication

    Science.gov (United States)

    2010-01-01

    Glenn Research Center awarded Small Business Innovation Research (SBIR) contracts to ManTech SRS Technologies, of Newport Beach, California, to develop thin film inflatable antennas for space communication. With additional funding, SRS modified the concepts for ground-based inflatable antennas. GATR (Ground Antenna Transmit and Receive) Technologies, of Huntsville, Alabama, licensed the technology and refined it to become the world s first inflatable antenna certified by the Federal Communications Commission. Capable of providing Internet access, voice over Internet protocol, e-mail, video teleconferencing, broadcast television, and other high-bandwidth communications, the systems have provided communication during the wildfires in California, after Hurricane Katrina in Mississippi, and following the 2010 Haiti earthquake.

  2. Child Protective Services: Complex Challenges Require New Strategies. Report to the to the Honorable Nydia Velazquez, House of Representatives.

    Science.gov (United States)

    General Accounting Office, Washington, DC. Health, Education, and Human Services Div.

    At the request of the U.S. House of Representatives, this study identified problems confronting child protective service (CPS) units, which affect the system's capacity to protect children from abuse and neglect. State and local responses to these problems, and opportunities for the federal government to assist in improving the system's capacity…

  3. Living antennas on communication satellites

    DEFF Research Database (Denmark)

    Lumholt, Michael

    2003-01-01

    Crises change the global pattern of communication. The communications problems occur because the satellites are optimized to cover specific geographic areas, and these areas cannot be altered once the satellites are in Earth orbit. An effective solution to the problem is to equip communication sa...... satellites with "living" antennas that can adjust their radiation coverage areas according to the new demands. The development of living antennas is, therefore, among the focus areas identified and supported by the European Space Agency, ESA....

  4. Radar techniques using array antennas

    CERN Document Server

    Wirth, Wulf-Dieter

    2013-01-01

    Radar Techniques Using Array Antennas is a thorough introduction to the possibilities of radar technology based on electronic steerable and active array antennas. Topics covered include array signal processing, array calibration, adaptive digital beamforming, adaptive monopulse, superresolution, pulse compression, sequential detection, target detection with long pulse series, space-time adaptive processing (STAP), moving target detection using synthetic aperture radar (SAR), target imaging, energy management and system parameter relations. The discussed methods are confirmed by simulation stud

  5. Series-Fed Microstrip Array Antenna with Circular Polarization

    Directory of Open Access Journals (Sweden)

    Tuan-Yung Han

    2012-01-01

    Full Text Available This study proposes a novel 2 × 2 array antenna design with broadband and circularly-polarized (CP operation. The proposed design uses a simple series-fed network to increase the CP bandwidth without requiring one-by-one adjustment of each array element or a complex feed network. Selecting the appropriate spacing between each array element allows the proposed array antenna to generate CP radiation with a low axial ratio. Experimental results based on a prototype show that this 2 × 2 microstrip array antenna achieves a wide 3 dB axial ratio bandwidth of more than 10%. Simulated data are also provided to confirm the measured results.

  6. Development of film antenna for diversity reception; Diversity taio film antenna no kaihatsu

    Energy Technology Data Exchange (ETDEWEB)

    Shigeta, K.; Taniguchi, T.; Kubota, K. [Mazda Motor Corp., Hiroshima (Japan)

    1997-10-01

    Based on the principle of capacitance-loaded window antennas, a new film antenna construction pasting an antenna element on a defogger element printed on a rear window was found. The film antennas show high reception performance, and can be used as television diversity antennas or a VICS-FM multiplex antenna. This paper describes the antenna design concept, the antenna construction and the application to a recreational vehicle which styling is 1.3-Box wagon for the electric accessory. 2 refs., 11 figs.

  7. Wide-Angle-Scanning Reflectarray Antennas Actuated by MEMS

    Science.gov (United States)

    Fang, Houfei; Huang, John; Thomson, Mark W.

    2009-01-01

    An effort to develop large-aperture, wide-angle-scanning reflectarray antennas for microwave radar and communication systems is underway. In an antenna of this type as envisioned, scanning of the radiated or incident microwave beam would be effected through mechanical rotation of the passive (reflective) patch antenna elements, using microelectromechanical systems (MEMS) stepping rotary actuators typified by piezoelectric micromotors. It is anticipated that the cost, mass, and complexity of such an antenna would be less than, and the reliability greater than, those of an electronically scanned phased-array antenna of comparable beam-scanning capability and angular resolution. In the design and operation of a reflectarray, one seeks to position and orient an array of passive patch elements in a geometric pattern such that, through constructive interference of the reflections from them, they collectively act as an efficient single reflector of radio waves within a desired frequency band. Typically, the patches lie in a common plane and radiation is incident upon them from a feed horn.

  8. Design and Development of Aerogel-Based Antennas for Aerospace Applications: A Final Report to the NARI Seedling

    Science.gov (United States)

    Meador, Mary Ann B.; Miranda, Felix A.

    2014-01-01

    As highly porous solids possessing low density and low dielectric permittivity combined with good mechanical properties, polyimide (PI) aerogels offer great promise as an enabling technology for lightweight aircraft antenna systems. While they have been aggressively explored for thermal insulation, barely any effort has been made to leverage these materials for antennas or other applications that take advantage of their aforementioned attributes. In Phase I of the NARI Seedling Project, we fabricated PI aerogels with properties tailored to enable new antenna concepts with performance characteristics (wide bandwidth and high gain) and material properties (low density, environmental stability, and robustness) superior to the state of practice (SOP). We characterized electromagnetic properties, including permittivity, reflectivity, and propagation losses for the aerogels. Simple, prototype planar printed circuit patch antennas from down-selected aerogel formulations were fabricated by molding the aerogels to net shapes and by gold-metalizing the pattern onto the templates via electron beam evaporation in a clean room environment. These aerogel based antennas were benchmarked against current antenna SOP, and exhibited both broader bandwidth and comparable or higher gain performance at appreciably lower mass. Phase II focused on the success of the Phase I results pushing the PI aerogel based antenna technology further by exploring alternative antenna design (i.e., slot coupled antennas) and by examining other techniques for fabricating the antennas including ink jet printing with the goal of optimizing antenna performance and simplifying production. We also examined new aerogel formulations with better moisture and solvent resistance to survive processing conditions. In addition, we investigated more complex antenna designs including passive phased arrays such as 2x4 and 4x8 element arrays to assess the scalability of the aerogel antenna concept. Furthermore, we

  9. Some Recent Developments of Microstrip Antenna

    Directory of Open Access Journals (Sweden)

    Yong Liu

    2012-01-01

    Full Text Available Although the microstrip antenna has been extensively studied in the past few decades as one of the standard planar antennas, it still has a huge potential for further developments. The paper suggests three areas for further research based on our previous works on microstrip antenna elements and arrays. One is exploring the variety of microstrip antenna topologies to meet the desired requirement such as ultrawide band (UWB, high gain, miniaturization, circular polarization, multipolarized, and so on. Another is to apply microstrip antenna to form composite antenna which is more potent than the individual antenna. The last is growing towards highly integration of antenna/array and feeding network or operating at relatively high frequencies, like sub-millimeter wave or terahertz (THz wave regime, by using the advanced machining techniques. To support our points of view, some examples of antennas developed in our group are presented and discussed.

  10. Multiple band circularly polarized microstrip antenna

    Science.gov (United States)

    Yu, I. P. (Inventor)

    1980-01-01

    A multiple antenna assembly for communicating electromagnetic radiation is disclosed. An antenna element stack is constructed of a plurality of elliptical lamina antenna elements mutally separated by layers of dielectric material, and separated from a ground plane by dielectric material. The antenna assembly is coupled through a feed line in contact with the top antenna element. A conductor joins the remaining antenna elements to the ground plane. Each individual antenna element is operable for communication reception and transmission within a frequency band determined by the size of the particular antenna element. The sizes of the antenna elements may be selected to provide electromagnetic radiation communication over several distinct frequency bands, or to connect the individual bands into a broad band.

  11. E-Textile Antennas for Space Environments

    Science.gov (United States)

    Kennedy, Timothy F.; Fink, Patrick W.; Chu, Andrew W.

    2007-01-01

    The ability to integrate antennas and other radio frequency (RF) devices into wearable systems is increasingly important as wireless voice, video, and data sources become ubiquitous. Consumer applications including mobile computing, communications, and entertainment, as well as military and space applications for integration of biotelemetry, detailed tracking information and status of handheld tools, devices and on-body inventories are driving forces for research into wearable antennas and other e-textile devices. Operational conditions for military and space applications of wireless systems are often such that antennas are a limiting factor in wireless performance. The changing antenna platform, i.e. the dynamic wearer, can detune and alter the radiation characteristics of e-textile antennas, making antenna element selection and design challenging. Antenna designs and systems that offer moderate bandwidth, perform well with flexure, and are electronically reconfigurable are ideally suited to wearable applications. Several antennas, shown in Figure 1, have been created using a NASA-developed process for e-textiles that show promise in being integrated into a robust wireless system for space-based applications. Preliminary characterization of the antennas with flexure indicates that antenna performance can be maintained, and that a combination of antenna design and placement are useful in creating robust designs. Additionally, through utilization of modern smart antenna techniques, even greater flexibility can be achieved since antenna performance can be adjusted in real-time to compensate for the antenna s changing environment.

  12. Single and dual-Gregorian reflector antenna shaped beam far-field synthesis

    Science.gov (United States)

    Mehler, M. J.

    The direct far-field G.O. synthesis of shaped beam reflector antennas has recently been treated by Mehler, Tun and Adatia (1986). These authors use a synthesis technique which exploits complex coordinates and which is based on a method originally considered by Norris and Westcott (1976). They describe the synthesis of single reflector antennas which radiate both elliptical beams and European coverage patterns. Here this technique is extended to consider a class of dual reflector antennas which possess shaped main reflectors and conic subreflectors. An example is given of a Gregorian duel reflector antenna which radiates a cross-polar field significantly smaller than that radiated by single shaped reflector antennas. In addition, the behavior of the radiation pattern as a function of the reflector diameter is investigated.

  13. Artificial Neural Network Analysis of Sierpinski Gasket Fractal Antenna: A Low Cost Alternative to Experimentation

    Directory of Open Access Journals (Sweden)

    Balwinder S. Dhaliwal

    2013-01-01

    Full Text Available Artificial neural networks due to their general-purpose nature are used to solve problems in diverse fields. Artificial neural networks (ANNs are very useful for fractal antenna analysis as the development of mathematical models of such antennas is very difficult due to complex shapes and geometries. As such empirical approach doing experiments is costly and time consuming, in this paper, application of artificial neural networks analysis is presented taking the Sierpinski gasket fractal antenna as an example. The performance of three different types of networks is evaluated and the best network for this type of applications has been proposed. The comparison of ANN results with experimental results validates that this technique is an alternative to experimental analysis. This low cost method of antenna analysis will be very useful to understand various aspects of fractal antennas.

  14. Multi-Frequency Analysis For Interstitial Microwave Hyperthermia Using Multi-Slot Coaxial Antenna

    Science.gov (United States)

    Gas, Piotr

    2015-01-01

    The presented paper shows a new concept of multi-slot coaxial antenna working at different frequencies to predict the best solution for interstitial microwave hyperthermia treatment. The described method concerns a microwave heating of unhealthy cells using a thin microwave antenna located in the human tissue. Therefore, the coupled wave equation in a sinusoidal steady-state and the transient bioheat equation under an axial symmetrical model are considered. The 4-Cole-Cole approximation has been used to compute the complex relative permittivity of the human tissues at different antenna operating frequencies. At the stage of numerical simulation the finite element method (FEM) is used. Special attention has been paid to estimate the optimal antenna parameters for thermal therapy for three microwave frequencies mainly used in medical practice and make comparison of the obtained results in the case of single-, double- and triple-slot antennas.

  15. A review of the state of the art in large spaceborne antenna technology

    Science.gov (United States)

    Smith, C. A.

    1978-01-01

    Three classes of antennas (reflectors, lenses, and arrays) are studied with a view toward their use as extremely large space antennas. RF performance characteristics, weight, manufacturing complexity, and cost are discussed for each class. Examples of antennas of each class which were built or analyzed are described to give an appreciation of current and expected industry capability. Multibeam antennas are discussed. General guidelines are given for use of the appropriate class of antenna to meet certain performance requirements, and recommendations are made for future study. The reflector emerges as the optimum choice for most very large aperture applications, though the lens and array appear ideally suited for use as feeds for multibeam near-field Cassegrain or Gregorian designs.

  16. A Tetravalent Dengue Vaccine Based on a Complex Adenovirus Vector Provides Significant Protection in Rhesus Monkeys against All Four Serotypes of Dengue Virus▿

    OpenAIRE

    Raviprakash, Kanakatte; Wang, Danher; Ewing, Dan; Holman, David H.; Block, Karla; Woraratanadharm, Jan; Chen, Lan; Hayes, Curtis; Dong., John Y.; Porter, Kevin

    2008-01-01

    Nearly a third of the human population is at risk of infection with the four serotypes of dengue viruses, and it is estimated that more than 100 million infections occur each year. A licensed vaccine for dengue viruses has become a global health priority. A major challenge to developing a dengue vaccine is the necessity to produce fairly uniform protective immune responses to all four dengue virus serotypes. We have developed two bivalent dengue virus vaccines, using a complex adenovirus vect...

  17. The Effect of Licopid and Bifid and Lactic Acid Bacteria Complex on Lysozyme Activity as the Factor of Nonspecific Immune Protection in Chronic Gastric and Duodenal Ulcer

    OpenAIRE

    Dugina V.V.; Shirali Rashmi; Lebedeva N.V.; Babayan S.R.; Rudakova G.V.; Khrulyova N.S.

    2012-01-01

    The aim of the investigation is to study the effect of Licopid and bifid and lactic acid bacteria complex on Helicobacter pylori eradication and lysozyme activity as the factor of nonspecific immune protection in gastric and duodenal ulcer. Materials and Methods. There were studied 30 patients suffering from Helicobacter associated gastric and duodenal ulcer, lysozyme activity was determined in 8 conditionally healthy individuals. There were used endoscopic, cytomorphological, and imm...

  18. Single Band Helical Antenna in Axial Mode

    Directory of Open Access Journals (Sweden)

    Parminder Singh

    2012-11-01

    Full Text Available Helical antennas have been widely used in a various useful applications, due to their low weight and low profile conformability, easy and cheap realization.Radiation properties of this antenna are examined both theoretically and experimentally. In this paper, an attempt has been made to investigate new helical antenna structure for Applications. CST MWS Software is used for the simulation and design calculations of the helical antennas. The axial ratio, return loss, VSWR, Directivity, gain, radiation pattern is evaluated. Using CST MWS simulation software proposed antenna is designed/simulated and optimized. The antenna exhibits a single band from 0 GHz to 3 GHz for GPS and several satellite applications

  19. Modern lens antennas for communications engineering

    CERN Document Server

    Thornton, John

    2012-01-01

    The aim of this book is to present the modern design principles and analysis of lens antennas. It gives graduates and RF/Microwave professionals the design insights in order to make full use of lens antennas.  Why do we want to write a book in lens antennas? Because this topic has not been thoroughly publicized, its importance is underestimated. As antennas play a key role in communication systems, recent development in wireless communications would indeed benefit from the characteristics of lens antennas: low profile, and low cost etc.  The major advantages of lens antennas are na

  20. Antennas in matter: Fundamentals, theory, and applications

    Science.gov (United States)

    King, R. W. P.; Smith, G. S.; Owens, M.; Wu, T. T.

    1981-01-01

    The volume provides an introduction to antennas and probes embedded within or near material bodies such as the earth, the ocean, or a living organism. After a fundamental analysis of insulated and bare antennas, an advanced treatment of antennas in various media is presented, including a detailed study of the electromagnetic equations in homogeneous isotropic media, the complete theory of the bare dipole in a general medium, and a rigorous analysis of the insulated antenna as well as bare and insulated loop antennas. Finally, experimental models and measuring techniques related to antennas and probes in a general dissipative or dielectric medium are examined.

  1. Broadband Multilayered Array Antenna with EBG Reflector

    Directory of Open Access Journals (Sweden)

    P. Chen

    2013-01-01

    Full Text Available Most broadband microstrip antennae are implemented in the form of slot structure or laminate structure. The impedance bandwidth is broadened, but meanwhile, the sidelobe of the directivity pattern and backlobe level are enlarged. A broadband stacked slot coupling microstrip antenna array with EBG structure reflector is proposed. Test results indicate that the proposed reflector structure can effectively improve the directivity pattern of stacked antenna and aperture coupled antenna, promote the front-to-back ratio, and reduce the thickness of the antenna. Therefore, it is more suitable to be applied as an airborne antenna.

  2. Vehicle antenna development for mobile satellite applications

    Science.gov (United States)

    Woo, K.

    1988-01-01

    The paper summarizes results of a vehicle antenna program at JPL in support of a developing U.S. mobile satellite services (MSS) designed to provide telephone and data services for the continental United States. Two classes of circularly polarized vehicle antennas have been considered for the MSS: medium-gain, satellite-tracking antennas with 10-12-dBic gain; and low-gain, azimuthally omnidirectional antennas with 3-5-dBic gain. The design and performance of these antennas are described, and the two antennas are shown to have peculiar advantages and disadvantages.

  3. Magnetic antenna excitation of whistler modes. II. Antenna arrays

    Energy Technology Data Exchange (ETDEWEB)

    Stenzel, R. L.; Urrutia, J. M. [Department of Physics and Astronomy, University of California, Los Angeles, California 90095-1547 (United States)

    2014-12-15

    The excitation of whistler modes from magnetic loop antennas has been investigated experimentally. The field topology of the excited wave driven by a single loop antenna has been measured for different loop orientations with respect to the uniform background field. The fields from two or more antennas at different locations are then created by superposition of the single-loop data. It is shown that an antenna array can produce nearly plane waves which cannot be achieved with single antennas. By applying a phase shift along the array, oblique wave propagation is obtained. This allows a meaningful comparison with plane wave theory. The Gendrin mode and oblique cyclotron resonance are demonstrated. Wave helicity and polarization in space and time are demonstrated and distinguished from the magnetic helicity of the wave field. The superposition of two oblique plane whistler modes produces in a “whistler waveguide” mode whose polarization and helicity properties are explained. The results show that single point measurements cannot properly establish the wave character of wave packets. The laboratory observations are relevant for excitation and detection of whistler modes in space plasmas.

  4. Design and application of single-antenna GPS/accelerometers attitude determination system

    Institute of Scientific and Technical Information of China (English)

    He Jie; Huang Xianlin; Wang Guofeng

    2008-01-01

    In view of the problem that the current single-antenna GPS attitude determination system can only determine the body attitude when the sideslip angle is zero and the multiantenna GPS/SINS integrated navigation system is of large volume, high cost, and complex structure, this approach is presented to determine the attitude based on vector space with single-antenna GPS and accelerometers in the micro inertial measurement unit (MIMU).It can provide real-time and accurate attitude information. Subsequently, the single-antenna GPS/SINS integrated navigation system is designed based on the combination of position, velocity, and attitude. Finally the semi-physical simulations of single-antenna GPS attitude determination system and single-antenna GPS/SINS integrated navigation system are carried out. The simulation results, based on measured data, show that the single-antenna GPS/SINS system can provide more accurate navigation information compared to the GPS/SINS system, based on the combination of position and velocity. Furthermore, the single-antenna GPS/SINS system is characteristic of lower cost and simpler structure. It provides the basis for the application of a single-antenna GPS/SINS integrated navigation system in a micro aerial vehicle (MAV).

  5. Gain Enhancement of a Microstrip Patch Antenna Using a Reflecting Layer

    Directory of Open Access Journals (Sweden)

    Anwer Sabah Mekki

    2015-01-01

    Full Text Available A low profile, unidirectional, dual layer, and narrow bandwidth microstrip patch antenna is designed to resonate at 2.45 GHz. The proposed antenna is suitable for specific applications, such as security and military systems, which require a narrow bandwidth and a small antenna size. This work is mainly focused on increasing the gain as well as reducing the size of the unidirectional patch antenna. The proposed antenna is simulated and measured. According to the simulated and measured results, it is shown that the unidirectional antenna has a higher gain and a higher front to back ratio (F/B than the bidirectional one. This is achieved by using a second flame retardant layer (FR-4, coated with an annealed copper of 0.035 mm at both sides, with an air gap of 0.04λ0 as a reflector. A gain of 5.2 dB with directivity of 7.6 dBi, F/B of 9.5 dB, and −18 dB return losses (S11 are achieved through the use of a dual substrate layer of FR-4 with a relative permittivity of 4.3 and a thickness of 1.6 mm. The proposed dual layer microstrip patch antenna has an impedance bandwidth of 2% and the designed antenna shows very low complexity during fabrication.

  6. Illustration of the Impedance Behaviour of Extremely Low-Profile Coupled Shorted-Patches Antennas for UHF RFID of People

    Directory of Open Access Journals (Sweden)

    Milan Svanda

    2014-01-01

    Full Text Available The recently introduced coupled shorted-patches technique for the design of extremely low-profile UHF RFID tag antennas is used to illustrate the flexibility of selected feeding methods for tuning the antenna input impedance for the complex values required for matching with typical RFID chips. We present parametric studies of the impedance behaviour of dipole-excited and directly excited antennas designed for radiofrequency identification of people in the European UHF frequency band. Our study can significantly facilitate the design of this class of on-body tag antennas.

  7. Design of LTCC Based Fractal Antenna

    KAUST Repository

    AdbulGhaffar, Farhan

    2010-09-01

    The thesis presents a Sierpinski Carpet fractal antenna array designed at 24 GHz for automotive radar applications. Miniaturized, high performance and low cost antennas are required for this application. To meet these specifications a fractal array has been designed for the first time on Low Temperature Co-fired Ceramic (LTCC) based substrate. LTCC provides a suitable platform for the development of these antennas due to its properties of vertical stack up and embedded passives. The complete antenna concept involves integration of this fractal antenna array with a Fresnel lens antenna providing a total gain of 15dB which is appropriate for medium range radar applications. The thesis also presents a comparison between the designed fractal antenna and a conventional patch antenna outlining the advantages of fractal antenna over the later one. The fractal antenna has a bandwidth of 1.8 GHz which is 7.5% of the centre frequency (24GHz) as compared to 1.9% of the conventional patch antenna. Furthermore the fractal design exhibits a size reduction of 53% as compared to the patch antenna. In the end a sensitivity analysis is carried out for the fractal antenna design depicting the robustness of the proposed design against the typical LTCC fabrication tolerances.

  8. Improved List Sphere Decoder for Multiple Antenna Systems

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    An improved list sphere decoder (ILSD) is proposed based on the conventional list sphere decoder (LSD) and the reduced-complexity maximum likelihood sphere-decoding algorithm. Unlike the conventional LSD with fixed initial radius, the ILSD adopts an adaptive radius to accelerate the list construction. Characterized by low-complexity and radius-insensitivity, the proposed algorithm makes iterative joint detection and decoding more realizable in multiple-antenna systems. Simulation results show that computational savings of ILSD over LSD are more apparent with more transmit antennas or larger constellations, and with no performance degradation. Because the complexity of the ILSD algorithm almost keeps invariant with the increasing of initial radius, the BER performance can be improved by selecting a sufficiently large radius.

  9. The Effect of Licopid and Bifid and Lactic Acid Bacteria Complex on Lysozyme Activity as the Factor of Nonspecific Immune Protection in Chronic Gastric and Duodenal Ulcer

    Directory of Open Access Journals (Sweden)

    Dugina V.V.

    2012-06-01

    Full Text Available The aim of the investigation is to study the effect of Licopid and bifid and lactic acid bacteria complex on Helicobacter pylori eradication and lysozyme activity as the factor of nonspecific immune protection in gastric and duodenal ulcer. Materials and Methods. There were studied 30 patients suffering from Helicobacter associated gastric and duodenal ulcer, lysozyme activity was determined in 8 conditionally healthy individuals. There were used endoscopic, cytomorphological, and immunological (polymerase chain reaction, photonephelometric techniques. To study the effect of immunomodulator and probiotic on eradication and nonspecific immune protection, there were determined H. pylori contamination and lysozyme activity of oropharyngeal secretion and gastric juice before and after the treatment. Results. The analysis of biopsy specimens and lysozyme biological tests revealed the use of immunomodulator (Licopid and bifid and lactic acid bacteria complex combined with anti-Helicobacter pylori therapy increases H. pylori eradication and enhances lysozyme activity of saliva and gastric juice compared to data on quadroscheme. Conclusion. The administration of Licopid and bifid and lactic acid bacteria complex can be recommended in complex therapy of patients suffering from Helicobacter associated gastric and duodenal ulcers.

  10. Evaluation of Optimized ICRF and LHRF Antennas in Alcator C-Mod

    International Nuclear Information System (INIS)

    Full text: Ion cyclotron range of frequency heating (ICRF) and lower hybrid range of frequency current drive (LHCD) are expected to be key heating and current drive actuators for future fusion reactors and devices. However, impurity contamination associated with ICRF antenna operation remains a major challenge, particularly in devices with metallic plasma facing components. For LHCD, maximizing coupled power to the plasma remains a challenge, particularly to maintain low reflection coefficient over range of plasma conditions. Here, we report on an experimental investigation to test whether a field aligned (FA) ICRF antenna can reduce the impurity contamination and SOL modification associated with antenna operation. We also report on results from a new limiter for the LH coupler designed to reduce reflection coefficients across a wider range of plasma conditions. The unique feature of the so-called FA-antenna is that the current straps and antenna box structure are perpendicular to the total magnetic field. This alignment allows integrated E|| (electric field along a magnetic field line) to be minimized through symmetry. Using finite element method and a cold plasma model, the FA-antenna has been found to have lower integrated E|| relative to the previous antenna geometry. Initial results indicate that the impurity contamination associated with the FA-antenna is lower relative to our standard ICRF antennas. Configured as a 2-strap antenna, the antenna has lower core impurity contamination and lower impurity source at the antenna at high power density (∼ 15 MW/m2). An array of core and boundary plasma diagnostics are presently being used to characterize the impurity behavior and impact on the SOL transport and SOL density profiles; the latest results will be presented. For LHCD, reflection coefficients are very sensitive to the local density and its profile in front of the LHCD coupler. Previously the local LH coupler protection limiter was fixed to the outer wall

  11. VLBI Antenna Calibration via GPS Project

    Data.gov (United States)

    National Aeronautics and Space Administration — We propose to investigate and develop an inexpensive system to determine: 1)VLBI antenna properties such as axis-offset, non-intersection of axis and antenna...

  12. International Mapping of Antenna-Measurement Facilities

    DEFF Research Database (Denmark)

    Boccia, Luigi; Breinbjerg, Olav; Di Massa, Giuseppe;

    2006-01-01

    This paper presents a comprehensive international mapping of antenna-measurement facilities. This initiative, conducted within the framework of the Antenna Centre of Excellence (ACE) of the European Union, is oriented toward all institutions having research, development, or operational activities...

  13. Wrap-rib antenna concept development overview

    Science.gov (United States)

    Woods, A. A., Jr.; Garcia, N. F.

    1983-01-01

    The wrap rib antenna design of a parabolic reflector large space antenna is discussed. Cost estimates, design/mission compatibility, deployment sequence, ground based tests, and fabrication are discussed.

  14. 47 CFR 74.641 - Antenna systems.

    Science.gov (United States)

    2010-10-01

    ..., AUXILIARY, SPECIAL BROADCAST AND OTHER PROGRAM DISTRIBUTIONAL SERVICES Television Broadcast Auxiliary... transmitted signal. Booster station antennas having narrower beamwidths and reduced sidelobe radiation may be... or with the minimum antenna gain requirement; and (B) With the minimum radiation suppression to...

  15. Multiband small zeroth-order metamaterial antenna

    Science.gov (United States)

    Dakhli, Nabil; Choubani, Fethi; David, Jacques

    2011-06-01

    A novel resonant metamaterial antenna based on the Composite Right/Left-Handed (CRLH) transmission line (TL) model is presented. The proposed small antenna is designed to operate simultaneously over multiple wireless services (UMTS-WLAN-WIMAX)

  16. Multifrequency Printed Antennas Loaded with Metamaterial Particles

    Directory of Open Access Journals (Sweden)

    D. Segovia-Vargas

    2009-06-01

    Full Text Available This paper provides a review of printed antennas loaded with metamaterial particles. This novel technique allows developing printed antennas with interesting features such as multifrequency (simultaneous operation over two or more frequency bands and multifunctionality (e. g. radiation pattern diversity. Moreover, compactness is also achieved and the main advantages of conventional printed antennas (light weight, low profile, low cost ... are maintained. Different types of metamaterial-loaded printed antennas are reviewed: printed dipoles and patch antennas. Several prototypes are designed, manufactured and measured showing good results. Furthermore, simple but accurate equivalent models are proposed. These models allow an easy and quick design of metamaterial-loaded printed antennas. Finally, two interesting applications based on the proposed antennas are reviewed: the patch antennas are used as radiating elements of emerging active RFID systems in the microwave band and the metamaterial-loaded printed dipoles are employed to increase the performance of log-periodic arrays.

  17. Integrated resonant tunneling diode based antenna

    Energy Technology Data Exchange (ETDEWEB)

    Hietala, Vincent M. (Placitas, NM); Tiggers, Chris P. (Albuquerque, NM); Plut, Thomas A. (Albuquerque, NM)

    2000-01-01

    An antenna comprising a plurality of negative resistance devices and a method for making same comprising employing a removable standoff layer to form the gap between the microstrip antenna metal and the bottom contact layer.

  18. Antenna Technology Shuttle Experiment (ATSE)

    Science.gov (United States)

    Freeland, R. E.; Mettler, E.; Miller, L. J.; Rahmet-Samii, Y.; Weber, W. J., III

    1987-06-01

    Numerous space applications of the future will require mesh deployable antennas of 15 m in diameter or greater for frequencies up to 20 GHz. These applications include mobile communications satellites, orbiting very long baseline interferometry (VLBI) astrophysics missions, and Earth remote sensing missions. A Lockheed wrap rip antennas was used as the test article. The experiments covered a broad range of structural, control, and RF discipline objectives, which is fulfilled in total, would greatly reduce the risk of employing these antenna systems in future space applications. It was concluded that a flight experiment of a relatively large mesh deployable reflector is achievable with no major technological or cost drivers. The test articles and the instrumentation are all within the state of the art and in most cases rely on proven flight hardware. Every effort was made to design the experiments for low cost.

  19. Offset unfurlable antenna, phase 1

    Science.gov (United States)

    1984-03-01

    The configuration, technology requirements, development aspects, and experimental activities for satellite reflectors for fixed and mobile communications and television broadcasting are outlined. A 4.5 m antenna for 4 GHz, and an 8 m antenna for 1.6 GHz were studied, assuming an L-Sat type satellite. A radial rib concept with auxiliary adjustment ribs, and a three dimensional scissors concept (spatial framework) with mesh adjustment elements were compared concerning mass, stowage, volume, development risk, and reliability. For antennas of diameter from 3.6 to 12 m (12 GHz to 800 MHz) the radial rib reflector is preferred. Main advantages (with rib folding for larger reflector diameters) are: lower costs; less critical technology problems; lower development risks; high deployment reliability; lightweight intermediate ribs can adapt surface accuracy to higher frequency requirements (high application flexibility); and folded main ribs provide high package capability at larger diameters. The scissors concept is advantageous for applications requiring reflectors from 12 m diameter onwards.

  20. Compact Low Frequency Radio Antenna

    Science.gov (United States)

    Punnoose, Ratish J.

    2008-11-11

    An antenna is disclosed that comprises a pair of conductive, orthogonal arches and a pair of conductive annular sector plates, wherein adjacent legs of each arch are fastened to one of the annular sector plates and the opposite adjacent pair of legs is fastened to the remaining annular sector plate. The entire antenna structure is spaced apart from a conductive ground plane by a thin dielectric medium. The antenna is driven by a feed conduit passing through the conductive ground plane and dielectric medium and attached to one of the annular sector plates, wherein the two orthogonal arched act as a pair of crossed dipole elements. This arrangement of elements provides a radiation pattern that is largely omni-directional above the horizon.

  1. Ultra-wideband RF helmet antenna

    OpenAIRE

    Lebaric, Jovan; Tan, Ah-Tuan

    2000-01-01

    This paper addresses the development of an ultra-wideband, vertically polarized communications antenna integrated into the camouflage cover of a standard military-issue Kevlar helmet. The Helmet Camouflage Cover Antenna (referred to as the “helmet antenna’y is one of three antennas based on the antenna COMbat Wear INtegration (COMWIN) concept developed at the Naval Postgraduate School (NPS) for the man -portable implementation of the new Joint Tactical Radio System (JTRS). The results of c...

  2. Bandwidth characteristics of monopulse slotted waveguide antennas

    Science.gov (United States)

    Derneryd, A.; Peterson, R.

    Slotted waveguide antennas are of resonant and nonresonant type; the former generate a beam normal to the aperture, rendering them suitable for monopulse antenna applications. Attention is presently given to the improvement of resonant antenna impedance matching through a process of waveguide overloading. The combination of an overloaded waveguide and a transformer will generally have a broader impedance match than the antenna matched by itself; this phenomenon is discussed from both impedance-match and sidelobe level viewpoints.

  3. Circularly polarized open-loop antenna

    OpenAIRE

    Li, Rong-Lin; Fusco, Vincent F.; Nakano, Hisamatsu

    2003-01-01

    A printed circular open-loop antenna is introduced as a simple structure for producing circular polarization; the antenna is fed with a coaxial probe. By introducing a gap within the circular loop a traveling-wave current is excited and thus circularly polarized radiation can be achieved. An optimized circularly polarized antenna is designed through numerical analysis using a so-called parametric method of moment technique. Experimental verification of the new antenna is presented. The antenn...

  4. A COMPACT CIRCULARLY POLARIZED SLOTTED MICROSTRIP ANTENNA

    OpenAIRE

    V. Jebaraj; K.R.S. Ravi Kumar; D. Mohanageetha

    2014-01-01

    Slot antennas are often used at UHF and microwave frequencies. In slot antenna for RFID reader applications the frequency ranges from 902-923MHz to achieve circular polarization. The shapes and size of the slot, as well as the driving frequency, determine the radiation distribution pattern. The proposed compact size circularly polarized slotted microstrip antenna are summarized with design rules. The circularly polarized radiation in square patch antenna can be obtained by perturbation techni...

  5. Wideband irregular-shaped fractal antennas

    OpenAIRE

    Kolesov, V. V.; Krupenin, S. V.

    2007-01-01

    This paper proposes an algorithm of generating fully reproducible irregular fractal structures for antenna design. Three types of pseudorandom fractal clusters are introduced. The multi-frequency behavior of the irregular-shaped fractal antennas is studied by means of numerical analysis. The antenna behavior is studied under feeder displacement. As shown by numerical results feeder displacements allow one to control the spatial-frequency antenna characteristics.

  6. Rectangular dielectric resonator antennas theory and design

    CERN Document Server

    Yaduvanshi, Rajveer S

    2016-01-01

    This book covers resonating modes inside device and gives insights into antenna design, impedance and radiation patterns. It discusses how higher-order modes generation and control impact bandwidth and antenna gain. The text covers new approaches in antenna design by investigation hybrid modes, H_Z and E_Z fields available simultaneously, and analysis and modelling on modes with practical applications in antenna design. The book will be prove useful to students, researchers and professionals alike.

  7. Knowledge-based antenna pattern extrapolation

    OpenAIRE

    Robinson, Michael

    2012-01-01

    We describe a theoretically-motivated algorithm for extrapolation of antenna radiation patterns from a small number of measurements. This algorithm exploits constraints on the antenna's underlying design to avoid ambiguities, but is sufficiently general to address many different antenna types. A theoretical basis for the robustness of this algorithm is developed, and its performance is verified in simulation using a number of popular antenna designs.

  8. Reconfigurable Monopole Antennas With Circular Polarization

    OpenAIRE

    Panahi, Afshin

    2015-01-01

    This thesis presents research on printed circularly-polarized monopole antennas and their application in reconfigurable monopole antennas. The proposed circularly-polarised monopole antennas benefit from advantages such as small size, low-cost, low-profile and simple designs. The first part of this thesis introduces three printed circularly-polarized monopole antennas for global navigation satellite systems and Wi-Fi applications. The primary focus is on the ground plane which is used as a ra...

  9. Research of Klopfenstein taper UWB monopole antenna

    OpenAIRE

    Wang, Nan-Nan; Qiu, Jinghui; Zhang, Zhi-Feng; Zong, Hua; Ling-Ling, Zhong; Wei-Bo, Deng

    2011-01-01

    The tapered line theory in circuit can be applied to the design of the special-shaped monopole antenna in order to obtain better electrical characteristics. So a novel Klopfenstein taper monopole antenna is proposed. The impedance matching characteristic of the Klopfenstein tapered line is the best, and the Klopfenstein taper monopole antenna is designed based on it. On this basis, the coplanar waveguide-fed planar Klopfenstein taper monopole antennas are designed. The simulation and measurem...

  10. A novel coaxial CTS antenna design

    OpenAIRE

    Qiu, Jinghui; Xing, Xiaohang; Ling-Ling, Zhong

    2007-01-01

    CTS (Continuous Transverse Stub) antenna radiates electromagnetic wave with its transverse stubs on transmission line, and its pattern in horizon plane is omnidirectional. This paper proposes a novel coaxial CTS structure, in which a monopole is applied in coaxial CTS antenna, instead of a matching load. This method may not only improve the radiation ratio, but also reduce the height of antenna. There are two stubs and a monopole composing an antenna, and the dielectric in stubs is air, which...

  11. Multi-Band Wireless Terminals With A Hybrid Antenna Along An End Portion, And Related Multi-Band Antenna Systems

    DEFF Research Database (Denmark)

    2014-01-01

    An antenna system may include a backplate that includes an end portion. The antenna system may also include a hybrid antenna that includes first and second antenna elements spaced apart from each other along the end portion of the backplate. The first antenna element may include a type of antenna...

  12. Texas Chenier Plain Refuge Complex: Final Environmental Impact Statement, Comprehensive Conservation Plan, and Land Protection Plan (Volumes 1 and 2)

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This Comprehensive Conservation Plan (CCP) was written to guide management on Texas Chenier Plains Refuge Complex for the next 15 years. This plan outlines the...

  13. Wireless Sensor Network Security Enhancement Using Directional Antennas: State of the Art and Research Challenges.

    Science.gov (United States)

    Curiac, Daniel-Ioan

    2016-01-01

    Being often deployed in remote or hostile environments, wireless sensor networks are vulnerable to various types of security attacks. A possible solution to reduce the security risks is to use directional antennas instead of omnidirectional ones or in conjunction with them. Due to their increased complexity, higher costs and larger sizes, directional antennas are not traditionally used in wireless sensor networks, but recent technology trends may support this method. This paper surveys existing state of the art approaches in the field, offering a broad perspective of the future use of directional antennas in mitigating security risks, together with new challenges and open research issues. PMID:27070601

  14. Receive antenna selection for underlay cognitive radio with instantaneous interference constraint

    KAUST Repository

    Hanif, Muhammad Fainan

    2015-06-01

    Receive antenna selection is a low complexity scheme to reap diversity benefits.We analyze the performance of a receive antenna selection scheme in spectrum sharing systems where the antenna that results in highest signal-to-interference plus noise ratio at the secondary receiver is selected to improve the performance of secondary transmission. Exact and asymptotic behaviours of the received SINR are derived for both general and interference limited scenarios over general fading environment. These results are then applied to the outage and average bit error rate analysis when the secondary transmitter changes the transmit power in finite discrete levels to satisfy the instantaneous interference constraint at the primary receiver.

  15. Wireless Sensor Network Security Enhancement Using Directional Antennas: State of the Art and Research Challenges.

    Science.gov (United States)

    Curiac, Daniel-Ioan

    2016-04-07

    Being often deployed in remote or hostile environments, wireless sensor networks are vulnerable to various types of security attacks. A possible solution to reduce the security risks is to use directional antennas instead of omnidirectional ones or in conjunction with them. Due to their increased complexity, higher costs and larger sizes, directional antennas are not traditionally used in wireless sensor networks, but recent technology trends may support this method. This paper surveys existing state of the art approaches in the field, offering a broad perspective of the future use of directional antennas in mitigating security risks, together with new challenges and open research issues.

  16. Wireless Sensor Network Security Enhancement Using Directional Antennas: State of the Art and Research Challenges

    Directory of Open Access Journals (Sweden)

    Daniel-Ioan Curiac

    2016-04-01

    Full Text Available Being often deployed in remote or hostile environments, wireless sensor networks are vulnerable to various types of security attacks. A possible solution to reduce the security risks is to use directional antennas instead of omnidirectional ones or in conjunction with them. Due to their increased complexity, higher costs and larger sizes, directional antennas are not traditionally used in wireless sensor networks, but recent technology trends may support this method. This paper surveys existing state of the art approaches in the field, offering a broad perspective of the future use of directional antennas in mitigating security risks, together with new challenges and open research issues.

  17. Antenna for Measuring Electric Fields Within the Inner Heliosphere

    Science.gov (United States)

    Sittler, Edward Charles

    2007-01-01

    A document discusses concepts for the design of an antenna to be deployed from a spacecraft for measuring the ambient electric field associated with plasma waves at a location within 3 solar radii from the solar photosphere. The antenna must be long enough to extend beyond the photoelectron and plasma sheaths of the spacecraft (expected to be of the order of meters thick) and to enable measurements at frequencies from 20 Hz to 10 MHz without contamination by spacecraft electric-field noise. The antenna must, therefore, extend beyond the thermal protection system (TPS) of the main body of the spacecraft and must withstand solar heating to a temperature as high as 2,000 C while not conducting excessive heat to the interior of the spacecraft. The TPS would be conical and its axis would be pointed toward the Sun. The antenna would include monopole halves of dipoles that would be deployed from within the shadow of the TPS. The outer potion of each monopole would be composed of a carbon-carbon (C-C) composite surface exposed to direct sunlight (hot side) and a C-C side in shadow (cold side) with yttria-stabilized zirconia spacers in-between. The hot side cannot view the spacecraft bus, while the cold side can. The booms also can be tilted to minimize heat input to spacecraft bus. This design allows one to reduce heat input to the spacecraft bus to acceptable levels.

  18. Hollow plasmonic antennas for broadband SERS spectroscopy.

    Science.gov (United States)

    Messina, Gabriele C; Malerba, Mario; Zilio, Pierfrancesco; Miele, Ermanno; Dipalo, Michele; Ferrara, Lorenzo; De Angelis, Francesco

    2015-01-01

    The chemical environment of cells is an extremely complex and multifaceted system that includes many types of proteins, lipids, nucleic acids and various other components. With the final aim of studying these components in detail, we have developed multiband plasmonic antennas, which are suitable for highly sensitive surface enhanced Raman spectroscopy (SERS) and are activated by a wide range of excitation wavelengths. The three-dimensional hollow nanoantennas were produced on an optical resist by a secondary electron lithography approach, generated by fast ion-beam milling on the polymer and then covered with silver in order to obtain plasmonic functionalities. The optical properties of these structures have been studied through finite element analysis simulations that demonstrated the presence of broadband absorption and multiband enhancement due to the unusual geometry of the antennas. The enhancement was confirmed by SERS measurements, which showed a large enhancement of the vibrational features both in the case of resonant excitation and out-of-resonance excitation. Such characteristics indicate that these structures are potential candidates for plasmonic enhancers in multifunctional opto-electronic biosensors.

  19. Antenna Construction and Propagation of Radio Waves.

    Science.gov (United States)

    Marine Corps Inst., Washington, DC.

    Developed as part of the Marine Corps Institute (MCI) correspondence training program, this course on antenna construction and propagation of radio waves is designed to provide communicators with instructions in the selection and/or construction of the proper antenna(s) for use with current field radio equipment. Introductory materials include…

  20. 47 CFR 101.115 - Directional antennas.

    Science.gov (United States)

    2010-10-01

    ... more than one point, a multi- or omni-directional antenna may be authorized if necessary. New Periscope... frequency congestion, antennas meeting performance Standard B may be used, subject to the requirements set... angle requirement. Antenna Standards Frequency (MHz) Category Maximum beamwidth to 3 dB points...

  1. Future Vogues in Handset Antenna Systems

    DEFF Research Database (Denmark)

    Pelosi, Mauro; Pedersen, Gert Frølund

    2011-01-01

    This paper exemplifies future trends in handset antenna systems, contextualizing their historical evolution and anticipating novel paradigms. It is shown through numerical simulations how narrow-band antennas used in transceiver separation mode can reduce the total loss in presence of the user......’s hand, improving at the same time the antenna isolation....

  2. Small X-Band Oscillator Antennas

    Science.gov (United States)

    Lee, Richard Q.; Miranda, Felix A.; Clark, Eric B.; Wilt, David M.; Mueller, Carl H.; Kory, Carol L.; Lambert, Kevin M.

    2009-01-01

    A small, segmented microstrip patch antenna integrated with an X-band feedback oscillator on a high-permittivity substrate has been built and tested. This oscillator antenna is a prototype for demonstrating the feasibility of such devices as compact, low-power-consumption building blocks of advanced, lightweight, phased antenna arrays that would generate steerable beams for communication and remotesensing applications.

  3. 47 CFR 73.753 - Antenna systems.

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 4 2010-10-01 2010-10-01 false Antenna systems. 73.753 Section 73.753 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) BROADCAST RADIO SERVICES RADIO BROADCAST SERVICES International Broadcast Stations § 73.753 Antenna systems. All international broadcasting stations shall operate with directional antennas....

  4. Wireless link design using a patch antenna

    Energy Technology Data Exchange (ETDEWEB)

    Hall, E

    2000-08-11

    A wireless link was designed using a patch antenna. In the process, several different models were tested. Testing proved a patch antenna was a viable solution for building a wireless link within the design specifications. Also, this experimentation provided a basis for future patch antenna design.

  5. Fundamentals of antennas concepts and applications

    CERN Document Server

    Christodoulou, Christos G

    2001-01-01

    This tutorial explains antenna design and application for various systems, including communications, remote sensing, radar, and biomedicine. It describes basic wire and array antennas in detail and introduces other types such as reflectors, lenses, horns, Yagi, microstrip, and frequency-independent antennas. Integration issues and technical challenges are discussed. Aimed at students, engineers, researchers, and technical professionals.

  6. Orthogonal antenna architecture for MIMO handsets

    DEFF Research Database (Denmark)

    Tatomirescu, Alexandru; Alrabadi, Osama; Pedersen, Gert Frølund

    2012-01-01

    The paper presents a method for decorrelating the antenna elements of a MIMO system in a compact handheld terminal at low bands. The architecture of the antenna system induces orthogonal currents over the closely spaced antennas resulting in a correlation free system. Nevertheless, due to the small...

  7. 47 CFR 80.967 - Antenna system.

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false Antenna system. 80.967 Section 80.967... MARITIME SERVICES Radiotelephone Installation Required for Vessels on the Great Lakes § 80.967 Antenna system. The antenna must be omni-directional, vertically polarized and located as high as practicable...

  8. 47 CFR 80.923 - Antenna system.

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false Antenna system. 80.923 Section 80.923... MARITIME SERVICES Compulsory Radiotelephone Installations for Small Passenger Boats § 80.923 Antenna system. An antenna must be provided in accordance with the applicable requirements of § 80.81 of this...

  9. Wide-band dipole-slot antenna

    OpenAIRE

    Tsaliev, T. A.

    2014-01-01

    Properties of the antenna in the form of parallel slots array cut in the flat well-conducting screen excited by symmetrical half-wave dipole are considered. On the basis of computer modeling frequency dependences of antenna input impedance, directivity and the VSWR are designed and analyzed. Results of researches evidently display advantages of such antenna.

  10. 47 CFR 80.1017 - Antenna system.

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false Antenna system. 80.1017 Section 80.1017... MARITIME SERVICES Radiotelephone Installations Required by the Bridge-to-Bridge Act § 80.1017 Antenna system. (a) An antenna must be provided for nonportable bridge-to-bridge radiotelephone...

  11. Near Field On Chip RFID Antenna Design

    OpenAIRE

    Vargas, Alberto; Vojtech, Lukas

    2010-01-01

    The process of fabricating the antenna on the top of the RFID chip eliminates the need for a separated and costly expensive process for antenna printing and assemblage, compulsory for a separated "off-chip" antenna which is much more times larger than the chip itself. This

  12. 47 CFR 74.737 - Antenna location.

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 4 2010-10-01 2010-10-01 false Antenna location. 74.737 Section 74.737... Booster Stations § 74.737 Antenna location. (a) An applicant for a new low power TV, TV translator, or TV.... (b) The transmitting antenna should be placed above growing vegetation and trees lying in...

  13. 47 CFR 73.69 - Antenna monitors.

    Science.gov (United States)

    2010-10-01

    ... citations affecting § 73.69 see the List of CFR Sections Affected, which appears in the Finding Aids section... 47 Telecommunication 4 2010-10-01 2010-10-01 false Antenna monitors. 73.69 Section 73.69... Broadcast Stations § 73.69 Antenna monitors. (a) Each station using a directional antenna must have...

  14. Monopole Antenna with Modify Ground Plane

    OpenAIRE

    kamal raj singh rajoriya; Singhal, P.K.

    2012-01-01

    This paper presents on modified the ground plane of monopole antenna with varying the shape and length. Basically the length of ground plane of monopole antenna is equal and greater than λ/4. Here analyzed a different ground plane of monopole antenna that is provided an efficient bandwidth with sufficient return loss.

  15. Monopole Antenna with Modify Ground Plane

    Directory of Open Access Journals (Sweden)

    kamal raj singh rajoriya

    2012-06-01

    Full Text Available This paper presents on modified the ground plane of monopole antenna with varying the shape and length. Basically the length of ground plane of monopole antenna is equal and greater than λ/4. Here analyzed a different ground plane of monopole antenna that is provided an efficient bandwidth with sufficient return loss.

  16. Accurate determination of antenna directivity

    DEFF Research Database (Denmark)

    Dich, Mikael

    1997-01-01

    The derivation of a formula for accurate estimation of the total radiated power from a transmitting antenna for which the radiated power density is known in a finite number of points on the far-field sphere is presented. The main application of the formula is determination of directivity from power......-pattern measurements. The derivation is based on the theory of spherical wave expansion of electromagnetic fields, which also establishes a simple criterion for the required number of samples of the power density. An array antenna consisting of Hertzian dipoles is used to test the accuracy and rate of convergence...

  17. Advanced antennas for SAR spacecraft

    Science.gov (United States)

    Gail, William B.

    1993-01-01

    Single and multi-frequency antenna concepts were developed to evaluate the feasibility of building large aperture polarimetric synthetic aperture radar (SAR) systems to be launched in low cost vehicles such as the Delta 2. The antennas are 18.9 m long by 2.6 m wide (L-band) and achieve single polarization imaging to an incidence angle of 55 degrees and dual/quad imaging to 42 degrees. When combined with strawman spacecraft designs, both concepts meet the mass and volume constraints imposed by a Delta 2 launch.

  18. Nested-cone transformer antenna

    Science.gov (United States)

    Ekdahl, Carl A.

    1991-01-01

    A plurality of conical transmission lines are concentrically nested to form n output antenna for pulsed-power, radio-frequency, and microwave sources. The diverging conical conductors enable a high power input density across a bulk dielectric to be reduced below a breakdown power density at the antenna interface with the transmitting medium. The plurality of cones maintain a spacing between conductors which minimizes the generation of high order modes between the conductors. Further, the power input feeds are isolated at the input while enabling the output electromagnetic waves to add at the transmission interface. Thus, very large power signals from a pulse rf, or microwave source can be radiated.

  19. On Transmit Antenna Selection for Multiuser MIMO Systems with Dirty Paper Coding

    CERN Document Server

    Mohaisen, Manar

    2010-01-01

    In this paper, we address the transmit antenna selection in multi-user MIMO systems with precoding. The optimum and reduced complexity sub-optimum antenna selection algorithms are introduced. QR-decomposition (QRD) based antenna selection is investigated and the reason behind its sub-optimality is analytically derived. We introduce the conventional QRD-based algorithm and propose an efficient QRD-based transmit antenna scheme (maxR) that is both implementation and performance efficient. Moreover, we derive explicit formulae for the computational complexities of the aforementioned algorithms. Simulation results and analysis demonstrate that the proposed maxR algorithm requires only 1% of the computational efforts required by the optimal algorithm for a degradation of 1dB and 0.1dB in the case of linear zero-forcing and Tomlinson-Harashima precoding schemes, respectively.

  20. Analysis of 4-strap ICRF Antenna Performance in Alcator C-Mod

    Energy Technology Data Exchange (ETDEWEB)

    G. Schilling; S.J. Wukitch; R.L. Boivin; J.A. Goetz; J.C. Hosea; J.H. Irby; Y. Lin; A. Parisot; M. Porkolab; J.R. Wilson; the Alcator C-Mod Team

    2003-07-31

    A 4-strap ICRF antenna was designed and fabricated for plasma heating and current drive in the Alcator C-Mod tokamak. Initial upgrades were carried out in 2000 and 2001, which eliminated surface arcing between the metallic protection tiles and reduced plasma-wall interactions at the antenna front surface. A boron nitride septum was added at the antenna midplane to intersect electric fields resulting from radio-frequency sheath rectification, which eliminated antenna corner heating at high power levels. The current feeds to the radiating straps were reoriented from an E||B to E parallel B geometry, avoiding the empirically observed {approx}15 kV/cm field limit and raising antenna voltage holding capability. Further modifications were carried out in 2002 and 2003. These included changes to the antenna current strap, the boron nitride tile mounting geometry, and shielding the BN-metal interface from the plasma. The antenna heating efficiency, power, and voltage characteristics under these various configurations will be presented.

  1. Particle-In-Cell Simulations on Electric Field Antenna Characteristics in the Spacecraft Environment

    Science.gov (United States)

    Miyake, Y.; Usui, H.; Kojima, H.; Omura, Y.; Matsumoto, H.

    2006-12-01

    The Solar Terrestrial Physics (STP) group in Japan has organized a new magnetospheric mission named SCOPE whose objective is to investigate the scale-coupling process of plasma dynamics in the Terrestrial magnetosphere. For the sophisticated electric field measurements planned in the SCOPE mission, we have to investigate the antenna characteristics which are essential for the precise calibration of observed data. Particularly, (1) realistic antenna geometries including spacecraft body and (2) inhomogeneous plasma environment created by plasma-spacecraft interactions should be taken into consideration in the antenna analysis for application to the scientific mission. However, the analysis of the antenna impedance is very complex because the plasma is a dispersive and anisotropic medium, and thus it is too difficult to consider the realistic plasma environment near the spacecraft by the theoretical approaches. In the present study, we apply the Particle-In-Cell simulations to the antenna analysis, which enables us to treat the antenna model including a spacecraft body and analyze the effects of photoelectron emission on antenna characteristics. The present antenna model consists of perfect conducting antennas and spacecraft body, and the photoelectron emission from the sunlit surfaces is also modeled. Using these models, we first performed the electrostatic simulations and examined the photoelectron environment around the spacecraft. Next, the antenna impedance under the obtained photoelectron environment was examined by the electromagnetic simulations. Impedance values obtained in photoelectron environment were much different from those in free space, and they were analogous to the impedance characteristics of an equivalent electric circuit consisting of a resistance and capacitance connected in parallel. The validity of the obtained values has been examined by the comparison with the measurements by the scientific spacecraft.

  2. Limitations of plasmid vaccines to complex viruses: selected myxoma virus antigens as DNA vaccines were not protective.

    Science.gov (United States)

    Adams, Mathew M; van Leeuwen, Barbara H; Kerr, Peter J

    2004-11-25

    Myxoma virus, a poxvirus of the genus Leporipoxvirus, is the causative agent of the disease myxomatosis which is highly lethal in European rabbits (Oryctolagus cuniculus). Current vaccines to protect against myxomatosis are either attenuated live strains of the virus or the antigenically related rabbit fibroma virus. We examined the immune response of outbred domestic rabbits to the individual myxoma virus antigens M055R, M073R, M115L and M121R, delivered as DNA vaccines co-expressing rabbit interleukin-2 or interleukin-4. M115L and M121R were also delivered simultaneously. None of the vaccine constructs were able to protect the rabbits from disease or reduce mortality after challenge with virulent myxoma virus, despite induction of antigen-specific cell-mediated and humoral immune responses. PMID:15531037

  3. Light-Harvesting Antenna System from the Phototrophic Bacterium Roseiflexus castenholzii

    Energy Technology Data Exchange (ETDEWEB)

    Collins, Aaron M. [Washington Univ., St. Louis, MO (United States); Qian, Pu [Univ. of Sheffield (United Kingdom); Tang, Qun [Univ. of California, Riverside, CA (United States); Bocian, David F [Univ. of California, Riverside, CA (United States); Hunter, C. Neil [Univ. of Sheffield (United Kingdom); Blankenship, Robert E. [Washington Univ., St. Louis, MO (United States)

    2010-08-12

    Photosynthetic organisms have evolved diverse light-harvesting complexes to harness light of various qualities and intensities. Photosynthetic bacteria can have (bacterio)chlorophyll Qy antenna absorption bands ranging from ~650 to ~1100 nm. This broad range of wavelengths has allowed many organisms to thrive in unique light environments. Roseiflexus castenholzii is a niche-adapted, filamentous anoxygenic phototroph (FAP) that lacks chlorosomes, the dominant antenna found in most green bacteria, and here we describe the purification of a full complement of photosynthetic complexes: the light-harvesting (LH) antenna, reaction center (RC), and core complex (RC-LH). By high-performance liquid chromatography separation of bacteriochlorophyll and bacteriopheophytin pigments extracted from the core complex and the RC, the number of subunits that comprise the antenna was determined to be 15 ± 1. Resonance Raman spectroscopy of the carbonyl stretching region displayed modes indicating that 3C-acetyl groups of BChl a are all involved in molecular interactions probably similar to those found in LH1 complexes from purple photosynthetic bacteria. Finally, two-dimensional projections of negatively stained core complexes and the LH antenna revealed a closed, slightly elliptical LH ring with an average diameter of 130 ± 10 Å surrounding a single RC that lacks an H-subunit but is associated with a tetraheme c-type cytochrome.

  4. Forward Scattering of Loaded and Unloaded Antennas

    DEFF Research Database (Denmark)

    Gustafsson, Mats; Andersen, Jørgen Bach; Kristensson, Gerhard;

    2012-01-01

    Forward scattering of antennas is related to antenna performance via the forward-scattering sum rule. The forward-scattering sum rule is an integral identity that shows that a weighted integral of the extinction cross section over all spectrum is proportional to the static polarizability...... of the antenna structure. Here, the forward-scattering sum rule is experimentally verified for loaded, short-circuit, and open-circuit cylindrical dipole antennas. It is also shown that the absorption efficiency cannot be greater than 1/2 for reciprocal linearly polarized lossless matched antennas...

  5. Measurement of Antenna Bore-Sight Gain

    Science.gov (United States)

    Fortinberry, Jarrod; Shumpert, Thomas H.

    2016-01-01

    The absolute or free-field gain of a simple antenna can be approximated using standard antenna theory formulae or for a more accurate prediction, numerical methods may be employed to solve for antenna parameters including gain. Both of these methods will result in relatively reasonable estimates but in practice antenna gain is usually verified and documented via measurements and calibration. In this paper, a relatively simple and low-cost, yet effective means of determining the bore-sight free-field gain of a VHF/UHF antenna is proposed by using the Brewster angle relationship.

  6. Antenna Design for Diversity and MIMO Application

    DEFF Research Database (Denmark)

    Ying, Zhinong; Chiu, Chi-Yuk; Zhao, Kun;

    2015-01-01

    efficiencies of MIMO elements would be degraded severely due to mutual couplings. In addition, the human body causes high losses on electromagnetic waves. In real applications, the presence of users may result in significant reduction of total antenna efficiencies, and the correlations of MIMO antenna systems...... are also highly affected. In this chapter, the performance of some basic MIMO antennas as well as recent technologies toimprove MIMO antenna performance of portable devices and mobile terminals are reviewed. The interactions between MIMO antennas and human body are also addressed particularly in...

  7. Multi-antenna synthetic aperture radar

    CERN Document Server

    Wang, Wen-Qin

    2013-01-01

    Synthetic aperture radar (SAR) is a well-known remote sensing technique, but conventional single-antenna SAR is inherently limited by the minimum antenna area constraint. Although there are still technical issues to overcome, multi-antenna SAR offers many benefits, from improved system gain to increased degrees-of-freedom and system flexibility. Multi-Antenna Synthetic Aperture Radar explores the potential and challenges of using multi-antenna SAR in microwave remote sensing applications. These applications include high-resolution imaging, wide-swath remote sensing, ground moving target indica

  8. PBG Based High Gain Microstrip Stacked Antenna

    Directory of Open Access Journals (Sweden)

    Babulal Chaudhary

    2013-03-01

    Full Text Available In this paper, authors have proposed the analysis of a rectangular stacked patch antenna operates at the frequency of 2.4 GHz with a photonic band-gap structure (PBG and compared its performances with a conventional patch antenna. Due to the presence of the PBG structure in the dielectric substrate, proposed antenna shows a significant reduction in surface wave levels than a conventional patch antenna. As a result, the gain of the proposed antenna is found to be improved by 3.2 dB

  9. Endfire tapered slot antennas on dielectric substrates

    Science.gov (United States)

    Yngvesson, K. S.; Schaubert, D. H.; Korzeniowski, T. L.; Kollberg, E. L.; Thungren, T.

    1985-01-01

    Endfire-tapered slot antennas are suitable for many integrated circuit applications, imaging and phased arrays. An investigation of single elements of such antennas, including slots which are exponentially tapered (Vivaldi), linearly tapered, and constant width. For antennas of all types, a good general agreement is obtained for curves of beamwidth-versus-length, normalized to wavelength, when one compares the data with that for traveling-wave antennas published by Zucker (1961). An important condition for this agreement is that the effective dielectric thickness, defined in the text, is in a certain optimum range. This condition is qualitatively explained in terms of the theory for traveling-wave antennas.

  10. TYK2 Protein-Coding Variants Protect against Rheumatoid Arthritis and Autoimmunity, with No Evidence of Major Pleiotropic Effects on Non-Autoimmune Complex Traits

    Science.gov (United States)

    Diogo, Dorothée; Bastarache, Lisa; Liao, Katherine P.; Graham, Robert R.; Fulton, Robert S.; Greenberg, Jeffrey D.; Eyre, Steve; Bowes, John; Cui, Jing; Lee, Annette; Pappas, Dimitrios A.; Kremer, Joel M.; Barton, Anne; Coenen, Marieke J. H.; Franke, Barbara; Kiemeney, Lambertus A.; Mariette, Xavier; Richard-Miceli, Corrine; Canhão, Helena; Fonseca, João E.; de Vries, Niek; Tak, Paul P.; Crusius, J. Bart A.; Nurmohamed, Michael T.; Kurreeman, Fina; Mikuls, Ted R.; Okada, Yukinori; Stahl, Eli A.; Larson, David E.; Deluca, Tracie L.; O'Laughlin, Michelle; Fronick, Catrina C.; Fulton, Lucinda L.; Kosoy, Roman; Ransom, Michael; Bhangale, Tushar R.; Ortmann, Ward; Cagan, Andrew; Gainer, Vivian; Karlson, Elizabeth W.; Kohane, Isaac; Murphy, Shawn N.; Martin, Javier; Zhernakova, Alexandra; Klareskog, Lars; Padyukov, Leonid; Worthington, Jane; Mardis, Elaine R.; Seldin, Michael F.; Gregersen, Peter K.; Behrens, Timothy; Raychaudhuri, Soumya; Denny, Joshua C.; Plenge, Robert M.

    2015-01-01

    Despite the success of genome-wide association studies (GWAS) in detecting a large number of loci for complex phenotypes such as rheumatoid arthritis (RA) susceptibility, the lack of information on the causal genes leaves important challenges to interpret GWAS results in the context of the disease biology. Here, we genetically fine-map the RA risk locus at 19p13 to define causal variants, and explore the pleiotropic effects of these same variants in other complex traits. First, we combined Immunochip dense genotyping (n = 23,092 case/control samples), Exomechip genotyping (n = 18,409 case/control samples) and targeted exon-sequencing (n = 2,236 case/controls samples) to demonstrate that three protein-coding variants in TYK2 (tyrosine kinase 2) independently protect against RA: P1104A (rs34536443, OR = 0.66, P = 2.3x10-21), A928V (rs35018800, OR = 0.53, P = 1.2x10-9), and I684S (rs12720356, OR = 0.86, P = 4.6x10-7). Second, we show that the same three TYK2 variants protect against systemic lupus erythematosus (SLE, Pomnibus = 6x10-18), and provide suggestive evidence that two of the TYK2 variants (P1104A and A928V) may also protect against inflammatory bowel disease (IBD; Pomnibus = 0.005). Finally, in a phenome-wide association study (PheWAS) assessing >500 phenotypes using electronic medical records (EMR) in >29,000 subjects, we found no convincing evidence for association of P1104A and A928V with complex phenotypes other than autoimmune diseases such as RA, SLE and IBD. Together, our results demonstrate the role of TYK2 in the pathogenesis of RA, SLE and IBD, and provide supporting evidence for TYK2 as a promising drug target for the treatment of autoimmune diseases. PMID:25849893

  11. TYK2 protein-coding variants protect against rheumatoid arthritis and autoimmunity, with no evidence of major pleiotropic effects on non-autoimmune complex traits.

    Science.gov (United States)

    Diogo, Dorothée; Bastarache, Lisa; Liao, Katherine P; Graham, Robert R; Fulton, Robert S; Greenberg, Jeffrey D; Eyre, Steve; Bowes, John; Cui, Jing; Lee, Annette; Pappas, Dimitrios A; Kremer, Joel M; Barton, Anne; Coenen, Marieke J H; Franke, Barbara; Kiemeney, Lambertus A; Mariette, Xavier; Richard-Miceli, Corrine; Canhão, Helena; Fonseca, João E; de Vries, Niek; Tak, Paul P; Crusius, J Bart A; Nurmohamed, Michael T; Kurreeman, Fina; Mikuls, Ted R; Okada, Yukinori; Stahl, Eli A; Larson, David E; Deluca, Tracie L; O'Laughlin, Michelle; Fronick, Catrina C; Fulton, Lucinda L; Kosoy, Roman; Ransom, Michael; Bhangale, Tushar R; Ortmann, Ward; Cagan, Andrew; Gainer, Vivian; Karlson, Elizabeth W; Kohane, Isaac; Murphy, Shawn N; Martin, Javier; Zhernakova, Alexandra; Klareskog, Lars; Padyukov, Leonid; Worthington, Jane; Mardis, Elaine R; Seldin, Michael F; Gregersen, Peter K; Behrens, Timothy; Raychaudhuri, Soumya; Denny, Joshua C; Plenge, Robert M

    2015-01-01

    Despite the success of genome-wide association studies (GWAS) in detecting a large number of loci for complex phenotypes such as rheumatoid arthritis (RA) susceptibility, the lack of information on the causal genes leaves important challenges to interpret GWAS results in the context of the disease biology. Here, we genetically fine-map the RA risk locus at 19p13 to define causal variants, and explore the pleiotropic effects of these same variants in other complex traits. First, we combined Immunochip dense genotyping (n = 23,092 case/control samples), Exomechip genotyping (n = 18,409 case/control samples) and targeted exon-sequencing (n = 2,236 case/controls samples) to demonstrate that three protein-coding variants in TYK2 (tyrosine kinase 2) independently protect against RA: P1104A (rs34536443, OR = 0.66, P = 2.3 x 10(-21)), A928V (rs35018800, OR = 0.53, P = 1.2 x 10(-9)), and I684S (rs12720356, OR = 0.86, P = 4.6 x 10(-7)). Second, we show that the same three TYK2 variants protect against systemic lupus erythematosus (SLE, Pomnibus = 6 x 10(-18)), and provide suggestive evidence that two of the TYK2 variants (P1104A and A928V) may also protect against inflammatory bowel disease (IBD; P(omnibus) = 0.005). Finally, in a phenome-wide association study (PheWAS) assessing >500 phenotypes using electronic medical records (EMR) in >29,000 subjects, we found no convincing evidence for association of P1104A and A928V with complex phenotypes other than autoimmune diseases such as RA, SLE and IBD. Together, our results demonstrate the role of TYK2 in the pathogenesis of RA, SLE and IBD, and provide supporting evidence for TYK2 as a promising drug target for the treatment of autoimmune diseases. PMID:25849893

  12. TYK2 protein-coding variants protect against rheumatoid arthritis and autoimmunity, with no evidence of major pleiotropic effects on non-autoimmune complex traits.

    Directory of Open Access Journals (Sweden)

    Dorothée Diogo

    Full Text Available Despite the success of genome-wide association studies (GWAS in detecting a large number of loci for complex phenotypes such as rheumatoid arthritis (RA susceptibility, the lack of information on the causal genes leaves important challenges to interpret GWAS results in the context of the disease biology. Here, we genetically fine-map the RA risk locus at 19p13 to define causal variants, and explore the pleiotropic effects of these same variants in other complex traits. First, we combined Immunochip dense genotyping (n = 23,092 case/control samples, Exomechip genotyping (n = 18,409 case/control samples and targeted exon-sequencing (n = 2,236 case/controls samples to demonstrate that three protein-coding variants in TYK2 (tyrosine kinase 2 independently protect against RA: P1104A (rs34536443, OR = 0.66, P = 2.3 x 10(-21, A928V (rs35018800, OR = 0.53, P = 1.2 x 10(-9, and I684S (rs12720356, OR = 0.86, P = 4.6 x 10(-7. Second, we show that the same three TYK2 variants protect against systemic lupus erythematosus (SLE, Pomnibus = 6 x 10(-18, and provide suggestive evidence that two of the TYK2 variants (P1104A and A928V may also protect against inflammatory bowel disease (IBD; P(omnibus = 0.005. Finally, in a phenome-wide association study (PheWAS assessing >500 phenotypes using electronic medical records (EMR in >29,000 subjects, we found no convincing evidence for association of P1104A and A928V with complex phenotypes other than autoimmune diseases such as RA, SLE and IBD. Together, our results demonstrate the role of TYK2 in the pathogenesis of RA, SLE and IBD, and provide supporting evidence for TYK2 as a promising drug target for the treatment of autoimmune diseases.

  13. Development of quercetin-phospholipid complex to improve the bioavailability and protection effects against carbon tetrachloride-induced hepatotoxicity in SD rats.

    Science.gov (United States)

    Zhang, Kexia; Zhang, Meiyu; Liu, Ziying; Zhang, Yuanyuan; Gu, Liqiang; Hu, Gaosheng; Chen, Xiaohui; Jia, Jingming

    2016-09-01

    Quercetin (QT) is a natural flavonoid with various biological activities and pharmacological actions. However, the bioavailability of QT is relatively low due to its low solubility which severely limits its use. In this study, we intended to improve the bioavailability of QT by preparing quercetin-phospholipid complex (QT-PC) and investigate the protective effect of QT-PC against carbon tetrachloride (CCl4) induced acute liver damage in Sprague-Dawley (SD) rats. The physicochemical properties of QT-PC were characterized in terms of infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), powder X-ray diffraction (XRPD) and water/n-octanol solubility. FTIR, DSC and XRPD data confirmed the formation of QT-PC. The water solubility of QT was improved significantly in the prepared complex, indicating its increased hydrophilicity. Oral bioavailability of QT and QT-PC was evaluated in SD rats, and the plasma QT was estimated by HPLC-MS. QT-PC exhibited higher Cmax (1.58±0.11 vs. 0.67±0.08μg/mL), increased AUC0-∞ (8.60±1.25 vs. 2.41±0.51mg/Lh) and t1/2z (7.76±1.09 vs. 4.81±0.87h) when compared to free QT. The greater absorption of QT-PC group suggested the improved bioavailability. Moreover, biochemical changes and histopathological observations revealed that QT-PC provided better protection to rat liver than free QT at the same dose. Thus, phospholipid complexation might be one of the suitable approaches to improve the oral bioavailability of QT and obtain better protective effects against CCl4 induced acute liver damage in SD rats than free QT at the same dose level. PMID:27431774

  14. Installing the antenna for STELLA

    CERN Multimedia

    1979-01-01

    The 3 metre diameter antenna for the STELLA satellite communication project is lowered into position on the roof of the Computer Building (see Weekly Bulletin 48/79 and CERN Courier 19 (1979) 444). STELLA stands for Satellite Transmission Experiment Linking Laboratories.

  15. Antenna surface contour control system

    Science.gov (United States)

    Ahl, Elvin L.; Miller, James B.

    1989-03-01

    The invention is a system for automatically controlling the surface contour of a deployable and restowable antenna having a mesh reflector surface supported by a circular, folding hoop affixed to a central, telescoping column. The antenna, when deployed, forms a quad-aperture reflector with each quadrant of the mesh surface shaped to provide an offset parabolic radio frequency (RF) reflector. The hoop is supported and positioned by quartz support cords attached to the top of a column and by lower graphite hoop control cords that extend between the hoop and base of the column. The antenna, an RF reflective surface, is a gold plated molybdenum wire mesh supported on a graphite cord truss structure that includes the hoop control cords and a plurality of surface control cords attached at selected points on the surface and to the base of the column. The contour of the three-dimensional surface of the antenna is controlled by selectively adjusting the lengths of the surface control cords and the graphite hoop control cords by means of novel actuator assemblies that automatically sense and change the lengths of the lower hoop control cords and surface control cords.

  16. Photogrammetry Of A Parabolic Antenna

    Science.gov (United States)

    Merrick, W. D.; Lansing, F. L.; Stoller, F. W.; Lobb, V. B.

    1988-01-01

    Surface measured with accuracy better than 10 to the negative fifth power times diameter. Report describes use of advanced close-range photogrammetry to determine deviations of 34-m-diameter antenna main reflector and subreflector from nominal paraboloidal shapes. Measurements enable removal of linear offsets and angular misalignments of subreflector, with consequent increase of 4 percent in aperture efficiency.

  17. The Antenna Bride and Bridegroom

    Science.gov (United States)

    2007-03-01

    ALMA Achieves Major Milestone With Antenna-Link Success The Atacama Large Millimeter/submillimeter Array (ALMA), an international telescope project, reached a major milestone on 2 March, when two 12-m ALMA prototype antennas were first linked together as an integrated system to observe an astronomical object. "This achievement results from the integration of many state-of-the-art components from Europe and North America and bodes well for the success of ALMA in Chile", said Catherine Cesarsky, ESO's Director General. ESO PR Photo 10/07 ESO PR Photo 10/07 The Prototype Antennas The milestone achievement, technically termed 'First Fringes', came at the ALMA Test Facility (ATF), located near Socorro in New Mexico. Faint radio waves emitted by the planet Saturn were collected by two ALMA prototype antennas, then processed by new, high-tech electronics to turn the two antennas into a single, high-resolution telescope system, called an interferometer. The planet's radio emissions at a frequency of 104 gigahertz were tracked by the ALMA system for more than an hour. Such pairs of antennas are the basic building blocks of the multi-antenna imaging system ALMA. In such a system, the signals recorded by each antenna are electronically combined with the signals of every other antenna to form a multitude of pairs. Each pair contributes unique information that is used to build a highly detailed image of the astronomical object under observation. When completed in the year 2012, ALMA will have 66 antennas. "Our congratulations go to the dedicated team of scientists, engineers and technicians who produced this groundbreaking achievement for ALMA. Much hard work and many long hours went into this effort, and we appreciate it all. This team should be very proud today," said NRAO Director Fred K.Y. Lo. "With this milestone behind us, we now can proceed with increased confidence toward completing ALMA," he added. ALMA, located at an elevation of 5,000m in the Atacama Desert of

  18. Radar techniques using array antennas

    CERN Document Server

    Wirth, Wulf-Dieter

    2001-01-01

    This book gives an introduction to the possibilities of radar technology based on active array antennas, giving examples of modern practical systems. There are many valuable lessons presented for designers of future high standard multifunction radar systems for military and civil applications. The book will appeal to graduate level engineers, researchers, and managers in the field of radar, aviation and space technology.

  19. DSS 13 microprocessor antenna controller

    Science.gov (United States)

    Gosline, R. M.

    1988-01-01

    A microprocessor-based antenna monitor and control system with multiple CPUs are described. The system was developed as part of the unattended station project for DSS 13 and was enhanced for use by the SETI project. The operational features, hardware, and software designs are described, and a discussion is provided of the major problems encountered.

  20. Tunable Antennas for Mobile Devices

    DEFF Research Database (Denmark)

    Morris, Art; Barrio, Samantha Caporal Del; Shin, J;

    2014-01-01

    Modern mobile terminal design has been driven by the user interface and broadband connectivity. Real world RF performance has substantially fallen recently which impacts data rates, battery life and often causes lost connections. This has been caused by changing antenna location and reduced anten...

  1. A method of phase control and impedance matching of mutually coupled ICRF antennas in LHD

    International Nuclear Information System (INIS)

    In the Large Helical Device (LHD), the installation of a pair of ion cyclotron range of frequencies (ICRF) antennas from upper and lower ports is planned. These antennas are geometrically symmetrical and located side by side. By changing the current phase on the straps, the wave number parallel to the magnetic field line can be controlled. However, antenna impedances will also be changed and reflected power will increase due to mutual coupling. For efficient power injection and the protection of tetrode tubes, the parameters of impedance matching devices must be controlled together with the current phase. A method was formulated and trials of phase control and impedance matching were successfully conducted with a simplified two-port dummy antenna. (author)

  2. Y-12 Groundwater Protection Program CY 2009 Triennial Report Of The Monitoring Well Inspection And Maintenance Program, Y-12 National Security Complex, Oak Ridge, Tennessee

    Energy Technology Data Exchange (ETDEWEB)

    None

    2013-06-01

    This document is the triennial report for the Well Inspection and Maintenance Program of the Y- 12 Groundwater Protection Program (GWPP), at the U.S. Department of Energy (DOE) Y-12 National Security Complex (Y-12). This report formally documents well inspection events conducted on active and inactive wells at Y-12 during calendar years (CY) 2007 through 2009; it documents well maintenance and plugging and abandonment activities completed since the last triennial inspection event (CY 2006); and provides summary tables of well inspection events, well maintenance events, and well plugging and abandonment events during the reference time period.

  3. A βPIX-PAK2 complex confers protection against Scrib-dependent and cadherin-mediated apoptosis

    DEFF Research Database (Denmark)

    Frank, Scott R; Bell, Jennifer H; Frödin, Morten;

    2012-01-01

    During epithelial morphogenesis, a complex comprising the βPIX (PAK-interacting exchange factor β) and class I PAKs (p21-activated kinases) is recruited to adherens junctions. Scrib, the mammalian ortholog of the Drosophila polarity determinant and tumor suppressor Scribble, binds βPIX directly. ...

  4. Design of broadband single polarized antenna

    Science.gov (United States)

    Shin, Phoo Kho; Aziz, Mohamad Zoinol Abidin Abd.; Ahmad, Badrul Hisham; Ramli, Mohamad Hafize Bin; Fauzi, Noor Azamiah Md; Malek, Mohd Fareq Abd

    2015-05-01

    In practical wireless communication application, bandwidth enhancement becomes one of the major design considerations. At the same time, circular polarized (CP) antenna received much attention for the applications of modern wireless communication system when compared to linear polarized (LP) antenna. This is because CP antenna can reduce the multipath effect. Hence, broadband antenna with operating frequency at 2.4GHz for WLAN application is proposed. The proposed antenna is done by using L-probe amendment with rectangular patch. The rectangular patch and copper ground plane is separated with 10mm air gap. This approach is used to enhance the bandwidth and the gain of the proposed antenna. The bandwidth of the designed antenna is more than 200MHz which meet broadband application. The return loss for the antenna is below -10dB to achieved 90% matching efficiency. The position of L-probe feed is altered in order to obtained different polarizations. The broadband antenna had been designed and simulated by using Computer Simulation Technology (CST) software. In this paper, the comparison for single polarized antenna with the design of non-inverted patch and inverted patch is discussed. The characteristics of the S-parameter, axial ratio, gain, surface current for each designed antenna are analyzed.

  5. Dynamic interrogation of wireless antenna sensor

    Science.gov (United States)

    Yao, J.; Tjuatja, S.; Huang, H.; Sanders, J.

    2014-03-01

    This paper presents the dynamic interrogation of a wireless antenna sensor for mechanical vibration monitoring. In order to interrogate the antenna resonant frequency at sufficient high speeds, a wireless interrogator that consists of a Frequency Modulated Continuous Wave (FMCW) synthesizer, a signal demodulation unit, and a real-time digital signal processing program was developed. The principle of operation of the dynamic wireless sensing system is first described, followed by the description of the design and implementation of the antenna sensor and the wireless interrogator. After calibrate the antenna sensor response using static tensile tests, dynamic interrogation of the wireless antenna sensor was carried out by subjecting the test specimen to a sinusoidal tensile load. The resonant frequency shifts of the antenna sensor were compared with the strains calculated from the applied loads. A good agreement between the antenna sensor readings and the strain values were achieved. A sampling rate of up to 50 Hz was demonstrated.

  6. Isolation between three antennas at 700 MHz

    DEFF Research Database (Denmark)

    Bahramzy, Pevand; Svendsen, Simon; Pedersen, Gert F.

    2015-01-01

    To address the antenna design challenges posed by many frequency bands, introduced with long-term evolution deployment, this study proposes the use of separate transmit (Tx) and receive (Rx) narrow-band antennas. In addition, a diversity Rx (Dx) antenna is needed for multiple-input multiple......-output performance. Although the isolation between two antennas at low frequencies (700 MHz) is crucial for the successful implementation of 4G in handheld terminals, it becomes more challenging when considering isolation among three antennas (one Tx and two Rx antennas) at low frequencies. Hence, a method...... that improves the isolation between the ports of one Tx and two Rx antennas is presented here. Publishe...

  7. Metamaterial-Inspired Efficient Electrically Small Antenna

    DEFF Research Database (Denmark)

    Erentok, Aycan; Ziolkowski, R. W.

    2008-01-01

    high overall efficiencies. The reported 2D and 3D EZ antenna designs are linearly scalable to a wide range of frequencies and yet maintain their easy-to-build characteristics. Several versions of the 2D EZ antennas were fabricated and tested. The measurement results confirm the performance predictions......Planar two-dimensional (2D) and volumetric three-dimensional (3D) metamaterial-inspired efficient electrically-small antennas that are easy to design; are easy and inexpensive to build; and are easy to test; are reported, i.e., the EZ antenna systems. The proposed 2D and 3D electrical- and magnetic......-based EZ antennas are shown to be naturally matched to a 50 source, i.e., without the introduction of a matching network. It is demonstrated numerically that these EZ antennas have high radiation efficiencies with very good impedance matching between the source and the antenna and, hence, that they have...

  8. New Diamond Antenna for Ultra Wideband Applications

    Directory of Open Access Journals (Sweden)

    Ziani Kerarti Djalal

    2012-07-01

    Full Text Available There has been a flourishing prospect of UWB technology in recent years in both communication and other purposes like microwave imaging and radar applications. Recent studies of UWB antenna structures are specially concentrated on microstrip , slot and planar monopole antennas . In this work, a small monopole antenna with diamond shape of the patch (30 x 26 mm printed microstrip fed monopole antenna has been designed, some parameters like return loss (S11, Voltage Standing Wave Ratio (VSWR, radiation pattern has been performed to test the validity of simulation and verify eligibility of the antenna for the wireless communications purpose. The proposed antenna is simulated in CST Microwave Studio and has surpassed the bandwidth of UWB requirement, which is from 3.1 GHz to 10.6 GHz, and exhibits good UWB characteristics. The 10 dB return loss bandwidth of this antenna element is from 3.39 GHz to more than 14 GHz.

  9. SKB - PNC. Development of tunnel radar antennas

    International Nuclear Information System (INIS)

    Tunnel antennas for the RAMAC borehole radar system have been developed and tested in the field. The antennas are of the loaded dipole type and the receiver and transmitter electronics have been rebuilt to screen them from the antennas. A series of measurements has demonstrated that the radar pulse is short and well shaped and relatively free from ringing, even compared with the existing borehole antennas. Two antenna sets were tested: one centered at 60 MHz and another above 100 MHz. Both produced excellent radar pictures when tested in tunnels in Stripa mine. The antennas have been designed to be easy to carry, since the signal quality often depends on the way the antenna is held relative to electric conductors in the tunnels. (au) (46 figs., 57 refs.)

  10. Multi-walled carbon nanotube-based RF antennas.

    Science.gov (United States)

    Elwi, Taha A; Al-Rizzo, Hussain M; Rucker, Daniel G; Dervishi, Enkeleda; Li, Zhongrui; Biris, Alexandru S

    2010-01-29

    A novel application that utilizes conductive patches composed of purified multi-walled carbon nanotubes (MWCNTs) embedded in a sodium cholate composite thin film to create microstrip antennas operating in the microwave frequency regime is proposed. The MWCNTs are suspended in an adhesive solvent to form a conductive ink that is printed on flexible polymer substrates. The DC conductivity of the printed patches was measured by the four probe technique and the complex relative permittivity was measured by an Agilent E5071B probe. The commercial software package, CST Microwave Studio (MWS), was used to simulate the proposed antennas based on the measured constitutive parameters. An excellent agreement of less than 0.2% difference in resonant frequency is shown. Simulated and measured results were also compared against identical microstrip antennas that utilize copper conducting patches. The proposed MWCNT-based antennas demonstrate a 5.6% to 2.2% increase in bandwidth, with respect to their corresponding copper-based prototypes, without significant degradation in gain and/or far-field radiation patterns.

  11. Tissue dielectric measurement using an interstitial dipole antenna.

    Science.gov (United States)

    Wang, Peng; Brace, Christopher L

    2012-01-01

    The purpose of this study was to develop a technique to measure the dielectric properties of biological tissues with an interstitial dipole antenna based upon previous efforts for open-ended coaxial probes. The primary motivation for this technique is to facilitate treatment monitoring during microwave tumor ablation by utilizing the heating antenna without additional intervention or interruption of the treatment. The complex permittivity of a tissue volume surrounding the antenna was calculated from reflection coefficients measured after high-temperature microwave heating by using a rational function model of the antenna's input admittance. Three referencing liquids were needed for measurement calibration. The dielectric measurement technique was validated ex vivo in normal and ablated bovine livers. Relative permittivity and effective conductivity were lower in the ablation zone when compared to normal tissue, consistent with previous results. The dipole technique demonstrated a mean 10% difference of permittivity values when compared to open-ended coaxial cable measurements in the frequency range of 0.5-20 GHz. Variability in measured permittivities could be smoothed by fitting to a Cole-Cole dispersion model. Further development of this technique may facilitate real-time monitoring of microwave ablation treatments through the treatment applicator.

  12. Design and Analysis of a Multiband Koch Fractal Monopole Antenna

    OpenAIRE

    Adam, Ismahayati; Soh, Ping Jack; Hadibah, R; Vandenbosch, Guy

    2011-01-01

    This work presents the design and investigation of the monopole and Koch fractal antenna. The fractal concept and geometry has been used in antenna design to obtain multi-band behavior and miniaturized size, as both of these characteristics are important requirements in current antenna design trends. The aim of this paper is to evaluate the antenna performance between monopole antenna and third iteration Koch fractal antenna. Antenna properties such as reflection coefficient (S11), bandwidth,...

  13. Design of optimized impedance transformer for ICRF antenna in LHD

    International Nuclear Information System (INIS)

    Highlights: ► We developed optimization method of impedance transformer for ICRF antenna. ► Power loss will be one-third with the optimized impedance transformer. ► Possibility of damage on the transmission line will be drastically reduced. ► High performance will be kept in the wide antenna impedance region. -- Abstract: A pair of ion cyclotron range of frequencies (ICRF) antennas in the large helical device (LHD), HAS antennas showed high efficiency in minority ion heating. However the low loading resistance must be increased to prevent breakdown in transmission line. Moreover, the voltage and the current around the feed-through must be reduced to protect it. For these purpose, we developed a design procedure of the impedance transformer for HAS antennas. To optimize the transformer, the inner conductors were divided into several segments and the radii of them were given discretely and independently. The maximum effective loading resistance was obtained by using all combinations of radii within the limitations of the voltage and current at the feed-through and the electric field on the transformer. To get a precise solution, this procedure was repeated several times by narrowing the range of radii of inner conductors. Then the optimized impedance transformer was designed by smoothing the radii of inner conductors. For the typical discharge, the voltage and current at the feed-through were reduced to the half of the original values with the same power. The effective loading resistance was increased to more than four times. High performance is expected in wide impedance region

  14. On the measurement of in situ antenna radiation parameters from scattering measurements using a general scattering parametric model

    Science.gov (United States)

    Mendez, Enrique Alberto

    The new concept of antenna radiation center (ARC) is introduced and an empirical method to measure it from complex scattering data is presented. This concept is different from the well-known antenna phase center utilized in reflector antenna applications. A novel and efficient procedure based on a General Parametric Scattering Model (GSPM) is utilized to extract in-situ antenna radiation properties from complex antenna scattering data. This model based measurement approach has the advantage that it only requires two swept frequency scattering measurements in order to obtain antenna RCS, antenna gain and antenna radiation center in its integrated operational environment. The GSPM structure required to accurately extract arbitrary target scattering data is developed based on basic electromagnetic principles. The mathematical model structure consists of an early time response based on a point scattering model and on a late time response based on the Singularity Expansion Method (SEM). Both of these methods are implemented to take into account the target dispersion in a general fashion. Robust signal processing algorithms are utilized to extract the model parameters by exploiting the model symmetry properties in the time and frequency domains. In particular, super-resolution algorithms such as ESPRIT and MUSIC are utilized to extract scattering center location and resonance frequency information, while Least Squares techniques are used to estimate the different model amplitude coefficients as a function of time or frequency in an optimal (i.e. mean square sense) fashion. Theoretical derivations are provided to demonstrate that the GSPM can be utilized to extract antenna gain and radiation center information from scattering data. Synthetic and measured antenna scattering data are utilized to demonstrate the GSPM superior gain and radiation center results over traditional Fourier techniques. Gain transfer measurements results are also compared to the GSPM derived gain

  15. From Antenna to Assay

    Science.gov (United States)

    Moore, Evan G.; Samuel, Amanda P. S.; Raymond, Kenneth N.

    2009-01-01

    Conspectus Ligand-sensitized, luminescent lanthanide(III) complexes are of considerable importance because their unique photophysical properties (microsecond to millisecond lifetimes, characteristic and narrow emission bands, and large Stokes shifts) make them well suited as labels in fluorescence-based bioassays. The long-lived emission of lanthanide(III) cations can be temporally resolved from scattered light and background fluorescence to vastly enhance measurement sensitivity. One challenge in this field is the design of sensitizing ligands that provide highly emissive complexes with sufficient stability and aqueous solubility for practical applications. In this Account, we give an overview of some of the general properties of the trivalent lanthanides and follow with a summary of advances made in our laboratory in the development of highly luminescent Tb(III) and Eu(III) complexes for applications in biotechnology. A focus of our research has been the optimization of these compounds as potential commercial agents for use in Homogeneous Time-Resolved Fluorescence (HTRF) technology. Our approach involves developing high-stability octadentate Tb(III) and Eu(III) complexes that rely on all-oxygen donor atoms and using multi-chromophore chelates to increase molar absorptivity; earlier examples utilized a single pendant chromophore (that is, a single “antenna”). Ligands based on 2-hydroxyisophthalamide (IAM) provide exceptionally emissive Tb(III) complexes with quantum yield values up to ∼60% that are stable at the nanomolar concentrations required for commercial assays. Through synthetic modification of the IAM chromophore and time-dependent density functional theory (TD-DFT) calculations, we have developed a method to predict absorption and emission properties of these chromophores as a tool to guide ligand design. Additionally, we have investigated chiral IAM ligands that yield Tb(III) complexes possessing both high quantum yield values and strong

  16. Evolution and Conservation on Top of the World: Phylogeography of the Marbled Water Frog (Telmatobius marmoratus Species Complex; Anura, Telmatobiidae) in Protected Areas of Chile.

    Science.gov (United States)

    Victoriano, Pedro F; Muñoz-Mendoza, Carla; Sáez, Paola A; Salinas, Hugo F; Muñoz-Ramírez, Carlos; Sallaberry, Michel; Fibla, Pablo; Méndez, Marco A

    2015-01-01

    The Andean Altiplano has served as a complex setting throughout its history, driving dynamic processes of diversification in several taxa. We investigated phylogeographic processes in the Telmatobius marmoratus species complex occurring in this region by studying the geographic patterns of genetic variability, genealogies, and historical migration, using the cytochrome b (cyt-b) gene as a marker. DNA sequences from Telmatobius gigas and Telmatobius culeus, Bolivian species with an uncertain taxonomic status, were also included. Additionally, we evaluated the phylogenetic diversity (PD) represented within Chilean protected areas and the complementary contribution from unprotected populations. Phylogenetic reconstructions from 148 cyt-b sequences revealed 4 main clades, one of which corresponded to T. culeus. T. gigas was part of T. marmoratus clade indicating paraphyletic relationships. Haplotypes from Chilean and Bolivian sites were not reciprocally monophyletic. Geographic distribution of lineages, spatial Bayesian analysis, and migration patterns indicated that T. marmoratus displays a weaker geographic structure than expected based on habitat distribution and physiological requirements. Demographic and statistical phylogeography analyses pointed out to a scenario of recent population expansion and high connectivity events of a more recent age than the post Last Glacial Maximum, probably associated to more humid events in Altiplano. PD of T. marmoratus populations within protected areas represents 55.6% of the total estimated PD. The unprotected populations that would contribute the most to PD are Caquena and Quebe (21%). Recent evolutionary processes and paleoclimatic changes, potentially driving shifts in habitat connectivity levels and population sizes, could explain the phylogeographic patterns recovered herein.

  17. Antenna design and characterization based on the elementary antenna concept

    Science.gov (United States)

    Ligthart, L. P.

    An antenna-design technique based on an elementary-antenna model (an infinitesimal pillbox structure carrying electric and magnetic currents and containing propagating TEM fields) is developed and demonstrated. An EM description of a waveguide aperture is obtained by applying approximate boundary conditions at specific points; the transmitted field is developed locally into a set of TEM field components to compute the radiation pattern; and aperture matching is achieved by calculating the aperture reflection as well. Parallel-plate, circular, and rectangular waveguides; two single-polarization TEM waveguide radiators (with and without dielectric filling); a dielectric-filled dual-polarization TE(01) waveguide radiator; and a hybrid reflector array with limited beam switching based on the TE(01) radiator are presented.

  18. Evaluation of soil corrosivity and aquifer protective capacity using geoelectrical investigation in Bwari basement complex area, Abuja

    Indian Academy of Sciences (India)

    A E Adeniji; O V Omonona; D N Obiora; J U Chukudebelu

    2014-04-01

    Bwari is one of the six municipal area councils of the Federal Capital Territory (FCT), Abuja with its attendant growing population and infrastructural developments. Groundwater is the main source of water supply in the area, and urbanization and industrialization are the predominant contributors of contaminants to the hydrological systems. In order to guarantee a continuous supply of potable water, there is a need to investigate the vulnerability of the aquifers to contaminants emanating from domestic and industrial wastes. A total of 20 vertical electrical soundings using Schlumberger electrode array with a maximum half current electrodes separation of 300 m was employed. The results show that the area is characterized by 3–6 geoelectric subsurface layers. The measured overburden thickness ranges from 1.0 to 24.3 m, with a mean value of 7.4 m. The resistivity and longitudinal conductance of the overburden units range from 18 to 11,908 m and 0.047 to 0.875 mhos, respectively. Areas considered as high corrosivity are the central parts with > 180 m. The characteristic longitudinal unit conductance was used to classify the area into zones of good (0.7–4.49 mhos), moderate (0.2–0.69 mhos), weak (0.1–0.19 mhos), and poor (> 0.1) aquifer protective capacity. Zones characterized by materials of moderate to good protective capacity serve as sealing potential for the underlying hydrogeological system in the area. This study is aimed at delineating zones that are very prone to groundwater contamination from surface contaminants and subsurface soils that are corrosive to utility pipes buried underground. Hence the findings of this work will constitute part of the tools for groundwater development and management and structural/infrastructural development planning of the area.

  19. Sounding Rocket Telemetry Emitter, MID Antenna and Ground Receiver Antennas

    OpenAIRE

    Marque, Alexandre; Ghiotto, Anthony

    2015-01-01

    IEEE MTT-S Undergraduate Scholarships Reports The goal of this research project is to design a complete 2.45 GHz data link for telemetry application between a sounding rocket and a ground station. The emission part is embedded in the rocket and has a lot of mechanical constraints. The design for the emitter, the rocket antenna and the ground station receiver are detailed.

  20. State-of-the-art and trends of Ground-Penetrating Radar antenna arrays

    Science.gov (United States)

    Vescovo, Roberto; Pajewski, Lara; Tosti, Fabio

    2016-04-01

    The aim of this contribution is to offer an overview on the antenna arrays for GPR systems, current trends and open issues. Antennas are a critical hardware component of a radar system, dictating its performance in terms of capability to detect targets. Nevertheless, most of the research efforts in the Ground-Penetrating Radar (GPR) area focus on the use of this imaging technique in a plethora of different applications and on the improvement of modelling/inversion/processing techniques, whereas a limited number of studies deal with technological issues related to the design of novel systems, including the synthesis, optimisation and characterisation of advanced antennas. Even fewer are the research activities carried out to develop innovative antenna arrays. GPR antennas operate in a strongly demanding environment and should satisfy a number of requirements, somehow unique and very different than those of conventional radar antennas. The same applies to GPR antenna arrays. The first requirement is an ultra-wide frequency band: the radar has to transmit and receive short-duration time-domain waveforms, in the order of a few nanoseconds, the time-duration of the emitted pulses being a trade-off between the desired radar resolution and penetration depth. Furthermore, GPR antennas should have a linear phase characteristic over the whole operational frequency range, predictable polarisation and gain. Due to the fact that a subsurface imaging system is essentially a short-range radar, the coupling between transmitting and receiving antennas has to be low and short in time. GPR antennas should have quick ring-down characteristics, in order to prevent masking of targets and guarantee a good resolution. The radiation patterns should ensure minimal interference with unwanted objects, usually present in the complex operational environment; to this aim, antennas should provide high directivity and concentrate the electromagnetic energy into a narrow solid angle. As GPR

  1. Y-12 Groundwater Protection Program Extent Of The Primary Groundwater Contaminants At The Y-12 National Security Complex

    Energy Technology Data Exchange (ETDEWEB)

    None

    2013-12-01

    This report presents data summary tables and maps used to define and illustrate the approximate lateral extent of groundwater contamination at the U.S. Department of Energy (DOE) Y-12 National Security Complex (Y-12) in Oak Ridge, Tennessee. The data tables and maps address the primary (i.e., most widespread and mobile) organic, inorganic, and radiological contaminants in the groundwater. The sampling locations, calculated contaminant concentrations, plume boundary values, and paired map format used to define, quantify, delineate, and illustrate the approximate extent of the primary organic, inorganic, and radiological contaminants in groundwater at Y-12 are described.

  2. Negative ion source with external RF antenna

    Science.gov (United States)

    Leung, Ka-Ngo; Hahto, Sami K.; Hahto, Sari T.

    2007-02-13

    A radio frequency (RF) driven plasma ion source has an external RF antenna, i.e. the RF antenna is positioned outside the plasma generating chamber rather than inside. The RF antenna is typically formed of a small diameter metal tube coated with an insulator. An external RF antenna assembly is used to mount the external RF antenna to the ion source. The RF antenna tubing is wound around the external RF antenna assembly to form a coil. The external RF antenna assembly is formed of a material, e.g. quartz, which is essentially transparent to the RF waves. The external RF antenna assembly is attached to and forms a part of the plasma source chamber so that the RF waves emitted by the RF antenna enter into the inside of the plasma chamber and ionize a gas contained therein. The plasma ion source is typically a multi-cusp ion source. A converter can be included in the ion source to produce negative ions.

  3. Simulation of Conformal Spiral Slot Antennas on Composite Platforms

    Science.gov (United States)

    Volakis, J. L.; Nurnberger, M. W.; Ozdemir,T.

    1998-01-01

    During the course of the grant, we wrote and distributed about 12 reports and an equal number of journal papers supported fully or in part by this grant. The list of reports (title & abstract) and papers are given in Appendices A and B. This grant has indeed been instrumental in developing a robust hybrid finite element method for the analysis of complex broadband antennas on doubly curved platforms. Previous to the grant, our capability was limited to simple printed patch antennas on mostly planar platforms. More specifically: (1) mixed element formulations were developed and new edge-based prisms were introduced; (2) these elements were important in permitting flexibility in geometry gridding for most antennas of interest; (3) new perfectly matched absorbers were introduced for mesh truncations associated with highly curved surfaces; (4) fast integral algorithms were introduced for boundary integral truncations reducing CPU time from O(N-2) down to O(N-1.5) or less; (5) frequency extrapolation schemes were developed for efficient broadband performance evaluations. This activity has been successfully continued by NASA researchers; (6) computer codes were developed and extensively tested for several broadband configurations. These include FEMA-CYL, FEMA-PRISM and FEMA-TETRA written by L. Kempel, T. Ozdemir and J. Gong, respectively; (7) a new infinite balun feed was designed nearly constant impedance over the 800-3000 MHz operational band; (8) a complete slot spiral antenna was developed, fabricated and tested at NASA Langley. This new design is a culmination of the projects goals and integrates the computational and experimental efforts. this antenna design resulted in a U.S. patent and was revised three times to achieve the desired bandwidth and gain requirements from 800-3000 MHz.

  4. A head and neck hyperthermia applicator: Theoretical antenna array design

    NARCIS (Netherlands)

    Paulides, M.M.; Bakker, J.F.; Zwamborn, A.P.M.; Rhoon, G.C. van

    2007-01-01

    Purpose: Investigation into the feasibility of a circular array of dipole antennas to deposit RF-energy centrally in the neck as a function of: 1) patient positioning, 2) antenna ring radius, 3) number of antenna rings, 4) number of antennas per ring and 5) distance between antenna rings. Materials

  5. A head and neck hyperthermia applicator: Theoretical antenna array design

    NARCIS (Netherlands)

    M.M. Paulides (Margarethus); J.F. Bakker (Jurriaan); A.P.M. Zwamborn; G.C. van Rhoon (Gerard)

    2007-01-01

    textabstractPurpose: Investigation into the feasibility of a circular array of dipole antennas to deposit RF-energy centrally in the neck as a function of: (1) patient positioning, (2) antenna ring radius, (3) number of antenna rings, (4) number of antennas per ring and (5) distance between antenna

  6. A multi octaves directive dielectric lens: The Pyramid Antenna

    NARCIS (Netherlands)

    Marliani, L.; Bruni, S.; Neto, A.

    2005-01-01

    Leaky wave antennas have been investigated for a long time and are typically an inexpensive solution for beam scanning antennas. We have designed a novel antenna topology, named the pyramid antenna, based on the broadband leaky concept. The pyramid antenna, currently covered by a patent application,

  7. Planar Millimeter-Wave Antennas: A Comparative Study

    OpenAIRE

    Pitra, K.; Z. Raida

    2011-01-01

    The paper describes the design and the experimental verification of three types of wideband antennas. Attention is turned to the bow-tie antenna, the Vivaldi antenna and the spiral antenna designed for the operation at millimeter waves. Bandwidth, input impedance, gain, and directivity pattern are the investigated parameters. Antennas are compared considering computer simulations in CST Microwave Studio and measured data.

  8. 47 CFR 22.365 - Antenna structures; air navigation safety.

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 2 2010-10-01 2010-10-01 false Antenna structures; air navigation safety. 22... Antenna structures; air navigation safety. Licensees that own their antenna structures must not allow these antenna structures to become a hazard to air navigation. In general, antenna structure owners...

  9. 47 CFR 73.316 - FM antenna systems.

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 4 2010-10-01 2010-10-01 false FM antenna systems. 73.316 Section 73.316... Broadcast Stations § 73.316 FM antenna systems. (a) It shall be standard to employ horizontal polarization...) Directional antennas. A directional antenna is an antenna that is designed or altered for the purpose...

  10. Immunostimulatory complexes containing Eimeria tenella antigens and low toxicity plant saponins induce antibody response and provide protection from challenge in broiler chickens.

    Science.gov (United States)

    Berezin, V E; Bogoyavlenskyi, A P; Khudiakova, S S; Alexuk, P G; Omirtaeva, E S; Zaitceva, I A; Tustikbaeva, G B; Barfield, R C; Fetterer, R H

    2010-01-20

    Immunostimulating complexes (ISCOMs) are unique multimolecular structures formed by encapsulating antigens, lipids and triterpene saponins and are one of the most successful antigen delivery systems for microbial antigens. In the current study, both the route of administration and the antigen concentration of ISCOMs, containing Eimeria tenella antigens and saponins from native plants, were evaluated in their ability to stimulate humoral immunity and to protect chickens against a challenge infection with E. tenella. Broiler chickens were immunized with ISCOM preparations containing E. tenella antigens and the purified saponins Gg6, Ah6 and Gp7 isolated from Glycyrrhiza glabra, Aesculus hippocastanum and Gipsophila paniculata, respectively. The effects of the route of administration, dose of antigen and type of saponin used for construction of ISCOMs were evaluated for ability to stimulate serum IgG and IgM and to protect chickens against a homologous challenge. A single intranasal immunization was the most effective route for administering ISCOMs although the in ovo route was also quite effective. Dose titration experiments demonstrated efficacy after single immunization with various ISCOM doses but maximum effects were observed when ISCOMs contain 5-10mug antigen. Immunization of birds by any of the three routes with E. tenella antigens alone or antigens mixed with alum hydroxide adjuvant resulted in lower serum antibody and reduced protection to challenge relative to immunization with ISCOMs. Overall the results of this study confirm that significant immunostimulation and protection to challenge are achieved by immunization of chickens with ISCOMs containing purified saponins and native E. tenella antigens and suggest that ISCOMs may be successfully used to develop a safe and effective vaccine for prevention of avian coccidiosis. PMID:19879050

  11. Control of large spaceborne antenna systems with flexible booms by mechanical decoupling

    Science.gov (United States)

    Wang, P. K. C.

    1983-01-01

    A simple practical method for designing antenna-feed attitude control systems for large deployable spaceborne antenna systems with long flexible booms is proposed. The basic idea is to mechanically decouple the antenna-feed from the boom so that the feed-attitude control system can be designed without taking the boom dynamics into consideration, thus avoiding a complex control problem involving an infinite-dimensional distributed parameter system. The validity of the proposed method is substantiated by analytical and numerical studies using a mathematical model for the flexible boom which could undergo both bending and torsional vibrations. This approach leads to simple antenna-feed attitude control systems which are amenable to physical implementation.

  12. Antenna Arrays and Automotive Applications

    CERN Document Server

    Rabinovich, Victor

    2013-01-01

    This book throws a lifeline to designers wading through mounds of antenna array patents looking for the most suitable systems for their projects. Drastically reducing the research time required to locate solutions to the latest challenges in automotive communications, it sorts and systematizes material on cutting-edge antenna arrays that feature multi-element communication systems with enormous potential for the automotive industry. These new systems promise to make driving safer and more efficient, opening up myriad applications, including vehicle-to-vehicle traffic that prevents collisions, automatic toll collection, vehicle location and fine-tuning for cruise control systems. This book’s exhaustive coverage begins with currently deployed systems, frequency ranges and key parameters. It proceeds to examine system geometry, analog and digital beam steering technology (including "smart" beams formed in noisy environments), maximizing signal-to-noise ratios, miniaturization, and base station technology that ...

  13. The ExaVolt Antenna

    Science.gov (United States)

    Dailey, Brian

    2014-03-01

    There are strong motivations for a flux of ultra-high energy (UHE) neutrinos that is observable on earth, yet they remain undetected. The proposed ExaVolt Antenna (EVA) uses a novel approach to increase the expected rate of neutrinos in a balloon-borne experiment such as ANITA by 100-fold by turning a 100m-diameter, long-duration, super pressure NASA balloon into an antenna reflector with receivers deployed in the interior of the balloon. EVA would be the world's largest airborne telescope with ~ 1000 m2 of collection area. I will present preliminary results from a 1:20 scale EVA prototype test conducted in early 2014 in a hangar at NASA's Wallops Flight Facility. I will conclude with the expected sensitivity of the full EVA experiment to UHE neutrino fluxes.

  14. The planar parabolic optical antenna.

    Science.gov (United States)

    Schoen, David T; Coenen, Toon; García de Abajo, F Javier; Brongersma, Mark L; Polman, Albert

    2013-01-01

    One of the simplest and most common structures used for directing light in macroscale applications is the parabolic reflector. Parabolic reflectors are ubiquitous in many technologies, from satellite dishes to hand-held flashlights. Today, there is a growing interest in the use of ultracompact metallic structures for manipulating light on the wavelength scale. Significant progress has been made in scaling radiowave antennas to the nanoscale for operation in the visible range, but similar scaling of parabolic reflectors employing ray-optics concepts has not yet been accomplished because of the difficulty in fabricating nanoscale three-dimensional surfaces. Here, we demonstrate that plasmon physics can be employed to realize a resonant elliptical cavity functioning as an essentially planar nanometallic structure that serves as a broadband unidirectional parabolic antenna at optical frequencies.

  15. Plasmonic Antenna Coupling for QWIPs

    Science.gov (United States)

    Hong, John

    2007-01-01

    In a proposed scheme for coupling light into a quantum-well infrared photodetector (QWIP), an antenna or an array of antennas made of a suitable metal would be fabricated on the face of what would otherwise be a standard QWIP. This or any such coupling scheme is required to effect polarization conversion: Light incident perpendicularly to the face is necessarily polarized in the plane of the face, whereas, as a matter of fundamental electrodynamics and related quantum selection rules, light must have a non-zero component of perpendicular polarization in order to be absorbed in the photodetection process. In a prior coupling scheme, gratings in the form of surface corrugations diffract normally gles, thereby imparting some perpendicular polarization. Unfortunately, the corrugation- fabrication process increases the overall nonuniformity of a large QWIP array. The proposed scheme is an alternative to the use of surface corrugations.

  16. Photo-generated THz antennas

    Science.gov (United States)

    Georgiou, G.; Tyagi, H. K.; Mulder, P.; Bauhuis, G. J.; Schermer, J. J.; Rivas, J. Gómez

    2014-01-01

    Electromagnetic resonances in conducting structures give rise to the enhancement of local fields and extinction efficiencies. Conducting structures are conventionally fabricated with a fixed geometry that determines their resonant response. Here, we challenge this conventional approach by demonstrating the photo-generation of THz linear antennas on a flat semiconductor layer by the structured optical illumination through a spatial light modulator. Free charge carriers are photo-excited only on selected areas, which enables the realization of different conducting antennas on the same sample by simply changing the illumination pattern, thus without the need of physically structuring the sample. These results open a wide range of possibilities for the all-optical spatial control of resonances on surfaces and the concomitant control of THz extinction and local fields.

  17. Rigorous calculation of active antennas

    OpenAIRE

    Danilchuk, V. L.

    1999-01-01

    Problems of development of compact antennas (in short-wave band, ultra-short or higher frequencies wave band) with a high sensitivity and/or a wide passband attend a stable non-reducing interest.The proposed approach and wide application of SAPR enables one to realise AA with a high reliability on the basis of computer designing as well as to achieve minimal experimental operational development.

  18. Membrane Shell Reflector Segment Antenna

    Science.gov (United States)

    Fang, Houfei; Im, Eastwood; Lin, John; Moore, James

    2012-01-01

    The mesh reflector is the only type of large, in-space deployable antenna that has successfully flown in space. However, state-of-the-art large deployable mesh antenna systems are RF-frequency-limited by both global shape accuracy and local surface quality. The limitations of mesh reflectors stem from two factors. First, at higher frequencies, the porosity and surface roughness of the mesh results in loss and scattering of the signal. Second, the mesh material does not have any bending stiffness and thus cannot be formed into true parabolic (or other desired) shapes. To advance the deployable reflector technology at high RF frequencies from the current state-of-the-art, significant improvements need to be made in three major aspects: a high-stability and highprecision deployable truss; a continuously curved RF reflecting surface (the function of the surface as well as its first derivative are both continuous); and the RF reflecting surface should be made of a continuous material. To meet these three requirements, the Membrane Shell Reflector Segment (MSRS) antenna was developed.

  19. Stepped conical zone plate antenna

    Science.gov (United States)

    Wiltse, James C.

    2001-07-01

    The Fresnel zone plate lens was invented and developed for optical frequencies. However, fabrication difficulties at the short optical wavelengths have prevented obtain good efficiencies. At longer microwave or millimeter-wavelengths fabrication is easier and phase correcting zone plate antennas have been used to obtain good efficiencies. This paper describes a new type of phase correcting zone plate having even better efficiency, namely a diffraction efficiency of 99 percent compared to a true lens, and an overall efficiency much better than a true lens. For the usual zone plate antenna employed at microwave or millimeter wavelengths, path length adjustment is accomplished by cutting different depths in a dielectric plate or by using two or more dielectrics having different dielectric constants. The new design uses a tilted cut in a dielectric plate, which more accurately matches the shape of a true lens and produces much lower phase error. The construction is still near and can be made for example, by a milling machine with a tilted bit. For a circular zone plate, the lens is a stepped conical or tapered shape. Because the phase steps are small, the far-field antenna pattern is excellent and sidelobe-levels are very low. Analysis of typical configurations will be given, showing that phase errors are small, lower than those for an eighth-wave corrected phase zone plate.

  20. Novel Electrically Small Spherical Electric Dipole Antenna

    DEFF Research Database (Denmark)

    Kim, Oleksiy S.

    2010-01-01

    This paper introduces a novel electrically small spherical meander antenna. Horizontal sections of the meander are composed of wire loops, radii of which are chosen so that the whole structure is conformal to a sphere of radius a. To form the meander the loops are connected by wires at a meridian...... plane. The antenna operates as an electric dipole, i.e. it radiates the TM10 spherical mode. The antenna is self-resonant and can be matched to a wide range of input feed lines without an external matching network. In this paper, a spherical meander antenna of the size ka = 0.27 and the input impedance...... of 72 ohms is numerically investigated and its performance is compared to that of the multiarm spherical helix antenna of the same size. Both antennas yield equal quality factors, which are about 1.5 times the Chu lower bound, but quite different cross-polarization characteristics....

  1. Compact Miniaturized Antenna for 210 MHz RFID

    Science.gov (United States)

    Lee, Richard Q.; Chun, Kue

    2008-01-01

    This paper describes the design and simulation of a miniaturized square-ring antenna. The miniaturized antenna, with overall dimensions of approximately one tenth of a wavelength (0.1 ), was designed to operate at around 210 MHz, and was intended for radio-frequency identification (RFID) application. One unique feature of the design is the use of a parasitic element to improve the performance and impedance matching of the antenna. The use of parasitic elements to enhance the gain and bandwidth of patch antennas has been demonstrated and reported in the literature, but such use has never been applied to miniaturized antennas. In this work, we will present simulation results and discuss design parameters and their impact on the antenna performance.

  2. Microfluidic serpentine antennas with designed mechanical tunability.

    Science.gov (United States)

    Huang, YongAn; Wang, Yezhou; Xiao, Lin; Liu, Huimin; Dong, Wentao; Yin, Zhouping

    2014-11-01

    This paper describes the design and characterization of microfluidic serpentine antennas with reversible stretchability and designed mechanical frequency modulation (FM). The microfluidic antennas are designed based on the Poisson's ratio of the elastomer in which the liquid alloy antenna is embedded, to controllably decrease, stabilize or increase its resonance frequency when being stretched. Finite element modelling was used in combination with experimental verification to investigate the effects of substrate dimensions and antenna aspect ratios on the FM sensitivity to uniaxial stretching. It could be designed within the range of -1.2 to 0.6 GHz per 100% stretch. When the aspect ratio of the serpentine antenna is between 1.0 and 1.5, the resonance frequency is stable under stretching, bending, and twisting. The presented microfluidic serpentine antenna design could be utilized in the field of wireless mobile communication for the design of wearable electronics, with a stable resonance frequency under dynamic applied strain up to 50%.

  3. Smart Antenna for Cellular Mobile Communication

    CERN Document Server

    Jain, R K; Agrawal, N K

    2012-01-01

    The adoption of smart / adaptive antenna techniques in future wireless systems is expected to have a significant impact on the efficient use of the spectrum, the minimization of the cost of establishing new wireless networks, the optimization of service quality and realization of transparent operation across multi technology wireless networks [1]. This paper presents brief account on smart antenna (SA) system. SAs can place nulls in the direction of interferers via adaptive updating of weights linked to each antenna element. SAs thus cancel out most of the co-channel interference resulting in better quality of reception and lower dropped calls. SAs can also track the user within a cell via direction of arrival algorithms [2]. This paper explains the architecture, evolution and how the smart / adaptive antenna differs from the basic format of antenna. The paper further explains about the radiation pattern of the antenna and why it is highly preferred in its relative field. The capabilities of smart / adaptive ...

  4. Millimeter-wave antennas configurations and applications

    CERN Document Server

    du Preez, Jaco

    2016-01-01

    This book comprehensively reviews the state of the art in millimeter-wave antennas, traces important recent developments and provides information on a wide range of antenna configurations and applications. While fundamental theoretical aspects are discussed whenever necessary, the book primarily focuses on design principles and concepts, manufacture, measurement techniques, and practical results. Each of the various antenna types scalable to millimeter-wave dimensions is considered individually, with coverage of leaky-wave and surface-wave antennas, printed antennas, integrated antennas, and reflector and lens systems. The final two chapters address the subject from a systems perspective, providing an overview of supporting circuitry and examining in detail diverse millimeter-wave applications, including high-speed wireless communications, radio astronomy, and radar. The vast amount of information now available on millimeter-wave systems can be daunting for researchers and designers entering the field. This b...

  5. Metamaterial Embedded Wearable Rectangular Microstrip Patch Antenna

    Directory of Open Access Journals (Sweden)

    J. G. Joshi

    2012-01-01

    Full Text Available This paper presents an indigenous low-cost metamaterial embedded wearable rectangular microstrip patch antenna using polyester substrate for IEEE 802.11a WLAN applications. The proposed antenna resonates at 5.10 GHz with a bandwidth and gain of 97 MHz and 4.92 dBi, respectively. The electrical size of this antenna is 0.254λ×0.5λ. The slots are cut in rectangular patch to reduce the bending effect. This leads to mismatch the impedance at WLAN frequency band; hence, a metamaterial square SRR is embedded inside the slot. A prototype antenna has been fabricated and tested, and the measured results are presented in this paper. The simulated and measured results of the proposed antenna are found to be in good agreement. The bending effect on the performance of this antenna is experimentally verified.

  6. Orthogonal feeding techniques for tapered slot antennas

    Science.gov (United States)

    Lee, Richard Q.; Simons, Rainee N.

    1998-01-01

    For array of "brick" configuration there are electrical and mechanical advantages to feed the antenna with a feed on a substrate perpendicular to the antenna substrate. Different techniques have been proposed for exciting patch antennas using such a feed structure.Rncently, an aperture-coupled dielectric resonator antenna using a perpendicular feed substrate has been demonstrated to have very good power coupling efficiency. For a two-dimensional rectangular array with tapered slot antenna elements, a power combining network on perpendicular substrate is generally required to couple power to or from the array. In this paper, we will describe two aperture-coupled techniques for coupling microwave power from a linearly tapered slot antenna (LTSA) to a microstrip feed on a perpendicular substrate. In addition, we will present measured results for return losses and radiation patterns.

  7. Compact UWB Antenna Design for MIMO Applications

    Directory of Open Access Journals (Sweden)

    Baskaran Kasi

    2013-12-01

    Full Text Available In this study, a compact printed Multiple-Input-Multiple-Output (MIMO antenna with a dimension of 32×70 mm2 has been proposed for Ultra-Wideband (UWB systems applications. The design constitutes of two identical UWB antenna elements, which is etched onto a Taconic TLC-30 printed circuit board. The proposed antenna has been designed and simulated using computer simulation software. For validation purposes, antenna prototype is fabricated and tested. The UWB-MIMO antenna yields an impedance bandwidth of 2.9 to 12 GHz with a return loss of less than-10 dB. Furthermore, the isolation characteristic between the two antenna elements is more than 15 dB within the operating frequency range. The designed structure is found to provide good MIMO/diversity characteristic across the UWB band.

  8. New band-notched UWB antenna

    Institute of Scientific and Technical Information of China (English)

    HE Xiao-xiang; DENG Hong-wei

    2009-01-01

    A simple and compact ultra wideband (UWB) printed monopole antenna with band-notched performance is proposed in this paper. The antenna is partially grounded so that the Q value is depressed and the impedance bandwidth is broadened. A small strip bar is loaded on each arm of the similar U-shaped radiator. The impedance bandwidth of the antenna overlap with IEEE 802.11a is rejected consequently. The geometry parameters of the antenna are investigated and optimized with HFSS. The measured bandwidth of the proposed antenna occupies about 7.89 GHz covering from 3.05 GHz to 10.94 GHz with expected notched band from 4.96 GHz to 5.98 GHz. A quasi-omnidirectional and quasi-symmetrical radiation pattern in the whole band is also obtained. As a result, a UWB wireless communication system can be simplified with the band-notched UWB antenna presented.

  9. A System Dynamic Analysis approach to deal with complexity in water resources management: the case of groundwater protection in the Apulia region (Southern Italy)

    Science.gov (United States)

    Giordano, Raffaele; Pluchinotta, Irene; Brugnach, Marcela; Pagano, Alessandro

    2015-04-01

    The increasing complexity and uncertainty of water resources management is claiming changes in the role of tools and methods aiming to support decision makers. Complexity due to the densely interconnected networks in which decision-actors operate. Uncertainty arises because of the fact that whatever action other decision agents involved in the network are going to do is largely unknown. In these complex and uncertain environments, it is very difficult to determine how effective a policy will be. Part of the difficulty resides in the fact that any action choice will influence and be influenced by the actions choices of the other actors. While these interactions among a diversity of actors may contribute to the development of beneficial adaptive behaviours, they can also result in dysfunctional dynamics, often leading to policy resistance. Action choices are not neutral, but commensurate with the problem frames held by the actors making the decisions. Our research hypothesis is that neglecting differences in problem framings leads decision makers to oversimplify the complexity of the interactions within the system to be managed, and to act as if the system is as simple as the decision makers presume it to be. Therefore, decision tools and methodologies should support the decision makers to become aware of the complexity of the interaction space, to disclose and analyse the existing interconnections, and to govern those interactions. In these circumstances, decision makers could take advantage from the interactional nature of the knowledge creation process. In order to demonstrate the research hypothesis, a methodology based on System Dynamic Modelling (SDM) was implemented in the Apulia Region (Southern Italy) to support the implementation of the groundwater (GW) protection policy. Due to the increasing of GW withdrawal for irrigation purposes, several phenomena are drastically reducing the quality of the GW resources. In order to protect the quality of GW, the

  10. Modeling of mixed-phasing antenna-plasma interactions applied to JET A2 antennas

    International Nuclear Information System (INIS)

    The use of mixed (monopole-dipole) phasing of a set of ICRF antennas is potentially useful to optimize tokamak performance and to do interesting physics experiments. However, recent mixed-phasing experiments on JET, described here, showed undesirable antenna-plasma interactions under certain circumstances. We explore a possible physical mechanism: parallel currents flowing between adjacent antennas with different phasings can lead to arcing on the antenna with the largest sheath voltage. Means of controlling the interaction are discussed

  11. Regional social protection mechanisms

    OpenAIRE

    Elena Alekseevna Morozova; Arina Yur'evna Dobrynina

    2012-01-01

    This paper focuses on the importance and essence of social protection mechanisms, describes their legal, economical and organizational components. Social protection mechanisms are important elements of the social protection system. Social protection mechanisms are understood as a complex of economical, organizational and legal measures aiming at smoothing social inequality of population.The legal foundations of the social protection mechanism consist in the fact that the protective a...

  12. Micromachined Horn Antenna Operating at 75 GHz

    OpenAIRE

    Grzegorczyk, Tomasz M.; Zurcher, Jean-François; Renaud, Philippe; Mosig, Juan R.

    2000-01-01

    We propose in this paper an integrated cavity-backed horn antenna, generalizing the well-known SSFIP (Strip-Slot-Foam-Inverted Patch) design, operating at 75 GHz. The antenna was optimized using a full-wave software and realized using micromachining technologies. The proposed structure can be used for high radiation ef-ficiency antennas and arrays in the millimeter-wave band, since surface waves are inherently suppressed by the use of a metallic horn and a cavity configuration.

  13. Quadric Resistive Sheet Profile for Wideband Antennas

    Directory of Open Access Journals (Sweden)

    Z. Raida

    2007-09-01

    Full Text Available A new type of a nonreflecting resistive dipole antenna with quadric continuous resistivity profile is presented in this paper. The antenna is mathematically described and compared with the antenna originally proposed by Wu and King. The verification of a proposed theory and the comparison between Wu-King and quadric profile are carried out by simulation models that were designed for this purpose. The attention is turned to the proper attenuation of a wave excited on the resistive sheet, especially.

  14. Ultrawideband antennas for microwave imaging systems

    CERN Document Server

    Denidni, Tayeb A

    2014-01-01

    This book presents ultrawideband antennas and their applications on microwave imaging. The chapters focus on recent techniques, analysis, and applications along with the future vision of this emerging field of applied electromagnetics. Several emerging topics are essayed, including dielectric resonator antennas and planar ultrawideband antennas for microwave imaging.This resource incorporates modern design concepts, analysis, and optimization techniques based on recent developments. Readers are also provided with an extensive overview of current regulations, including those related to microwav

  15. Dual-band Omnidirectional Circularly Polarized Antenna

    OpenAIRE

    Narbudowicz, Adam; Bao, Xiulong; Ammann, Max

    2013-01-01

    A dual-band omnidirectional circularly polarized antenna is proposed. The antenna comprises back-to-back microstrip patches fed by a coplanar waveguide. A very low frequency ratio of 1.182 has been achieved, which can be easily tuned by adjusting four lumped capacitors incorporated into the antenna. An analysis of the omnidirectional circular polarization mechanism as well the dual band operation is provided and confirmed by numerical and experimental data. Key parameters to tune the resonant...

  16. An antenna design for PANSAT using NEC.

    OpenAIRE

    Ellrick, Daniel A.

    1991-01-01

    Approved for public release; distribution is unlimited In this thesis the Numerical Electromagnetics Code (NEC) is used to design an omnidirectional antenna for the Petite Amateur Navy Satellite (PANSAT). The completed antenna design uses a tangential turnstile antenna to achieve a circularly polarized radiation pattern with predicted worst nulls of approximately -3.0 dBi. The use of NEC-3, recently ported to 80386 personal computers, demonstrates the potential of personal computers for ...

  17. Multi-Mode Broadband Patch Antenna

    Science.gov (United States)

    Romanofsky, Robert R. (Inventor)

    2001-01-01

    A multi-mode broad band patch antenna is provided that allows for the same aperture to be used at independent frequencies such as reception at 19 GHz and transmission at 29 GHz. Furthermore, the multi-mode broadband patch antenna provides a ferroelectric film that allows for tuning capability of the multi-mode broadband patch antenna over a relatively large tuning range. The alternative use of a semiconductor substrate permits reduced control voltages since the semiconductor functions as a counter electrode.

  18. Characterization of Transponder Antennas Using Intermodulation Response

    OpenAIRE

    Hannula, Jari-Matti; Rasilainen, Kimmo; Viikari, Ville

    2015-01-01

    The intermodulation measurement technique enables measuring transponder antennas without any cable connections. This contactless technique exploits the inherent nonlinearity of the transponder to generate intermodulation products that can be measured. In this paper, we relate the transponder antenna properties to the intermodulation response, and use this relation to calculate the gain andimpedance matching of the transponder antenna. Additionally, we consider the limitations of the measureme...

  19. Compact, Frequency Reconfigurable, Printed Monopole Antenna

    OpenAIRE

    Ricardo Gonçalves; Pedro Pinho; Nuno B. Carvalho

    2012-01-01

    This paper proposes a possible implementation of a compact printed monopole antenna, useful to operate in UMTS and WLAN bands. In order to accomplish that, a miniaturization technique based on the application of chip inductors is used in conjunction with frequency reconfiguration capability. The chip inductors change the impedance response of the monopole, allowing to reduce the resonant frequency. In order to be able to operate the antenna in these two different frequencies, an antenna recon...

  20. 1.2 Meter Shielded Cassegrain Antenna for Close-Packed Radio Interferometer

    CERN Document Server

    Koch, Patrick M; Huang, Yau-De; Chen, Ming-Tang; Han, Chih-Chiang; Lin, Kai-Yang; Altamirano, Pablo; Granet, Christophe; Ho, Paul T P; Huang, Chih-Wei L; Kesteven, Michael; Li, Chao-Te; Liao, Yu-Wei; Liu, Guo-Chin; Nishioka, Hiroaki; Ong, Ching-Long; Oshiro, Peter; Umetsu, Keiichi; Wang, Fu-Cheng; Wu, Jiun-Huei Proty

    2010-01-01

    Interferometric millimeter observations of the cosmic microwave background and clusters of galaxies with arcmin resolutions require antenna arrays with short spacings. Having all antennas co-mounted on a single steerable platform sets limits to the overall weight. A 25 kg lightweight novel carbon-fiber design for a 1.2 m diameter Cassegrain antenna is presented. The finite element analysis predicts excellent structural behavior under gravity, wind and thermal load. The primary and secondary mirror surfaces are aluminum coated with a thin TiO$_2$ top layer for protection. A low beam sidelobe level is achieved with a Gaussian feed illumination pattern with edge taper, designed based on feedhorn antenna simulations and verified in a far field beam pattern measurement. A shielding baffle reduces inter-antenna coupling to below $\\sim$ -135 dB. The overall antenna efficiency, including a series of efficiency factors, is estimated to be around 60%, with major losses coming from the feed spillover and secondary block...

  1. Selected asymptotic methods with applications to electromagnetics and antennas

    CERN Document Server

    Fikioris, George; Bakas, Odysseas N

    2013-01-01

    This book describes and illustrates the application of several asymptotic methods that have proved useful in the authors' research in electromagnetics and antennas. We first define asymptotic approximations and expansions and explain these concepts in detail. We then develop certain prerequisites from complex analysis such as power series, multivalued functions (including the concepts of branch points and branch cuts), and the all-important gamma function. Of particular importance is the idea of analytic continuation (of functions of a single complex variable); our discussions here include som

  2. Mathcad computer applications predicting antenna parameters from antenna physical dimensions and ground characteristics

    OpenAIRE

    Gerry, Donald D.

    1993-01-01

    Approved for public release; distribution is unlimited. This report provides the documentation for a set of computer applications for the evaluation of antenna parameters. The applications are written for the Mathcad personal computer software for various antenna types listed in the thesis index. Antenna dimen Lieutenant Commander, United States Navy

  3. TOLPA (Tripod Omnidirectional Low Profile Antenna): a vertically polarized antenna with 90% bandwidth

    OpenAIRE

    Zürcher, J.-F.

    2013-01-01

    A new vertically polarized omnidirectional antenna, inspired by an old design, has been studied, optimized, realized and measured. With a radiation pattern similar to the classical monopole on a ground plane, the proposed antenna concept provides a much larger bandwidth and a very low profile. This antenna has numerous potential applications for mobile communications, UWB and others.

  4. U-Slotted Microstrip Patch Antenna

    Directory of Open Access Journals (Sweden)

    Yogesh Bhomia

    2013-05-01

    Full Text Available A new U–slotted microstrip antenna is proposed. A patch antenna is a narrowband, wide-beam antenna These antennas are low profile, conformal to planar and non-planar surface, simple and inexpensive to manufacture using modern printed circuit technology, mechanically robust when mounted on rigid surface, compatible with MMIC designs and when the particular shape and mode are selected they are very versatile in terms of resonant frequency, polarization, field pattern and impedance. Microstrip antenna consist of a very thin metallic strip (patch placed a small fraction of a wavelength above a ground plane. The patch is generally made of conducting material such as copper or gold and can take any possible shape. This paper presents a design of U - slotted microstrip patch antenna and experimentally studied on IE3D software. This design is achieved by cutting U shape in a patch. With U - slotted shapes patch antenna is designed on a FR4 substrate of thickness 1.524 mm and relative permittivity of 4.4 and mounted above the ground plane at a height of 6 mm. Bandwidth as high as 39% are achieved with stable pattern characteristics, such as gain and cross polarization, within its bandwidth. Impedance bandwidth, antenna gain and return loss are observed for the proposed antenna. Details of the measured and simulated results are presented and discussed

  5. Carbon Nanotube Thin-Film Antennas.

    Science.gov (United States)

    Puchades, Ivan; Rossi, Jamie E; Cress, Cory D; Naglich, Eric; Landi, Brian J

    2016-08-17

    Multiwalled carbon nanotube (MWCNT) and single-walled carbon nanotube (SWCNT) dipole antennas have been successfully designed, fabricated, and tested. Antennas of varying lengths were fabricated using flexible bulk MWCNT sheet material and evaluated to confirm the validity of a full-wave antenna design equation. The ∼20× improvement in electrical conductivity provided by chemically doped SWCNT thin films over MWCNT sheets presents an opportunity for the fabrication of thin-film antennas, leading to potentially simplified system integration and optical transparency. The resonance characteristics of a fabricated chlorosulfonic acid-doped SWCNT thin-film antenna demonstrate the feasibility of the technology and indicate that when the sheet resistance of the thin film is >40 ohm/sq no power is absorbed by the antenna and that a sheet resistance of antenna. The dependence of the return loss performance on the SWCNT sheet resistance is consistent with unbalanced metal, metal oxide, and other CNT-based thin-film antennas, and it provides a framework for which other thin-film antennas can be designed.

  6. Three-dimensional winged nanocone optical antennas.

    Science.gov (United States)

    Huttunen, Mikko J; Lindfors, Klas; Andriano, Domenico; Mäkitalo, Jouni; Bautista, Godofredo; Lippitz, Markus; Kauranen, Martti

    2014-06-15

    We introduce 3D optical antennas based on winged nanocones. The antennas support particle plasmon oscillations with current distributions that facilitate transformation of transverse far-field radiation to strong longitudinal local fields near the cone apices. We characterize the optical responses of the antennas by their extinction spectra and by second-harmonic generation microscopy with cylindrical vector beams. The results demonstrate a new 3D polarization-controllable optical antenna for applications in apertureless near-field microscopy, spectroscopy, and plasmonic sensing.

  7. Perspectives for future SAR Antenna Developement

    OpenAIRE

    Keydel, Wolfgang

    2007-01-01

    Goal of the paper is to present the expected development of future antennas for space borne SAR based on the state-of-the-art and to point out under that aspect some perspectives and visions for future space borne SAR systems. Future space borne SAR systems will consist mainly of the antenna with a small number of peripheral elements only, like solar cells, GPS, power supply, downlink equipment etc.. The present spaceborne SAR Antenna will mutate to a complete Antenna SAR that means a SAR...

  8. Thermal Analysis of the Chinese SAR Antenna

    Science.gov (United States)

    Ma, Huitao; Jiang, Hai; Liu, Qiang

    2002-01-01

    success or failure of the mission directly. In general, the SAR Antenna is very large, about 9500mm×4000mm in the deployed configuration. The SAR Antenna system is also very complicated, consisting of 5 antenna panels, deployment mechanism, hinges, tie-downs, extendible support structure and drivers. complicated space heat fluxes( the solar radiation, earth IR and albedo) and so on. However, the SAR Antenna in the orbital flying is directly exposed to the bad space environment. If the thermal design is not correct, the unreasonable temperature distribution of the SAR Antenna will be resulted in, which maybe causes too large thermal deformation to ensure the normal deployment and operation performance of the SAR Antenna. So it is necessary to conduct the thermal design for the SAR Antenna. respectively. The temperature distributions and the worst gradients of the SAR Antenna were obtained in the different cases. These results provide an important theoretic reference for the thermal design of the SAR Antenna. Based on the thermal analysis, some important conclusions are obtained. the software NEVADA and SINDA/G.

  9. A Design of Double Broadband MIMO Antenna

    Directory of Open Access Journals (Sweden)

    Yanfeng Geng

    2015-01-01

    Full Text Available The MIMO antenna applied to LTE mobile system should be miniaturization and can work in the current communication frequency band; isolation between each antenna unit also should be good so as to reduce loss of radio wave energy and improve the antenna performance of the MIMO system. This paper puts forward the design scheme of a broadband MIMO double antenna. And the design of antenna unit and debugging and related technical measures, such as bending antenna bracket, are both presented; the integration design of high isolation of ultra broadband MIMO antenna is realized on the plate with the volume of 100 × 52 × 0.8 mm3; antenna working bands are 698 MHz~960 MHz and 1710 MHz~2700 MHz; in the whole spectrum, the 10 dB of port isolation can be basically achieved; in low frequency band, the isolation degree of antenna port can reach 12 dB.

  10. Wideband Monopole Antenna for WLAN Applications

    Directory of Open Access Journals (Sweden)

    Muhammad Umar

    2013-03-01

    Full Text Available This paper presents a circular patch antenna for WLAN applications with wideband characteristics. It is shown that impedance of the antenna is matched over wideband by using the partial ground plane and quarter wave transformer with slotted TX-Line. Ansoft HFSS is used for simulation tool to map the numerical results for the return loss frequency behavior of antenna. Measure of bandwidth, return loss and radiation pattern are also reported with satisfactory performance. As the patch is circular in shape so substrate is kept in the same shape. The shape of the substrate is also discussed in details for specific antenna designs.

  11. Analysis on two novel spherical helical antennas

    Institute of Scientific and Technical Information of China (English)

    Hou ZHANG; Yingzeng YIN; Dongyu XIA

    2009-01-01

    Two novel spherical helical antennas are designed by projecting the planar equiangular spiral antenna onto hemisphere and partial sphere surfaces.Their radiation properties are analyzed by the moment method with curved basis and test function,and the curves of the voltage standing wave ratio (VSWR),gain,polarization and pattern that change with frequency are also given,respectively.It can be seen that the circular polarization band of the novel hemispherical helical antenna is broader.The gain curve of the partial spherical helical antenna is flatter and the structure is simpler.

  12. A COMPACT CIRCULARLY POLARIZED SLOTTED MICROSTRIP ANTENNA

    Directory of Open Access Journals (Sweden)

    V. Jebaraj

    2014-12-01

    Full Text Available Slot antennas are often used at UHF and microwave frequencies. In slot antenna for RFID reader applications the frequency ranges from 902-923MHz to achieve circular polarization. The shapes and size of the slot, as well as the driving frequency, determine the radiation distribution pattern. The proposed compact size circularly polarized slotted microstrip antenna are summarized with design rules. The circularly polarized radiation in square patch antenna can be obtained by perturbation technique with different shapes of slot in the orthogonal direction. A single feed configuration based symmetric slotted microstrip antenna is adapted to realize the compact circularly polarized microstrip antennas. Based on the perimeter, the size of the slot on microstrip slot antenna are studied and compared. The Operating frequency of the antenna is 912MHz that can be tuned by varying the perimeter of the slot while the keeping the circularly polarized radiation unchanged. The schematic and layout are configured by using Advanced Design System (ADS. Return loss, Resonant Frequency, Axial Ratio (AR, and Gain were determined for the proposed system using ADS. A measured 3dB Axial Ratio (AR bandwidth around 6MHz with 16MHz impedance bandwidth has been achieved for the antenna on a RO3004C substrate with dielectric constant 3.38.

  13. Broadband Suspended Microstrip Antenna For Circular Polarization

    OpenAIRE

    Kasabegoudar, VG; Vinoy, KJ

    2009-01-01

    In this paper we propose a circularly polarized (CP) microstrip antenna on a suspended substrate with a coplanar capacitive feed and a slot within the rectangular patch. The antenna has an axial ratio bandwidth (< 3 dB) of 7.1%. The proposed antenna exhibits a much higher impedance bandwidth of about 49% (S11 < -10 dB) and also yields return loss better than -15 dB in the useful range of circular polarization. Measured characteristics of the antenna are in good agreement with the simulated re...

  14. Matching Parasitic Antenna for Single RF MIMO

    DEFF Research Database (Denmark)

    Han, Bo; Kalis, A; Nielsen, Rasmus Hjorth;

    2012-01-01

    order to have such performance, an antenna with rich pattern modes is required by the system, thus the ESPAR antenna is investigated. The critical part on such antenna is parasitic element impedance matching. Unlike the conventional smith-chart matching method which assumes the minimal resistance is...... zero and with goal of 50 ohm or 75 ohm matching, matching on such parasitic antenna will adopt negative value as well. This paper presents a matching network with controllable impedance even to the range of negative values....

  15. Handbook of smart antennas for RFID systems

    CERN Document Server

    2010-01-01

    The Handbook of Smart Antennas for RFID Systems is a single comprehensive reference on the smart antenna technologies applied to RFID. This book will provide a timely reference book for researchers and students in the areas of both smart antennas and RFID technologies. It is the first book to combine two of the most important wireless technologies together in one book. The handbook will feature chapters by leading experts in both academia and industry offering an in-depth description of terminologies and concepts related to smart antennas in various RFID systems applications.

  16. 47 CFR 73.1680 - Emergency antennas.

    Science.gov (United States)

    2010-10-01

    ... the FCC in Washington, DC, Attention: Audio Division (radio) or Video Division (television), Media... output power, radiation limits, or other operating conditions when using an emergency antenna,...

  17. Resonance spectra of diabolo optical antenna arrays

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Hong; Guo, Junpeng, E-mail: guoj@uah.edu [Department of Electrical and Computer Engineering, University of Alabama in Huntsville, 301 Sparkman Drive, Huntsville, AL 35899 (United States); Simpkins, Blake; Caldwell, Joshua D. [Naval Research Laboratory, 4555 Overlook Ave., SW Washington, DC 20375 (United States)

    2015-10-15

    A complete set of diabolo optical antenna arrays with different waist widths and periods was fabricated on a sapphire substrate by using a standard e-beam lithography and lift-off process. Fabricated diabolo optical antenna arrays were characterized by measuring the transmittance and reflectance with a microscope-coupled FTIR spectrometer. It was found experimentally that reducing the waist width significantly shifts the resonance to longer wavelength and narrowing the waist of the antennas is more effective than increasing the period of the array for tuning the resonance wavelength. Also it is found that the magnetic field enhancement near the antenna waist is correlated to the shift of the resonance wavelength.

  18. Whip antenna design for portable rf systems

    Science.gov (United States)

    Ponnapalli, Saila; Canora, Frank J.

    1995-12-01

    Whip type antennas are probably the most commonly used antennas in portable rf systems, such as cordless and cellular phones, rf enabled laptop computers, personal digital assistants (PDAs), and handheld computers. Whip antennas are almost always mounted on the chassis which contains the radio and other electronics. The chassis is usually a molded plastic which is coated with a conducting paint for EMI purposes. The chassis which appears as a lossy conductor to the antenna, has several effects -- detuning, altering the gain of the antenna, and shadowing its radiation pattern. Extensive modeling and measurements must be performed in order to fully characterize the affects of the chassis on the whip antenna, and to optimize antenna type, orientation and position. In many instances, modeling plays a more important role in prediction of the performance of whip antennas, since measurements become difficult due to the presence of common mode current on feed cables. In this paper models and measurements are used to discuss the optimum choice of whip antennas and the impact of the chassis on radiation characteristics. A modeling tool which has been previously described and has been successfully used to predict radiated field patterns is used for simulations, and measured and modeled results are shown.

  19. A Compact Diversity Antenna for Handheld Terminals

    Institute of Scientific and Technical Information of China (English)

    Hai-Lin Xiao; Zai-Ping Nie; Yu-Jing Wu

    2009-01-01

    The handheld terminals antenna should have a small size, sufficient gain and big bandwidth. In this paper, a compact planar inverted-L diversity antenna for handheld terminals is proposed. Three diversity antennas operating at 2.15 GHz are designed and the effect of important parameters of the proposed antenna is measured. The isolation is found to be better than 13 dB, the usable bandwidth is about 13%. Moreover, the measured radiation patterns are also obtained that the backward radiation is decreased.

  20. Switchable Electromagnetic Bandgap Surface Wave Antenna

    Directory of Open Access Journals (Sweden)

    Qiang Bai

    2014-01-01

    Full Text Available This paper presents a novel switchable electromagnetic bandgap surface wave antenna that can support both a surface wave and normal mode radiation for communications at 2.45 GHz. In the surface wave mode, the antenna has a monopole-like radiation pattern with a measured gain of 4.4 dBi at ±49° and a null on boresight. In the normal mode, the antenna operates like a back-fed microstrip patch antenna.

  1. Selective detection of bacterial layers with terahertz plasmonic antennas

    CERN Document Server

    Berrier, Audrey; Nonglaton, Guillaume; Bergquist, Jonas; Rivas, Jaime Gómez

    2012-01-01

    Current detection and identification of micro-organisms is based on either rather unspecific rapid microscopy or on more accurate complex, time-consuming procedures. In a medical context, the determination of the bacteria Gram type is of significant interest. The diagnostic of microbial infection often requires the identification of the microbiological agent responsible for the infection, or at least the identification of its family (Gram type), in a matter of minutes. In this work, we propose to use terahertz frequency range antennas for the enhanced selective detection of bacteria types. Several microorganisms are investigated by terahertz time-domain spectroscopy: a fast, contactless and damage-free investigation method to gain information on the presence and the nature of the microorganisms. We demonstrate that plasmonic antennas enhance the detection sensitivity for bacterial layers and allow the selective recognition of the Gram type of the bacteria.

  2. Selective detection of bacterial layers with terahertz plasmonic antennas.

    Science.gov (United States)

    Berrier, Audrey; Schaafsma, Martijn C; Nonglaton, Guillaume; Bergquist, Jonas; Rivas, Jaime Gómez

    2012-11-01

    Current detection and identification of micro-organisms is based on either rather unspecific rapid microscopy or on more accurate but complex and time-consuming procedures. In a medical context, the determination of the bacteria Gram type is of significant interest. The diagnostic of microbial infection often requires the identification of the microbiological agent responsible for the infection, or at least the identification of its family (Gram type), in a matter of minutes. In this work, we propose to use terahertz frequency range antennas for the enhanced selective detection of bacteria types. Several microorganisms are investigated by terahertz time-domain spectroscopy: a fast, contactless and damage-free investigation method to gain information on the presence and the nature of the microorganisms. We demonstrate that plasmonic antennas enhance the detection sensitivity for bacterial layers and allow the selective recognition of the Gram type of the bacteria.

  3. Discrete cyclic porphyrin arrays as artificial light-harvesting antenna.

    Science.gov (United States)

    Aratani, Naoki; Kim, Dongho; Osuka, Atsuhiro

    2009-12-21

    The importance of photosynthesis has driven researchers to seek ways to mimic its fundamental features in simplified systems. The absorption of a photon by light-harvesting (antenna) complexes made up of a large number of protein-embedded pigments initiates photosynthesis. Subsequently the many pigments within the antenna system shuttle that photon via an efficient excitation energy transfer (EET) until it encounters a reaction center. Since the 1995 discovery of the circularly arranged chromophoric assemblies in the crystal structure of light-harvesting antenna complex LH2 of purple bacteria Rps. Acidophila, many designs of light-harvesting antenna systems have focused on cyclic porphyrin wheels that allow for efficient EET. In this Account, we review recent research in our laboratories in the synthesis of covalently and noncovalently linked discrete cyclic porphyrin arrays as models of the photosynthetic light-harvesting antenna complexes. On the basis of the silver(I)-promoted oxidative coupling strategy, we have prepared a series of extremely long yet discrete meso-meso-linked porphyrin arrays and covalently linked large porphyrin rings. We examined the photophysical properties of these molecules using steady-state absorption, fluorescence, fluorescence lifetime, fluorescence anisotropy decay, and transient absorption measurements. Both the pump-power dependence on the femtosecond transient absorption and the transient absorption anisotropy decay profiles are directly related to the EET processes within the porphyrin rings. Within these structures, the exciton-exciton annihilation time and the polarization anisotropy rise time are well-described in terms of the Forster-type incoherent energy hopping model. In noncoordinating solvents such as CHCl(3), meso-pyridine-appended zinc(II) porphyrins and their meso-meso-linked dimers spontaneously assemble to form tetrameric porphyrin squares and porphyrin boxes, respectively. In the latter case, we have demonstrated

  4. Groundwater Protection Program Management Plan for the U.S. Department of Energy Y-12 National Security Complex, Oak Ridge, Tennessee; FINAL

    International Nuclear Information System (INIS)

    This document presents the Groundwater Protection Program (GWPP) management plan for the U.S. Department of Energy (DOE) Y-12 National Security Complex (hereafter referenced as Y-12). The Y-12 GWPP functions as the primary point-of-contact for groundwater-related issues at Y-12, provides stewardship of the extensive network of groundwater monitoring wells at Y-12, and serves as a resource for technical expertise, support, and historical data for groundwater-related activities at Y-12. These organizational functions each serve the primary programmatic purpose of the GWPP, which is to ensure that groundwater monitoring activities within areas under Y-12 administrative control provide representative data in compliance with the multiple purposes of applicable state and federal regulations, DOE orders, and the corporate policies of BWXT Y-12, L.L.C. (hereafter referenced as BWXT Y-12), the Y-12 management and operations (M and O) subcontractor for DOE

  5. Y-12 Groundwater Protection Program CY2012 Triennial Report Of The Monitoring Well Inspection And Maintenance Program Y-12 National Security Complex, Oak Ridge, Tennessee

    Energy Technology Data Exchange (ETDEWEB)

    None

    2013-09-01

    This document is the triennial report for the Well Inspection and Maintenance Program of the Y- 12 Groundwater Protection Program (GWPP), at the U.S. Department of Energy (DOE) Y-12 National Security Complex (Y-12). This report formally documents well inspections completed by the GWPP on active and inactive wells at Y-12 during calendar years (CY) 2010 through 2012. In addition, this report also documents well inspections performed under the Y-12 Water Resources Restoration Program, which is administered by URS|CH2M Oak Ridge (UCOR). This report documents well maintenance activities completed since the last triennial inspection event (CY 2009); and provides summary tables of well inspections and well maintenance activities during the reference time period.

  6. A telemetry antenna system for unmanned air vehicles

    OpenAIRE

    DOĞAN, Mustafa; Dogan, Mustafa; Üstüner, Fatih; Ustuner, Fatih

    2010-01-01

    This paper presents a low VSWR high gain telemetry antenna system manufactured for UAVs that provides 360± coverage in the roll plane of the UAV. Proposed telemetry antenna system includes four telemetry antennas, one power divider that has one input and four output terminals which feeds the telemetry antennas with equal magnitude and phase. Proposed high gain telemetry antennas are based on the feeding of the microstrip patch antenna via aperture coupling. Full coverage in the roll plane of ...

  7. Improved patch antenna performance by using a metamaterial cover

    Institute of Scientific and Technical Information of China (English)

    ZHU Fang-ming; HU Jun

    2007-01-01

    A new patch antenna system with a metamaterial cover is presented in this paper. The impedance, radiation pattern, and directivity of such an antenna are studied. A performance comparison between the conventional patch antenna and the new metamaterial patch antenna is given. The results show that the directivity of the metamaterial patch antenna is significantly improved. The effect of the metamaterial cover's layer numbers on the radiation pattern of the patch antenna is also studied.

  8. CPW-Fed Ring Antenna For UWB Applications

    OpenAIRE

    Sheetal Kamboj; Amit Kumar

    2014-01-01

    This paper presents a Coplanar waveguide feed ( CPW) monopole ring antenna for ultra wideband applications. The proposed antenna consist of ring type patch embedded with horizontal strip in the patch. The parametric study is performed to understand the characteristics of the proposed antenna. The antenna exhibits impedance bandwidth from 3.7 GHz to 10.7 GHz. The various antenna parameters are studied. The proposed antenna is suitable for UWB applications.

  9. A Simple Low-Cost Shared-Aperture Dual-Band Dual-Polarized High Gain Antenna for Synthetic Aperture Radars

    OpenAIRE

    Qin, Fan; Gao, Steven; Qi, Luo; Mao, Chunxu; Gu, Chao; Wei, Gao; Xu, Jiadong; Li, Jianzhou; Wu, Changying; Zheng, Kuisong; Zheng, Shufeng

    2016-01-01

    This paper presents a novel shared-aperture dual-band dual-polarized high-gain antenna for potential applications in synthetic aperture radars (SAR). To reduce the complexity of SAR antennas, a dual-band dual-polarized high gain antenna based on the concept of Fabry-Perot resonant cavity is designed. This antenna operates in both C and X bands with a frequency ratio of 1:1.8. To form two separate resonant cavities, two frequency selective surface (FSS) layers are employed, leading to high fle...

  10. Magnetic antenna excitation of whistler modes. IV. Receiving antennas and reciprocity

    Energy Technology Data Exchange (ETDEWEB)

    Stenzel, R. L., E-mail: stenzel@physics.ucla.edu; Urrutia, J. M. [Department of Physics and Astronomy, University of California, Los Angeles, California 90095-1547 (United States)

    2015-07-15

    Antenna radiation patterns are an important property of antennas. Reciprocity holds in free space and the radiation patterns for exciting and receiving antennas are the same. In anisotropic plasmas, radiation patterns are complicated by the fact that group and phase velocities differ and certain wave properties like helicity depend on the direction of wave propagation with respect to the background magnetic field B{sub 0}. Interference and wave focusing effects are different than in free space. Reciprocity does not necessarily hold in a magnetized plasma. The present work considers the properties of various magnetic antennas used for receiving whistler modes. It is based on experimental data from exciting low frequency whistler modes in a large uniform laboratory plasma. By superposition of linear waves from different antennas, the radiation patterns of antenna arrays are derived. Plane waves are generated and used to determine receiving radiation patterns of different receiving antennas. Antenna arrays have radiation patterns with narrow lobes, whose angular position can be varied by physical rotation or electronic phase shifting. Reciprocity applies to broadside antenna arrays but not to end fire arrays which can have asymmetric lobes with respect to B{sub 0}. The effect of a relative motion between an antenna and the plasma has been modeled by the propagation of a short wave packet moving along a linear antenna array. An antenna moving across B{sub 0} has a radiation pattern characterized by an oscillatory “whistler wing.” A receiving antenna in motion can detect any plane wave within the group velocity resonance cone. The radiation pattern also depends on loop size relative to the wavelength. Motional effects prevent reciprocity. The concept of the radiation pattern loses its significance for wave packets since the received signal does not only depend on the antenna but also on the properties of the wave packet. The present results are of fundamental

  11. Major technological innovations introduced in the large antennas of the Deep Space Network

    Science.gov (United States)

    Imbriale, W. A.

    2002-01-01

    The NASA Deep Space Network (DSN) is the largest and most sensitive scientific, telecommunications and radio navigation network in the world. Its principal responsibilities are to provide communications, tracking, and science services to most of the world's spacecraft that travel beyond low Earth orbit. The network consists of three Deep Space Communications Complexes. Each of the three complexes consists of multiple large antennas equipped with ultra sensitive receiving systems. A centralized Signal Processing Center (SPC) remotely controls the antennas, generates and transmits spacecraft commands, and receives and processes the spacecraft telemetry.

  12. Photosynthetic antennas and reaction centers: Current understanding and prospects for improvement

    Energy Technology Data Exchange (ETDEWEB)

    Blankenship, R.E. [Arizona State Univ., Tempe, AZ (United States)

    1996-09-01

    A brief introduction to the principles, structures and kinetic processes that take place in natural photosynthetic reaction center complexes is presented. Energy is first collected by an antenna system, and is transferred to a reaction center complex where primary electron transfer takes place. Secondary reactions lead to oxidation of water and reduction of CO{sub 2} in some classes of organisms. Antenna systems are highly regulated to maximize energy collection efficiency while avoiding photodamage. Some areas that are presently not well understood are listed.

  13. Electrostatic Evaluation of the ARES I FTS Antenna Materials

    Science.gov (United States)

    Hogue, Michael D.; Calle, Carlos I.

    2010-01-01

    Surface resistivity and volume resistivity data show all the tested non-metallic materials of the Ares I FTS antenna assembly to be insulative. The external materials (White foam, phenolic) should be able to develop a large surface charge density upon tribocharging with ice crystal impingement. Dielectric breakdown tests on the FTS antenna housing materials show that each of the insulative materials are very resistive to electrical breakdown. The thicknesses of these materials in a nominal housing should protect the antenna from direct breakdown from external triboelectric charging potentials. Per data from the Air Force study, a maximum external electric potential in the range of 100kV can be developed on surfaces tribocharged by ice crystal impingement. Testing showed that under operational pressure ranges, this level of exterior voltage can result in a potential of about 6 kV induced on the electrically floating interior antenna vanes. Testing the vanes up to this voltage level showed that electrostatic discharges can occur between the electrically floating vanes and the center, grounded screw heads. Repeated tests with multiple invisible and visible discharges caused only superficial physical damage to the vanes. Fourier analysis of the discharge signals showed that the frequency range of credible discharges would not interfere with the nominal operation of the FTS antenna. However, due to the limited scope, short timetable, and limited funding of this study, a direct measurement of the triboelectric charge that could be generated on the Ares I antenna housing when the rocket traverses an ice cloud at supersonic speeds was not performed. Instead, data for the limited Air Force study [3] was used as input for our experiments. The Air Force data used was not collected with a sensor located to provide us with the best approximation at the geometry of the Ares I rocket, namely that of the windshield electrometer, because brush discharges to the metal frame of the

  14. Survey on various design of microchip patch antenna

    Directory of Open Access Journals (Sweden)

    A.Anusuya

    2014-11-01

    Full Text Available Due to fast advancement in wireless communication technology, use of small size antenna has rapidly increased. Not only the size of the antenna its cost, performance, ease of installation everything have been taken care while designing the antenna. To meet this entire requirement micro-strip antenna is proposed. Nowadays microstrip antennas are used in many places such as aircrafts, spacecraft’s, satellite and missile applications. In this paper, we discuss the microstrip antenna, types of microstrip antenna, various substrates used for designing the antenna and the literature survey which we have done

  15. Micro strip Patch Antenna and its Applications: a Survey

    Directory of Open Access Journals (Sweden)

    Indrasen Singh

    2011-09-01

    Full Text Available The study of microstrip patch antennas has made great progress in recent years. Compared with conventional antennas, microstrip patch antennas have more advantages and better prospects. They are lighter in weight, low volume, low cost, low profile, smaller in dimension and ease of fabrication and conformity. Moreover, the microstrip patch antennas can provide dual and circular polarizations, dual-frequency operation, frequency agility, broad band-width, feedline flexibility, beam scanning omnidirectional patterning. In this paper we discuss the microstrip antenna, types of microstrip antenna, feeding techniques and application of microstrip patch antenna with their advantage and disadvantages over conventional microwave antennas.

  16. Enabling Technologies for Fabrication of Large Area Flexible Antennas Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Flexible, foldable, and/or inflatable antenna systems open up a wealth of opportunities. Integrating antenna elements and related electronics onto flexible...

  17. Compact planar UWB antennas for wireless device applications

    OpenAIRE

    Liu, Li; 劉荔

    2014-01-01

    The thesis report presents the designs of compact planar ultra-wideband (UWB) antennas for wireless devices applications. Three main designs of UWB antennas are studied, namely, single UWB antennas, UWB multiple-input-multiple-out(MIMO)antennas, and transparent UWB antennas on the screens of mobile phones. For single UWB antennas, the designs of two compact planar monopole antennas with compact sizes of 26×28 mm2and 30×39.3mm2are presented. The UWB operations of the antennas are achieved ...

  18. Breadboard Signal Processor for Arraying DSN Antennas

    Science.gov (United States)

    Jongeling, Andre; Sigman, Elliott; Chandra, Kumar; Trinh, Joseph; Soriano, Melissa; Navarro, Robert; Rogstad, Stephen; Goodhart, Charles; Proctor, Robert; Jourdan, Michael; Rayhrer, Benno

    2008-01-01

    A recently developed breadboard version of an advanced signal processor for arraying many antennas in NASA s Deep Space Network (DSN) can accept inputs in a 500-MHz-wide frequency band from six antennas. The next breadboard version is expected to accept inputs from 16 antennas, and a following developed version is expected to be designed according to an architecture that will be scalable to accept inputs from as many as 400 antennas. These and similar signal processors could also be used for combining multiple wide-band signals in non-DSN applications, including very-long-baseline interferometry and telecommunications. This signal processor performs functions of a wide-band FX correlator and a beam-forming signal combiner. [The term "FX" signifies that the digital samples of two given signals are fast Fourier transformed (F), then the fast Fourier transforms of the two signals are multiplied (X) prior to accumulation.] In this processor, the signals from the various antennas are broken up into channels in the frequency domain (see figure). In each frequency channel, the data from each antenna are correlated against the data from each other antenna; this is done for all antenna baselines (that is, for all antenna pairs). The results of the correlations are used to obtain calibration data to align the antenna signals in both phase and delay. Data from the various antenna frequency channels are also combined and calibration corrections are applied. The frequency-domain data thus combined are then synthesized back to the time domain for passing on to a telemetry receiver

  19. HspB5/αB-crystallin increases dendritic complexity and protects the dendritic arbor during heat shock in cultured rat hippocampal neurons.

    Science.gov (United States)

    Bartelt-Kirbach, Britta; Moron, Margarethe; Glomb, Maximilian; Beck, Clara-Maria; Weller, Marie-Pascale; Golenhofen, Nikola

    2016-10-01

    The small heat shock protein ΗspΒ5 (αB-crystallin) exhibits generally cytoprotective functions and possesses powerful neuroprotective capacity in the brain. However, little is known about the mode of action of ΗspΒ5 or other members of the HspB family particularly in neurons. To get clues of the neuronal function of HspBs, we overexpressed several HspBs in cultured rat hippocampal neurons and investigated their effect on neuronal morphology and stress resistance. Whereas axon length and synapse density were not affected by any HspB, dendritic complexity was enhanced by HspB5 and, to a lesser extent, by HspB6. Furthermore, we could show that this process was dependent on phosphorylation, since a non-phosphorylatable mutant of HspB5 did not show this effect. Rarefaction of the dendritic arbor is one hallmark of several neurodegenerative diseases. To investigate if HspB5, which is upregulated at pathophysiological conditions, might be able to protect dendrites during such situations, we exposed HspB5 overexpressing neuronal cultures to heat shock. HspB5 prevented heat shock-induced rarefaction of dendrites. In conclusion, we identified regulation of dendritic complexity as a new function of HspB5 in hippocampal neurons. PMID:27085702

  20. An Integrated Circuit for Radio Astronomy Correlators Supporting Large Arrays of Antennas

    CERN Document Server

    D'Addario, Larry R

    2016-01-01

    Radio telescopes that employ arrays of many antennas are in operation, and ever larger ones are being designed and proposed. Signals from the antennas are combined by cross-correlation. For $N$ antennas, the cost and power consumption of cross-correlation are proportional to $N^2$ and dominate at sufficiently large $N$. Here we report the design of an integrated circuit (IC) that performs digital cross-correlations for arbitrarily many antennas in a power-efficient way. It uses an intrinsically low-power architecture in which the movement of data between devices is minimized. In our design, the correlations are performed in an array of 4096 complex multiply-accumulate (CMAC) units. This is sufficient to perform all correlations in parallel for 64 signals ($N$=32 antennas with 2 opposite-polarization signals per antenna). When $N$ is larger, the input data are buffered in an on-chip memory and the CMACs are re-used as many times as needed to compute all correlations. The design has been synthesized and simulat...