Vlasov moments, integrable systems and singular solutions
Energy Technology Data Exchange (ETDEWEB)
Gibbons, John [Department of Mathematics, Imperial College London, London SW7 2AZ (United Kingdom); Holm, Darryl D. [Department of Mathematics, Imperial College London, London SW7 2AZ (United Kingdom); Computer and Computational Science Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States)], E-mail: d.holm@ic.ac.uk; Tronci, Cesare [Department of Mathematics, Imperial College London, London SW7 2AZ (United Kingdom); TERA Foundation for Oncological Hadrontherapy, 11 V. Puccini, Novara 28100 (Italy)
2008-02-11
The Vlasov equation governs the evolution of the single-particle probability distribution function (PDF) for a system of particles interacting without dissipation. Its singular solutions correspond to the individual particle motions. The operation of taking the moments of the Vlasov equation is a Poisson map. The resulting Lie-Poisson Hamiltonian dynamics of the Vlasov moments is found to be integrable is several cases. For example, the dynamics for coasting beams in particle accelerators is associated by a hodograph transformation to the known integrable Benney shallow-water equation. After setting the context, the Letter focuses on geodesic Vlasov moment equations. Continuum closures of these equations at two different orders are found to be integrable systems whose singular solutions characterize the geodesic motion of the individual particles.
The Einstein-Vlasov System/Kinetic Theory
Directory of Open Access Journals (Sweden)
Håkan Andréasson
2011-05-01
Full Text Available The main purpose of this article is to provide a guide to theorems on global properties of solutions to the Einstein-Vlasov system. This system couples Einstein’s equations to a kinetic matter model. Kinetic theory has been an important field of research during several decades in which the main focus has been on non-relativistic and special relativistic physics, i.e., to model the dynamics of neutral gases, plasmas, and Newtonian self-gravitating systems. In 1990, Rendall and Rein initiated a mathematical study of the Einstein-Vlasov system. Since then many theorems on global properties of solutions to this system have been established. This paper gives introductions to kinetic theory in non-curved spacetimes and then the Einstein–Vlasov system is introduced. We believe that a good understanding of kinetic theory in non-curved spacetimes is fundamental to a good comprehension of kinetic theory in general relativity.
The Einstein-Vlasov System/Kinetic Theory
Directory of Open Access Journals (Sweden)
Andréasson Håkan
2005-01-01
Full Text Available The main purpose of this article is to provide a guide to theorems on global properties of solutions to the Einstein-Vlasov system. This system couples Einsteins equations to a kinetic matter model. Kinetic theory has been an important field of research during several decades in which the main focus has been on nonrelativistic and special relativistic physics, i.e. to model the dynamics of neutral gases, plasmas, and Newtonian self-gravitating systems. In 1990, Rendall and Rein initiated a mathematical study of the Einstein-Vlasov system. Since then many theorems on global properties of solutions to this system have been established. The Vlasov equation describes matter phenomenologically, and it should be stressed that most of the theorems presented in this article are not presently known for other such matter models (i.e. fluid models. This paper gives introductions to kinetic theory in non-curved spacetimes and then the Einstein-Vlasov system is introduced. We believe that a good understanding of kinetic theory in non-curved spacetimes is fundamental to good comprehension of kinetic theory in general relativity.
On global solutions for the Vlasov-Poisson system
Directory of Open Access Journals (Sweden)
Peter E. Zhidkov
2004-04-01
Full Text Available In this article we show that the Vlasov-Poisson system has a unique weak solution in the space $L_1cap L_infty$. For this purpose, we use the method of characteristics, unlike the approach in [12].
Yang-Mills-Vlasov system in the temporal gauge. Systeme de Yang-Mills-Vlasov en jauge temporelle
Energy Technology Data Exchange (ETDEWEB)
Choquet-Bruhat, Y.; Noutchegueme, N. (Paris-6 Univ., 75 (FR))
1991-01-01
We prove a local in time existence theorem of a solution of the Cauchy problem for the Yang-Mills-Vlasov integrodifferential system. Such equations govern the evolution of plasmas, for instance of quarks and gluons (quagmas), where non abelian gauge fields and Yang-Mills charges replace the usual electromagnetic field and electric charge. We work with the temporal gauge and use functional spaces with appropriate weight on the momenta, but no fall off is required in the space direction.
Trapping scaling for bifurcations in the Vlasov systems.
Barré, J; Métivier, D; Yamaguchi, Y Y
2016-04-01
We study nonoscillating bifurcations of nonhomogeneous steady states of the Vlasov equation, a situation occurring in galactic models, or for Bernstein-Greene-Kruskal modes in plasma physics. Through an unstable manifold expansion, we show that in one spatial dimension the dynamics is very sensitive to the initial perturbation: the instability may saturate at small amplitude-generalizing the "trapping scaling" of plasma physics-or may grow to produce a large-scale modification of the system. Furthermore, resonances are strongly suppressed, leading to different phenomena with respect to the homogeneous case. These analytical findings are illustrated and extended by direct numerical simulations with a cosine interaction potential.
Trapping scaling for bifurcations in the Vlasov systems
Barré, J.; Métivier, D.; Yamaguchi, Y. Y.
2016-04-01
We study nonoscillating bifurcations of nonhomogeneous steady states of the Vlasov equation, a situation occurring in galactic models, or for Bernstein-Greene-Kruskal modes in plasma physics. Through an unstable manifold expansion, we show that in one spatial dimension the dynamics is very sensitive to the initial perturbation: the instability may saturate at small amplitude—generalizing the "trapping scaling" of plasma physics—or may grow to produce a large-scale modification of the system. Furthermore, resonances are strongly suppressed, leading to different phenomena with respect to the homogeneous case. These analytical findings are illustrated and extended by direct numerical simulations with a cosine interaction potential.
Computer controlled antenna system
Raumann, N. A.
1972-01-01
The application of small computers using digital techniques for operating the servo and control system of large antennas is discussed. The advantages of the system are described. The techniques were evaluated with a forty foot antenna and the Sigma V computer. Programs have been completed which drive the antenna directly without the need for a servo amplifier, antenna position programmer or a scan generator.
On axisymmetric and stationary solutions of the self-gravitating Vlasov system
Ames, Ellery; Andréasson, Håkan; Logg, Anders
2016-08-01
Axisymmetric and stationary solutions are constructed to the Einstein-Vlasov and Vlasov-Poisson systems. These solutions are constructed numerically, using finite element methods and a fixed-point iteration in which the total mass is fixed at each step. A variety of axisymmetric stationary solutions are exhibited, including solutions with toroidal, disk-like, spindle-like, and composite spatial density configurations, as are solutions with non-vanishing net angular momentum. In the case of toroidal solutions, we show for the first time, solutions of the Einstein-Vlasov system which contain ergoregions.
On Axisymmetric and Stationary Solutions of the Self-Gravitating Vlasov System
Ames, Ellery; Logg, Anders
2016-01-01
Axisymmetric and stationary solutions are constructed to the Einstein--Vlasov and Vlasov--Poisson systems. These solutions are constructed numerically, using finite element methods and a fixed-point iteration in which the total mass is fixed at each step. A variety of axisymmetric stationary solutions are exhibited, including solutions with toroidal, disk-like, spindle-like, and composite spatial density configurations, as are solutions with non-vanishing net angular momentum. In the case of toroidal solutions, we show for the first time, solutions of the Einstein--Vlasov system which contain ergoregions.
Noundjeu, P
2003-01-01
Using the iterative Scheme we prove the local existence and uniqueness of solutions of the spherically symmetric Einstein-Vlasov-Maxwell system with small initial data. We prove a continuation criterion to global in-time solutions.
MASTER TELEVISION ANTENNA SYSTEM.
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)
Linear stability of stationary solutions of the Vlasov-Poisson system in three dimensions
Energy Technology Data Exchange (ETDEWEB)
Batt, J.; Rein, G. (Muenchen Univ. (Germany). Mathematisches Inst.); Morrison, P.J. (Texas Univ., Austin, TX (United States))
1993-03-01
Rigorous results on the stability of stationary solutions of the Vlasov-Poisson system are obtained in both the plasma physics and stellar dynamics contexts. It is proven that stationary solutions in the plasma physics (stellar dynamics) case are linearly stable if they are decreasing (increasing) functions of the local, i.e. particle, energy. The main tool in the analysis is the free energy of the system, a conserved quantity. In addition, an appropriate global existence result is proven for the linearized Vlasov-Poisson system and the existence of stationary solutions that satisfy the above stability condition is established.
On global classical solutions of the three dimensional relativistic Vlasov-Darwin system
Li, Xiuting; Zhang, Xianwen
2016-08-01
We study the Cauchy problem of the relativistic Vlasov-Darwin system with generalized variables proposed by Sospedra-Alfonso et al. ["Global classical solutions of the relativistic Vlasov-Darwin system with small Cauchy data: the generalized variables approach," Arch. Ration. Mech. Anal. 205, 827-869 (2012)]. We prove global existence of a non-negative classical solution to the Cauchy problem in three space variables under small perturbation of the initial datum, and as a consequence, we obtain that nearly spherically symmetric solutions with required regularity exist globally in time.
Cosmology and gravitational waves in the Nordstrom-Vlasov system, a laboratory for Dark Energy
Corda, Christian
2013-01-01
We discuss a cosmological solution of the system which was originally introduced by Calogero and is today popularly known as "Nordstrom-Vlasov system". Although the model is un-physical, its cosmological solution results interesting for the same reasons for which the Nordstrom-Vlasov system was originally introduced in the framework of galactic dynamics. In fact, it represents a theoretical laboratory where one can rigorously study some problems, like the importance of the gravitational waves in the dynamics, which at the present time are not well understood within the physical model of the Einstein-Vlasov system. As the cosmology of the Nordstrom-Vlasov system is founded on a scalar field, a better understanding of the system is important also in the framework of the Dark Energy problem. In fact, various attempts to achieve Dark Energy by using scalar fields are present in the literature. In the solution an analytical expression for the time dependence of the cosmological evolution of the Nordstrom's scalar ...
Convergence of the Vlasov-Poisson-Fokker- Planck system to the incompressible Euler equations
Institute of Scientific and Technical Information of China (English)
无
2006-01-01
We establish the convergence of the Vlasov-Poisson-Fokker-Planck system to the incompressible Euler equations in this paper. The convergence is rigorously proved on the time interval where the smooth solution to the incompressible Euler equations exists. The proof relies on the compactness argument and the so-called relative-entropy method.
The Cauchy Problem for the 3-D Vlasov-Poisson System with Point Charges
Marchioro, Carlo; Miot, Evelyne; Pulvirenti, Mario
2011-07-01
In this paper we establish global existence and uniqueness of the solution to the three-dimensional Vlasov-Poisson system in the presence of point charges with repulsive interaction. The present analysis extends an analogous two-dimensional result (Caprino and Marchioro in Kinet. Relat. Models 3(2):241-254, 2010).
The Cauchy problem for the 3-D Vlasov-Poisson system with point charges
Marchioro, Carlo; Pulvirenti, Mario
2010-01-01
In this paper we establish global existence and uniqueness of the solution to the three-dimensional Vlasov-Poisson system in presence of point charges in case of repulsive interaction. The present analysis extends an analogeous two-dimensional result by Caprino and Marchioro [On the plasma-charge model, to appear in Kinetic and Related Models (2010)].
On the energy conservation by weak solutions of the relativistic Vlasov-Maxwell system
Sospedra-Alfonso, Reinel
2010-01-01
We show that weak solutions of the relativistic Vlasov-Maxwell system preserve the total energy provided that the electromagnetic field is locally of bounded variation and, for any $\\lambda$> 0, the one-particle distribution function has a square integrable $\\lambda$-moment in the momentum variable.
Resolution of the Vlasov-Maxwell system by PIC discontinuous Galerkin method on GPU with OpenCL
Directory of Open Access Journals (Sweden)
Crestetto Anaïs
2013-01-01
Full Text Available We present an implementation of a Vlasov-Maxwell solver for multicore processors. The Vlasov equation describes the evolution of charged particles in an electromagnetic field, solution of the Maxwell equations. The Vlasov equation is solved by a Particle-In-Cell method (PIC, while the Maxwell system is computed by a Discontinuous Galerkin method. We use the OpenCL framework, which allows our code to run on multicore processors or recent Graphic Processing Units (GPU. We present several numerical applications to two-dimensional test cases.
On classical solutions of the relativistic Vlasov-Klein-Gordon system
Directory of Open Access Journals (Sweden)
Michael Kunzinger
2005-01-01
Full Text Available We consider a collisionless ensemble of classical particles coupled with a Klein-Gordon field. For the resulting nonlinear system of partial differential equations, the relativistic Vlasov-Klein-Gordon system, we prove local-in-time existence of classical solutions and a continuation criterion which says that a solution can blow up only if the particle momenta become large. We also show that classical solutions are global in time in the one-dimensional case.
Veiled singularities for the spherically symmetric massless Einstein-Vlasov system
Rendall, Alan D
2016-01-01
This paper continues the investigation of the formation of naked singularities in the collapse of collisionless matter initiated in [RV]. There the existence of certain classes of non-smooth solutions of the Einstein-Vlasov system was proved. Those solutions are self-similar and hence not asymptotically flat. To obtain solutions which are more physically relevant it makes sense to attempt to cut off these solutions in a suitable way so as to make them asymptotically flat. This task, which turns out to be technically challenging, will be carried out in this paper. [RV] A. D. Rendall and J. J. L. Vel\\'{a}zquez, A class of dust-like self-similar solutions of the massless Einstein-Vlasov system. Annales Henri Poincare 12, 919-964, (2011).
The Goursat Problem for the Einstein-Vlasov System: (I) The Initial Data Constraints
Calvin, Tadmon
2011-01-01
We show how to assign, on two intersecting null hypersurfaces, initial data for the Einstein-Vlasov system in harmonic coordinates. As all the components of the metric appear in each component of the stress-energy tensor, the hierarchical method of Rendall can not apply strictly speaking. To overcome this difficulty, an additional assumption have been imposed to the metric on the initial hypersurfaces. Consequently, the distribution function is constrained to satisfy some integral equations on the initial hypersurfaces.
One-species Vlasov-Poisson-Landau system for soft potentials in ℝ3
He, Cong; Lei, Yuanjie
2016-12-01
We consider the global classical solution near a global Maxwellian to the one-species Vlasov-Poisson-Landau system in the whole space Rx 3 . It is shown that our global solvability result is obtained under the weaker smallness condition on the initial perturbation than that of Duan et al., [preprint arXiv:1112.3261 (2011)] and Lei et al., [Kinet. Relat. Models 7(3), 551-590 (2014)].
A distributed array antenna system
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.
Reduced Vlasov-Maxwell simulations
Helluy, Philippe; Navoret, Laurent; Pham, Nhung; Crestetto, Anaïs
2014-10-01
In this paper we review two different numerical methods for Vlasov-Maxwell simulations. The first method is based on a coupling between a Discontinuous Galerkin (DG) Maxwell solver and a Particle-In-Cell (PIC) Vlasov solver. The second method only uses a DG approach for the Vlasov and Maxwell equations. The Vlasov equation is first reduced to a space-only hyperbolic system thanks to the finite-element method. The two numerical methods are implemented using OpenCL in order to achieve high performance on recent Graphic Processing Units (GPU).
Goursat problem for the Yang-Mills-Vlasov system in temporal gauge
Directory of Open Access Journals (Sweden)
Marcel Dossa
2011-12-01
Full Text Available This article studies the characteristic Cauchy problem for the Yang-Mills-Vlasov (YMV system in temporal gauge, where the initial data are specified on two intersecting smooth characteristic hypersurfaces of Minkowski spacetime $(mathbb{R}^{4},eta $. Under a $mathcal{C}^{infty }$ hypothesis on the data, we solve the initial constraint problem and the evolution problem. Local in time existence and uniqueness results are established thanks to a suitable combination of the method of characteristics, Leray's Theory of hyperbolic systems and techniques developed by Choquet-Bruhat for ordinary spatial Cauchy problems related to (YMV systems.
Explicit Solutions of the One-dimensional Vlasov-Poisson System with Infinite Mass and Energy
Pankavich, Stephen
2010-01-01
A collisionless plasma is modeled by the Vlasov-Poisson system in one-dimension. A fixed background of positive charge, dependent only upon velocity, is assumed and the situation in which the mobile negative ions balance the positive charge as x tends to positive or negative infinity. Thus, the total positive charge and the total negative charge are infinite. In this paper, the charge density of the system is shown to be compactly supported. More importantly, both the electric field and the number density are determined explicitly for large values of x.
Local null-controllability of the 2-D Vlasov-Navier-Stokes system
Moyano, Iván
2016-01-01
We prove a null controllability result for the Vlasov-Navier-Stokes system, which describes the interaction of a large cloud of particles immersed in a fluid. We show that one can modify both the distribution of particles and the velocity field of the fluid from any initial state to the zero steady state, by means of an internal control. Indeed, we can modify the non-linear dynamics of the system in order to absorb the particles and let the fluid at rest. The proof is achieved thanks to the r...
Quasineutral limit of the Vlasov-Poisson system with massless electrons
Han-Kwan, Daniel
2010-01-01
In this paper, we study the quasineutral limit (in other words the limit when the Debye length tends to zero) of Vlasov-Poisson like equations describing the behaviour of ions in a plasma. We consider massless electrons, with a charge density following a Maxwell-Boltzmann law. For cold ions, using the relative entropy method, we derive the classical Isothermal Euler or the (inviscid) Shallow Water systems from fluid mechanics. In a second time, we study the combined quasineutral and strong magnetic field regime for such plasmas.
47 CFR 80.863 - Antenna system.
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...
Nungesser, Ernesto
2014-01-01
We show future global non-linear stability of surface symmetric solutions of the Einstein-Vlasov system with a positive cosmological constant. Estimates of higher derivatives of the metric and the matter terms are obtained using an inductive argument. In a recent research monograph Ringstr\\"{o}m shows future non-linear stability of (not necessarily symmetric) solutions of the Einstein-Vlasov system with a non-linear scalar field if certain local estimates on the geometry and the matter terms are fulfilled. We show that these assumptions are satisfied at late times for the case under consideration here which together with Cauchy stability leads to our main conclusion.
Qin, Hong
2016-10-01
Littlejohn's introduction of the non-canonical symplectic structure for the gyrocenter dynamics revolutionized plasma kinetic theory. The discovery of the non-canonical symplectic algorithm for gyrocenters initiated the search for symplectic algorithms for the gyrokinetic system. This effort is enforced by the recent discovery of canonical and non-canonical symplectic algorithms for the Vlasov-Maxwell (VM) system. However, symplectic algorithms for the gyrokinetic system remain elusive despite intense effort. In retrospect, the success of the symplectic algorithms for the VM system can be attributed to its global canonicalizability. Darboux's theorem ensures that any symplectic structure is locally canonicalizable, but not necessarily globally. Indeed, Littlejohn's gyrocenter is not globally canonicalizable. In this talk, I will show to construct a different gyrocenter that is globally canonicalizable. It should be a good starting point for developing symplectic algorithms for the gyrokinetic system. Research supported by the U.S. Department of Energy (DE-AC02-09CH11466).
Small Antennas for Wireless Micro-Systems
Rainer Wansch
2002-01-01
This paper will describe the topology of wireless micro-systems networks and some of their key components. In particular we will deal with the antennas: loops, helices, F-antennas, patches and dielectrically loaded antennas.
Asymptotic-preserving Particle-In-Cell methods for the Vlasov-Maxwell system near quasi-neutrality
Degond, Pierre; Doyen, David
2015-01-01
In this article, we design Asymptotic-Preserving Particle-In-Cell methods for the Vlasov-Maxwell system in the quasi-neutral limit, this limit being characterized by a Debye length negligible compared to the space scale of the problem. These methods are consistent discretizations of the Vlasov-Maxwell system which, in the quasi-neutral limit, remain stable and are consistent with a quasi-neutral model (in this quasi-neutral model, the electric field is computed by means of a generalized Ohm law). The derivation of Asymptotic-Preserving methods is not straightforward since the quasi-neutral model is a singular limit of the Vlasov-Maxwell model. The key step is a reformulation of the Vlasov-Maxwell system which unifies the two models in a single set of equations with a smooth transition from one to another. As demonstrated in various and demanding numerical simulations, the Asymptotic-Preserving methods are able to treat efficiently both quasi-neutral plasmas and non-neutral plasmas, making them particularly we...
Degond, P.; Deluzet, F.; Doyen, D.
2017-02-01
In this article, we design Asymptotic-Preserving Particle-In-Cell methods for the Vlasov-Maxwell system in the quasi-neutral limit, this limit being characterized by a Debye length negligible compared to the space scale of the problem. These methods are consistent discretizations of the Vlasov-Maxwell system which, in the quasi-neutral limit, remain stable and are consistent with a quasi-neutral model (in this quasi-neutral model, the electric field is computed by means of a generalized Ohm law). The derivation of Asymptotic-Preserving methods is not straightforward since the quasi-neutral model is a singular limit of the Vlasov-Maxwell model. The key step is a reformulation of the Vlasov-Maxwell system which unifies the two models in a single set of equations with a smooth transition from one to another. As demonstrated in various and demanding numerical simulations, the Asymptotic-Preserving methods are able to treat efficiently both quasi-neutral plasmas and non-neutral plasmas, making them particularly well suited for complex problems involving dense plasmas with localized non-neutral regions.
Measurement of mobile antenna systems
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
A Reduction of the Vlasov--Maxwell System Using Phase-Space Blobs
Shadwick, B. A.; Lee, Frank M.; Faeh, Luke
2011-10-01
We develop a new computational approach to solving the Vlasov-Maxwell equation by representing the distribution function by a supper-position of finite-extent phase- space ``blobs.'' Each blob evolves as a warm beamletdriven by the collective plasma fields. The underlying approximation treats each blob as a different plasma species and, as such, makes a counting error which we expect to be reflected in the system entropy. This approach results in a non-canonical Hamiltonian model, inheriting various properties of the original system. The primary advance of this technique over traditional Lagrangian particle methods is the near elimination of macro-particle ``noise.'' Since we are evolving elements of phase-space, the distribution function can be readily reconstructed at any instant. We discuss the performance and convergence of this model using a variety of standard examples. Supported by the U.S. DoE under Contract DE-FG02-08ER55000
Energy Technology Data Exchange (ETDEWEB)
Squire, J.; Tang, W. M. [Plasma Physics Laboratory, Princeton University, Princeton, New Jersey 08543 (United States); Qin, H. [Plasma Physics Laboratory, Princeton University, Princeton, New Jersey 08543 (United States); Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026 (China); Chandre, C. [Centre de Physique Theorique, CNRS - Aix-Marseille Universite, Campus de Luminy, Marseille 13009 (France)
2013-02-15
We present a new variational principle for the gyrokinetic system, similar to the Maxwell-Vlasov action presented in H. Cendra et al., [J. Math. Phys. 39, 3138 (1998)]. The variational principle is in the Eulerian frame and based on constrained variations of the phase space fluid velocity and particle distribution function. Using a Legendre transform, we explicitly derive the field theoretic Hamiltonian structure of the system. This is carried out with a modified Dirac theory of constraints, which is used to construct meaningful brackets from those obtained directly from Euler-Poincare theory. Possible applications of these formulations include continuum geometric integration techniques, large-eddy simulation models, and Casimir type stability methods.
Microelectromechanical Systems Actuator Based Reconfigurable Printed Antenna
Simons, Rainee N. (Inventor)
2005-01-01
A polarization reconfigurable patch antenna is disclosed. The antenna includes a feed element, a patch antenna element electrically connected to the feed element, and at least one microelectromechanical systems (MEMS) actuator, with a partial connection to the patch antenna element along an edge of the patch antenna element. The polarization of the antenna can be switched between circular polarization and linear polarization through action of the at least one MEMS actuator.
47 CFR 73.510 - Antenna systems.
2010-10-01
... 47 Telecommunication 4 2010-10-01 2010-10-01 false Antenna systems. 73.510 Section 73.510... Noncommercial Educational FM Broadcast Stations § 73.510 Antenna systems. (a) All noncommercial educational... § 73.316 concerning antenna systems contained in subpart B of this part. (b) Directional antenna. No...
Calogero, Simone
2016-01-01
The Einstein-Vlasov-Fokker-Planck system describes the kinetic diffusion dynamics of self-gravitating particles within the Einstein theory of general relativity. We study the Cauchy problem for spatially homogeneous and isotropic solutions and prove the existence of both global solutions and solutions that blow-up in finite time depending on the size of certain functions of the initial data. We also derive information on the large-time behavior of global solutions and toward the singularity for solutions which blow-up in fine time. Our results entail the existence of a phase of decelerated expansion followed by a phase of accelerated expansion, in accordance with the physical expectations in cosmology.
The Vlasov-Navier-Stokes system in a 2D pipe: existence and stability of regular equilibria
Glass, Olivier; Han-Kwan, Daniel; Moussa, Ayman
2016-01-01
In this paper, we study the Vlasov-Navier-Stokes system in a 2D pipe with partially absorbing boundary conditions. We show the existence of stationary states for this system near small Poiseuille flows for the fluid phase, for which the kinetic phase is not trivial. We prove the asymptotic stability of these states with respect to appropriately compactly supported perturbations. The analysis relies on geometric control conditions which help to avoid any concentration phenomenon for the kineti...
Wideband Antennas for Modern Radar Systems
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 ...
A class of dust-like self-similar solutions of the massless Einstein-Vlasov system
Rendall, Alan D
2010-01-01
In this paper the existence of a class of self-similar solutions of the Einstein-Vlasov system is proved. The initial data for these solutions are not smooth, with their particle density being supported in a submanifold of codimension one. They can be thought of as intermediate between smooth solutions of the Einstein-Vlasov system and dust. The motivation for studying them is to obtain insights into possible violation of weak cosmic censorship by solutions of the Einstein-Vlasov system. By assuming a suitable form of the unknowns it is shown that the existence question can be reduced to that of the existence of a certain type of solution of a four-dimensional system of ordinary differential equations depending on two parameters. This solution starts at a particular point $P_0$ and converges to a stationary solution $P_1$ as the independent variable tends to infinity. The existence proof is based on a shooting argument and involves relating the dynamics of solutions of the four-dimensional system to that of s...
Tchapnda, S B; Tchapnda, Sophonie Blaise; Noutchegueme, Norbert
2003-01-01
The Einstein-Vlasov system describes a self-gravitating, collisionless gas within the framework of general relativity. We investigate the initial value problem in a cosmological setting with surface symmetry and a non-zero cosmological constant and prove local existence and continuation criteria in both time directions. The continuation criterion says that as long as the maximum velocity remains bounded and the lapse function remains bounded then the solution can be continued. This applies to either time direction.
47 CFR 74.641 - Antenna systems.
2010-10-01
... 47 Telecommunication 4 2010-10-01 2010-10-01 false Antenna systems. 74.641 Section 74.641... Stations § 74.641 Antenna systems. (a) For fixed stations operating above 2025 MHz, the following standards... elevation planes. (2) New periscope antenna systems will be authorized upon a certification that the...
47 CFR 78.105 - Antenna systems.
2010-10-01
... 47 Telecommunication 4 2010-10-01 2010-10-01 false Antenna systems. 78.105 Section 78.105... SERVICE Technical Regulations § 78.105 Antenna systems. (a) For fixed stations operating in the 12.7-13.2... planes. (2) New periscope antenna systems will be authorized upon a certification that the radiation, in...
Multiple Antenna Systems with Inherently Decoupled Radiators
DEFF Research Database (Denmark)
Pelosi, Mauro; Knudsen, Mikael B.; Pedersen, Gert Frølund
2012-01-01
In multiple antenna systems mutual coupling needs to be minimized. We propose an alternative novel decoupling technique, investigating several multiple antenna configurations for small handsets through measurements and numerical simulations. The influence of different novel designs on performance...... metrics such as total loss, antenna isolation and envelope correlation coefficient are investigated. By varying antenna impedance bandwidth and antenna location with respect to the handset, both Planar Inverted F Antenna (PIFA) and Inverted F Antennas (IFA) were investigated in different UMTS frequency...... bands in proximity with the users body. Results show that antennas may experience very different losses and envelope correlation coefficients depending on their relative position with respect to the handset, as the influence of the users hand is not symmetrical in most cases. Narrow-band antennas...
47 CFR 80.923 - Antenna system.
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...
47 CFR 80.1017 - Antenna system.
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...
47 CFR 80.967 - Antenna system.
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...
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....
Optical antenna for photofunctional molecular systems.
Ikeda, Katsuyoshi; Uosaki, Kohei
2012-02-06
Optical antennas can enhance the efficiency of photon-molecule interactions. To design efficient antenna structures, it is essential to consider physicochemical aspects in addition to electromagnetic considerations. Specifically, chemical interactions between optical antennas and molecules have to be controlled to enhance the overall efficiency. For this purpose, sphere-plane nanostructures are suitable optical antennas for molecular-modified functional electrode systems when a well-defined electrode is utilized as a platform.
Improvement of antenna decoupling in radar systems
Anchidin, Liliana; Topor, Raluca; Tamas, Razvan D.; Dumitrascu, Ana; Danisor, Alin; Berescu, Serban
2015-02-01
In this paper we present a type of antipodal Vivaldi antenna design, which can be used for pulse radiation in UWB communication. The Vivaldi antenna is a special tapered slot antenna with planar structure which is easily to be integrated with transmitting elements and receiving elements to form a compact structure. When the permittivity is very large, the wavelength of slot mode is so short that the electromagnetic fields concentrate in the slot to form an effective and balanced transmission line. Due to its simple structure and small size the Vivaldi antennas are one of the most popular designs used in UWB applications. However, for a two-antenna radar system, there is a high mutual coupling between two such antennas due to open configuration. In this paper, we propose a new method for reducing this effect. The method was validated by simulating a system of two Vivaldi antennas in front of a standard target.
Geometric Integration Of The Vlasov-Maxwell System With A Variational Particle-in-cell Scheme
Energy Technology Data Exchange (ETDEWEB)
J. Squire, H. Qin and W.M. Tang
2012-03-27
A fully variational, unstructured, electromagnetic particle-in-cell integrator is developed for integration of the Vlasov-Maxwell equations. Using the formalism of Discrete Exterior Calculus [1], the field solver, interpolation scheme and particle advance algorithm are derived through minimization of a single discrete field theory action. As a consequence of ensuring that the action is invariant under discrete electromagnetic gauge transformations, the integrator exactly conserves Gauss's law.
Geometric integration of the Vlasov-Maxwell system with a variational particle-in-cell scheme
Energy Technology Data Exchange (ETDEWEB)
Squire, J.; Tang, W. M. [Plasma Physics Laboratory, Princeton University, Princeton, New Jersey 08543 (United States); Qin, H. [Plasma Physics Laboratory, Princeton University, Princeton, New Jersey 08543 (United States); Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026 (China)
2012-08-15
A fully variational, unstructured, electromagnetic particle-in-cell integrator is developed for integration of the Vlasov-Maxwell equations. Using the formalism of discrete exterior calculus [Desbrun et al., e-print arXiv:math/0508341 (2005)], the field solver, interpolation scheme, and particle advance algorithm are derived through minimization of a single discrete field theory action. As a consequence of ensuring that the action is invariant under discrete electromagnetic gauge transformations, the integrator exactly conserves Gauss's law.
Geometric integration of the Vlasov-Maxwell system with a variational particle-in-cell scheme
2014-01-01
A fully variational, unstructured, electromagnetic particle-in-cell integrator is developed for integration of the Vlasov-Maxwell equations. Using the formalism of Discrete Exterior Calculus, the field solver, interpolation scheme and particle advance algorithm are derived through minimization of a single discrete field theory action. As a consequence of ensuring that the action is invariant under discrete electromagnetic gauge transformations, the integrator exactly conserves Gauss's law.
China's Largest Radio Antenna System
Institute of Scientific and Technical Information of China (English)
无
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.
Handbook of smart antennas for RFID systems
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.
Planar antenna system for direction finding
Mardale, Iulia-Cezara; Cocias, Gabriela; Dumitrascu, Ana; Tamas, Razvan; Berescu, Serban
2015-02-01
Applications of direction finding techniques include detection and localization of pulsed electromagnetic sources. This paper presents the design and analysis of a planar antenna system for direction finding. Our proposed system includes 4 hybrid couplers that generate 900 shifted signals, 2 crossover couplers also known as 0dB couplers, two 450 phase shifters, two 00 phase shifters and 4 patch antennas.
Multiple Antennas Arm Effective MIMO Systems
DEFF Research Database (Denmark)
Thaysen, Jesper; Jakobsen, Kaj Bjarne
2007-01-01
Understanding the interactions among different combinations of receive and transmit antenna elements can help increase the capacity of cellular wireless systems.......Understanding the interactions among different combinations of receive and transmit antenna elements can help increase the capacity of cellular wireless systems....
47 CFR 73.753 - Antenna systems.
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...
Geometric integration of the Vlasov-Maxwell system with a variational particle-in-cell scheme
Squire, Jonathan; Qin, Hong; Tang, William
2012-10-01
A fully variational, unstructured, electromagnetic particle-in-cell integrator is developed for integration of the Vlasov-Maxwell equations. Using the formalism of Discrete Exterior Calculus [1], the field solver, interpolation scheme and particle advance algorithm are derived through minimization of a single discrete field theory action. As a consequence of ensuring that the action is invariant under discrete electromagnetic gauge transformations, the integrator exactly conserves Gauss's law. This work was supported by USDOE Contract DE-AC02-09CH11466.[4pt] [1] M. Desbrun, A. N. Hirani, M. Leok, and J. E. Marsden, (2005), arXiv:math/0508341
Antenna technology for advanced mobile communication systems
Rammos, Emmanuel; Roederer, Antoine; Rogard, Roger
1988-01-01
The onboard antenna front end is the key subsystem conditioning configuration and performance of mobile communication satellites. The objectives of this paper are to demonstrate this key role and to review L-band satellite antenna technology for earth coverage and regional applications. Multibeam arrays are first discussed, then unfurlable and inflatable reflector antennas are described. These technologies are now qualified in Europe for future mobile systems, for which the optimum choice of antenna technology has been found to be the key to efficient use of spectrum and power resources.
47 CFR 73.316 - FM antenna systems.
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...
Whip antenna design for portable rf systems
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.
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...
Scalable Notch Antenna System for Multiport Applications
Directory of Open Access Journals (Sweden)
Abdurrahim Toktas
2016-01-01
Full Text Available A novel and compact scalable antenna system is designed for multiport applications. The basic design is built on a square patch with an electrical size of 0.82λ0×0.82λ0 (at 2.4 GHz on a dielectric substrate. The design consists of four symmetrical and orthogonal triangular notches with circular feeding slots at the corners of the common patch. The 4-port antenna can be simply rearranged to 8-port and 12-port systems. The operating band of the system can be tuned by scaling (S the size of the system while fixing the thickness of the substrate. The antenna system with S: 1/1 in size of 103.5×103.5 mm2 operates at the frequency band of 2.3–3.0 GHz. By scaling the antenna with S: 1/2.3, a system of 45×45 mm2 is achieved, and thus the operating band is tuned to 4.7–6.1 GHz with the same scattering characteristic. A parametric study is also conducted to investigate the effects of changing the notch dimensions. The performance of the antenna is verified in terms of the antenna characteristics as well as diversity and multiplexing parameters. The antenna system can be tuned by scaling so that it is applicable to the multiport WLAN, WIMAX, and LTE devices with port upgradability.
A novel space-diversity antenna system
Cocias, Gabriela; Mardale, Iulia-Cezara; Dumitrascu, Ana; Tamas, Razvan D.; Berescu, Serban
2015-02-01
This paper presents the structure and analysis of a space diversity antenna system designed for indoor applications. The proposed antenna system consists of two meander monopole antennas with a 0.7 mm wide connection and a 85x35 mm ground plane, conceived and optimized to reduce the mutual coupling between the two radiating elements. We used a simplified deterministic model, based on geometric optics, consisting of two reflecting perpendicular walls, in order to assess the performance of our radiating system in a multipath environment.
Directive Antenna for Ultrawideband Medical Imaging Systems
Directory of Open Access Journals (Sweden)
Amin M. Abbosh
2008-01-01
Full Text Available A compact and directive ultrawideband antenna is presented in this paper. The antenna is in the form of an antipodal tapered slot with resistive layers to improve its directivity and to reduce its backward radiation. The antenna operates over the frequency band from 3.1 GHz to more than 10.6 GHz. It features a directive radiation with a peak gain which is between 4 dBi and 11 dBi in the specified band. The time domain performance of the antenna shows negligible distortion. This makes it suitable for the imaging systems which require a very short pulse for transmission/reception. The effect of the multilayer human body on the performance of the antenna is also studied. The breast model is used for this purpose. It is shown that the antenna has more than 90% fidelity factor when it works in free space, whereas the fidelity factor decreases as the signal propagates inside the human body. However, even inside the human body, the fidelity factor is still larger than 70% revealing the possibility of using the proposed antenna in biomedical imaging systems.
Slot Antenna for Wireless Temperature Measurement Systems
DEFF Research Database (Denmark)
Acar, Öncel; Jakobsen, Kaj Bjarne
2016-01-01
This paper presents a novel clover-slot antenna for a surface-acoustic-wave sensor based wireless temperature measurement system. The slot is described by a parametric locus curve that has the shape of a clover. The antenna is operated at high temperatures, in rough environments, and has a 43......% fractional bandwidth at the 2.4 GHz ISM-band. The slot antenna has been optimized for excitation by a passive chip soldered onto it. Measurement results are compared with simulation results and show good agreements....
Multiport antenna systems for space-time communications
DEFF Research Database (Denmark)
Tsakalaki, Elpiniki; Alrabadi, Osama; Pelosi, Mauro
2013-01-01
The paper presents the concept of multiport antenna systems where multiple active and passive ports are deployed. The passive ports, implemented via tunable reactance-assisted (parasitic) antennas, can alter the far-field and near-field properties of the antenna system expressed by the antenna ef...
Multiport antenna systems for space-time communications
DEFF Research Database (Denmark)
Tsakalaki, Elpiniki; Alrabadi, Osama; Pelosi, Mauro
2013-01-01
The paper presents the concept of multiport antenna systems where multiple active and passive ports are deployed. The passive ports, implemented via tunable reactance-assisted (parasitic) antennas, can alter the far-field and near-field properties of the antenna system expressed by the antenna ef...
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.
Explicit high-order non-canonical symplectic particle-in-cell algorithms for Vlasov-Maxwell systems
Xiao, Jianyuan; Liu, Jian; He, Yang; Zhang, Ruili; Sun, Yajuan
2015-01-01
Explicit high-order non-canonical symplectic particle-in-cell algorithms for classical particle-field systems governed by the Vlasov-Maxwell equations are developed. The algorithm conserves a discrete non-canonical symplectic structure derived from the Lagrangian of the particle-field system, which is naturally discrete in particles. The electromagnetic field is spatially-discretized using the method of discrete exterior calculus with high-order interpolating differential forms for a cubic grid. The resulting time-domain Lagrangian assumes a non-canonical symplectic structure. It is also gauge invariant and conserves charge. The system is then solved using a splitting method discovered by He et al., which produces five exactly-soluable sub-systems, and high-order structure- preserving algorithms follow by combinations. The explicit, high-order, and conservative nature of the algorithms is especially suitable for long-term simulations of particle-field systems with extremely large number of degrees of freedom ...
Explicit high-order non-canonical symplectic particle-in-cell algorithms for Vlasov-Maxwell systems
Energy Technology Data Exchange (ETDEWEB)
Xiao, Jianyuan [School of Nuclear Science and Technology and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026, China; Key Laboratory of Geospace Environment, CAS, Hefei, Anhui 230026, China; Qin, Hong [School of Nuclear Science and Technology and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026, China; Plasma Physics Laboratory, Princeton University, Princeton, New Jersey 08543, USA; Liu, Jian [School of Nuclear Science and Technology and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026, China; Key Laboratory of Geospace Environment, CAS, Hefei, Anhui 230026, China; He, Yang [School of Nuclear Science and Technology and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026, China; Key Laboratory of Geospace Environment, CAS, Hefei, Anhui 230026, China; Zhang, Ruili [School of Nuclear Science and Technology and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026, China; Key Laboratory of Geospace Environment, CAS, Hefei, Anhui 230026, China; Sun, Yajuan [LSEC, Academy of Mathematics and Systems Science, Chinese Academy of Sciences, P.O. Box 2719, Beijing 100190, China
2015-11-01
Explicit high-order non-canonical symplectic particle-in-cell algorithms for classical particle-field systems governed by the Vlasov-Maxwell equations are developed. The algorithms conserve a discrete non-canonical symplectic structure derived from the Lagrangian of the particle-field system, which is naturally discrete in particles. The electromagnetic field is spatially discretized using the method of discrete exterior calculus with high-order interpolating differential forms for a cubic grid. The resulting time-domain Lagrangian assumes a non-canonical symplectic structure. It is also gauge invariant and conserves charge. The system is then solved using a structure-preserving splitting method discovered by He et al. [preprint arXiv: 1505.06076 (2015)], which produces five exactly soluble sub-systems, and high-order structure-preserving algorithms follow by combinations. The explicit, high-order, and conservative nature of the algorithms is especially suitable for long-term simulations of particle-field systems with extremely large number of degrees of freedom on massively parallel supercomputers. The algorithms have been tested and verified by the two physics problems, i.e., the nonlinear Landau damping and the electron Bernstein wave. (C) 2015 AIP Publishing LLC.
Explicit high-order non-canonical symplectic particle-in-cell algorithms for Vlasov-Maxwell systems
Energy Technology Data Exchange (ETDEWEB)
Xiao, Jianyuan; Liu, Jian; He, Yang; Zhang, Ruili [School of Nuclear Science and Technology and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026 (China); Key Laboratory of Geospace Environment, CAS, Hefei, Anhui 230026 (China); Qin, Hong, E-mail: hongqin@ustc.edu.cn [School of Nuclear Science and Technology and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026 (China); Plasma Physics Laboratory, Princeton University, Princeton, New Jersey 08543 (United States); Sun, Yajuan [LSEC, Academy of Mathematics and Systems Science, Chinese Academy of Sciences, P.O. Box 2719, Beijing 100190 (China)
2015-11-15
Explicit high-order non-canonical symplectic particle-in-cell algorithms for classical particle-field systems governed by the Vlasov-Maxwell equations are developed. The algorithms conserve a discrete non-canonical symplectic structure derived from the Lagrangian of the particle-field system, which is naturally discrete in particles. The electromagnetic field is spatially discretized using the method of discrete exterior calculus with high-order interpolating differential forms for a cubic grid. The resulting time-domain Lagrangian assumes a non-canonical symplectic structure. It is also gauge invariant and conserves charge. The system is then solved using a structure-preserving splitting method discovered by He et al. [preprint http://arxiv.org/abs/arXiv:1505.06076 (2015)], which produces five exactly soluble sub-systems, and high-order structure-preserving algorithms follow by combinations. The explicit, high-order, and conservative nature of the algorithms is especially suitable for long-term simulations of particle-field systems with extremely large number of degrees of freedom on massively parallel supercomputers. The algorithms have been tested and verified by the two physics problems, i.e., the nonlinear Landau damping and the electron Bernstein wave.
Shuttle Millimeter Wave Communications Experiment (MWCE) antenna system development
1978-01-01
An antenna system requirements report is presented. Topics reported include: (1) antenna system specifications; (2) waveguide circuitry; (3) feed horn design; (4) dish reflectors; (5) gimbal systems; and (6) summary of system design.
AN ASYMPTOTIC PRESERVING SCHEME FOR THE VLASOV-POISSON-FOKKER-PLANCK SYSTEM IN THE HIGH FIELD REGIME
Institute of Scientific and Technical Information of China (English)
Shi Jin; Li Wang
2011-01-01
The Vlasov-Poisson-Fokker-Planck system under the high field scaling describes the Brownian motion of a large system of particles in a surrounding bath where both collision and field effects (electrical or gravitational) are dominant. Numerically solving this system becomes challenging due to the stiff collision term and stiff nonlinear transport term with respect to the high field.We present a class of Asymptotic-Preserving scheme which is efficient in the high field regime,namely,large time steps and coarse meshes can be used,yet the high field limit is still captured.The idea is to combine the two stiff terms and treat them implicitly.Thanks to the linearity of the collision term,using the discretization described in [Jin S,Yan B.J.Comp.Phys.,2011,230:6420-6437]we only need to invert a symmetric matrix.This method can be easily extended to higher dimensions.The method is shown to be positive,stable,mass and asymptotic preserving.Numerical experiments validate its efficiency in both kinetic and high field regimes including mixing regimes.
Improvement of Power Efficiency using Smart Antenna System in MANETs
Directory of Open Access Journals (Sweden)
Abhishek Kumar
2014-11-01
Full Text Available Performance of ad-hoc networks is low under omnidirectional antenna systems compared to smart antenna system. Directional antennas cover large area {&} save some amount of transmitted power because it focuses in desired direction accordance with mobility of nodes while Omni-directional antennas cover small area {&} needs large transmitted power as compared to Smart Antenna System (SAS. In this paper, we will overcome the problem of unnecessary transmitted power wastage with omnidirectional antenna system in ad-hoc wireless networks by using Smart Antenna Systems (SAS. We will calculate {&} analyze transmitted power variations with different number of mobile nodes in mobile ad-hoc networks [MANETs] with smart antenna system (SAS {&} Omni-directional antenna system in different conditions. Firstly, we will calculate {&} analyze transmitted power during flooding of packets means in case of route creation, and secondly, when communication will established between transmitter {&} receiver
Gundlach, Carsten
2016-01-01
We express the Einstein-Vlasov system in spherical symmetry in terms of a dimensionless momentum variable $z$ (radial over angular momentum). This regularises the limit of massless particles, and in that limit allows us to obtain a reduced system in independent variables $(t,r,z)$ only. Similarly, in this limit the Vlasov density function $f$ for static solutions depends on a single variable $Q$ (energy over angular momentum). This reduction allows us to show that any given static metric which has vanishing Ricci scalar, is vacuum at the centre and for $r>3M$ and obeys certain energy conditions uniquely determines a consistent $f=\\bar k(Q)$ (in closed form). Vice versa, any $\\bar k(Q)$ within a certain class uniquely determines a static metric (as the solution of a system of two first-order quasilinear ODEs). Hence the space of static spherically symmetric solutions of Einstein-Vlasov is locally a space of functions of one variable. For a simple 2-parameter family of functions $\\bar k(Q)$, we construct the co...
Alard, C
2004-01-01
We propose to integrate the Vlasov-Poisson equations giving the evolution of a dynamical system in phase-space using a continuous set of local basis functions. In practice, the method decomposes the density in phase-space into small smooth units having compact support. We call these small units ``clouds'' and choose them to be Gaussians of elliptical support. Fortunately, the evolution of these clouds in the local potential has an analytical solution, that can be used to evolve the whole system during a significant fraction of dynamical time. In the process, the clouds, initially round, change shape and get elongated. At some point, the system needs to be remapped on round clouds once again. This remapping can be performed optimally using a small number of Lucy iterations. The remapped solution can be evolved again with the cloud method, and the process can be iterated a large number of times without showing significant diffusion. Our numerical experiments show that it is possible to follow the 2 dimensional ...
Canonical derivation of the Vlasov-Coulomb noncanonical Poisson structure
Energy Technology Data Exchange (ETDEWEB)
Kaufman, A.N.; Dewar, R.L.
1983-09-01
Starting from a Lagrangian formulation of the Vlasov-Coulomb system, canonical methods are used to define a Poisson structure for this system. Successive changes of representation then lead systematically to the noncanonical Lie-Poisson structure for functionals of the Vlasov distribution.
Wireless communication system via nanoscale plasmonic antennas.
Merlo, Juan M; Nesbitt, Nathan T; Calm, Yitzi M; Rose, Aaron H; D'Imperio, Luke; Yang, Chaobin; Naughton, Jeffrey R; Burns, Michael J; Kempa, Krzysztof; Naughton, Michael J
2016-08-24
Present on-chip optical communication technology uses near-infrared light, but visible wavelengths would allow system miniaturization and higher energy confinement. Towards this end, we report a nanoscale wireless communication system that operates at visible wavelengths via in-plane information transmission. Here, plasmonic antenna radiation mediates a three-step conversion process (surface plasmon → photon → surface plasmon) with in-plane efficiency (plasmon → plasmon) of 38% for antenna separation 4λ0 (with λ0 the free-space excitation wavelength). Information transmission is demonstrated at bandwidths in the Hz and MHz ranges. This work opens the possibility of optical conveyance of information using plasmonic antennas for on-chip communication technology.
Wireless communication system via nanoscale plasmonic antennas
Merlo, Juan M.; Nesbitt, Nathan T.; Calm, Yitzi M.; Rose, Aaron H.; D'Imperio, Luke; Yang, Chaobin; Naughton, Jeffrey R.; Burns, Michael J.; Kempa, Krzysztof; Naughton, Michael J.
2016-08-01
Present on-chip optical communication technology uses near-infrared light, but visible wavelengths would allow system miniaturization and higher energy confinement. Towards this end, we report a nanoscale wireless communication system that operates at visible wavelengths via in-plane information transmission. Here, plasmonic antenna radiation mediates a three-step conversion process (surface plasmon → photon → surface plasmon) with in-plane efficiency (plasmon → plasmon) of 38% for antenna separation 4λ0 (with λ0 the free-space excitation wavelength). Information transmission is demonstrated at bandwidths in the Hz and MHz ranges. This work opens the possibility of optical conveyance of information using plasmonic antennas for on-chip communication technology.
Efficiency Improvement of Vehicular Antenna Systems for Ubiquitous Intelligent Systems
Directory of Open Access Journals (Sweden)
Kyubong Yeon
2014-11-01
Full Text Available This paper describes the design of a high-efficiency vehicular roof-mounted antenna for wireless access for vehicular environment (WAVE communication systems used for ubiquitous intelligent systems. The main objective of the ubiquitous intelligent system’s automotive IT technology is to enhance the connectivity among vehicles to ensure seamless communication and to reduce the initial access time using high-performance antenna systems. The efficiency of WAVE communication systems used for ubiquitous intelligent systems depends on the antenna efficiency. The proposed vehicular antenna for WAVE communication systems shows an improvement of approximately 4.77 dB in the return loss, as compared with a conventional antenna system.
Directory of Open Access Journals (Sweden)
R. Seller
2007-09-01
Full Text Available A novel radio channel compensation method aiming to give optimal calibration for microstrip antenna array systems is presented in this paper, realized for an actual DOA measurement antenna system using microstrip antennas to sample the electromagnetic field, operating at 4.5GHz. This new approach considers mismatch between antennas and channel RF ports, channel transmission inequalities, and also decreases the effects of multipath propagation components of calibration reference signals by placing the calibration reference signal feeding network on the microstrip antenna array bearer, directly beside the antenna patches. It is combined with orthogonal spread spectrum calibration signal utility for continuous uninterrupted measurements. The spread spectrum calibration signal is orthogonal to the continuous wave (CW signal to be measured, therefore, the 2 signals can be separated in the receiver, enabling them to be present simultaneously. DOA measurement results are shown, measured with the realized integrated microstrip patch antenna array with calibration network hardware.
47 CFR 73.68 - Sampling systems for antenna monitors.
2010-10-01
... 47 Telecommunication 4 2010-10-01 2010-10-01 false Sampling systems for antenna monitors. 73.68... RADIO BROADCAST SERVICES AM Broadcast Stations § 73.68 Sampling systems for antenna monitors. (a) Each AM station permittee authorized to construct a new directional antenna system which will be...
47 CFR 73.45 - AM antenna systems.
2010-10-01
... 47 Telecommunication 4 2010-10-01 2010-10-01 false AM antenna systems. 73.45 Section 73.45... Broadcast Stations § 73.45 AM antenna systems. (a) All applicants for new, additional, or different AM... existing station must specify an antenna system, the efficiency of which complies with the requirements...
Colombo, Maria
2017-01-01
The first part of the book is devoted to the transport equation for a given vector field, exploiting the lagrangian structure of solutions. It also treats the regularity of solutions of some degenerate elliptic equations, which appear in the eulerian counterpart of some transport models with congestion. The second part of the book deals with the lagrangian structure of solutions of the Vlasov-Poisson system, which describes the evolution of a system of particles under the self-induced gravitational/electrostatic field, and the existence of solutions of the semigeostrophic system, used in meteorology to describe the motion of large-scale oceanic/atmospheric flows.
47 CFR 73.685 - Transmitter location and antenna system.
2010-10-01
... 47 Telecommunication 4 2010-10-01 2010-10-01 false Transmitter location and antenna system. 73.685... RADIO BROADCAST SERVICES Television Broadcast Stations § 73.685 Transmitter location and antenna system... and antenna height above average terrain employed, the following minimum field strength in dB...
A Unified Mutual Coupling Model for Multiple Antenna Systems
Institute of Scientific and Technical Information of China (English)
WU Yu-jiang; NIE Zai-ping
2006-01-01
A unified mutual coupling model for multiple antenna communication systems based on moment methods is proposed. This model combines antenna coupling and RF front-end circuit coupling, thus providing a more accurate and complete analysis of the mutual coupling effect on multiple antenna systems.
47 CFR 74.1235 - Power limitations and antenna systems.
2010-10-01
... 47 Telecommunication 4 2010-10-01 2010-10-01 false Power limitations and antenna systems. 74.1235... Translator Stations and FM Broadcast Booster Stations § 74.1235 Power limitations and antenna systems. (a) An...) value determined in accordance with this paragraph. The antenna height above average terrain...
47 CFR 73.33 - Antenna systems; showing required.
2010-10-01
... 47 Telecommunication 4 2010-10-01 2010-10-01 false Antenna systems; showing required. 73.33... RADIO BROADCAST SERVICES AM Broadcast Stations § 73.33 Antenna systems; showing required. (a) An application for authority to install a broadcast antenna shall specify a definite site and include...
47 CFR 73.150 - Directional antenna systems.
2010-10-01
... 47 Telecommunication 4 2010-10-01 2010-10-01 false Directional antenna systems. 73.150 Section 73... BROADCAST SERVICES AM Broadcast Stations § 73.150 Directional antenna systems. (a) For each station employing a directional antenna, all determinations of service provided and interference caused shall...
47 CFR 80.876 - VHF radiotelephone antenna system.
2010-10-01
... 47 Telecommunication 5 2010-10-01 2010-10-01 false VHF radiotelephone antenna system. 80.876... to Subpart W § 80.876 VHF radiotelephone antenna system. A vertically polarized nondirectional antenna must be provided for VHF radiotelephone installations. The construction and installation of...
A Case Study on Distributed Antenna Systems
DEFF Research Database (Denmark)
Sørensen, Troels Bundgaard
2007-01-01
Passive distributed antenna systems (DASs) consisting of distributed feeder lines or single point antennas are now often installed in large office buildings where they provide efficient coverage throughout the building. More sophisticated DASs with intelligent reuse and the ability to adapt...... to changing interference and traffic conditions are less common, despite their potential for increased capacity in comparison with traditional (pico)cellular based concepts. This chapter explores a case study of one indoor environment where the site-specific propagation characteristics are taken into account...... is described in terms of algorithms for power allocation and access port assignment, as well as algorithms for (dynamic) channel assignment. After an outline of simulation assumptions, system capacity comparisons are given between the adaptive DAS and a system with fixed channel and access port assignment...
Gundlach, Carsten
2016-12-01
We express the Einstein-Vlasov system in spherical symmetry in terms of a dimensionless momentum variable z (radial over angular momentum). This regularizes the limit of massless particles, and in that limit allows us to obtain a reduced system in independent variables (t ,r ,z ) only. Similarly, in this limit the Vlasov density function f for static solutions depends on a single variable Q (energy over angular momentum). This reduction allows us to show that any given static metric that has vanishing Ricci scalar, is vacuum at the center and for r >3 M and obeys certain energy conditions uniquely determines a consistent f =k ¯(Q ) (in closed form). Vice versa, any k ¯(Q ) within a certain class uniquely determines a static metric (as the solution of a system of two first-order quasilinear ordinary differential equations). Hence the space of static spherically symmetric solutions of the Einstein-Vlasov system is locally a space of functions of one variable. For a simple two-parameter family of functions k ¯(Q ), we construct the corresponding static spherically symmetric solutions, finding that their compactness is in the interval 0.7 ≲maxr(2 M /r )≤8 /9 . This class of static solutions includes one that agrees with the approximately universal type-I critical solution recently found by Akbarian and Choptuik (AC) in numerical time evolutions. We speculate on what singles it out as the critical solution found by fine-tuning generic data to the collapse threshold, given that AC also found that all static solutions are one-parameter unstable and sit on the threshold of collapse.
Computer program aids dual reflector antenna system design
Firnett, P.; Gerritsen, R.; Jarvie, P.; Ludwig, A.
1968-01-01
Computer program aids in the design of maximum efficiency dual reflector antenna systems. It designs a shaped cassegrainian antenna which has nearly 100 percent efficiency, and accepts input parameters specifying an existing conventional antenna and produces as output the modifications necessary to conform to a shaped design.
Full-duplex MIMO system based on antenna cancellation technique
DEFF Research Database (Denmark)
Foroozanfard, Ehsan; Franek, Ondrej; Tatomirescu, Alexandru
2014-01-01
The performance of an antenna cancellation technique for a multiple-input– multiple-output (MIMO) full-duplex system that is based on null-steering beamforming and antenna polarization diversity is investigated. A practical implementation of a symmetric antenna topology comprising three dual-pola...
Phased Antenna Array for Global Navigation Satellite System Signals
Turbiner, Dmitry (Inventor)
2015-01-01
Systems and methods for phased array antennas are described. Supports for phased array antennas can be constructed by 3D printing. The array elements and combiner network can be constructed by conducting wire. Different parameters of the antenna, like the gain and directivity, can be controlled by selection of the appropriate design, and by electrical steering. Phased array antennas may be used for radio occultation measurements.
1972-01-01
The development of a facsimile camera to serve as the antenna aspect system for the second generation Radio Astronomy Explorer Satellite designated RAE-B is summarized. The camera system consists of two cameras and a data encoder. The program deliverables were two flight cameras, a flight encoder and one spare flight encoder. The RAE-B satellite was originally intended for an earth orbit mission and the facsimile subsystem characteristics were specified with this in mind. Subsequently the flight mission was changed to orbit the moon; however the change occurred too late to significantly influence the facsimile system design. Therefore, this report considers only compliance of the system to earth orbit requirements.
A Review of Antennas for Indoor Positioning Systems
Directory of Open Access Journals (Sweden)
Luis Brás
2012-01-01
Full Text Available This paper provides a review of antennas applied for indoor positioning or localization systems. The desired requirements of those antennas when integrated in anchor nodes (reference nodes are discussed, according to different localization techniques and their performance. The described antennas will be subdivided into the following sections according to the nature of measurements: received signal strength (RSS, time of flight (ToF, and direction of arrival (DoA. This paper intends to provide a useful guide for antenna designers who are interested in developing suitable antennas for indoor localization systems.
Vlasov-Poisson in 1D for initially cold systems: post-collapse Lagrangian perturbation theory
Colombi, Stephane
2014-01-01
We study analytically the collapse of an initially smooth, cold, self-gravitating collisionless system in one dimension. The system is described as a central "S" shape in phase-space surrounded by a nearly stationary halo acting locally like a harmonic background on the S. To resolve the dynamics of the S under its self-gravity and under the influence of the halo, we introduce a novel approach using post-collapse Lagrangian perturbation theory. This approach allows us to follow the evolution of the system between successive crossing times and to describe in an iterative way the interplay between the central S and the halo. Our theoretical predictions are checked against measurements in entropy conserving numerical simulations based on the waterbag method. While our post-collapse Lagrangian approach does not allow us to compute rigorously the long term behavior of the system, i.e. after many crossing times, it explains the close to power-law behavior of the projected density observed in numerical simulations. ...
Conformal, Transparent Printed Antenna Developed for Communication and Navigation Systems
Lee, Richard Q.; Simons, Rainee N.
1999-01-01
Conformal, transparent printed antennas have advantages over conventional antennas in terms of space reuse and aesthetics. Because of their compactness and thin profile, these antennas can be mounted on video displays for efficient integration in communication systems such as palmtop computers, digital telephones, and flat-panel television displays. As an array of multiple elements, the antenna subsystem may save weight by reusing space (via vertical stacking) on photovoltaic arrays or on Earth-facing sensors. Also, the antenna could go unnoticed on automobile windshields or building windows, enabling satellite uplinks and downlinks or other emerging high-frequency communications.
Nonlinear evolution of parallel propagating Alfven waves: Vlasov - MHD simulation
Nariyuki, Y; Kumashiro, T; Hada, T
2009-01-01
Nonlinear evolution of circularly polarized Alfv\\'en waves are discussed by using the recently developed Vlasov-MHD code, which is a generalized Landau-fluid model. The numerical results indicate that as far as the nonlinearity in the system is not so large, the Vlasov-MHD model can validly solve time evolution of the Alfv\\'enic turbulence both in the linear and nonlinear stages. The present Vlasov-MHD model is proper to discuss the solar coronal heating and solar wind acceleration by Alfve\\'n waves propagating from the photosphere.
Combined ICR heating antenna for ion separation systems
Energy Technology Data Exchange (ETDEWEB)
Timofeev, A. V. [Russian Research Centre Kurchatov Institute (Russian Federation)
2011-01-15
A combination of one- and two-wave antennas (one and two turns of conductors around a plasma cylinder, respectively) is proposed. This combined antenna localizes an RF field within itself. It is shown that spent nuclear fuel processing systems based on ICR heating of nuclear ash by such a combined antenna have high productivity. A theory of the RF field excitation in ICR ion separation systems is presented in a simple and compact form.
Effects of Spatial Characteristics on Smart Antenna System with Uniform Linear Antenna Array
Institute of Scientific and Technical Information of China (English)
CAO Wei-feng; WANG Wen-bo
2005-01-01
The effect of the spatial characteristics of antenna array on smart antenna systems can not be neglected. In the paper, the relation between spatial correlation and inter-antenna distance, impinging angle, angle spread is first investigated. With the same beamforming algorithm, we simulate the performance of smart antenna system with different Angle Spread (AS) values on the conditions of ideal and real Angle of Arrival (AOA) estimation. The results show that with the ideal AOA estimation, the AOA is enough accurate to guarantee that the system only has little performance degradation even in the case of 20 degreee AS value while the real AOA estimation influenced by channel environment degrades the performance very obviously, up to about 7 dB.
Multiple-Active Multiple-Passive Antenna Systems and Applications
DEFF Research Database (Denmark)
Tsakalaki, Elpiniki
2013-01-01
-passive (MAMP) antenna topologies, as explained in Sect. 8.1. Then, Sect. 8.2 proposes MAMP antenna structures with application to reconfigurable MIMO transmission in the presence of antenna mutual coupling under poor scattering channel conditions. For this purpose, the section presents an adaptive MAMP antenna......This chapter focuses on extensions and foreseen applications of the parasitic antenna array technology. Moving beyond the single-active (single-RF) communication setup, hitherto discussed in the previous chapters, the work in this chapter extends the analysis to generalized multiple-active multiple...... adaptive MAMP system can be limited to practical dimensions whereas the passive antennas require no extra RF hardware, thus meeting the cost, space, and power constrains of the users’ mobile terminals. The simulation results show that the adaptive MAMP system, thanks to its “adaptivity”, is able to achieve...
A Modified E Shaped Patch Antenna For Mimo Systems
Directory of Open Access Journals (Sweden)
K. Jagadeesh Babu
2010-10-01
Full Text Available A compact E shaped patch antenna is proposed in the present work, which can be used for Multiple Input Multiple output (MIMO systems. The modified E shaped patch antenna proposed in this paper offers improved directivity, bandwidth, and return loss characteristics compared to normal E shaped antenna. The antenna system resonates at 5.36GHz and 5.89GHz frequencies for VSWR≤2 which can be used for WiMAX (Wireless interoperability for microwave access applications. The simulation results of return loss, VSWR, gain and radiation pattern are presented.
Innovative Techniques for Antenna Synthesis in Modern Wireless Communication Systems
Leonardo, Lizzi
2011-01-01
This thesis deals with the study and development of innovative techniques for the synthesis of antennas able to fulfill the tight requirements of modern wireless communication systems. By exploiting the advantages given by the use of geometries based on spline and fractal shapes, the aim of the proposed synthesis techniques is the design of small Ultra-Wideband (UWB) and multi-band antennas. The synthesis of UWB antennas is carried out by means of two different approaches which consider the a...
Direction finding antenna system for spark detection and localization
Topor, Raluca E.; Bucuci, Stefania C.; Tamas, Razvan D.; Danisor, Alin; Dumitrascu, Ana; Berescu, Serban
2015-02-01
This paper proposes a novel UWB antenna system for spark detection and localization by using the amplitude comparison direction finding (DF) method. The proposed design consists of two identical axially crossed "padlock" shaped UWB antennas, with unbalanced feeding. Simulation results show that such radiating systems can be used for assessing the direction of arrival for short pulses.
Antenna-in-package system integrated with meander line antenna based on LTCC technology
Institute of Scientific and Technical Information of China (English)
Gang DONG; Wei XIONG; Zhao-yao WU; Yin-tang YANG
2016-01-01
We present an antenna-in-package system integrated with a meander line antenna based on low temperature co-fi red ceramic (LTCC) technology. The proposed system employs a meander line patch antenna, a packaging layer, and a laminated multi-chip module (MCM) for integration of integrated circuit (IC) bare chips. A microstrip feed line is used to reduce the interaction between patch and package. To decrease electromagnetic coupling, a via hole structure is designed and analyzed. The meander line antenna achieved a bandwidth of 220 MHz with the center frequency at 2.4 GHz, a maximum gain of 2.2 dB, and a radiation eﬃciency about 90% over its operational frequency. The whole system, with a small size of 20.2 mm×6.1 mm×2.6 mm, can be easily realized by a standard LTCC process. This antenna-in-package system integrated with a meander line antenna was fabricated and the experimental results agreed with simulations well.
Antenna-in-package system integrated with meander line antenna based on LTCC technology
Institute of Scientific and Technical Information of China (English)
Gang DONG; Wei XIONG; Zhao-yao WU; Yin-tang YANG
2016-01-01
We present an antenna-in-package system integrated with a meander line antenna based on low temperature co-fired ceramic （LTCC） technology. The proposed system employs a meander line patch antenna, a packaging layer, and a laminated multi-chip module （MCM） for integration of integrated circuit （IC） bare chips. A microstrip feed line is used to reduce the interaction between patch and package. To decrease electromagnetic coupling, a via hole structure is designed and analyzed. The meander line antenna achieved a bandwidth of 220 MHz with the center frequency at 2.4 GHz, a maximum gain of 2.2 dB, and a radiation efficiency about 90% over its operational frequency. The whole system, with a small size of 20.2 minx6.1 mmx2.6 mm, can be easily realized by a standard LTCC process. This antenna-in-package system integrated with a meander line antenna was fabricated and the experimental results agreed with simulations well.
Location tracking system using wearable on-body GPS antenna
Directory of Open Access Journals (Sweden)
Sabapathy Thennarasan
2017-01-01
Full Text Available An on-body location tracking system is developed and integrated with a wearable GPS antenna. Such system is beneficial in human location tracking of patients and elderly within a radius of 1 km. The system consists of a wearable antenna, a GPS module, a low cost microcontroller, two RF modules and a local monitoring system. A user equipped with the GPS antenna, GPS module and a RF transmitter is able send his/her location to the local monitoring system via a RF receiver. The proposed wearable antenna is validated to be safe for human use in terms of specific absorption rate (SAR. This antenna was then incorporated into the complete prototype and tested. Several suggestions for future improvements are also proposed and discussed.
System overview on electromagnetic compensation for reflector antenna surface distortion
Acosta, R. J.; Zaman, A. J.; Terry, J. D.
1993-01-01
The system requirements and hardware implementation for electromagnetic compensation of antenna performance degradations due to thermal effects was investigated. Future commercial space communication antenna systems will utilize the 20/30 GHz frequency spectrum and support very narrow multiple beams (0.3 deg) over wide angle field of view (15-20 beamwidth). On the ground, portable and inexpensive very small aperture terminals (VSAT) for transmitting and receiving video, facsimile and data will be employed. These types of communication system puts a very stringent requirement on spacecraft antenna beam pointing stability (less than .01 deg), high gain (greater than 50 dB) and very lowside lobes (less than -25 dB). Thermal analysis performed on the advanced communication technology satellite (ACTS) has shown that the reflector surfaces, the mechanical supporting structures and metallic surfaces on the spacecraft body will distort due thermal effects from a varying solar flux. The antenna performance characteristics (e.g., pointing stability, gain, side lobe, etc.) will degrade due to thermal distortion in the reflector surface and supporting structures. Specifically, antenna RF radiation analysis has shown that pointing error is the most sensitive antenna performance parameter to thermal distortions. Other antenna parameters like peak gain, cross polarization level (beam isolation), and side lobe level will also degrade with thermal distortions. In order to restore pointing stability and in general antenna performance several compensation methods were proposed. In general these compensation methods can be classified as being either of mechanical or electromagnetic type. This paper will address only the later one. In this approach an adaptive phased array antenna feed is used to compensate for the antenna performance degradation. Extensive work has been devoted to demonstrate the feasibility of adaptive feed compensation on space communication antenna systems. This
Mouhot, Clément
2012-01-01
This paper reviews the recent mathematical progresses made on the study of the orbital stability properties for the gravitational Vlasov-Poisson system. We present in details the paper of Lemou, M\\'ehats and Rapha\\"el (Inventiones 2011) and we review also the previous works by Dolbeault, Guo, Hadzic, Lin, Rein, S\\'anchez, Soler, Wan, Wolansky. We also include a discussion of the history of this topic and the pioneering works by physicists like Antonov, Lynden-Bell and Aly. This is the text of a Bourbaki seminar given in november 2011 (in french).
Switched steerable multiple beam antenna system
Iwasaki, Richard S. (Inventor)
1988-01-01
A steerable multibeam five element cross-feed cluster antenna system is described. The feed power is divided into five branches. Each branch includes a switching network comprised of a plurality of time delay elements each individually controlled by a respective electromagnetic latching switch. Frequency independent individual two-dimensional beam steering at intermediate (IF) scanning frequencies is thereby provided wherein discrete incremental time delays are introduced by the switching networks into each branch and the signals recombined thereafter to form each beam. The electromagnetic latched switching reduces power consumption and permits higher power switching and reciprocal coincident tranmsit and receive operation. Frequency independence due to incremental time delay switching permits coincident reciprocal operation and steering for transmit-receive signal paths carrying different transmit-receive frequencies. Diagonal quarter wave plates in the waveguides alter polarization from the circular to orthogonal linear to provide transmitter-receiver isolation.
47 CFR 73.6025 - Antenna system and station location.
2010-10-01
... RADIO BROADCAST SERVICES Class A Television Broadcast Stations § 73.6025 Antenna system and station... should be used for the maximum radiation. The plot of the pattern should be oriented so that 0 degrees (True North) corresponds to the maximum radiation of the directional antenna or, alternatively in...
Reconfigurable Array Antenna Using Microelectromechanical Systems (MEMS) Actuators
Simons, Rainee N.; Chun, Donghoon; Katehi, Linda P. B.
2001-01-01
The paper demonstrates a patch antenna integrated with a novel microelectromechanical systems (MEMS) actuator for reconfiguring the operating frequency. Experimental results demonstrate that the center frequency can be reconfigured by as much as 1.6 percent of the nominal operating frequency at K-Band In addition, a novel on-wafer antenna pattern measurement technique is demonstrated.
Design of energy conscious antenna system for WLAN frequency band
CSIR Research Space (South Africa)
Bembe, MJ
2009-08-01
Full Text Available loading the parasitic elements. These imply the achievement of low power antenna system with low fabrication cost. The ESPAR antenna can be designed to cover the frequency bands of the wireless local area network (WLAN), which are 2.4GHz and 5.8GHz...
Advanced system characterizes antennas to 65 GHz
Francis, Michael H.; Kremer, Douglas P.; Repjar, Andrew G.
1990-03-01
The antenna measurement service offered by the National Institute of Standards and Technology provides radiation-pattern, on-axis gain, and polarization measurements to 65 GHz using planar near-field and extrapolation techniques. It is pointed out that measurements of millimeter-wave antennas are both difficult and costly to make and that such measurements require low-noise, high-power signal sources and exceptionally stable and repeatable connections. The process of the three-antenna extrapolation technique and subsequent measurements of dual-port circularly polarized antennas and swept-frequency gain measurements are analyzed, and antenna standards are noted. Insertion-loss measurements and attenuator calibration are discussed, and measurement uncertainties and far-field patterns are analyzed.
Microelectromechanical Systems (MEMS) Actuator for Reconfigurable Patch Antenna Demonstrated
Simons, Rainee N.
2001-01-01
A microstrip patch antenna with two contact actuators along the radiating edges for frequency reconfiguration was demonstrated at K-band frequencies. The layout of the antenna is shown in the following figure. This antenna has the following advantages over conventional semiconductor varactor-diode-tuned patch antennas: 1. By eliminating the semiconductor diode and its nonlinear I-V characteristics, the antenna minimizes intermodulation signal distortion. This is particularly important in digital wireless systems, which are sensitive to intersymbol interference caused by intermodulation products. 2. Because the MEMS actuator is an electrostatic device, it does not draw any current during operation and, hence, requires a negligible amount of power for actuation. This is an important advantage for hand-held, battery-operated, portable wireless systems since the battery does not need to be charged frequently. 3. The MEMS actuator does not require any special epitaxial layers as in the case of diodes and, hence, is cost effective.
Automatic reference level control for an antenna pattern recording system
Lipin, R., Jr.
1971-01-01
Automatic gain control system keeps recorder reference levels within 0.2 decibels during operation. System reduces recorder drift during antenna radiation distribution determinations over an eight hour period.
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.
Missile antenna pattern coordinate system and data formats
1993-08-01
Antenna performance data pertains to missile, space, and aerodynamic vehicles' transmitting or receiving antennas used with range data collection, missile trajectory measurements, impact predictions, communications, or flight termination systems. As used in this document, the terms missile space vehicle, airborne, and aerodynamic vehicle are synonymous. This standard is intended to cover antennas for telemetry, pulsed radar beacons, continuous wave (CW) transponders, communication transmitters and receivers, command control/flight termination, receivers/decoders, pseudo random noise (PRN) ranging systems, and the Global Positioning System.
Low Cost Phased Array Antenna System Project
National Aeronautics and Space Administration — JEM Engineering proved the technical feasibility of the FlexScan array?a very low-cost, highly-efficient, wideband phased array antenna?in Phase I, and stands ready...
Tunable Patch Antennas Using Microelectromechanical Systems
2011-05-11
wavelength of the desired resonant frequency [1]. (25) To aid in the design process a MATLAB script was written to solve for patch antenna...10–12, the widths of 50 Ω and 112 Ω microstrip lines were calculated using a MATLAB script included as an appendix to this report. The calculated...2009, pp. 50–55. [11] W.L. Stutzman, G.A. Thiele , Antenna Theory and Design, Second Edition, John Wiley & Sons, Inc. (Hoboken, New Jersey), 1998, pp
Institute of Scientific and Technical Information of China (English)
HAN Shuangfeng; ZHOU Shidong; WANG Jing; PARK Woogoo
2006-01-01
High spectral efficiency distributed antenna systems (DAS) require vertical Bell-Labs layered space-time (V-BLAST) like spatial multiplexing schemes. However, unlike normal point-to-point multiple input multiple output (MIMO) channels, DAS channels have different large-scale fadings from different transmit antennas, thus making equal power and rate transmission that is feasible in MIMO channels unrealistic in DAS channels. This paper proposes a novel transmit antenna selection scheme with power and rate allocation. The scheme is based on large-scale fading (shadow fading and path loss) and is suitable for V-BLAST structures with zero-forcing and successive interference cancellation (ZF-SIC) receivers, ensuring balanced average symbol error rate (SER) performance in each layer. On the receiver side, a fixed detection order is used, which is obtained in the transmit antenna selection process. Simulation results show that the proposed scheme gives good performance gains over equal power and rate transmission systems without antenna selection.
Ortho-mode Vivaldi antennas for agile polarization systems
Macedo, A. D.; Mosso, M. M.
The design criteria and assembly techniques for the ortho-mode Vivaldi (OMV) antenna system are described. The system is composed of a set of two orthogonal linearly polarized elements that are fed by an ortho-mode tee. The performances of two prototype OMV antennas system are examined and the applicability OMV is noted. Diagrams of the two prototypes and graphs of their performance are provided.
Smart Antenna UKM Testbed for Digital Beamforming System
Islam, Mohammad Tariqul; Misran, Norbahiah; Yatim, Baharudin
2009-12-01
A new design of smart antenna testbed developed at UKM for digital beamforming purpose is proposed. The smart antenna UKM testbed developed based on modular design employing two novel designs of L-probe fed inverted hybrid E-H (LIEH) array antenna and software reconfigurable digital beamforming system (DBS). The antenna is developed based on using the novel LIEH microstrip patch element design arranged into [InlineEquation not available: see fulltext.] uniform linear array antenna. An interface board is designed to interface to the ADC board with the RF front-end receiver. The modular concept of the system provides the capability to test the antenna hardware, beamforming unit, and beamforming algorithm in an independent manner, thus allowing the smart antenna system to be developed and tested in parallel, hence reduces the design time. The DBS was developed using a high-performance [InlineEquation not available: see fulltext.] floating-point DSP board and a 4-channel RF front-end receiver developed in-house. An interface board is designed to interface to the ADC board with the RF front-end receiver. A four-element receiving array testbed at 1.88-2.22 GHz frequency is constructed, and digital beamforming on this testbed is successfully demonstrated.
Smart Antenna UKM Testbed for Digital Beamforming System
Directory of Open Access Journals (Sweden)
2009-03-01
Full Text Available A new design of smart antenna testbed developed at UKM for digital beamforming purpose is proposed. The smart antenna UKM testbed developed based on modular design employing two novel designs of L-probe fed inverted hybrid E-H (LIEH array antenna and software reconfigurable digital beamforming system (DBS. The antenna is developed based on using the novel LIEH microstrip patch element design arranged into 4×1 uniform linear array antenna. An interface board is designed to interface to the ADC board with the RF front-end receiver. The modular concept of the system provides the capability to test the antenna hardware, beamforming unit, and beamforming algorithm in an independent manner, thus allowing the smart antenna system to be developed and tested in parallel, hence reduces the design time. The DBS was developed using a high-performance TMS320C6711TM floating-point DSP board and a 4-channel RF front-end receiver developed in-house. An interface board is designed to interface to the ADC board with the RF front-end receiver. A four-element receiving array testbed at 1.88–2.22 GHz frequency is constructed, and digital beamforming on this testbed is successfully demonstrated.
Worst-case tolerance optimization of antenna systems
DEFF Research Database (Denmark)
Schjær-Jacobsen, Hans
1980-01-01
The application of recently developed algorithms to antenna systems design is demonstrated by the worst-case tolerance optimization of linear broadside arrays, using both spacings and excitation coefficients as design parameters. The resulting arrays are optimally immunized against deviations...
Phase Noise in Photonic Phased-Array Antenna Systems
Logan, Ronald T., Jr.; Maleki, Lute
1998-01-01
The total noise of a phased-array antenna system employing a photonic feed network is analyzed using a model for the individual component noise including both additive and multiplicative equivalent noise generators.
Polarization Reconfigurable Patch Antenna Using Microelectromechanical Systems (MEMS) Actuators
Simons, Rainee N.; Chun, Donghoon; Katehi, Linda P. B.
2002-01-01
The paper demonstrates a nearly square patch antenna integrated with a novel microelectromechanical systems (MEMS) actuator for reconfiguring the polarization. Experimental results demonstrate that at a fixed frequency, the polarization can be reconfigured, from circular to linear.
Power Control Imperfection in CDMA Systems with Adaptive Antennas
Wieser, V.; Hrudkay, K.
2002-01-01
This paper deals with a simulation of cellular CDMA system using base station adaptive antennas. The model assumes two tiers area, four types of antennas, lognormal shadowing corresponding to three types of environments and perfect power control or two values of power control error, respectively. The capacity of system in up-link is evaluated by a number of mobile stations with higher signal to interference ratio than threshold with given outage probability.
Power Control Imperfection in CDMA Systems with Adaptive Antennas
Directory of Open Access Journals (Sweden)
V. Wieser
2002-12-01
Full Text Available This paper deals with a simulation of cellular CDMA system usingbase station adaptive antennas. The model assumes two tiers area, fourtypes of antennas, lognormal shadowing corresponding to three types ofenvironments and perfect power control or two values of power controlerror, respectively. The capacity of system in up-link is evaluated bya number of mobile stations with higher signal to interference ratiothan threshold with given outage probability.
Hussain, Rifaqat
2015-06-18
© The Institution of Engineering and Technology 2015. A compact, novel multi-mode, multi-band frequency reconfigurable multiple-input-multiple-output (MIMO) antenna system, integrated with ultra-wideband (UWB) sensing antenna, is presented. The developed model can be used as a complete antenna platform for cognitive radio applications. The antenna system is developed on a single substrate area of dimensions 65 × 120 mm^{2}. The proposed sensing antenna is used to cover a wide range of frequency bands from 710 to 3600 MHz. The frequency reconfigurable dual-element MIMO antenna is integrated with P-type, intrinsic, N-type (PIN) diodes for frequency agility. Different modes of selection are used for the MIMO antenna system reconfigurability to support different wireless system standards. The proposed MIMO antenna configuration is used to cover various frequency bands from 755 to 3450 MHz. The complete system comprising the multi-band reconfigurable MIMO antennas and UWB sensing antenna for cognitive radio applications is proposed with a compact form factor.
Maximum Throughput in Multiple-Antenna Systems
Zamani, Mahdi
2012-01-01
The point-to-point multiple-antenna channel is investigated in uncorrelated block fading environment with Rayleigh distribution. The maximum throughput and maximum expected-rate of this channel are derived under the assumption that the transmitter is oblivious to the channel state information (CSI), however, the receiver has perfect CSI. First, we prove that in multiple-input single-output (MISO) channels, the optimum transmission strategy maximizing the throughput is to use all available antennas and perform equal power allocation with uncorrelated signals. Furthermore, to increase the expected-rate, multi-layer coding is applied. Analogously, we establish that sending uncorrelated signals and performing equal power allocation across all available antennas at each layer is optimum. A closed form expression for the maximum continuous-layer expected-rate of MISO channels is also obtained. Moreover, we investigate multiple-input multiple-output (MIMO) channels, and formulate the maximum throughput in the asympt...
Parasitic antenna arrays for wireless MIMO systems
Kanatas, Athanasios; Papadias, Constantinos
2014-01-01
This book covers a cross-section of two technologies: parasitic antenna arrays driven via analogue circuits; and MIMO technology for multi-antenna arrays. The combination of these two technologies results in novel functionality. Relevant technical angles, ranging from theoretic to electromagnetic considerations; from analogue circuit to digital baseband control for signal generation; and from channel modeling to communication theoretic aspects are detailed by the contributors. Potential applications are considered in conjunction with current and upcoming wireless standards is provided.
ANTENNAS ARRAY ADJUST WITH ADAPTIVE NEURONAL SYSTEM
Directory of Open Access Journals (Sweden)
A. Padrón
2004-12-01
Full Text Available In this work an array failure correction for Linear Antenna Array (LAA is presented. This is carried out by means ofan Adaptive Artificial Neural Network (AANN that adjusts the amplitude and phase at beamforming. Theappropriated corrections are given, when one, or two, or three elements have a failure in the antenna linear array.The AANN corrects the corresponding parameters in the radiation pattern obtained due to the failure, when weknow the coefficients of the array factor (AF. This yields a reduction of side lobe level and some interferencesdisappear.
Difference Antenna Selection and Power Allocation for Wireless Cognitive Systems
Wang, Yue
2010-01-01
In this paper, we propose an antenna selection method in a wireless cognitive radio (CR) system, namely difference selection, whereby a single transmit antenna is selected at the secondary transmitter out of $M$ possible antennas such that the weighted difference between the channel gains of the data link and the interference link is maximized. We analyze mutual information and outage probability of the secondary transmission in a CR system with difference antenna selection, and propose a method of optimizing these performance metrics of the secondary data link subject to practical constraints on the peak secondary transmit power and the average interference power as seen by the primary receiver. The optimization is performed over two parameters: the peak secondary transmit power and the difference selection weight $\\delta\\in [0, 1]$. We show that, difference selection using the optimized parameters determined by the proposed method can be, in many cases of interest, superior to a so called ratio selection me...
Directional pattern measurement of the BRAMS beacon antenna system
Martínez Picar, A.; Marqué, C.; Anciaux, M.; Lamy, H.
2015-01-01
The typical methods for measuring antenna characteristics are mostly based on the use of remote transmitters or receivers. For antennas used in radio communications, calibrations are usually done on an antenna test stand using transmitters with known power output. In order to minimize the ground effects while performing measurements, it is necessary to place the transmitter or receiver high above ground with the aid of aircrafts. It is, however, necessary to determine precisely the coordinates of the airborne devices as well as to maintain high stability. This used to be excessively difficult to carry out, but recent advances in Unmanned Aerial Vehicle (UAV) technologies have brought a feasible option. In this paper, the results of using a low-cost system for measuring the directional pattern of BRAMS beacon antenna system based on an UAV are presented.
Integrated analysis system for box truss antenna mesh performance
Bachtell, E. E.; Bettadapur, S. S.; Coyner, J. V.
1986-01-01
An integrated analysis system has been developed to more efficiently design and analyze the mesh reflective surface and the mesh tie system of the box truss antenna. Six integrated computer programs using nonlinear finite-element, surface topography and interpolation, and RF aperture integration techniques, analyze the effects of manufacturing errors, mesh pillowing, and operating environment on antenna performance. The level of rigor of analysis can be varied, providing the possibility of a lower cost preliminary study on various designs using a minimum number of reduced box section models. By including the random and systematic errors with the aperture integration of minimum rms reflector surface roughness, the RF Performance Solver determines the far-field pattern, including the beam efficiency, and thus the antenna performance of the mesh reflector antenna.
Antenna array geometry optimization for a passive coherent localisation system
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.
Hardware implementation of antenna array system for maximum SLL reduction
Directory of Open Access Journals (Sweden)
Amr H. Hussein
2017-06-01
Full Text Available Side lobe level (SLL reduction has a great importance in recent communication systems. It is considered as one of the most important applications of digital beamforming since it reduces the effect of interference arriving outside the main lobe. This interference reduction increases the capacity of the communication systems. In this paper, the hardware implementation of an antenna array system for SLL reduction is introduced using microstrip technology. The proposed antenna array system consists of two main parts, the antenna array, and its feeding network. Power dividers play a vital role in various radio frequency and communication applications. A power divider can be utilized as a feeding network of an antenna array. For the synthesis of a radiation pattern, an unequal-split power divider is required. A new design for a four ports unequal circular sector power divider and its application to antenna array SLL reduction is introduced. The amplitude and phase of the signals emerging from each power divider branch are adjusted using stub and inset matching techniques. These matching techniques are used to adjust the branches impedances according to the desired power ratio. The design of the antenna array and the power divider are made using the software package CST MICROWAVE STUDIO. The power divider is realized on Rogers R03010 substrate with dielectric constant εr=10.2, loss tangent of 0.0035, and height h=1.28mm. In addition, a design for ultra-wide band (UWB antenna element and array are introduced. The antenna elements and the array are realized on the FR4 (lossy substrate with dielectric constant εr=4.5, loss tangent of 0.025, and height h=1.5mm. The fabrication is done using thin film technology and photolithographic technique. The experimental measurements are done using the vector network analyzer (VNA HP8719Es. Good agreement is found between the measurements and the simulation results.
Absolute Calibration of the Lopes Antenna System
Nehls, S.; Bähren, L.; Buitink, S.J.; Falcke, H.D.E.; Horneffer, K.H.A.; Kuijpers, J.M.E.; Lafebre, S.J.; Nigl, A.; Petrovic, J.
2006-01-01
Radio emission in extensive air showers arises from an interaction with the geomagnetic field and is subject of theoretical studies. This radio emission has advantages for the detection of high energy cosmic rays compared to secondary particle or fluorescence measurement methods. Radio antennas like
Electromagnetics of body area networks antennas, propagation, and RF systems
Werner, Douglas H
2016-01-01
The book is a comprehensive treatment of the field, covering fundamental theoretical principles and new technological advancements, state-of-the-art device design, and reviewing examples encompassing a wide range of related sub-areas. In particular, the first area focuses on the recent development of novel wearable and implantable antenna concepts and designs including metamaterial-based wearable antennas, microwave circuit integrated wearable filtering antennas, and textile and/or fabric material enabled wearable antennas. The second set of topics covers advanced wireless propagation and the associated statistical models for on-body, in-body, and off-body modes. Other sub-areas such as efficient numerical human body modeling techniques, artificial phantom synthesis and fabrication, as well as low-power RF integrated circuits and related sensor technology are also discussed. These topics have been carefully selected for their transformational impact on the next generation of body-area network systems and beyo...
Novel metamaterial based antennas for flexible wireless systems
Khaleel, Haider Raad
Recent years have witnessed a great deal of interest from both academia and industry in the field of flexible electronic systems. This research topic tops the pyramid of research priorities requested by many national research agencies. Consistently, flexible electronic systems require the integration of flexible antennas operating in specific frequency bands to provide wireless connectivity which is highly demanded by today's information oriented society. On the other hand, metamaterials have become very popular in the design of contemporary antenna and microwave devices due to their wide range of applications derived from their unique properties which significantly enhances the performance of antennas and RF systems. Accordingly, the integration of metamaterial structures within flexible wireless systems is very beneficial in this growing field of research. A systematic approach to the analysis and design of flexible and conformal antennas and metamaterials is ultimately needed. The research reported in this thesis focuses on developing flexible low profile antennas and metamaterial structures in addition to characterizing their performance when integrated within flexible wireless systems. Three flexible, compact, and extremely low profile (50.8 microm) antennas intended for WLAN, Bluetooth and Ultra Wide Band (UWB) applications are presented. Next, a novel miniaturized Artificial Magnetic Conductor (AMC) and a new technique to enhance the bandwidth of micro-Negative (MNG) metamaterial are reported. Furthermore, the effect of bending on the AMC and MNG metamaterial is investigated in this thesis for the first time. Finally, the findings of this research are utilized in practical applications with specific design constraints including mutual coupling reduction between radiating elements in antenna arrays and MIMO systems and Specific Absorption Rate (SAR) reduction in telemedicine systems.
Distributed MIMO Systems with Oblivious Antennas
Simeone, Osvaldo; Poor, H Vincent; Shamai, Shlomo
2008-01-01
A scenario in which a single source communicates with a single destination via a distributed MIMO transceiver is considered. The source operates each of the transmit antennas via finite-capacity links, and likewise the destination is connected to the receiving antennas through capacity-constrained channels. Targeting a nomadic communication scenario, in which the distributed MIMO transceiver is designed to serve different standards or services, transmitters and receivers are assumed to be oblivious to the encoding functions shared by source and destination. Adopting a Gaussian symmetric interference network as the channel model (as for regularly placed transmitters and receivers), achievable rates are investigated and compared with an upper bound. It is concluded that in certain asymptotic and non-asymptotic regimes obliviousness of transmitters and receivers does not cause any loss of optimality.
Multi-Polarization Reconfigurable Antenna for Wireless Biomedical System.
Wong, Hang; Lin, Wei; Huitema, Laure; Arnaud, Eric
2017-01-23
This paper presents a multi-polarization reconfigurable antenna with four dipole radiators for biomedical applications in body-centric wireless communication system (BWCS). The proposed multi-dipole antenna with switchable 0°, +45°, 90° and -45° linear polarizations is able to overcome the polarization mismatching and multi-path distortion in complex wireless channels as in BWCS. To realize this reconfigurable feature for the first time among all the reported antenna designs, we assembled four dipoles together with 45° rotated sequential arrangements. These dipoles are excited by the same feeding source provided by a ground tapered Balun. A metallic reflector is placed below the dipoles to generate a broadside radiation. By introducing eight PIN diodes as RF switches between the excitation source and the four dipoles, we can control a specific dipole to operate. As the results, 0°, +45°, 90° and -45° linear polarizations can be switched correspondingly to different operating dipoles. Experimental results agree with the simulation and show that the proposed antenna well works in all polarization modes with desirable electrical characteristics. The antenna has a wide impedance bandwidth of 34% from 2.2 to 3.1 GHz (for the reflection coefficient ≤ -10 dB) and exhibits a stable cardioid-shaped radiation pattern across the operating bandwidth with a peak gain of 5.2 dBi. To validate the effectiveness of the multi-dipole antenna for biomedical applications, we also designed a meandered PIFA as the implantable antenna. Finally, the communication link measurement shows that our proposed antenna is able to minimize the polarization mismatching and maintains the optimal communication link thanks to its polarization reconfigurability.
Microelectrical Mechanical Systems Switch for Designing Multi-Band Antenna
Directory of Open Access Journals (Sweden)
A. H.M.Z. Alam
2009-01-01
Full Text Available Problem statement: In this study Microelectrical Mechanical System (MEMS switches were proposed to design a reconfigurable/multi-band antenna to replaced PIN diode switches or semiconductor switches due to lower insertion losses, good isolation, much lower intermodulation distortion, and lower power consumption. The antenna is able to operate at very high frequencies. Approach: A reconfigurable antenna that is capable to operate at several frequencies was proposed by introducing two adjacent patches along with main radiating patch and two MEMS switches. Parametric analysis of the size of the wing patches was done for finding optimum size. A comparative study was done for Alumina, SiN, GaAs and Teflon as MEMS bridge materials for finding better results in terms of return loss and number of bands. The design was performed by using 3D electromagnetic simulator HFSS considering ideal MEMS switches. Results: It was found that SiN as MEMS bridge material makes the antenna to operate at 16.76, 23.56 and 27.7 GHz in the OFF states and operate at 20.9 and 21.91 GHz in the ON states of MEMS switches. Conclusion/Recommendations: MEMS cantilever beam material played an important role for providing antenna to operate at multi-band frequencies. The proposed multiband/reconfigurable antenna can be implemented with easy fabrication process steps by the Sandwich method of fabrication.
A Reconfigurable Spiral Antenna for Adaptive MIMO Systems
Directory of Open Access Journals (Sweden)
Qian JY
2005-01-01
Full Text Available We present a reconfigurable spiral antenna for use in adaptive MIMO systems. The antenna is capable of changing the sense of polarization of the radiated field. It is fabricated by using an RF-MEMS technology compatible with microwave laminate substrates developed within the author's group. The proposed antenna structure is built on a number of rectangular-shaped bent metallic strips interconnected to each other with RF-MEMS actuators. Two senses of polarization, RHCP and LHCP, are achieved by configuring the physical structure of the antenna, that is, by changing the winding sense of the spiral, through judicious activation of MEM actuators. The fabrication process for the monolithic integration of MEM actuators with bent microstrip pixels on RO4003-FR4 microwave laminate substrate is described. The measured and calculated radiation and impedance characteristics of the antenna are given. The operating frequency of the presented antenna design can easily be adjusted to be compatible with popular IEEE networking standards such as 802.11a.
A Reconfigurable Spiral Antenna for Adaptive MIMO Systems
Directory of Open Access Journals (Sweden)
Cetiner Bedri A.
2005-01-01
Full Text Available We present a reconfigurable spiral antenna for use in adaptive MIMO systems. The antenna is capable of changing the sense of polarization of the radiated field. It is fabricated by using an RF-MEMS technology compatible with microwave laminate substrates developed within the author's group. The proposed antenna structure is built on a number of rectangular-shaped bent metallic strips interconnected to each other with RF-MEMS actuators. Two senses of polarization, RHCP and LHCP, are achieved by configuring the physical structure of the antenna, that is , by changing the winding sense of the spiral, through judicious activation of MEM actuators. The fabrication process for the monolithic integration of MEM actuators with bent microstrip pixels on RO4003-FR4 microwave laminate substrate is described. The measured and calculated radiation and impedance characteristics of the antenna are given. The operating frequency of the presented antenna design can easily be adjusted to be compatible with popular IEEE networking standards such as 802.11a.
Highly Compact MIMO Antenna System for LTE/ISM Applications
Directory of Open Access Journals (Sweden)
Lingsheng Yang
2015-01-01
Full Text Available Planar monopole antenna is proposed as the antenna element to form a compact dual-element multiple-input-multiple-output (MIMO antenna system for LTE2300 (used in Asia and Africa and ISM band operation. The system can cover a 310 MHz (2.20–2.51 GHz operating bandwidth, with the total size of 15.5 mm × 18 mm × 1.6 mm. Measured isolation higher than 16 dB is obtained without any specially designed decoupling structures, while the edge-to-edge element spacing is only 7.8 mm (0.08λ at 2.20 GHz. Radiation characteristics, correlation coefficient, and the performance of the whole system with a metal sheet and a plastic housing show this system is competitive for practical MIMO applications. The antenna element is further used to build an eight-element MIMO antenna system; also good results are achieved.
FTTA System Demo Using Optical Fiber-Coupled Active Antennas
Directory of Open Access Journals (Sweden)
Niels Neumann
2014-08-01
Full Text Available The convergence of optical and wireless systems such as Radio-over-Fiber (RoF networks is the key to coping with the increasing bandwidth demands due to the increasing popularity of video and other high data rate applications. A high level of integration of optical technologies enables simple base stations with a fiber-to-the-antenna (FTTA approach. In this paper, we present a complete full-duplex RoF–FTTA system consisting of integrated active fiber-coupled optical receiving and transmitting antennas that are directly connected to a standard single mode fiber optical link. Data rates up to 1 Gbit/s could be shown without advanced modulation formats on a 1.5 GHz carrier frequency. The antennas as well as the whole system are explained and the results of the system experiments are discussed.
A 2-order MIMO Full-Duplex Antenna System
DEFF Research Database (Denmark)
Tsakalaki, Elpiniki; Foroozanfard, Ehsan; De Carvalho, Elisabeth
2014-01-01
The paper presents an antenna system with combined full-duplex and 2-order multiple-input-multiple-output (MIMO) functionalities, i.e., a system capable of spatially multiplexing and spatially demultiplexing 2 datastreams in the same frequency and in the same time. By exploiting symmetries....... On the other hand, the 2 MIMO ports (either at the Tx or at the Rx) are sufficiently decoupled thanks to polarization diversity. The proposed antenna system exhibits a remarkable level of fullduplex isolation over a wide bandwidth while maintaining low coupling between its MIMO ports and can serve...... as a concrete implementation of an antenna system equipped with both MIMO as well as full-duplex capabilities....
A Dual-Band Antenna for RF Energy Harvesting Systems in Wireless Sensor Networks
A. Bakkali; Pelegri-Sebastia, J.; Sogorb, T.; V. Llario; Bou-Escriva, A.
2016-01-01
In this paper, we focus on ambient radio frequency energy available from commercial broadcasting stations in order to provide a system based on RF energy harvesting using a new design of receiving antenna. Several antenna designs have been proposed for use in RF energy harvesting systems, as a pertinent receiving antenna design is highly required since the antenna features can affect the amount of energy harvested. The proposed antenna is aimed at greatly increasing the energy harves...
Active Probing Feedback based Self Configurable Intelligent Distributed Antenna System
DEFF Research Database (Denmark)
Kumar, Ambuj
challenge through a viable solution that is based on injecting intelligence and services in parallel layers through a Distributed Antenna Systems (DAS) network. This approach would enable the remote sites to acquire intelligence and a resource pool at the same time, thereby managing the network dynamics...... as Self Configurable Distributed Antenna System (SCIDAS)....... collectively as Place Time Coverage & Capacity (PTC2). The dissertation proves through the concept of the PTC2 that the network performance can severely be degraded by the excessive and unrealistic site demands, the network management inefficiency, and the consequence of the accumulation of subscribers...
Dual-frequency feed system for 26-meter antenna conversion
Hartop, R. W.
1977-01-01
New cassegrain feed cone assemblies were designed as part of the upgrade of three 26-meter diameter antennas to 34-meter diameter with improved performance. The new dual-frequency feed cone (SXD) will provide both S- and X-band feed systems and traveling wave masers, with a reflex reflector system to permit simultaneous operation analogous to the 64-meter antennas. Tasks involved in adding the X-band receiving capability and improving the S-band feed performance in support of Voyager and later missions described in.
Pentagonal shaped microstrip patch antenna in wireless capsule endoscopy system
Directory of Open Access Journals (Sweden)
Bondili Kohitha Bai
2012-01-01
Full Text Available Wireless capsule endoscopy is a best option for exploring inaccessible areas of small intestine for inspection of gastrointestinal tract. This technique brings less pain compare to conventional endoscopy technique. The wireless endoscopy system comprises of three main modules: an ingestible capsule that is swallowed by the patient, an external control unit and display device for image display. In this paper we proposed pentagonal shape microstrip patch antenna for wireless capsule endoscopy system. Inhibiting characteristics of a single microstrip patch like low gain, light weight, thin thickness and smaller bandwidth, make it more popular. This kind of antenna is aggressive miniaturized to meet the requirements of the wireless capsule endoscope. The simulation results show that the designed Circular Polarization (CP pentagonal shaped microstrip patch antenna gives axial ratio of 0.6023 at 2.38 GHz and CP axial ratio bandwidth of 36MHz with 1.5%. The antenna designed for wireless capsule endoscopy is a proposed one, which may work effectively when compared to other antennas in the capsule.
Directory of Open Access Journals (Sweden)
Gan Jiansong
2007-01-01
Full Text Available We investigate the uplink of a power-controlled multi-user distributed antenna system (DAS with antennas deployed on a circle. Applying results from random matrix theory, we prove that for such a DAS, the per-user sum rate and the total transmit power both converge as user number and antenna number go to infinity with a constant ratio. The relationship between the asymptotic per-user sum rate and the asymptotic total transmit power is revealed for all possible values of the radius of the circle on which antennas are placed. We then use this rate-power relationship to find the optimal radius. With this optimal radius, the circular layout DAS (CL-DAS is proved to offer a significant gain compared with a traditional colocated antenna system (CAS. Simulation results are provided, which demonstrate the validity of our analysis.
Directory of Open Access Journals (Sweden)
Jiansong Gan
2007-08-01
Full Text Available We investigate the uplink of a power-controlled multi-user distributed antenna system (DAS with antennas deployed on a circle. Applying results from random matrix theory, we prove that for such a DAS, the per-user sum rate and the total transmit power both converge as user number and antenna number go to infinity with a constant ratio. The relationship between the asymptotic per-user sum rate and the asymptotic total transmit power is revealed for all possible values of the radius of the circle on which antennas are placed. We then use this rate-power relationship to find the optimal radius. With this optimal radius, the circular layout DAS (CL-DAS is proved to offer a significant gain compared with a traditional colocated antenna system (CAS. Simulation results are provided, which demonstrate the validity of our analysis.
Maximum MIMO System Mutual Information with Antenna Selection and Interference
Directory of Open Access Journals (Sweden)
Rick S. Blum
2004-05-01
Full Text Available Maximum system mutual information is considered for a group of interfering users employing single user detection and antenna selection of multiple transmit and receive antennas for flat Rayleigh fading channels with independent fading coefficients for each path. In the case considered, the only feedback of channel state information to the transmitter is that required for antenna selection, but channel state information is assumed at the receiver. The focus is on extreme cases with very weak interference or very strong interference. It is shown that the optimum signaling covariance matrix is sometimes different from the standard scaled identity matrix. In fact, this is true even for cases without interference if SNR is sufficiently weak. Further, the scaled identity matrix is actually that covariance matrix that yields worst performance if the interference is sufficiently strong.
Optical design of the oblique Ece antenna system for JET
Energy Technology Data Exchange (ETDEWEB)
Sozzi, C. [Istituto di Fisica del Plasma, Associazione EURATOM-ENEA-CNR, Milan (Italy)]. E-mail: sozzi@ifp.cnr.it; Bruschi, A. [Istituto di Fisica del Plasma, Associazione EURATOM-ENEA-CNR, Milan (Italy); Simonetto, A. [Istituto di Fisica del Plasma, Associazione EURATOM-ENEA-CNR, Milan (Italy); DeLaLuna, E. [Asociacion EURATOM-CIEMAT, CIEMAT, Madrid (Spain); Fessey, J. [EURATOM-UKAEA Association, Culham Science Centre, Abingdon (United Kingdom); Riccardo, V. [EURATOM-UKAEA Association, Culham Science Centre, Abingdon (United Kingdom)
2005-11-15
Systematic disagreements between Ece and Thomson Scattering diagnostics observed in various fusion devices led to the proposal of the so called Oblique Ece diagnostics on JET. This system will allow the study of the electron distribution function at low energies to reveal deviations from the Maxwellian distribution. This paper is devoted to the design of the quasi optical antenna for this diagnostics. The physical bases of the diagnostics imply two lines of sight at about 10{sup o} and 20{sup o} respectively from the magnetic field gradient. Severe geometrical constraints are imposed by the location of the antenna. The design strategy and physical optics calculations used to validate it are presented.
Institute of Scientific and Technical Information of China (English)
无
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.
Systems design and comparative analysis of large antenna concepts
Garrett, L. B.; Ferebee, M. J., Jr.
1983-01-01
Conceptual designs are evaluated and comparative analyses conducted for several large antenna spacecraft for Land Mobile Satellite System (LMSS) communications missions. Structural configurations include trusses, hoop and column and radial rib. The study was conducted using the Interactive Design and Evaluation of Advanced Spacecraft (IDEAS) system. The current capabilities, development status, and near-term plans for the IDEAS system are reviewed. Overall capabilities are highlighted. IDEAS is an integrated system of computer-aided design and analysis software used to rapidly evaluate system concepts and technology needs for future advanced spacecraft such as large antennas, platforms, and space stations. The system was developed at Langley to meet a need for rapid, cost-effective, labor-saving approaches to the design and analysis of numerous missions and total spacecraft system options under consideration. IDEAS consists of about 40 technical modules efficient executive, data-base and file management software, and interactive graphics display capabilities.
On the performance of spectrum sharing systems with multiple antennas
Yang, Liang
2012-01-01
In this paper, we study the capacity of spectrum sharing (SS) multiple-input multiple-output (MIMO) systems over Rayleigh fading channels. More specifically, we present closed-form capacity formulas for such systems with and without optimal power and rate adaptation. A lower bound on the capacity is also derived to characterize the scaling law of the capacity. Results show that increasing the number of antennas has a negative effect on the system capacity in the low signal-to-noise (SNR) regime and the scaling law at high SNR is similar to the conventional MIMO systems. In addition, a lower bound on the capacity of the SS keyhole MIMO channels is analyzed. We also present a capacity analysis of SS MIMO maximal ratio combining (MRC) systems and the results show that the capacity of such systems always decreases with the increase of the number of antennas. Numerical results are finally given to illustrate our analysis. © 2012 ICST.
Design and Implementation of Double-Transmitter-Coil Antenna Used for the Tag Test System
Directory of Open Access Journals (Sweden)
Bin You
2013-01-01
Full Text Available At present, more and more electronic tags are used in Antitheft system; it is important to examine the performance of electronic tags. The traditional single-transmitter-coil antenna (STC antenna of the electronic tags tester has some serious drawbacks. So a novel double-transmitter-coil antenna (DTC antenna is presented in this paper. Compared to the traditional STC antenna, this new antenna has a more excellent performance in the tag test systems, especially when it is used for testing the quality factor of tags.
Energy Technology Data Exchange (ETDEWEB)
Omnes, P
1999-01-25
This work is dedicated to the study of the behaviour of a magnetic confined plasma that is excited by a purely sinusoidal electric current delivered by an antenna. The response of the electrons to the electromagnetic field is considered as linear,whereas the ions of the plasma are represented by a non-relativistic Vlasov equation. In order to avoid transients, the coupled Maxwell-Vlasov equations are solved in a periodic mode and in a bounded domain. An equivalent electric conductivity tensor has been defined, this tensor is a linear operator that links the electric current generated by the movement of the particles to the electromagnetic field. Theoretical considerations can assure the existence and uniqueness of a periodical solution to Vlasov equations and of a solution to Maxwell equations in harmonic mode. The system of equations is periodical and has been solved by using an iterative method. The application of this method to the simulation of a isotopic separation device based on ionic cyclotron resonance has shown that the convergence is reached in a few iterations and that the solution is valid. Furthermore a method based on a finite-volume formulation of Maxwell equations in the time domain is presented. 2 new variables are defined in order to better take into account the Gauss' law and the conservation of the magnetic flux, the new system is still hyperbolic. The parallelization of the process has been successfully realized. (A.C.)
Piezoelectric Driven Antenna System for Health Monitoring Gadgets
Directory of Open Access Journals (Sweden)
Omar A. Saraereh
2016-10-01
Full Text Available Advancement in medical science is emerging day by day, and application of engineering technology in the field of medical science plays a very important role. In this paper, a novel method to monitor the health condition of an individual is developed. The proposed system uses piezoelectric devices to operate a health monitoring gadget with antenna that is suitable to operate for the piezoelectric based power source. The present day health monitoring gadgets require battery replacement or need to be charged. These would be a problem for the user when the device runs out of the charge. In order to overcome these challenges, the concept of piezoelectricity is applied to charge the gadget. The gadget consists of a transmitter, which is a wearable device, which will be worn by the patient, whose health condition has to be monitored. The receiver unit is placed in the nearest hospital, which will receive the physical conditions of the patient and, monitoring of the health condition is done. Piezoelectric based charging system is used to drive the proposed gadget. The transmission and reception is accomplished by GSM. In order to achieve better performance, microstrip antenna is used for transmission and reception. The simulation of the proposed system is done using Multisim, and simulation results are presented. The piezoelectric simulation is done using MATLAB and also the simulation of micro strip antenna is presented. Here the microstrip antennas will be stimulated for frequency range of 2-3 GHz and 5-6 GHz (preferably 2.2 and 2.5 GHz, using HFSS and MATLAB. The piezoelectric beam is simulated and the voltage produced for the deflection is noted. It was found that for deflection of 33um, a voltage of 100V is produced.The various performance parameters of the antenna, such as impedance, VSWR, reflection coefficient, return loss are obtained and presented.
MULTIPLE TRELLIS CODED ORTHOGONAL TRANSMIT SCHEME FOR MULTIPLE ANTENNA SYSTEMS
Institute of Scientific and Technical Information of China (English)
无
2006-01-01
In this paper, a novel multiple trellis coded orthogonal transmit scheme is proposed to exploit transmit diversity in fading channels. In this scheme, a unique vector from a set of orthogonal vectors is assigned to each transmit antenna. Each of the output symbols from the multiple trellis encoder is multiplied with one of these orthogonal vectors and transmitted from corresponding transmit antennas. By correlating with corresponding orthogonal vectors, the receiver separates symbols transmitted from different transmit antennas.This scheme can be adopted in coherent/differential systems with any number of transmit antennas. It is shown that the proposed scheme encompasses the conventional trellis coded unitary space-time modulation based on the optimal cyclic group codes as a special case. We also propose two better designs over the conventional trellis coded unitary space-time modulation. The first design uses 8 Phase Shift Keying (8-PSK) constellations instead of 16 Phase Shift Keying (16-PSK) constellations in the conventional trellis coded unitary space-time modulation. As a result, the product distance of this new design is much larger than that of the conventional trellis coded unitary space-time modulation. The second design introduces constellations with multiple levels of amplitudes into the design of the multiple trellis coded orthogonal transmit scheme. For both designs, simulations show that multiple trellis coded orthogonal transmit schemes can achieve better performance than the conventional trellis coded unitary space-time schemes.
Antenna system characteristic and solar radio burst observation
Li, Sha; Chen, Zhijun; Wang, Wei; Liu, Donghao
2015-01-01
Chinese Spectral Radio Heliograph (CSRH) is an advanced aperture synthesis solar radio heliograph, developed by National Astronomical Observatories, Chinese Academy of Sciences independently. It consists of 100 reflector antennas, which are grouped into two antenna arrays (CSRH-I and CSRH-II) for low and high frequency bands respectively. The frequency band of CSRH-I is 0.4-2GHz and for CSRH-II, the frequency band is 2-15GHz. In the antenna and feed system, CSRH uses an Eleven feed to receive signals coming from the Sun, the radiation pattern with lower side lobe and back lobe of the feed is well radiated. The characteristics of gain G and antenna noise temperature T effect the quality of solar radio imaging. For CSRH, measured G is larger than 60 dBi and $ T $ is less than 120K, after CSRH-I was established, we have successfully captured a solar radio burst between 1.2-1.6GHz on November 12, 2010 through this instrument and this event was confirmed through the observation of Solar Broadband Radio Spectromete...
Tokamak-like Vlasov equilibria
Tasso, H
2014-01-01
Vlasov equilibria of axisymmetric plasmas with vacuum toroidal magnetic field can be reduced, up to a selection of ions and electrons distributions functions, to a Grad-Shafranov-like equation. Quasineutrality narrow the choice of the distributions functions. In contrast to two-dimensional translationally symmetric equilibria whose electron distribution function consists of a displaced Maxwellian, the toroidal equilibria need deformed Maxwellians. In order to be able to carry through the calculations, this deformation is produced by means of either a Heaviside step function or an exponential function. The resulting Grad-Shafranov-like equations are established explicitly.
Multi-platform laser communication networking optical antenna system design
Zhang, Tao
2016-10-01
In this paper, a new conclusion based on rotating parabolic model and a different scheme of laser communication networking antenna system has been put forward in the paper. Based on rotating parabolic antenna, a new theory of the optical properties have been deduced, which can realize larger dynamic, duplex, networking communications among multiple platforms in 360° azimuth and pitch range. Meanwhile, depending on the operation mode of the system, multiple mathematical optimization models have been established. Tracking communication range, emission energy efficiency and receiving energy efficiency have been analyzed and optimized. Relationship among opening up and low apertures, the lens unit aperture, focal length of lens unit as well as rotating parabolic focal length have been analyzed. Tracking pitching range and emission energy utilization has carried on the theoretical derivation and optimization and networking platform link between energy receiver and transmitter has been analyzed. Taking some parameters of this new system into calculation, optimized results can be utilized with MATLAB software for its application and system of communication engineering. The rotating parabolic internal can form a hollow structure, which is utilized for miniaturization, light-weighted design and realize duplex communication in a wide range and distance. Circular orbit guidance is the modern way used in dynamic tracking system. The new theory and optical antenna system has widespread applications value as well.
A Multiple-Antenna System for ISM-Band Transmission
Directory of Open Access Journals (Sweden)
Rinas J
2004-01-01
Full Text Available We present a multiple antenna system for industrial, scientific, and medical (ISM-band transmission (MASI. The hardware demonstrator was developed and realized at our institute. It enables multiple-input multiple-output (MIMO-communication applications and is capable of transmiting arbitrary signals using transmit and receive antennas in parallel. It operates in the 2.4 GHz ISM-band. The hardware concept is introduced and some design specifications are discussed. Using this transmission system, we present some measurement results to show the feasibility of MIMO concepts currently under discussion. The applications include transmit and receive diversity for single carrier and OFDM as well as blind source separation (BSS techniques.
Spacecraft multibeam antenna system for 30/20 GHz
Roberts, T. E.; Scott, W. F.
1984-01-01
The major technical tasks that led to the definitions of operational and demonstration multiple beam antenna (MBA) flight systems and a proof of concept model (POC) are described. Features of the POC Model and its measured performance are presented in detail. Similar MBA's are proposed for transmitting and receiving with the POC Model representing the 20 GHz transmitting antenna. This POC MBA is a dual shaped-surface reflector system utilizing a movable free array to simulate complete CONUS coverage. The beam forming network utilizes ferrite components for switching from one beam to another. Measured results for components, subsystems and the complete MBA confirm the feasibility of the approach and also show excellent correlation with calculated values.
NASA ACTS Multibeam Antenna (MBA) System. [Advanced Communications Technology Satellite
Choung, Youn H.; Stiles, W. Herschel; Wu, Joseph; Wong, William C.; Chen, C. Harry
1986-01-01
The design of the Advanced Communications Technology Satellite MBA system, which provides both spot beam and scanning beam coverage to both high and low burst rates data-users is examined. The MBA consists of receive and transmit antennas installed on a common precision mounting platform that is integrated to the bus through three flexures; a lightweight system with low thermal distortion is obtained by using composite materials for the MBA structures. The RF design, which is a Cassegrain reflector with a large equivalent focal length/aperture size, is described. Consideration is given to the position of the feed in order to minimize scan loss and sidelobe levels, the size of the subreflector in order to minimize feed spillover, and antenna performance degradation caused by reflector surface distortion. Breadbroad model test result reveal that the maximum sidelobe level outside the 2.5 HPBW region is -30 dB or lower relative to the power.
Mehrenberger, M; Marradi, L; Crouseilles, N; Sonnendrucker, E; Afeyan, B
2013-01-01
This work concerns the numerical simulation of the Vlasov-Poisson set of equations using semi- Lagrangian methods on Graphical Processing Units (GPU). To accomplish this goal, modifications to traditional methods had to be implemented. First and foremost, a reformulation of semi-Lagrangian methods is performed, which enables us to rewrite the governing equations as a circulant matrix operating on the vector of unknowns. This product calculation can be performed efficiently using FFT routines. Second, to overcome the limitation of single precision inherent in GPU, a {\\delta}f type method is adopted which only needs refinement in specialized areas of phase space but not throughout. Thus, a GPU Vlasov-Poisson solver can indeed perform high precision simulations (since it uses very high order reconstruction methods and a large number of grid points in phase space). We show results for rather academic test cases on Landau damping and also for physically relevant phenomena such as the bump on tail instability and t...
Performance Analysis of a Sectorized Distributed Antenna System with Reduced Co-Channel Interference
Institute of Scientific and Technical Information of China (English)
无
2006-01-01
This paper proposes a sectorized distributed antenna system for the orthogonal frequency division multiplexing access system in order to both reduce the co-channel interference introduced by frequency reuse and maintain high spectral efficiency. The proposed system is composed of many 120-degree sectorized antennas that are uniformly distributed throughout the whole coverage area. Three adjacent sectors from different antennas share the same frequency band, which can be reused on the adjacent antennas. The new structure provides downlink interference divergence that greatly reduces co-channel interference and improves the system capacity, compared to the traditional cell structure with frequency reuse factor equal to 3. Multiple antennas broadcasting the same signal for a user using the same frequency, known as simulcasting,has been widely studied in distributed antenna systems. However, this paper demonstrates that simulcasting is not suitable for the close interfering structure. Multiple input multiple output distributed antenna systems might be a better choice.
Antenna set for multi-channel TV system
Gryanik, M. V.; Ilyinov, M. D.; Pasechnik, S. G.
1995-01-01
One of the directions in the development of the urban TV networks is switching to the non-traditional frequency ranges. In particular, this is the range, which is widely used in systems of direct satellite TV broadcasting. The choice of this range can be explained by the saturation of commercial market of receiving equipment such as converters and tuners first of all. Transmitting antenna for such a network should have a circular horizontal plane directional pattern (DP) and have as high gain...
TLM modeling and system identification of optimized antenna structures
Directory of Open Access Journals (Sweden)
N. Fichtner
2008-05-01
Full Text Available The transmission line matrix (TLM method in conjunction with the genetic algorithm (GA is presented for the bandwidth optimization of a low profile patch antenna. The optimization routine is supplemented by a system identification (SI procedure. By the SI the model parameters of the structure are estimated which is used for a reduction of the total TLM simulation time. The SI utilizes a new stability criterion of the physical poles for the parameter extraction.
47 CFR 73.625 - DTV coverage of principal community and antenna system.
2010-10-01
... 47 Telecommunication 4 2010-10-01 2010-10-01 false DTV coverage of principal community and antenna... community and antenna system. (a) Transmitter location. (1) The DTV transmitter location shall be chosen so that, on the basis of the effective radiated power and antenna height above average terrain...
Improved List Sphere Decoder for Multiple Antenna Systems
Institute of Scientific and Technical Information of China (English)
无
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.
Excitation migration in fluctuating light-harvesting antenna systems.
Chmeliov, Jevgenij; Trinkunas, Gediminas; van Amerongen, Herbert; Valkunas, Leonas
2016-01-01
Complex multi-exponential fluorescence decay kinetics observed in various photosynthetic systems like photosystem II (PSII) have often been explained by the reversible quenching mechanism of the charge separation taking place in the reaction center (RC) of PSII. However, this description does not account for the intrinsic dynamic disorder of the light-harvesting proteins as well as their fluctuating dislocations within the antenna, which also facilitate the repair of RCs, state transitions, and the process of non-photochemical quenching. Since dynamic fluctuations result in varying connectivity between pigment-protein complexes, they can also lead to non-exponential excitation decay kinetics. Based on this presumption, we have recently proposed a simple conceptual model describing excitation diffusion in a continuous medium and accounting for possible variations of the excitation transfer pathways. In the current work, this model is further developed and then applied to describe fluorescence kinetics originating from very diverse antenna systems, ranging from PSII of various sizes to LHCII aggregates and even the entire thylakoid membrane. In all cases, complex multi-exponential fluorescence kinetics are perfectly reproduced on the entire relevant time scale without assuming any radical pair equilibration at the side of the excitation quencher, but using just a few parameters reflecting the mean excitation energy transfer rate as well as the overall average organization of the photosynthetic antenna.
On Secure NOMA Systems with Transmit Antenna Selection Schemes
Lei, Hongjiang
2017-08-09
This paper investigates the secrecy performance of a two-user downlink non-orthogonal multiple access systems. Both single-input and single-output and multiple-input and singleoutput systems with different transmit antenna selection (TAS) strategies are considered. Depending on whether the base station has the global channel state information of both the main and wiretap channels, the exact closed-form expressions for the secrecy outage probability (SOP) with suboptimal antenna selection and optimal antenna selection schemes are obtained and compared with the traditional space-time transmission scheme. To obtain further insights, the asymptotic analysis of the SOP in high average channel power gains regime is presented and it is found that the secrecy diversity order for all the TAS schemes with fixed power allocation is zero. Furthermore, an effective power allocation scheme is proposed to obtain the nonzero diversity order with all the TAS schemes. Monte-Carlo simulations are performed to verify the proposed analytical results.
Stability analysis of cylindrical Vlasov equilibria
Energy Technology Data Exchange (ETDEWEB)
Short, R.W.
1979-01-01
A general method of stability analysis is described which may be applied to a large class of such problems, namely those which are described dynamically by the Vlasov equation, and geometrically by cylindrical symmetry. The method is presented for the simple case of the Vlasov-Poisson (electrostatic) equations, and the results are applied to a calculation of the lower-hybrid-drift instability in a plasma with a rigid rotor distribution function. The method is extended to the full Vlasov-Maxwell (electromagnetic) equations. These results are applied to a calculation of the instability of the extraordinary electromagnetic mode in a relativistic E-layer interacting with a background plasma.
DEFF Research Database (Denmark)
Kumar, Ambuj; Mihovska, Albena Dimitrova; Prasad, Ramjee
2016-01-01
to their respective Base Stations (BS). Moreover, in earlier generations of MCC, antennas were deemed collocated with their respective BSs. Later, the concepts like Distributed Antenna Systems (DAS) and Cloud RAN (C-RAN) made it possible to place these antennas distant from their respective BSs. However, being mapped...... with their respective base stations, spectrum pooling and management at antenna end is not efficient. The situation worsens in Heterogeneous and Dense-net conditions in an Area of Interest (AoI). In this paper, we propose a DAS based intelligent architecture referred to as Self Configurable Intelligent Distributed...... Antenna System (SCIDAS) that can simultaneously accommodate multilayer communication environment over a common BS....
Design and characteristics of a multiband communication satellite antenna system
Ueno, Kenji; Itanami, Takao; Kumazawa, Hiroyuki; Ohtomo, Isao
1995-04-01
Feasibility studies on a multiband communication satellite antenna system and the key technologies involved in devising this system are described. The proposed multiband communication satellite utilizes four frequency bands: Ka (30/20 GHz), Ku (14/12 GHz), C (6/4 GHz), and S (2.6/2.5 GHz). It has six beam configurations, three multibeam and three shaped-beam. The following key technologies are presented: (1) a low-loss frequency selective subreflector (FSR) for compact feeds, (2) a low-loss and broadband frequency selective surface (FSS), and (3) a highly accurate and reliable mesh reflector.
Research on Resistor-Loaded Half-Ellipse Antenna System for GPR Application
Directory of Open Access Journals (Sweden)
Xueping Li
2016-01-01
Full Text Available A resistor-loaded half-ellipse antenna system mounted on a vehicle as a candidate for the exploration of the lunar subsurface is investigated. The antenna system includes two identical half-ellipse antennas, one is used for transmission, and the other is for reception. A resistive loading technique for broadening the bandwidth and improving impulse radiation is introduced. The performance of the proposed antenna with different height above ground surface is studied, and the influence of the vehicle on the antenna is analyzed. Then the antenna is manufactured and mounted on a vehicle as some tests are done. The simulated and measured antenna VSWR and radiation patterns are compared together, and good agreements between them are achieved.
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.
Interrogation zone determination in HF RFID systems with multiplexed antennas*
Directory of Open Access Journals (Sweden)
Jankowski-Mihułowicz Piotr
2015-09-01
Full Text Available The operation of an anti-collision RFID system is characterized by the interrogation zone which should be estimated in any direction of 3D space for a group of electronic transponders. The interrogation zone should be as large as possible. However, the many problems in this area are due to the fact that energy can be transferred to transponders only on a limited distance. The greatest flexibility in developing RFID applications and shaping the interrogation zone can be achieved using the system with an antenna multiplexer. Therefore the problem of the interrogation zone determination in HF RFID systems with two orthogonal RWD antennas is presented in the paper. The perceived issues have been effectively dealt with and the solution has been proposed on the basis of the elaborated model. Conducted studies have been used to develop the software tool JankoRFIDmuxHF in the Mathcad environment. The research results are analysed in an example system configuration. The specialized measuring stand has been used for experimental verification of the identification efficiency. The convergence of the measurements and calculations confirms a practical usefulness of the presented concept of interrogation zone determination in anti-collision systems. It also shows the practical utility of the developed model and software tools.
Hamiltonian formalism of two-dimensional Vlasov kinetic equation.
Pavlov, Maxim V
2014-12-08
In this paper, the two-dimensional Benney system describing long wave propagation of a finite depth fluid motion and the multi-dimensional Russo-Smereka kinetic equation describing a bubbly flow are considered. The Hamiltonian approach established by J. Gibbons for the one-dimensional Vlasov kinetic equation is extended to a multi-dimensional case. A local Hamiltonian structure associated with the hydrodynamic lattice of moments derived by D. J. Benney is constructed. A relationship between this hydrodynamic lattice of moments and the two-dimensional Vlasov kinetic equation is found. In the two-dimensional case, a Hamiltonian hydrodynamic lattice for the Russo-Smereka kinetic model is constructed. Simple hydrodynamic reductions are presented.
Linear Vlasov analysis for stability of a bunched beam
Energy Technology Data Exchange (ETDEWEB)
Warnock, Robert; Stupakov, Gennady; Venturini, Marco; Ellison, James A.
2004-06-30
We study the linearized Vlasov equation for a bunched beam subject to an arbitrary wake function. Following Oide and Yokoya, the equation is reduced to an integral equation expressed in angle-action coordinates of the distorted potential well. Numerical solution of the equation as a formal eigenvalue problem leads to difficulties, because of singular eigenmodes from the incoherent spectrum. We rephrase the equation so that it becomes non-singular in the sense of operator theory, and has only regular solutions for coherent modes. We report on a code that finds thresholds of instability by detecting zeros of the determinant of the system as they enter the upper-half frequency plane, upon increase of current. Results are compared with a time-domain integration of the nonlinear Vlasov equation with a realistic wake function for the SLC damping rings. There is close agreement between the two calculations.
Linear Vlasov Analysis for Stability of a Bunched Beam
Energy Technology Data Exchange (ETDEWEB)
Warnock, R
2004-08-12
The authors study the linearized Vlasov equation for a bunched beam subject to an arbitrary wake function. Following Oide and Yokoya, the equation is reduced to an integral equation expressed in angle-action coordinates of the distorted potential well. Numerical solution of the equation as a formal eigenvalue problem leads to difficulties, because of singular eigenmodes from the incoherent spectrum. The authors rephrase the equation so that it becomes non-singular in the sense of operatory theory, and has only regular solutions for coherent modes. They report on a code that finds thresholds of instability by detecting zeros of the determinant of the system as they enter the upper-half frequency plane, upon increase of current. Results are compared with a time-domain integration of the nonlinear Vlasov equation with a realistic wake function for the SLC damping rings. There is close agreement between the two calculations.
A simple ship-borne antenna stabilizer for limited area maritime satellite communication systems
Satoh, K.; Nakamae, M.; Mishima, H.
1984-10-01
This paper deals with a simple ship-borne antenna stabilizer for use in limited area multi-beam maritime satellite communication systems. A limited area system with high satellite e.i.r.p. is expected to be a more economical satellite system than a global system, because a low-gain ship-borne antenna and a simplified antenna stabilizer can be used. An optimum configuration is proposed for small size and low cost pendulum-type antenna stabilizers which are suitable for low gain ship-borne antennas. Also, a performance evaluation of the stabilizers is discussed using a statistical analysis of ship motion characteristics. Furthermore, fading characteristics of received signal strength due to antenna off-beam fluctuation and sea surface random reflection are experimentally evaluated.
Mark 4A antenna control system data handling architecture study
Briggs, H. C.; Eldred, D. B.
1991-01-01
A high-level review was conducted to provide an analysis of the existing architecture used to handle data and implement control algorithms for NASA's Deep Space Network (DSN) antennas and to make system-level recommendations for improving this architecture so that the DSN antennas can support the ever-tightening requirements of the next decade and beyond. It was found that the existing system is seriously overloaded, with processor utilization approaching 100 percent. A number of factors contribute to this overloading, including dated hardware, inefficient software, and a message-passing strategy that depends on serial connections between machines. At the same time, the system has shortcomings and idiosyncrasies that require extensive human intervention. A custom operating system kernel and an obscure programming language exacerbate the problems and should be modernized. A new architecture is presented that addresses these and other issues. Key features of the new architecture include a simplified message passing hierarchy that utilizes a high-speed local area network, redesign of particular processing function algorithms, consolidation of functions, and implementation of the architecture in modern hardware and software using mainstream computer languages and operating systems. The system would also allow incremental hardware improvements as better and faster hardware for such systems becomes available, and costs could potentially be low enough that redundancy would be provided economically. Such a system could support DSN requirements for the foreseeable future, though thorough consideration must be given to hard computational requirements, porting existing software functionality to the new system, and issues of fault tolerance and recovery.
Vlasov versus N-body: the H\\'enon sphere
Colombi, S; Peirani, S; Plum, G; Suto, Y
2015-01-01
We perform a detailed comparison of the phase-space density traced by the particle distribution in Gadget simulations to the result obtained with a spherical Vlasov solver using the splitting algorithm. The systems considered are apodized H\\'enon spheres with two values of the virial ratio, R ~ 0.1 and 0.5. After checking that spherical symmetry is well preserved by the N-body simulations, visual and quantitative comparisons are performed. In particular we introduce new statistics, correlators and entropic estimators, based on the likelihood of whether N-body simulations actually trace randomly the Vlasov phase-space density. When taking into account the limits of both the N-body and the Vlasov codes, namely collective effects due to the particle shot noise in the first case and diffusion and possible nonlinear instabilities due to finite resolution of the phase-space grid in the second case, we find a spectacular agreement between both methods, even in regions of phase-space where nontrivial physical instabi...
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
Ka-band Dielectric Waveguide Antenna Array for Millimeter Wave Active Imaging System
Fang, Weihai; Fei, Peng; Nian, Feng; Yang, Yujie; Feng, Keming
2014-11-01
Ka-band compact dielectric waveguide antenna array for active imaging system is given. Antenna array with WR28 metal waveguide direct feeding is specially designed with small size, high gain, good radiation pattern, easy realization, low insertion loss and low mutual coupling. One practical antenna array for 3-D active imaging system is shown with theoretic analysis and experimental results. The mutual coupling of transmitting and receiving units is less than -30dB, the gain from 26.5GHz to 40GHz is (12-16) dB. The results in this paper provide guidelines for the designing of millimeter wave dielectric waveguide antenna array.
MIMO channel capacity versus mutual coupling in multi antenna element system
DEFF Research Database (Denmark)
Thaysen, Jesper; Jakobsen, Kaj Bjarne
2004-01-01
capacity, configurations with the lowest envelope correlations are not necessarily the most suitable for a MIMO system. A certain bandwidth is required as well. Three planar inverted F-antennas (PIFA) located on the same 40 mm x 100 mm ground plane. The antennas that haves a resonant frequency of 1.8 GHz......In this paper the influence of mutual coupling on the capacity of a multiple-input multiple-output (MIMO) antenna system is demonstrated. No direct relation between the envelope correlation and the actual location and orientation of the antennas is found. Even though being essential for high MIMO...
Influence of the underlying surface on the antenna system of the ground penetrating radar
Balzovsky, E. V.; Buyanov, Yu I.; Shipilov, S. E.
2017-08-01
Simulation results of the antenna system of the radar of subsurface sounding intended for contactless investigation of the road condition are presented. The elements of the antenna system of ground penetrating radar with extended bandwidth made as a combination of electric and magnetic type radiators have been designed. The transmission coefficient between the elements of the antenna array determining their mutual influence has been calculated. Despite the close arrangement of the elements in the array, the level of mutual influence of the elements is not critical. The developed antenna array can be used both for excitation with short ultrawideband pulses and for frequency steering in the range of 0.8-4 GHz.
A novel paradigm for high isolation in multiple antenna systems with user's influence
DEFF Research Database (Denmark)
Pelosi, Mauro; Pedersen, Gert Frølund; Knudsen, Mikael Bergholz
2010-01-01
(UMTS) bands are investigated, showing also the influence of different hand phantoms in average use trough Finite-Difference TimeDomain (FDTD) simulations. It is confirmed that the way a mobile phone is held is very important in determining the amount of absorption loss, detuning and antenna isolation......In this paper, a novel paradigm is proposed to overcome the limitations posed by conventional small antenna design, exploiting the high isolation potential of narrow-band antenna systems. Several planar inverted-F antennas (PIFAs) operating in different Universal Mobile Telecommunications System...
Numerical GPR Imaging through Directional Antenna Systems in Complex Scenarios
Comite, Davide; Murgia, Federica; Barbara, Martina; Catapano, Ilaria; Soldovieri, Francesco; Galli, Alessandro
2017-04-01
The capability of imaging hidden targets and interfaces in non-accessible and complex scenarios is a topic of increasing interest for several practical applications, such as civil engineering, geophysics, and planetary explorations [1]. In this frame, Ground Penetrating Radar (GPR) has been proven as an efficient and reliable technique, also thanks to the development of effective imaging procedures based on linear modeling of the scattering phenomenon, which is usually considered as activated by ideal sources [1],[2]. Actually, such modeling simplifications are rarely verified in typical operative scenarios, when a number of heterogeneous targets can interact each other and with the surrounding environment, producing undesired contributions such as clutter and ghosts targets. From a physical viewpoint, these phenomena are mainly due to multipath contributions at the receiving antenna system, and different solutions have been proposed to mitigate these effects on the final image reconstruction (see, e.g., [2] and references therein). In this work we investigate on the possible improvements achievable when the directional features of the transmitting antenna system are taken into account in the imaging algorithm. Following and extending the recent investigations illustrated in [2] and [3], we consider in particular arrays of antennas, made by arbitrary types of elements, as activating the scattering phenomenon: hence, the effects of neglecting or accounting for the inherent directional radiation of the considered array are investigated as regards the accuracy of the final reconstruction of targets. Taking into account the resolution losses linked to the relevant synthetic aperture, we analyze the possibility of improving the quality of imaging, mitigating the presence of spurious contributions. By implementing a 'synthetic setup' that analyzes the scenarios under test through different electromagnetic CAD tools (mainly CST Microwave Studio and gprMax), it has been
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).
Integer lattice dynamics for Vlasov-Poisson
Mocz, Philip; Succi, Sauro
2017-03-01
We revisit the integer lattice (IL) method to numerically solve the Vlasov-Poisson equations, and show that a slight variant of the method is a very easy, viable, and efficient numerical approach to study the dynamics of self-gravitating, collisionless systems. The distribution function lives in a discretized lattice phase-space, and each time-step in the simulation corresponds to a simple permutation of the lattice sites. Hence, the method is Lagrangian, conservative, and fully time-reversible. IL complements other existing methods, such as N-body/particle mesh (computationally efficient, but affected by Monte Carlo sampling noise and two-body relaxation) and finite volume (FV) direct integration schemes (expensive, accurate but diffusive). We also present improvements to the FV scheme, using a moving-mesh approach inspired by IL, to reduce numerical diffusion and the time-step criterion. Being a direct integration scheme like FV, IL is memory limited (memory requirement for a full 3D problem scales as N6, where N is the resolution per linear phase-space dimension). However, we describe a new technique for achieving N4 scaling. The method offers promise for investigating the full 6D phase-space of collisionless systems of stars and dark matter.
Impact of WCDMA channel multiplexing on smart antenna systems
Institute of Scientific and Technical Information of China (English)
戎璐; 谢剑英; 支小莉
2004-01-01
Smart antenna has been regarded as one promising technology to enhance the performance of CDMA mobile communication systems. However, when applied to 3G systems, the performance of traditional adaptive arrays may degrade due to code and time multiplexing in dedicated physical channels. A novel semiblind adaptive array approach is proposed to solve this problem. It overcomes the self-interfering problem by introducing a quasi-despreading technique for the control channel, and contains a time-multipexed structure to utilize both pilot symbols and unknown control symbols within the control channel. The blind part of the proposed approach is based on the competition of two parallel branches with different reference sequences. Simulation results show significant improvement can be achieved by the proposed approach in a fast-fading WCDMA environment.
Leaky-Wave Slot Array Antenna Fed by a Dual Reflector System
Maci, S.; Ettorre, M.; Neto, A.; Gerini, G.
2008-01-01
A leaky-wave slot array antenna fed by a dual offset Gregorian reflector system is realized by pins in a parallel plate waveguide. The radiating part of the antenna is composed by parallel slots etched on one side of the same parallel plate waveguide. The dual offset Gregorian reflector system is fe
A Dual-Band Antenna for RF Energy Harvesting Systems in Wireless Sensor Networks
Directory of Open Access Journals (Sweden)
A. Bakkali
2016-01-01
Full Text Available In this paper, we focus on ambient radio frequency energy available from commercial broadcasting stations in order to provide a system based on RF energy harvesting using a new design of receiving antenna. Several antenna designs have been proposed for use in RF energy harvesting systems, as a pertinent receiving antenna design is highly required since the antenna features can affect the amount of energy harvested. The proposed antenna is aimed at greatly increasing the energy harvesting efficiency over Wi-Fi bands: 2.45 GHz and 5 GHz. This provides a promising alternative energy source in order to power sensors located in harsh environments or remote places, where other energy sources are impracticable. The dual-band antenna can be easily integrated with RF energy harvesting system on the same circuit board. Simulations and measurements were carried out to evaluate the antenna performances and investigate the effects of different design parameters on the antenna performance. The receiving antenna meets the required bandwidth specification and provides peak gain of more than 4 dBi across the operating band.
Low complexity transmit antenna selection with power balancing in OFDM systems
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.
A TRIBAND SWASTIKA SHAPED PATCH ANTENNA WITH REDUCED MUTUAL COUPLING FOR WIRELESS MIMO SYSTEMS
Institute of Scientific and Technical Information of China (English)
K Jagadeesh Babu; K Sri Ramakrishna; L Pratap Reddy
2011-01-01
A novel compact Swastika shaped patch antenna is designed in the present work,which can be used for Multiple Input Multiple Output (MIMO) systems.The proposed two element MIMO system resonates at a triband of 3.3 GHz,5.8 GHz,and 7.1 GHz with an improved impedance bandwidth of 37％ and a reduced mutual coupling of -33 dB.These results are better compared to a normal E shaped patch antenna designed with same size and thickness,achieved without using any additional decoupling methods.A 2 × 2 MIMO system employing the Swastika shaped patch antennas is analyzed using computational electromagnetic ray tracing software for an indoor environment.The results show an improvement in the capacity compared to a 2 × 2 MIMO system developed with dipole antennas.The proposed antenna is a good choice for MIMO systems operating for several Ultra WideBand (UWB) applications.
Vlasov simulations of parallel potential drops
Directory of Open Access Journals (Sweden)
H. Gunell
2013-07-01
Full Text Available An auroral flux tube is modelled from the magnetospheric equator to the ionosphere using Vlasov simulations. Starting from an initial state, the evolution of the plasma on the flux tube is followed in time. It is found that when applying a voltage between the ends of the flux tube, about two thirds of the potential drop is concentrated in a thin double layer at approximately one Earth radius altitude. The remaining part is situated in an extended region 1–2 Earth radii above the double layer. Waves on the ion timescale develop above the double layer, and they move toward higher altitude at approximately the ion acoustic speed. These waves are seen both in the electric field and as perturbations of the ion and electron distributions, indicative of an instability. Electrons of magnetospheric origin become trapped between the magnetic mirror and the double layer during its formation. At low altitude, waves on electron timescales appear and are seen to be non-uniformly distributed in space. The temporal evolution of the potential profile and the total voltage affect the double layer altitude, which decreases with an increasing field aligned potential drop. A current–voltage relationship is found by running several simulations with different voltages over the system, and it agrees with the Knight relation reasonably well.
Vlasov-Poisson in 1D: waterbags
Colombi, Stéphane
2014-01-01
We revisit in one dimension the waterbag method to solve numerically Vlasov-Poisson equations. In this approach, the phase-space distribution function $f(x,v)$ is initially sampled by an ensemble of patches, the waterbags, where $f$ is assumed to be constant. As a consequence of Liouville theorem it is only needed to follow the evolution of the border of these waterbags, which can be done by employing an orientated, self-adaptive polygon tracing isocontours of $f$. This method, which is entropy conserving in essence, is very accurate and can trace very well non linear instabilities as illustrated by specific examples. As an application of the method, we generate an ensemble of single waterbag simulations with decreasing thickness, to perform a convergence study to the cold case. Our measurements show that the system relaxes to a steady state where the gravitational potential profile is a power-law of slowly varying index $\\beta$, with $\\beta$ close to $3/2$ as found in the literature. However, detailed analys...
Integer Lattice Dynamics for Vlasov-Poisson
Mocz, Philip
2016-01-01
We revisit the integer lattice (IL) method to numerically solve the Vlasov-Poisson equations, and show that a slight variant of the method is a very easy, viable, and efficient numerical approach to study the dynamics of self-gravitating, collisionless systems. The distribution function lives in a discretized lattice phase-space, and each time-step in the simulation corresponds to a simple permutation of the lattice sites. Hence, the method is Lagrangian, conservative, and fully time-reversible. IL complements other existing methods, such as N-body/particle mesh (computationally efficient, but affected by Monte-Carlo sampling noise and two-body relaxation) and finite volume (FV) direct integration schemes (expensive, accurate but diffusive). We also present improvements to the FV scheme, using a moving mesh approach inspired by IL, to reduce numerical diffusion and the time-step criterion. Being a direct integration scheme like FV, IL is memory limited (memory requirement for a full 3D problem scales as N^6, ...
Solving the Vlasov equation in complex geometries
Directory of Open Access Journals (Sweden)
Sonnendrücker E.
2011-11-01
Full Text Available This paper introduces an isoparametric analysis to solve the Vlasov equation with a semi-Lagrangian scheme. A Vlasov-Poisson problem modeling a heavy ion beam in an axisymmetric configuration is considered. Numerical experiments are conducted on computational meshes targeting different geometries. The impact of the computational grid on the accuracy and the computational cost are shown. The use of analytical mapping or Bézier patches does not induce a too large computational overhead and is quite accurate. This approach successfully couples an isoparametric analysis with a semi-Lagrangian scheme, and we expect to apply it to a gyrokinetic Vlasov solver. Nous présentons ici une analyse isoparamétrique pour résoudre l’équation de Vlasov à l’aide d’un schéma Semi-Lagrangien. Le cas test d’un faisceau axisymétrique d’ions lourds est étudié dans le cadre du système Vlasov-Poisson. Des tests numériques sont effectués sur différents maillages a fin d’étudier diverses géométries. L’impact du choix de maillage sur la précision numérique et le coût de calcul est quantifié. L’utilisation de mapping analytique ou de patches de Bézier ne semble pas trop coûteux et permet une précision numérique suffisante. Le couplage de l’analyse isoparamétrique au schéma Semi-Lagrangien est donc réeussi, nous espérons pouvoir appliquer cette méthode à des solveurs de l’équation de Vlasov gyrocinétique.
Implementing Smart Antenna System in Mobile Ad Hoc Networks
Directory of Open Access Journals (Sweden)
Supriya Kulkarni P
2014-06-01
Full Text Available As the necessity of exchanging and sharing data increases, users demand easy connectivity, and fast networks whether they are at work, at home, or on the move. Nowadays, users are interested in interconnecting all their personal electronic devices (PEDs in an ad hoc fashion on the move. This type of network is referred to as Mobile Ad hoc NETwork (MANET. When in such network a smart antenna System (SAS is implemented then we can achieve maximum capacity and improve the quality and coverage. So we are intended to implement such a SAS in the MANET. In this paper we have shown significance of Throughput and Bit Error Rate by implementing SAS in MANET using MATLABR2010a.
An active reflector antenna using a laser angle metrology system
Institute of Scientific and Technical Information of China (English)
Yong Zhang; Jie Zhang; De-Hua Yang; Guo-Hua Zhou; Ai-Hua Li; Guo-Ping Li
2012-01-01
An active reflector is one of the key technologies for constructing large telescopes,especially for millimeter/sub-millimeter radio telescopes.This article introduces a new efficient laser angle metrology system for an active reflector antenna on large radio telescopes.Our experiments concentrate on developing an active reflector for improving the detection precisions and the maintenance of the surface shape in real time on the 65-meter prototype radio telescope constructed by Nanjing Institute of Astronomical Optics and Technology (NIAOT; http://65m.shao.cas.cn/).The test results indicate that the accuracy of the surface shape segmentation and maintenance has the dimensions of microns,and the time-response can be on the order of minutes.Our efforts proved to be workable for sub-millimeter radio telescopes.
Microcomputer design and analysis of the cable catenary large space antenna system
Akle, W.
1984-01-01
The use of microcomputers in the design of a cable catenary large space antenna system is discussed. The development of a system design capability, data base utilization, systems integration, program structure and logic, and integrated graphics output are discussed.
Kinetic Boltzmann, Vlasov and Related Equations
Sinitsyn, Alexander; Vedenyapin, Victor
2011-01-01
Boltzmann and Vlasov equations played a great role in the past and still play an important role in modern natural sciences, technique and even philosophy of science. Classical Boltzmann equation derived in 1872 became a cornerstone for the molecular-kinetic theory, the second law of thermodynamics (increasing entropy) and derivation of the basic hydrodynamic equations. After modifications, the fields and numbers of its applications have increased to include diluted gas, radiation, neutral particles transportation, atmosphere optics and nuclear reactor modelling. Vlasov equation was obtained in
Directory of Open Access Journals (Sweden)
Jianfeng Zheng
2012-01-01
Full Text Available This paper is aimed at studying the impacts of mutual coupling, matching networks, and polarization of antennas on performances of Multiple-Input Multiple-Output (MIMO systems employing Spatial Multiplexing (SM. In particular, the uncoded average Bit Error Rate (BER of MIMO systems is investigated. An accurate signal analysis framework based on circuit network parameters is presented to describe the transmit/receive characteristics of the matched/unmatched antenna array. The studied arrays consist of matched/unmatched compact copolarization and polarization diversity antenna array. Monte-Carlo numerical simulations are used to study the BER performances of the SM MIMO systems using maximum-likelihood and/or zero-forcing detection schemes. The simulation results demonstrate that the use of matching networks can improve the BER performance of SM MIMO systems significantly, and the BER performance deterioration due to antenna orientation randomness can be compensated by use of polarization diversity antenna arrays.
Diversity and MIMO Performance Evaluation of Common Phase Center Multi Element Antenna Systems
Directory of Open Access Journals (Sweden)
V. Papamichael
2008-06-01
Full Text Available The diversity and Multiple Input Multiple Output (MIMO performance provided by common phase center multi element antenna (CPCMEA systems is evaluated using two practical methods which make use of the realized active element antenna patterns. These patterns include both the impact of the mutual coupling and the mismatch power loss at antenna ports. As a case study, two and four printed Inverted F Antenna (IFA systems are evaluated by means of Effective Diversity Gain (EDG and Capacity (C. EDG is measured in terms of the signal-to-noise ratio (SNR enhancement at a specific outage probability and in terms of the SNR reduction for achieving a desired average bit error rate (BER. The concept of receive antenna selection in MIMO systems is also investigated and the simulation results show a 43% improvement in the 1% outage C of a reconfigurable 2x2 MIMO system over a fixed 2x2 one.
Analysis, design and implementation of Front-End Reconfigurable Antenna Systems (FERAS)
Tawk, Youssef Antoine
2011-12-01
The increase in demand on reconfigurable systems and especially for wireless communications applications has stressed the need for smart and agile RF devices that sense and respond to the RF changes in the environment. Many different applications require frequency agility with software control ability such as in a cognitive radio environment where antenna systems have to be designed to fulfill the extendable and reconfigurable multi-service and multi-band requirements. Such applications increase spectrum efficiency as well as the power utilization in modern wireless systems. The emphasis of this dissertation revolves around the following question: "Is it possible to come up with new techniques to achieve reconfigurable antenna systems with better performance?" Two main branches constitute the outline of this work. The first one is based on the design of reconfigurable antennas by incorporating photoconductive switching elements in order to change the antenna electrical properties. The second branch relies on the change in the physical structure of the antenna via a rotational motion. In this work a new photoconductive switch is designed with a new light delivery technique. This switch is incorporated into new optically pumped reconfigurable antenna systems (OPRAS). The implementation of these antenna systems in applications such as cognitive radio is demonstrated and discussed. A new radio frequency (RF) technique for measuring the semiconductor carrier lifetime using optically reconfigurable transmission lines is proposed. A switching time investigation for the OPRAS is also accomplished to better cater for the cognitive radio requirements. Moreover, different reconfiguration mechanisms are addressed such as physical alteration of antenna parts via a rotational motion. This technique is supported by software to achieve a complete controlled rotatable reconfigurable cognitive radio antenna system. The inter-correlation between neural networks and cellular automata
Flexible, Polarization-Diverse UWB Antennas for Implantable Neural Recording Systems.
Bahrami, Hadi; Mirbozorgi, S Abdollah; Ameli, Reza; Rusch, Leslie A; Gosselin, Benoit
2016-02-01
Implanted antennas for implant-to-air data communications must be composed of material compatible with biological tissues. We design single and dual-polarization antennas for wireless ultra-wideband neural recording systems using an inhomogeneous multi-layer model of the human head. Antennas made from flexible materials are more easily adapted to implantation; we investigate both flexible and rigid materials and examine performance trade-offs. The proposed antennas are designed to operate in a frequency range of 2-11 GHz (having S11 below -10 dB) covering both the 2.45 GHz (ISM) band and the 3.1-10.6 GHz UWB band. Measurements confirm simulation results showing flexible antennas have little performance degradation due to bending effects (in terms of impedance matching). Our miniaturized flexible antennas are 12 mm×12 mm and 10 mm×9 mm for single- and dual-polarizations, respectively. Finally, a comparison is made of four implantable antennas covering the 2-11 GHz range: 1) rigid, single polarization, 2) rigid, dual polarization, 3) flexible, single polarization and 4) flexible, dual polarization. In all cases a rigid antenna is used outside the body, with an appropriate polarization. Several advantages were confirmed for dual polarization antennas: 1) smaller size, 2) lower sensitivity to angular misalignments, and 3) higher fidelity.
Bit and Power Loading Approach for Broadband Multi-Antenna OFDM System
DEFF Research Database (Denmark)
Rahman, Muhammad Imadur; Das, Suvra S.; Wang, Yuanye
2007-01-01
In this work, we have studied bit and power allocation strategies for multi-antenna assisted Orthogonal Frequency Division Multiplexing (OFDM) systems and investigated the impact of different rates of bit and power allocations on various multi-antenna diversity schemes. It is observed that, if we...... allocations across OFDM sub-channels are required together for efficient exploitation of wireless channel....
Paynter, C.; Cuchanski, M.
1995-01-01
The paper discusses various aspects of the system design for a satellite in a highly elliptical inclined orbit, and presents a number of antenna design options for the proposed Archimedes mission. A satellite constellation was studied for the provision of multi media communication services in the L and S Band for northern latitudes. The inclined elliptical orbit would allow coverage of Europe, America, and East Asia. Using Canada and North America as the baseline coverage area, this paper addresses system considerations such as the satellite configuration and pointing, beam configuration, and requirements for antennas. A trade-off is performed among several antenna candidates including a direct radiating array, a focal-fed reflector, and a single reflector imaging system. Antenna geometry, performance, and beam forming methods are described. The impact of the designs on the antenna deployment is discussed.
Reconfigurable Antennas for High Data Rate Multi-beam Communication Systems
Bernhard, Jennifer T.; Michielssen, Eric
2005-01-01
High-speed (2-100 Mb/sec) wireless data communication - whether land- or satellite-based - faces a major challenge: high error rates caused by interference and unpredictable environments. A planar antenna system that can be reconfigured to respond to changing conditions has the potential to dramatically improve data throughput and system reliability. Moreover, new planar antenna designs that reduce array size, weight, and cost can have a significant impact on terrestrial and satellite communication system performance. This research developed new individually-reconfigurable planar antenna array elements that can be adjusted to provide multiple beams while providing increased scan angles and higher aperture efficiency than traditional diffraction-limited arrays. These new elements are microstrip spiral antennas with specialized tuning mechanisms that provide adjustable radiation patterns. We anticipate that these new elements can be used in both large and small arrays for inter-satellite communication as well as tracking of multiple mobile surface-based units. Our work has developed both theoretical descriptions as well as experimental prototypes of the antennas in both single element and array embodiments. The technical summary of the results of this work is divided into six sections: A. Cavity model for analysis and design of pattern reconfigurable antennas; B. Performance of antenna in array configurations for broadside and endfire operation; C. Performance of antenna in array configurations for beam scanning operation; D. Simulation of antennas in infinite phased arrays; E. Demonstration of antenna with commercially-available RF MEMS switches; F. Design of antenna MEMS switch combinations for direct simultaneous fabrication.
Integration of Directional Antennas in an RSS Fingerprinting-Based Indoor Localization System.
Guzmán-Quirós, Raúl; Martínez-Sala, Alejandro; Gómez-Tornero, José Luis; García-Haro, Joan
2015-12-23
In this paper, the integration of directional antennas in a room-level received signal strength (RSS) fingerprinting-based indoor localization system (ILS) is studied. The sensor reader (SR), which is in charge of capturing the RSS to infer the tag position, can be attached to an omnidirectional or directional antenna. Unlike commonly-employed omnidirectional antennas, directional antennas can receive a stronger signal from the direction in which they are pointed, resulting in a different RSS distributions in space and, hence, more distinguishable fingerprints. A simulation tool and a system management software have been also developed to control the system and assist the initial antenna deployment, reducing time-consuming costs. A prototype was mounted in a real scenario, with a number of SRs with omnidirectional and directional antennas properly positioned. Different antenna configurations have been studied, evidencing a promising capability of directional antennas to enhance the performance of RSS fingerprinting-based ILS, reducing the number of required SRs and also increasing the localization success.
Information-Theoretic Limits on Broadband Multi-Antenna Systems in the Presence of Mutual Coupling
Taluja, Pawandeep Singh
2011-12-01
Multiple-input, multiple-output (MIMO) systems have received considerable attention over the last decade due to their ability to provide high throughputs and mitigate multipath fading effects. While most of these benefits are obtained for ideal arrays with large separation between the antennas, practical devices are often constrained in physical dimensions. With smaller inter-element spacings, signal correlation and mutual coupling between the antennas start to degrade the system performance, thereby limiting the deployment of a large number of antennas. Various studies have proposed transceiver designs based on optimal matching networks to compensate for this loss. However, such networks are considered impractical due to their multiport structure and sensitivity to the RF bandwidth of the system. In this dissertation, we investigate two aspects of compact transceiver design. First, we consider simpler architectures that exploit coupling between the antennas, and second, we establish information-theoretic limits of broadband communication systems with closely-spaced antennas. We begin with a receiver model of a diversity antenna selection system and propose novel strategies that make use of inactive elements by virtue of mutual coupling. We then examine the limits on the matching efficiency of a single antenna system using broadband matching theory. Next, we present an extension to this theory for coupled MIMO systems to elucidate the impact of coupling on the RF bandwidth of the system, and derive optimal transceiver designs. Lastly, we summarize the main findings of this dissertation and suggest open problems for future work.
Jiang, Ping; Yang, Huajun; Mao, Shengqian
2015-10-05
A Cassegrain antenna system and an optical fiber coupling system which consists of a plano-concave lens and a plano-convex lens are designed based on the vector theory of reflection and refraction, so as to improve the transmission performance of the optical antenna and fiber coupling system. Three-dimensional ray tracing simulation are performed and results of the optical aberrations calculation and the experimental test show that the aberrations caused by on-axial defocusing, off-axial defocusing and deflection of receiving antenna can be well corrected by the optical fiber coupling system.
Hamiltonian particle-in-cell methods for Vlasov-Maxwell equations
He, Yang; Qin, Hong; Liu, Jian
2016-01-01
In this paper, we develop Hamiltonian particle-in-cell methods for Vlasov-Maxwell equations by applying conforming finite element methods in space and splitting methods in time. For the spatial discretisation, the criteria for choosing finite element spaces are presented such that the semi-discrete system possesses a discrete non-canonical Poisson structure. We apply a Hamiltonian splitting method to the semi-discrete system in time, then the resulting algorithm is Poisson preserving and explicit. The conservative properties of the algorithm guarantee the efficient and accurate numerical simulation of the Vlasov-Maxwell equations over long-time.
Hydrodynamic limits of the Vlasov equation
Energy Technology Data Exchange (ETDEWEB)
Caprino, S. (Universita' de L' Aquila Coppito (Italy)); Esposito, R.; Marra, R. (Universita' di Roma tor Vergata, Roma (Italy)); Pulvirenti, M. (Universita' di Roma la Sapienza, Roma (Italy))
1993-01-01
In the present work, the authors study the Vlasov equation for repulsive forces in the hydrodynamic regime. For initial distributions at zero temperature the limit equations turn out to be the compressible and incompressible Euler equations under suitable space-time scalings. 17 refs.
Irreversible energy flow in forced Vlasov dynamics
Plunk, Gabriel G.
2014-10-01
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag. The recent paper of Plunk [G.G. Plunk, Phys. Plasmas 20, 032304 (2013)] considered the forced linear Vlasov equation as a model for the quasi-steady state of a single stable plasma wavenumber interacting with a bath of turbulent fluctuations. This approach gives some insight into possible energy flows without solving for nonlinear dynamics. The central result of the present work is that the forced linear Vlasov equation exhibits asymptotically zero (irreversible) dissipation to all orders under a detuning of the forcing frequency and the characteristic frequency associated with particle streaming. We first prove this by direct calculation, tracking energy flow in terms of certain exact conservation laws of the linear (collisionless) Vlasov equation. Then we analyze the steady-state solutions in detail using a weakly collisional Hermite-moment formulation, and compare with numerical solution. This leads to a detailed description of the Hermite energy spectrum, and a proof of no dissipation at all orders, complementing the collisionless Vlasov result.
Antenna System for Nano-satelite Mission GOMX-3
DEFF Research Database (Denmark)
Tatomirescu, Alexandru; Pedersen, Gert F.; Christiansen, J.
2016-01-01
In this paper, we present the antenna design for a nano-satellite mission launched in September, the GOMX-3 mission. Some of the key design challenges are discussed and the chosen solutions are presented. In an effort to minimize development and manufacturing costs for future missions, this study...... shows how to modify off the shelf components in order to tailor them to the specifications of the mission at hand. The performance of the antenna is increased by up to 1.4 dB with a simple modification to adjust the resonance frequency. The antenna system’s performance is investigated through simulation...
The Digital Motion Control System for the Submillimeter Array Antennas
Hunter, T R; Kimberk, R; Leiker, P S; Patel, N A; Blundell, R; Christensen, R D; Diven, A R; Maute, J; Plante, R J; Riddle, P; Young, K H
2013-01-01
We describe the design and performance of the digital servo and motion control system for the 6-meter diameter parabolic antennas of the Submillimeter Array (SMA) on Mauna Kea, Hawaii. The system is divided into three nested layers operating at a different, appropriate bandwidth. (1) A rack-mounted, real-time Unix system runs the position loop which reads the high resolution azimuth and elevation encoders and sends velocity and acceleration commands at 100 Hz to a custom-designed servo control board (SCB). (2) The microcontroller-based SCB reads the motor axis tachometers and implements the velocity loop by sending torque commands to the motor amplifiers at 558 Hz. (3) The motor amplifiers implement the torque loop by monitoring and sending current to the three-phase brushless drive motors at 20 kHz. The velocity loop uses a traditional proportional-integral-derivative (PID) control algorithm, while the position loop uses only a proportional term and implements a command shaper based on the Gauss error functi...
ICRF antenna matching systems with ferrite tuners for the Alcator C-Mod tokamak
Energy Technology Data Exchange (ETDEWEB)
Lin, Y., E-mail: ylin@psfc.mit.edu; Binus, A.; Wukitch, S.J.; Koert, P.; Murray, R.; Pfeiffer, A.
2015-11-15
Highlights: • We have developed a fast ferrite tuner (FFT) based antenna matching system. • The FFT system works well on the ICRF antennas on the Alcator C-Mod tokamak. • The FFT system maintains <1% RF power reflection for most plasma discharges. • The FFT system can deal with plasma transients. • The FFT system can handle high RF power operation. - Abstract: Real-time fast ferrite tuning (FFT) has been successfully implemented on the ICRF antennas on Alcator C-Mod. The former prototypical FFT system on the E-port 2-strap antenna has been upgraded using new ferrite tuners. A new FFT system with two ferrite tuners and one fixed-length stub has been installed on the transmission line of the D-port 2-strap antenna. These two systems are able to achieve and maintain the reflected power to the transmitters to less than 1% in real time under almost all plasma conditions and help ensure reliable high power operation of the antennas. The loading insensitivity feature vs. plasma conditions of the innovative field-aligned (FA) 4-strap antenna on the J-port allows us to significantly improve the matching by installing a carefully designed stub on each of the two transmission lines. The reduction of the RF voltages in the transmission lines has enabled the J-port FA antenna to deliver 3.7 MW RF power to plasmas out of 4 MW source power. The matching on the J-port antenna can be further improved by adding a single ferrite tuner under real-time control on each transmission line and this scheme will be implemented in the near future.
Numerical solution to the Vlasov equation: The 2D code
Fijalkow, Eric
1999-02-01
The present code solves the two-dimensional Vlasov equation for a periodic in space system, in presence of an external magnetic field B O. The self coherent electric field given by Poisson equation is computed by Fast Fourier Transform (FFT). The output of the code consist of a list of diagnostics, such as total mass conservation, total momentum and energies, and of projections of the distribution function in different subspaces as the x- v x space, the x- y space and so on.
Transient growth of a Vlasov plasma in a weakly inhomogeneous magnetic field
Ratushnaya, Valeria
2016-12-17
We investigate the stability properties of a collisionless Vlasov plasma in a weakly inhomogeneous magnetic field using non-modal stability analysis. This is an important topic in a physics of tokamak plasma rich in various types of instabilities. We consider a thin tokamak plasma in a Maxwellian equilibrium, subjected to a small arbitrary perturbation. Within the framework of kinetic theory, we demonstrate the emergence of short time scale algebraic instabilities evolving in a stable magnetized plasma. We show that the linearized governing operator (Vlasov operator) is non-normal leading to the transient growth of the perturbations on the time scale of several plasma periods that is subsequently followed by Landau damping. We calculate the first-order distribution function and the electric field and study the dependence of the transient growth characteristics on the magnetic field strength and perturbation parameters of the system. We compare our results with uniformly magnetized plasma and field-free Vlasov plasma.
Transient growth of a Vlasov plasma in a weakly inhomogeneous magnetic field
Ratushnaya, Valeria; Samtaney, Ravi
2016-12-01
We investigate the stability properties of a collisionless Vlasov plasma in a weakly inhomogeneous magnetic field using non-modal stability analysis. This is an important topic in a physics of tokamak plasma rich in various types of instabilities. We consider a thin tokamak plasma in a Maxwellian equilibrium, subjected to a small arbitrary perturbation. Within the framework of kinetic theory, we demonstrate the emergence of short time scale algebraic instabilities evolving in a stable magnetized plasma. We show that the linearized governing operator (Vlasov operator) is non-normal leading to the transient growth of the perturbations on the time scale of several plasma periods that is subsequently followed by Landau damping. We calculate the first-order distribution function and the electric field and study the dependence of the transient growth characteristics on the magnetic field strength and perturbation parameters of the system. We compare our results with uniformly magnetized plasma and field-free Vlasov plasma.
Relativistic Vlasov-Maxwell modelling using finite volumes and adaptive mesh refinement
Wettervik, Benjamin Svedung; Siminos, Evangelos; Fülöp, Tünde
2016-01-01
The dynamics of collisionless plasmas can be modelled by the Vlasov-Maxwell system of equations. An Eulerian approach is needed to accurately describe processes that are governed by high energy tails in the distribution function, but is of limited efficiency for high dimensional problems. The use of an adaptive mesh can reduce the scaling of the computational cost with the dimension of the problem. Here, we present a relativistic Eulerian Vlasov-Maxwell solver with block-structured adaptive mesh refinement in one spatial and one momentum dimension. The discretization of the Vlasov equation is based on a high-order finite volume method. A flux corrected transport algorithm is applied to limit spurious oscillations and ensure the physical character of the distribution function. We demonstrate a speed-up by a factor of five, because of the use of an adaptive mesh, in a typical scenario involving laser-plasma interaction in the self-induced transparency regime.
A New Class of Non-Linear, Finite-Volume Methods for Vlasov Simulation
Energy Technology Data Exchange (ETDEWEB)
Banks, J W; Hittinger, J A
2009-11-24
Methods for the numerical discretization of the Vlasov equation should efficiently use the phase space discretization and should introduce only enough numerical dissipation to promote stability and control oscillations. A new high-order, non-linear, finite-volume algorithm for the Vlasov equation that discretely conserves particle number and controls oscillations is presented. The method is fourth-order in space and time in well-resolved regions, but smoothly reduces to a third-order upwind scheme as features become poorly resolved. The new scheme is applied to several standard problems for the Vlasov-Poisson system, and the results are compared with those from other finite-volume approaches, including an artificial viscosity scheme and the Piecewise Parabolic Method. It is shown that the new scheme is able to control oscillations while preserving a higher degree of fidelity of the solution than the other approaches.
Electrical alignment of antenna coordinate system in a planar near-field setup
DEFF Research Database (Denmark)
Mynster, Anders P.; Nielsen, Jeppe Majlund; Pivnenko, Sergey
2011-01-01
In this paper, a simple and efficient electrical alignment procedure known as flip-test is adapted and applied to check and correct two errors in the mechanical setup of a planar near-field system: the mis-pointing of the z-axis of the antenna coordinate system with respect to the scan plane...... and the displacement of the center point of the scan plane with respect to the z-axis of the antenna coordinate system. Simulations of the errors and their correction algorithms were carried out with different models of antennas composed of Hertzian dipoles and an optimum algorithm was then selected. The proposed...
Antenna-load interactions at optical frequencies: impedance matching to quantum systems.
Olmon, R L; Raschke, M B
2012-11-09
resonance, (ii) subsequent transformation of that mode into a nanoscale spatial localization, and (iii) near-field coupling via an enhanced local density of states to a quantum load. These three steps define the goal of efficient transformation of incident radiation into a quantum excitation in an impedance-matched fashion. We review the physical basis of the light-matter interaction at the transition from the RF to optical regime, discuss the extension of antenna theory as needed for the design of impedance-matched optical antenna-load coupled systems, and provide several examples of the state of the art in design strategies and suggest future extensions. We furthermore suggest new performance metrics based on the combination of electric vector field, field enhancement and capture cross section measurement to aid in comparison between different antenna designs and optimization of optical antenna performance within the physical parameter space.
Analysis of a generalized dual reflector antenna system using physical optics
Acosta, Roberto J.; Lagin, Alan R.
1992-01-01
Reflector antennas are widely used in communication satellite systems because they provide high gain at low cost. Offset-fed single paraboloids and dual reflector offset Cassegrain and Gregorian antennas with multiple focal region feeds provide a simple, blockage-free means of forming multiple, shaped, and isolated beams with low sidelobes. Such antennas are applicable to communications satellite frequency reuse systems and earth stations requiring access to several satellites. While the single offset paraboloid has been the most extensively used configuration for the satellite multiple-beam antenna, the trend toward large apertures requiring minimum scanned beam degradation over the field of view 18 degrees for full earth coverage from geostationary orbit may lead to impractically long focal length and large feed arrays. Dual reflector antennas offer packaging advantages and more degrees of design freedom to improve beam scanning and cross-polarization properties. The Cassegrain and Gregorian antennas are the most commonly used dual reflector antennas. A computer program for calculating the secondary pattern and directivity of a generalized dual reflector antenna system was developed and implemented at LeRC. The theoretical foundation for this program is based on the use of physical optics methodology for describing the induced currents on the sub-reflector and main reflector. The resulting induced currents on the main reflector are integrated to obtain the antenna far-zone electric fields. The computer program is verified with other physical optics programs and with measured antenna patterns. The comparison shows good agreement in far-field sidelobe reproduction and directivity.
ICRF antenna matching system with ferrite tuners for the Alcator C-Mod tokamak
Lin, Y.; Binus, A.; Wukitch, S. J.; Koert, P.; Murray, R.; Pfeiffer, A.
2015-12-01
Real-time fast ferrite tuning (FFT) has been successfully implemented on the ICRF antennas on Alcator C-Mod. The former prototypical FFT system on the E-port 2-strap antenna has been upgraded using new ferrite tuners that have been designed specifically for the operational parameters of the Alcator C-Mod ICRF system (˜ 80 MHz). Another similar FFT system, with two ferrite tuners and one fixed-length stub, has been installed on the transmission line of the D-port 2-strap antenna. These two systems share a Linux-server-based real-time controller. These FFT systems are able to achieve and maintain the reflected power to the transmitters to less than 1% in real time during the plasma discharges under almost all plasma conditions, and help ensure reliable high power operation of the antennas. The innovative field-aligned (FA) 4-strap antenna on J-port has been found to have an interesting feature of loading insensitivity vs. plasma conditions. This feature allows us to significantly improve the matching for the FA J-port antenna by installing carefully designed stubs on the two transmission lines. The reduction of the RF voltages in the transmission lines has enabled the FA J-port antenna to deliver 3.7 MW RF power to plasmas out of the 4 MW source power in high performance I-mode plasmas.
A New Agile Radiating System Called Electromagnetic Band Gap Matrix Antenna
Directory of Open Access Journals (Sweden)
Hussein Abou Taam
2014-01-01
Full Text Available Civil and military applications are increasingly in need for agile antenna devices which respond to wireless telecommunications, radars, and electronic warfare requirements. The objective of this paper is to design a new agile antenna system called electromagnetic band gap (EBG matrix. The working principle of this antenna is based on the radiating aperture theory and constitutes the subject of an accepted CNRS patent. In order to highlight the interest and the originality of this antenna, we present a comparison between it and a classical patch array only for the (one-dimensional 1D configuration by using a rigorous full wave simulation (CST Microwave software. In addition, EBG matrix antenna can be controlled by specific synthesis algorithms. These algorithms use inside their; optimization loop an analysis procedure to evaluate the radiation pattern. The analysis procedure is described and validated at the end of this paper.
PhantomNet: Exploring Optimal Multicellular Multiple Antenna Systems
Directory of Open Access Journals (Sweden)
Foschini Gerard J
2004-01-01
Full Text Available We present a network framework for evaluating the theoretical performance limits of wireless data communication. We address the problem of providing the best possible service to new users joining the system without affecting existing users. Since, interference-wise, new users are required to be invisible to existing users, the network is dubbed PhantomNet. The novelty is the generality obtained in this context. Namely, we can deal with multiple users, multiple antennas, and multiple cells on both the uplink and the downlink. The solution for the uplink is effectively the same as for a single cell system since all the base stations (BSs simply amount to one composite BS with centralized processing. The optimum strategy, following directly from known results, is successive decoding (SD, where the new user is decoded before the existing users so that the new users' signal can be subtracted out to meet its invisibility requirement. Only the BS needs to modify its decoding scheme in the handling of new users, since existing users continue to transmit their data exactly as they did before the new arrivals. The downlink, even with the BSs operating as one composite BS, is more problematic. With multiple antennas at each BS site, the optimal coding scheme and the capacity region for this channel are unsolved problems. SD and dirty paper (DP are two schemes previously reported to achieve capacity in special cases. For PhantomNet, we show that DP coding at the BS is equal to or better than SD. The new user is encoded before the existing users so that the interference caused by his signal to existing users is known to the transmitter. Thus the BS modifies its encoding scheme to accommodate new users so that existing users continue to operate as before: they achieve the same rates as before and they decode their signal in precisely the same way as before. The solutions for the uplink and the downlink are particularly interesting in the way they exhibit a
Hamiltonian reductions of the one-dimensional Vlasov equation using phase-space moments
Chandre, C.; Perin, M.
2016-03-01
We consider Hamiltonian closures of the Vlasov equation using the phase-space moments of the distribution function. We provide some conditions on the closures imposed by the Jacobi identity. We completely solve some families of examples. As a result, we show that imposing that the resulting reduced system preserves the Hamiltonian character of the parent model shapes its phase space by creating a set of Casimir invariants as a direct consequence of the Jacobi identity. We exhibit three main families of Hamiltonian models with two, three, and four degrees of freedom aiming at modeling the complexity of the bunch of particles in the Vlasov dynamics.
Online Calibration for LTE-Based Antenna Array System
Directory of Open Access Journals (Sweden)
Kyunghoon Kim
2016-01-01
Full Text Available This paper presents a novel calibration method that equalizes the impulse responses of all the Radio Frequency (RF modules of an antenna array system operating in Long-Term Evolution (LTE evolved NodeB (eNB. The proposed technique utilizes the Zadoff-Chu (Z-C sequence of the Primary Synchronization Signal (PSS and Sounding Reference Signal (SRS that are available in every LTE data frame for downlink and uplink, respectively, for estimating and compensating the differences in the impulse responses among the RF modules. The proposed calibration method is suitable for wide bandwidth signal environments of LTE because it equalizes the impulse response of each RF module, which is ultimately equivalent to compensate the phase and amplitude differences among RF modules for the entire frequency band. In addition, the proposed method is applicable while the target eNB is transmitting or receiving a data stream. From various experimental tests obtained from a test-bed implemented with 2 RF modules, it has been verified that the proposed method provides a reliable calibration for Release 10 Time Division Duplex (TDD LTE signals. Phase errors after the calibration in our test-bed have been found to be about 2.418° and 2.983° for downlink and uplink, respectively.
Integration of Directional Antennas in an RSS Fingerprinting-Based Indoor Localization System
National Research Council Canada - National Science Library
Guzmán-Quirós, Raúl; Martínez-Sala, Alejandro; Gómez-Tornero, José Luis; García-Haro, Joan
...) fingerprinting-based indoor localization system (ILS) is studied. The sensor reader (SR), which is in charge of capturing the RSS to infer the tag position, can be attached to an omnidirectional or directional antenna...
Optimization of Planar Monopole Wideband Antenna for Wireless Communication System.
Shakib, Mohammed Nazmus; Moghavvemi, Mahmoud; Mahadi, Wan Nor Liza
2016-01-01
In this paper, a new compact wideband monopole antenna is presented for wireless communication applications. This antenna comprises of a new radiating patch, a new arc-shaped strip, microstrip feed line, and a notched ground plane. The proposed radiating patch is combined with a rectangular and semi-circular patch and is integrated with a partial ground plane to provide a wide impedance bandwidth. The new arc-shaped strip between the radiating patch and microstrip feed line creates an extra surface on the patch, which helps further widen the bandwidth. Inserting one step notch on the ground plane further enhances the bandwidth. The antenna has a compact size of 16×20×1.6mm3. The measured result indicated that the antenna achieves a 127% bandwidth at VSWR≤2, ranging from 4.9GHz to 22.1GHz. Stable radiation patterns with acceptable gain are achieved. Also, a measured bandwidth of 107.7% at VSWR≤1.5 (5.1-17GHz) is obtained, which is suitable for UWB outdoor propagation. This antenna is compatible with a good number of wireless standards, including UWB band, Wimax 5.4 GHz band, MVDDS (12.2-12.7GHz), and close range radar and satellite communication in the X-band (8-12GHz), and Ku band (12-18GHz).
Dou, Wenbin; Sun, Zhong Liang; Zeng, G.
1998-11-01
integrated antennas have the advantages of low cost and can be readily mass produced using standard IC fabrication processes. However, integrated antennas suffer from the surface wave effect at millimeter waves. One of the ways to avoid this problem is to integrate the antennas on a dielectric lens. This structure does not support surface-waves and tend to radiate most of their power into the dielectric side making the pattern unidirectional on high dielectric constant lenses. The dielectric lens also provides mechanical rigidity and thermal stability. There are various dielectric lenses which can be used for receiver application. Among them the extended hemispherical lens is very practical, since it can synthesize other lenses such as hemispherical, hyperhemispherical, or ellipsoidal simply by varying the extension length behind the hemispherical position. In reference five, investigation on such antenna/lens system is presented. In reference 6, slot- ring antennas on dielectric lens is investigated. In many applications the extended hemispherical lens/objective lens antenna system is more attractive, because it can provide higher gain and may be used in imaging system. On the other hand, monopulse direction-finding techniques are currently the most accurate and rapid method for locating a target electronically. This antenna system can also be used as monopulse antenna. However, the treatments on such antenna system are not presented yet. In this paper, the radiation pattern of the antenna system fed by double-slot antenna are computed using ray-tracing and diffraction integration methods. Although the double-slot antenna is used as feed antenna, other antenna such as slot-ring, bow-tie antenna can be used too.
Antenna selection based on large-scale fading for distributed MIMO systems
Institute of Scientific and Technical Information of China (English)
施荣华
2016-01-01
An antenna selection algorithm based on large-scale fading between the transmitter and receiver is proposed for the uplink receive antenna selection in distributed multiple-input multiple-output ( D-MIMO) systems.By utilizing the radio access units ( RAU) selection based on large-scale fa-ding , the proposed algorithm decreases enormously the computational complexity .Based on the characteristics of distributed systems , an improved particle swarm optimization ( PSO) has been pro-posed for the antenna selection after the RAU selection .In order to apply the improved PSO algo-rithm better in antenna selection , a general form of channel capacity was transformed into a binary expression by analyzing the formula of channel capacity .The proposed algorithm can make full use of the advantages of D-MIMO systems , and achieve near-optimal performance in terms of channel ca-pacity with low computational complexity .
Nonlinear Photonic Systems for V- and W-Band Antenna Remoting Applications
2016-10-22
AFRL-AFOSR-JP-TR-2016-0088 Nonlinear Photonic Systems for V- and W-Band Antenna Remoting Applications Sheng-Kwang Hwang NATIONAL CHENG KUNG... Antenna Remoting Applications 5a. CONTRACT NUMBER 5b. GRANT NUMBER FA2386-15-1-4026 5c. PROGRAM ELEMENT NUMBER 61102F 6. AUTHOR(S) Sheng-Kwang Hwang...TERMS nonlinear, photonic, antenna , remote, microwave, amplification, bandwith, modulation 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF ABSTRACT SAR
Avser, Bilgehan
2015-01-01
The thesis presents three dual-band frequency tunable antennas for carrier aggregation systems and two new feeding networks for reducing the number of phase shifters in limited-scan arrays. First, single- and dual-feed, dual-frequency, low-profile antennas with independent frequency tuning using varactor diodes are presented. The dual-feed planar inverted F-antenna (PIFA) has two operating frequencies which are independently tuned at 0.7--1.1 GHz and at 1.7--2.3 GHz with better than −10 dB im...
The whistler mode in a Vlasov plasma
Tokar, R. L.; Gary, S. P.
1985-01-01
In this study, properties of small-amplitude parallel and oblique whistler-mode waves are investigated for a wide range of plasma parameters by numerically solving the full electromagnetic Vlasov-dispersion equation. To investigate the cold-plasma and electrostatic approximations for the whistler mode, the results are compared with results obtained using these descriptions. For large wavelengths, the cold-plasma description is often accurate, while for short wavelengths and sufficiently oblique propagation, the electrostatic description is often accurate. The study demonstrates that in a Vlasov plasma the whistler mode near resonance has a group velocity more nearly parallel to the magnetic field than that predicted by cold-plasma theory.
Ill-Posedness of the Hydrostatic Euler and Singular Vlasov Equations
Han-Kwan, Daniel; Nguyen, Toan T.
2016-09-01
In this paper, we develop an abstract framework to establish ill-posedness, in the sense of Hadamard, for some nonlocal PDEs displaying unbounded unstable spectra. We apply this to prove the ill-posedness for the hydrostatic Euler equations as well as for the kinetic incompressible Euler equations and the Vlasov-Dirac-Benney system.
Directory of Open Access Journals (Sweden)
M. Waqas A. Khan
2017-01-01
Full Text Available Minimally invasive approach to intracranial pressure monitoring is desired for long-term diagnostics. The monitored pressure is transmitted outside the skull through an implant antenna. We present a new miniature (6 mm × 5 mm coplanar implant antenna and its integration on a sensor platform to establish a far-field data link for the sensor readout at distances of 0.5 to 1 meter. The implant antenna was developed using full-wave electromagnetic simulator and measured in a liquid phantom mimicking the dielectric properties of the human head. It achieved impedance reflection coefficient better than −10 dB from 2.38 GHz to 2.54 GHz which covers the targeted industrial, scientific, and medical band. Experiments resulted in an acceptable peak gain of approximately −23 dBi. The implant antenna was submerged in the liquid phantom and interfaced to a 0.5 mW voltage controlled oscillator. To verify the implant antenna performance as a part of the ICP monitoring system, we recorded the radiated signal strength using a spectrum analyzer. Using a half-wavelength dipole as the receiving antenna, we captured approximately −58.7 dBm signal at a distance of 1 m from the implant antenna which is well above for the reader with sensitivity of −80 dBm.
Vlasov simulation in multiple spatial dimensions
Rose, Harvey A
2011-01-01
A long-standing challenge encountered in modeling plasma dynamics is achieving practical Vlasov equation simulation in multiple spatial dimensions over large length and time scales. While direct multi-dimension Vlasov simulation methods using adaptive mesh methods [J. W. Banks et al., Physics of Plasmas 18, no. 5 (2011): 052102; B. I. Cohen et al., November 10, 2010, http://meetings.aps.org/link/BAPS.2010.DPP.NP9.142] have recently shown promising results, in this paper we present an alternative, the Vlasov Multi Dimensional (VMD) model, that is specifically designed to take advantage of solution properties in regimes when plasma waves are confined to a narrow cone, as may be the case for stimulated Raman scatter in large optic f# laser beams. Perpendicular grid spacing large compared to a Debye length is then possible without instability, enabling an order 10 decrease in required computational resources compared to standard particle in cell (PIC) methods in 2D, with another reduction of that order in 3D. Fur...
Design and analysis of a conformal patch antenna for a wearable breast hyperthermia treatment system
Curto, Sergio; Ramasamy, Manoshika; Suh, Minyoung; Prakash, Punit
2015-03-01
To overcome the limitations of currently available clinical hyperthermia systems which are based on rigid waveguide antennas, a wearable microwave hyperthermia system is presented. A light wearable system can improve patient comfort and be located in close proximity to the breast, thereby enhancing energy deposition and reducing power requirements. The objective of this work was to design and assess the feasibility of a conformal patch antenna element of an array system to be integrated into a wearable hyperthermia bra. The feasibility of implementing antennas with silver printed ink technology on flexible substrates was evaluated. A coupled electromagnetic-bioheat transfer solver and a hemispheric heterogeneous numerical breast phantom were used to design and optimize a 915 MHz patch antenna. The optimization goals were device miniaturization, operating bandwidth, enhanced energy deposition pattern in targets, and reduced Efield back radiation. The antenna performance was evaluated for devices incorporating a hemispheric conformal groundplane and a rectangular groundplane configuration. Simulated results indicated a stable -10 dB return loss bandwidth of 88 MHz for both the conformal and rectangular groundplane configurations. Considering applied power levels restricted to 15 W, treatment volumes (T>410C) and depth from the skin surface were 11.32 cm3 and 27.94 mm, respectively, for the conformal groundplane configuration, and 2.79 cm3 and 19.72 mm, respectively, for the rectangular groundplane configuration. E-field back-radiation reduced by 85.06% for the conformal groundplane compared to the rectangular groundplane configuration. A prototype antenna with rectangular groundplane was fabricatd and experimentally evaluated. The groundplane was created by printing silver ink (Metalon JS-B25P) on polyethylene terephthalate (PET) film surface. Experiments revealed stable antenna performance for power levels up to 15.3 W. In conclusion, the proposed patch antenna with
Spectrum Sensing in relation to Distributed Antenna System for Coverage Predictions
DEFF Research Database (Denmark)
Kumar, Ambuj; Mihovska, Albena D.; Prasad, Ramjee
2014-01-01
(BTS)/Nodes at one location known as BTS hotel and the antennas are distributed all over target area by fiber optic network, is discussed. The very concept of splitting Base Station (BS) from its antenna system and putting it at one location (BS Hotel) and distributing antenna as nodes (Remote Unit......Distributed Antenna Systems (DAS) is one of the most promising ways of network deployment now-a-days. Mostly it is used in indoor environment for shopping areas and office locations. Here the Outdoor application of DAS, where multiple service providers can install their Base Transceiver Station...... technology adaptability, efficient energy usage etc. make O-DAS (Outdoor-DAS) network very lucrative. However, for an O-DAS network with large distribution of Remote Units, it is required to have complete knowledge of the spectrum environment at all the locations of remote unit for understanding actual...
Directory of Open Access Journals (Sweden)
Yanjie Dong
2013-01-01
Full Text Available The capacity of Multiple Input Multiple Output (MIMO system is highly related to the number of active antennas. But as the active antenna number increases, the MIMO system will consume more energy. To maximize the energy efficiency of MIMO system, we propose an antenna selection scheme which can maximize the energy efficiency of BS cluster. In the scheme, ergodic energy efficiency is derived according to large scale channel state information (CSI. Based on this ergodic energy efficiency, we introduce a cost function varied with the number of antennas, in which the effect to the energy efficiency of both the serving BS and the neighbor BS is considered. With this function, we can transform the whole system optimization problem to a sectional optimization problem and obtain a suboptimal antenna set using a heuristic algorithm. Simulation results verify that the proposed approach performs better than the comparison schemes in terms of network energy efficiency and achieves 98% network energy efficiency of the centralized antenna selection scheme. Besides, since the proposed scheme does not need the complete CSI of the neighbor BS, it can effectively reduce the signaling overhead.
Integrated Antenna/Solar Array Cell (IA/SAC) System for Flexible Access Communications
Lee, Ricard Q.; Clark, Eric B.; Pal, Anna Maria T.; Wilt, David M.; Mueller, Carl H.
2004-01-01
Present satellite communications systems normally use separate solar cells and antennas. Since solar cells generally account for the largest surface area of the spacecraft, co-locating the antenna and solar cells on the same substrate opens the possibility for a number of data-rate-enhancing communications link architecture that would have minimal impact on spacecraft weight and size. The idea of integrating printed planar antenna and solar array cells on the same surface has been reported in the literature. The early work merely attempted to demonstrate the feasibility by placing commercial solar cells besides a patch antenna. Recently, Integrating multiple antenna elements and solar cell arrays on the same surface was reported for both space and terrestrial applications. The application of photovoltaic solar cell in a planar antenna structure where the radiating patch antenna is replaced by a Si solar cell has been demonstrated in wireless communication systems (C. Bendel, J. Kirchhof and N. Henze, 3rd Would Photovotaic Congress, Osaka, Japan, May 2003). Based on a hybrid approach, a 6x1 slot array with circularly polarized crossdipole elements co-located on the same surface of the solar cells array has been demonstrated (S. Vaccaro, J. R. Mosig and P. de Maagt, IEEE Trans. Ant. and Propag., Vol. 5 1, No. 8, Aug. 2003). Amorphous silicon solar cells with about 5-10% efficiency were used in these demonstrations. This paper describes recent effort to integrate advanced solar cells with printed planar antennas. Compared to prior art, the proposed WSAC concept is unique in the following ways: 1) Active antenna element will be used to achieve dynamic beam steering; 2) High efficiency (30%) GaAs multi-junction solar cells will be used instead of Si, which has an efficiency of about 15%; 3) Antenna and solar cells are integrated on a common GaAs substrate; and 4) Higher data rate capability. The IA/SAC is designed to operate at X-band (8-12 GH) and higher frequencies
Use of the Analog Neural Networks in the Adaptive Antenna Control Systems
Directory of Open Access Journals (Sweden)
Z. Raida
2002-09-01
Full Text Available In the paper, original control system of adaptive antennas, which isbased on Kalman filter, is presented and compared with earlierapproaches to this problem. The designed control circuit eliminatessome disadvantages of the control circuits based on the classicalKalman neural network and the Wang one, and enables a real timeprocessing of quickly changing signals processed by adaptive antennas.Especially, the dependence of the convergence rate on ratio ofeigenvalues and the risk of instability are significantly reduced.
An Automatic Antenna Tuning System Using Only RF Signal Amplitudes
Firrao, E.L.; Annema, A.J.; Nauta, B.
2008-01-01
The operating environment of mobile phones fluctuates continuously, due to changing handling onditions and nearby objects. The resulting fluctuations in antenna impedance cause both a decrease in link quality and a higher standing wave ratio, that requires more robust and hence less efficient PA imp
DEVELOPMENT OFA LOG-PERIODIC DIPOLE ANTENNA SYSTEM
African Journals Online (AJOL)
2005-06-10
Jun 10, 2005 ... I Department of Physics, Benue State University, Makurdi, Nigeria. 2 Department of Physics, .... D=4P/§2;where Q is the solid angle and P is the radiated power. ..... Silvered, S. (1949): Microwave Antenna Theory and Design ...
Antenna System for Nano-satelite Mission GOMX-3
DEFF Research Database (Denmark)
Tatomirescu, Alexandru; Pedersen, Gert F.; Christiansen, J.;
2016-01-01
In this paper, we present the antenna design for a nano-satellite mission launched in September, the GOMX-3 mission. Some of the key design challenges are discussed and the chosen solutions are presented. In an effort to minimize development and manufacturing costs for future missions, this study...
Photonic antenna system for light harvesting, transport and trapping
Calzaferri, G.; Pauchard, M.; Maas, H.; Huber, S.; Khatyr, A.; Schaafsma, T.J.
2002-01-01
Host¿guest composites with photonic antenna properties are described. The material consists of cylindrical zeolite L crystals the channels of which are filled with chains of joined but electronically non-interacting dye molecules. Light shining on a crystal is first absorbed and the energy is then t
Design of a Printed Dipole Antenna Array for a Passive Radar System
Directory of Open Access Journals (Sweden)
Peter Knott
2013-01-01
Full Text Available Passive radar (or Passive Coherent Localisation is an advancing technology for covert operation. The signal transmitted from sources of opportunity such as radio or TV stations is used as illumination for a certain area of interest. Part of the transmitted signal is reflected by radar targets, for example, moving objects such as vehicles or aircraft. Typical radar parameters are derived from the comparison between the direct line-of-sight from the transmitter and the signal scattered from the target object. Such systems are an attractive addition to existing active radar stations because they have the potential to discover low-flying and low-observable targets and no active radar transmitter is required. Printed dipole antennas are very attractive antenna elements for such systems because of their easy fabrication, low-cost, polarisation purity, and low-profile properties. The present paper describes the design of an antenna array using printed dipole elements with flared arms for a passive radar system operating in the GSM900 frequency range. Isolated antenna elements and a small uniform linear antenna array were designed and optimised using computational electromagnetic methods. Several prototypes have been fabricated on conventional microwave PCB substrate material. Preliminary measurement results for antenna matching and far-field radiation patterns are shown.
In-flight calibration of STEREO-B/WAVES antenna system
Panchenko, M; Rucker, H O; Fischer, G; Oswald, T H; Cecconi, B; Maksimovic, M
2015-01-01
The STEREO/WAVES (SWAVES) experiment on board the two STEREO spacecraft (Solar Terrestrial Relations Observatory) launched on 25 October 2006 is dedicated to the measurement of the radio spectrum at frequencies between a few kilohertz and 16 MHz. The SWAVES antenna system consists of 6 m long orthogonal monopoles designed to measure the electric component of the radio waves. With this configuration direction finding of radio sources and polarimetry (analysis of the polarization state) of incident radio waves is possible. For the evaluation of the SWAVES data the receiving properties of the antennas, distorted by the radiation coupling with the spacecraft body and other onboard devices, have to be known accurately. In the present context, these properties are described by the antenna effective length vectors. We present the results of an in-flight calibration of the SWAVES antennas using the observations of the nonthermal terrestrial auroral kilometric radiation (AKR) during STEREO roll maneuvers in an early s...
Simulation of the Optical System for the ASTRO-G Offset Cassegrain Antenna
Kimura, K.; Toshikawa, T.; Shiroyama, N.; Kurozumi, A.; Ojima, T. K.; Abe, Y.; Yonekura, Y.; Ogawa, H.; Ujihara, H.; Murata, Y.; Tsuboi, M.; Kasuga, T.
2009-08-01
We are developing the satellite (ASTRO-G) for the space VLBI mission, called VSOP-2 (Hirabayashi et al. 2004). This system will have an offset cassegrain antenna, and the three multi-mode feed horns (8, 22, 43 GHz bands) will be chosen by the Cassegrain focus position. We are designing the antenna optics of the three band receivers by using the GRASP physical optics software package on simulated feed configurations. The result of these simulations shows low cross-polarization level, a good radiation pattern, and the antenna efficiencies are 63--68 percent in these bands, assuming a perfect reflector. In this paper, we present these results of simulation of ASTRO-G antenna optics.
On Transmit Antenna Selection for Multiuser MIMO Systems with Dirty Paper Coding
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.
Meandered conformai antenna for ISM-band ingestible capsule communication systems.
Arefin, Md Shamsul; Redoute, Jean-Michel; Yuce, Mehmet Rasit
2016-08-01
The wireless capsule has been used to measure physiological parameters in the gastrointestinal tract where communication from in-body to external receiver is necessary using a miniaturized antenna with high gain and onmidirectional radiation pattern. This paper presents a meandered conformal antenna with center frequency of 433 MHz for a wireless link between an in-body capsule system and an ex-body receiver system. The antenna is wrapped around the wireless capsule, which provides extra space for other circuits and sensors inside the capsule as well as allows it having larger dimensions compared to inner antennas. This paper analyses return loss, radiation pattern, antenna gain, and propagation loss using pork as the gastrointestinal tissue simulating medium. From the radiation pattern and return loss results, the antenna shows an omni-directional radiation pattern and an ultrawide bandwidth of 124.4 MHz (371.6 to 496 MHz) for VSWR <; 2. Experimental results shows that the path loss is 17.24 dB for an in-body propagation distance of 140 mm.
Experimental Study of a Membrane Antenna Surface Adaptive Control System
Fang, H.; Quijano, U.; Bach, V.; Hill, J.; Wang, K. W.
2011-01-01
Due to their ultra lightweight and high packaging efficiency, membrane reflectors are getting more and more attentions for mission architectures that need extremely large inspace deployable antennas. However how to maintain the surface shape of a membrane reflector to the instrument precision requirements is a very challenging problem. This experimental study investigated using PVDF membrane piezoelectric material as actuators to control the surface figures of membrane reflectors. The feasibility of this approach is demonstrated by several sets of test results.
Performance of Antenna Selection in MIMO System Using Channel Reciprocity with Measured Data
Directory of Open Access Journals (Sweden)
Peerapong Uthansakul
2011-01-01
Full Text Available The channel capacity of MIMO system increases as a function of antenna pairs between transmitter and receiver but it suffers from multiple expensive RF chains. To reduce cost of RF chains, antenna selection (AS method can offer a good tradeoff between expense and performance. For a transmitting AS system, channel state information (CSI feedback is required to choose the best subset of available antennas. However, the delay and error in feedback channel are the most dominant factors to degrade performances. In this paper, the concept of AS method using reciprocal CSI instead of feedback channel is proposed. The capacity performance of proposed system is investigated by own developing Testbed. The obtained results indicate that the reciprocity technique offers a capacity close to a system with perfect CSI and gains a higher capacity than a system without AS method. This benefit is from 0.9 to 2.2 bps/Hz at SNR 10 dB.
Directory of Open Access Journals (Sweden)
Tommy Hult
2010-01-01
Full Text Available We analyze the destructive effects of mutual coupling and spatial correlation between the separate antenna elements on a combined diversity system consisting of multiple HAPs (High-Altitude Platforms employing various compact MIMO (Multiple-Input Multiple-Output antenna array configurations, in order to enhance the mutual information in HAP communication links. In addition, we assess the influence of the separation angle between HAPs on system performance, and determine the optimal separation angles that maximize the total mutual information of the system for various compact MIMO antennas. Simulation results show that although the mutual information is degraded by mutual coupling and spatial correlation, the proposed HAP diversity system still provides better performance compared to a nondiversity system for all tested scenarios.
Design analysis of an implant and antenna system by using Taguchi method
Celik, Nevin; Turgut, Emre; Bayazit, Yilmaz
2017-08-01
In present study, to investigate the thermal effects of the rechargeable neuromodulation implants (an implant and antenna together) in the body, a numerical analysis is performed by using commercial software ANSYS. Since it is well established that both the antenna and the implant generate heat, both of these heat sources may increase the tissue temperature in the subcutaneous zone and may also increase the temperature in the deeper tissue. Therefore, the sizes and heat generation amounts of the implant-antenna system gain great importance and a parametric evaluation that shows the effects of the design parameters on the temperature becomes necessary. For this aim, an optimization study is performed. The runs of the numerical simulations are determined by well-known design analysis method, namely Taguchi and the parametric evaluation of the study is carried out by Analysis of Variance (ANOVA) method. The design parameters considered are; (i) heat generated by the antenna q a (50, 52 and 54 W/m2), (ii) heat generated by the implant q i (30 and 35 W/m2), (iii) thickness of the implant t i (9, 11, and 13 mm) and finally (iv) the radius of the antenna R a (31, 35, 39 mm). The results showed that higher antenna radii result in higher temperatures in the tissue, whilst the least effective design parameter on the temperature is the heat generation of the implant.
ESTIMATION OF CARRIER FREQUENCY OFFSETS FOR MIMO SYSTEMS WITH DISTRIBUTED TRANSMIT ANTENNAS
Institute of Scientific and Technical Information of China (English)
Deng Kai; Tang Youxi; Lei Xia; Li Shaoqian
2007-01-01
The problem of estimating the carrier frequency offsets in Multiple-Input Multiple-Output (MIMO) systems with distributed transmit antennas is addressed. It is supposed that the transmit antennas are distributed while the receive antennas are still centralized, and the general case where both the time delays and the frequency offsets are possibly different for each transmit antenna is considered. The channel is supposed to be frequency flat, and the macroscopic fading is also taken into consideration. A carrier frequency offset estimator based on Maximum Likelihood (ML) is proposed,which can separately estimate the frequency offset for each transmit antenna and exploit the spatial diversity. The Cramer-Rao Bound (CRB) for synchronous MIMO (i.e., the time delays for each transmit antenna are all equal) is also derived. Simulation results are given to illustrate the performance of the estimator and compare it with the CRB. It is shown that the estimator can provide satisfactory frequency offset estimates and its performance is close to the CRB for the Signal-to-Noise Ratio (SNR) below 20dB.
Surface control system for the 15 meter hoop-column antenna
Miller, James B.; Ahl, Elvin L., Jr.; Butler, David H.; Peri, Frank, Jr.
1986-01-01
The 15-meter hoop-column antenna fabricated by the Harris Corporation under contract to the NASA Langley Research Center is described. The antenna is a deployable and restowable structure consisting of a central telescoping column, a 15-meter-diameter folding hoop, and a mesh reflector surface. The hoop is supported and positioned by 48 quartz cords attached to the column above the hoop, and by 24 graphite cords from the base of the antenna column. The RF reflective surface is a gold plated molybdenum wire mesh supported on a graphite cord truss structure which is attached between the hoop and the column. The surface contour is controlled by 96 graphite cords from the antenna base to the rear of the truss assembly. The antenna is actually a quadaperture reflector with each quadrant of the surface mesh shaped to produce an offset parabolic reflector. Results of near-field and structural tests are given. Controls structures and electromagnetics interaction, surface control system requirements, mesh control adjustment, surface control system actuator assembly, surface control system electronics, the system interface unit, and control stations are discussed.
Beam Tracking in Switched-Beam Antenna System for V2V Communication
Directory of Open Access Journals (Sweden)
Settawit Poochaya
2016-01-01
Full Text Available This paper presents the proposed switched beam antenna system for V2V communication including optimum antenna half power beamwidth determination in urban road environments. SQP optimization method is selected for the computation of optimum antenna half power beamwidth. In addition, beam tracking algorithm is applied to guarantee the best beam selection with maximum RSSI. The results present the success of the proposed system with the increasing of V2V performance metrics. Also, V2V data dissemination via the proposed system introduces the enhancement of V2V link in terms of RSSI, PER, BER, Tsafe, and Rsafe. The results indicate the improvement of V2V link reliability. Consequently, the road safety is improved.
Analysis and design of antennas for air traffic collision avoidance systems.
Balanis, C. A.; Cockrell, C. R.
1971-01-01
The analysis and design procedure of an antenna for a CW Doppler radar system being developed for pilot warning of midair collision hazards is presented. The antenna consists of two vertical arrays of half-wavelength dipoles mounted near a circular conducting cylinder. Each vertical array is composed of three vertical dipoles. Each array provides relatively uniform illumination (2.3 dB) in the forward 180-deg angular segment of the horizontal plane and approximately plus or minus 10 to 15 deg coverage in the vertical plane. The antenna could be used in a two-mode operation, either in a standard monopulse radar system (sum and difference amplitude patterns) or in a system where amplitude and phase are the measurable quantities.
Efficient spread space-time block coding scheme in multiple antenna systems
Institute of Scientific and Technical Information of China (English)
Qiu Ling; Zheng Xiayu
2006-01-01
Space-time coding is an important technique that can improve transmission performance at fading environments in mobile communication systems. In this paper, we propose a novel diversity scheme using spread spacetime block coding (SSTBC) in multiple antenna systems. At the transmitter, the primitive data are serial to parallel converted to multiple data streams, and each stream is rotated in constellation. Then Walsh codes are used to spread each symbol to all antenna space in a space-time block. The signals received from all receiver antennas are combined with the maximum ratio combining (MRC), equalized with linear equalizer to eliminate the inter-code interference and finally demodulated to recover to transmit data by using the one-symbol maximum likelihood detector. The proposed scheme does not sacrifice the spectrum efficiency meanwhile maintains the transceiver with low complexity. Owing to the transmission symbols of different transmit antennas passing through all the spatial subchannels between transceiver antenna pairs, the system obtains the partial additional space diversity gain of all spatial paths. It is also shown that the diversity gain is better than the previous space-time block coding (STBC) schemes with full transmission rate.
Design of a compact antenna with flared groundplane for a wearable breast hyperthermia system.
Curto, Sergio; Prakash, Punit
2015-01-01
Currently available microwave hyperthermia systems for breast cancer treatment do not conform to the intact breast and provide limited control of heating patterns, thereby hindering an effective treatment. A compact patch antenna with a flared groundplane that may be integrated within a wearable hyperthermia system for the treatment of the intact breast disease is proposed. A 3D simulation-based approach was employed to optimise the antenna design with the objective of maximising the hyperthermia treatment volume (41 °C iso-therm) while maintaining good impedance matching. The optimised antenna design was fabricated and experimentally evaluated with ex vivo tissue measurements. The optimised compact antenna yielded a -10 dB bandwidth of 90 MHz centred at 915 MHz, and was capable of creating hyperthermia treatment volumes up to 14.4 cm(3) (31 mm × 28 mm × 32 mm) with an input power of 15 W. Experimentally measured reflection coefficient and transient temperature profiles were in good agreement with simulated profiles. Variations of + 50% in blood perfusion yielded variations in the treatment volume up to 11.5%. When compared to an antenna with a similar patch element employing a conventional rectangular groundplane, the antenna with flared groundplane afforded 22.3% reduction in required power levels to reach the same temperature, and yielded 2.4 times larger treatment volumes. The proposed patch antenna with a flared groundplane may be integrated within a wearable applicator for hyperthermia treatment of intact breast targets and has the potential to improve efficiency, increase patient comfort, and ultimately clinical outcomes.
Contribution of LPP/ERM-KMS to the modern developments of ICRH antenna systems
Energy Technology Data Exchange (ETDEWEB)
Messiaen, A., E-mail: a.messiaen@fz-juelich.de; Ongena, J.; Dumortier, P.; Durodié, F.; Louche, F.; Ragona, R.; Vervier, M.
2016-11-15
Highlights: • Overview of ICRF antenna coupling physics, showing from first principles how to develop a state of the art ICRF system for ITER and DEMO. • Physics of conceptual solutions for the compact ITER antenna array, intended to radiate ∼10 MW/m2. • Implementing novel ideas into the matching-decoupling network of the ITER antenna array to avoid cross-coupling and to control the RF current distribution in the array. • Experimental tests of the theoretical predictions using scaled mock-ups of the ICRF antenna, including a dielectric dummy load to mimick the plasma. • Demonstrating an operational feedback control of the matching-decoupling network for the ITER antenna array, with 23 simultaneously active actuators. - Abstract: The paper gives an overview of the coupling physics of an ICRF antenna array to the plasma and of the original conceptual solutions proposed by the LPP/ERM-KMS group for the compact ITER antenna array and its matching to the RF power sources. The main contributions are (i) the use of an array of short straps grouped in triplets, (ii) the triplet feed by a four port junction and the use of a service stub to enlarge its frequency response, (iii) the multistep prematching to decrease the VSWR and minimise the voltage in the feeding transmission lines, (iv) the use of a decoupler network to neutralize the mutual coupling effects between different RF power sources and to simultaneously control the current distribution of the antenna array, (v) the various options to connect the decouplers and 3 dB hybrids for different array phasing cases in order to maintain the correct functioning of the decouplers together with load resiliency to fast variations of the plasma density in the edge (caused by e.g. pellet injection or Edge Localized Modes), (vi) the solution of the grounding problem of the ITER antenna plug-in, (vii) the test on mock-ups in front of a dielectric dummy load of the performance of the different solutions and particularly
Transient Growth in a Magnetized Vlasov Plasma
Ratushnaya, Valeria; Samtaney, Ravi
2015-11-01
Collisionless plasmas, such as those encountered in tokamaks, exhibit a rich variety of instabilities. The physical origin, triggering mechanisms and fundamental understanding of many tokamak instabilities, however, is still an open problem. Aiming to gain a better insight into this question, we investigate the stability properties of a collisionless Vlasov plasma for the case of: (a) stationary homogeneous magnetic field, and (b) weakly non-stationary and non-homogeneous magnetic field. We narrow the scope of our investigation to the case of a Maxwellian plasma and examine its evolution with an electrostatic approximation. We show that the linearized Vlasov operator is non-normal, which leads to an algebraic growth of perturbations in a magnetized plasma followed by exponential decay, i.e., classical Landau damping behaviour. This is a so-called transient growth phenomenon, developed in the framework of non-modal stability theory in the context of hydrodynamics. In a homogeneous magnetic field the typical time scales of the transient growth are of the order of several plasma periods. The first-order distribution function and the corresponding electric field are calculated and the dependence on the initial conditions is studied. Supported by baseline research funds at KAUST.
DEFF Research Database (Denmark)
Prince, Kamau; Chiuchiarelli, A; Presi, M
2008-01-01
We introduce a novel continuously-variable optical delay technique to support beam-forming wireless communications systems using antenna arrays. We demonstrate delay with 64-QAM modulated signals at a rate of 15 Msymbol/sec with 2.5 GHz carrier frequency.......We introduce a novel continuously-variable optical delay technique to support beam-forming wireless communications systems using antenna arrays. We demonstrate delay with 64-QAM modulated signals at a rate of 15 Msymbol/sec with 2.5 GHz carrier frequency....
Souza, André L. G.; Ishihara, João Y.; Ferreira, Henrique C.; Borges, Renato A.; Borges, Geovany A.
2016-12-01
The present work proposes a new approach for an antenna pointing system for satellite tracking. Such a system uses the received signal to estimate the beam pointing deviation and then adjusts the antenna pointing. The present work has two contributions. First, the estimation is performed by a Kalman filter based conical scan technique. This technique uses the Kalman filter avoiding the batch estimator and applies a mathematical manipulation avoiding the linearization approximations. Secondly, a control technique based on the model predictive control together with an explicit state feedback solution are obtained in order to reduce the computational burden. Numerical examples illustrate the results.
Millimeter Wave Antenna with Mounted Horn Integrated on FR4 for 60 GHz Gbps Communication Systems
Directory of Open Access Journals (Sweden)
Waleed Tariq Sethi
2013-01-01
Full Text Available A compact high gain and wideband millimeter wave (MMW antenna for 60 GHz communication systems is presented. The proposed antenna consists of a multilayer structure with an aperture coupled microstrip patch and a surface mounted horn integrated on FR4 substrate. The proposed antenna contributes impedance bandwidth of 8.3% (57.4–62.4 GHz. The overall antenna gain and directivity are about 11.65 dBi and 12.51 dBi, which make it suitable for MMW applications and short-range communications. The proposed antenna occupies an area of 7.14 mm × 7.14 mm × 4 mm. The estimated efficiency is 82%. The proposed antenna finds application in V-band communication systems.
Hopf, J. F.; Lindenmeier, H. K.; Reiter, L. M.
2003-04-01
For modern cars, antennas are required for AM reception, FM and TV diversity reception, weatherband reception (USA), terrestrial digital radio, remote control functions, keyless entry, mobile phone for all worldwide used systems, GPS, and in the future, satellite broadcast radio services. Those services cover the frequency range from 150 kHz up to 2.4 GHz. Such kind of a multiantenna system developed for station wagons is presented in this paper. The obtainable FM and TV diversity effectiveness is discussed for several types of antenna arrangements in detail. This value is the number of fictitious completely decorrelated antenna signals and is obtained by virtual test drives. The characteristic of the respective antennas under test is introduced in the software as antenna pattern, measured or calculated with respect to amplitude and phase. During the computer analysis the car with the antennas is driven virtually through a Rayleigh field scenario with desired and undesired signals.
Directory of Open Access Journals (Sweden)
Seung-Hyun Eom
2015-12-01
Full Text Available In this paper, we propose a paper-based pattern switchable antenna system using inkjet-printing technology for bi-direction sensor applications. The proposed antenna system is composed of two directional bow-tie antennas and a switching network. The switching network consists of a single-pole-double-throw (SPDT switch and a balun element. A double-sided parallel-strip line (DSPSL is employed to convert the unbalanced microstrip mode to the balanced strip mode. Two directional bow-tie antennas have different radiation patterns because of the different orientation of the reflectors and antennas. It is demonstrated from electromagnetic (EM simulation and measurement that the radiation patterns of the proposed antenna are successfully switched by the SPDT switch.
Gao, Mingguang; Lan, Tian; Zhao, Tao; Zhang, Yilun; Cui, Zhenghua; Ni, Guoqiang
2015-08-01
Optical receiving antenna is usually positioned before the detector of an indoor visible light communication (VLC) system in order to collect more optical energy into the detector. Besides optical gain of the antenna, the field of view (FOV) plays also an important role to the performance of a VLC system. In this paper, the signal noise ratio (SNR) and inter-symbol interference (ISI) versus FOV of the antenna are simulated via Line-of-Sight (LOS) and non-Line-of-Sight (NLOS) links within a room with a size of 5m × 5m × 3m. Results show that, the blind area appears while the FOV is less than 40 deg. and the SNR reduces as FOV increases and keeps small when FOV is more than 70 deg.. Furthermore, the average power of ISI rises with the increase of FOV, and the rising trend is relatively moderate when FOV is below 50 deg., while there is a rapid increase between 50 deg. and 70 deg. and finally tends to be stable after 70 deg. Therefore, it is practical to determine the FOV of the optical receiving antenna in the scope of 40 to 50 deg. based on the installment of LED lights on the ceiling here so as to avoid the blind area, attain high SNR, and reduce the influence of ISI. It is also worthwhile in practice to provide an identifiable evidence for the determination of FOV of the optical antenna.
Sum Rate and Power Consumption of a Circular-Layout Distributed Antenna System with MMSE Receivers
Institute of Scientific and Technical Information of China (English)
GAN Jiansong; LI Yunzhou; ZHOU Shidong; WANG Jing
2008-01-01
The distributed antenna system (DAS) is considered as a promising architecture for future wireless access. This paper describes the uplink of a power-controlled circular-layout DAS (CL-DAS) with minimum mean-square error (MMSE) receivers. Results from random matrix theory are used to show that for such a DAS, the per-user sum rate and the total transmit power both converge as the number of users and antennas goes to infinity with a constant ratio of antennas to users. The relationship between the asymptotic per-user sum rate and the asymptotic total transmit power is given for all possible values of the radius of the circle on which antennas are placed. This rate-power relationship is then used to find the optimal radius. With this op-timal radius, the CL-DAS is proved to offer a significant gain compared with a traditional co-located antenna system. Simulation results demonstrate the validity of the analysis and the superiority of the DAS.
On the contribution of exchange interactions to the Vlasov equation
Zamanian, J; Marklund, M
2014-01-01
Exchange effects play an important role in determining the equilibrium properties of dense matter systems, as well as for magnetic phenomena. There exists an extensive literature concerning, e.g., the effects of exchange interactions on the equation of state of dense matter. Here, a generalization of the Vlasov equation to include exchange effects is presented allowing for electromagnetic mean fields, thus incorporating some of the dynamic effects due to the exchange interactions. Treating the exchange term perturbatively, the correction to classical Langmuir waves in plasmas is found, and the results are compared with previous work. It is noted that the relative importance of exchange effects scales similarly with density and temperature as particle dispersive effects, but that the overall magnitude is sensitive to the details of the specific problem. The implications of our results are discussed.
Vlasov equation for long-range interactions on a lattice
Bachelard, Romain; De Ninno, Giovanni; Ruffo, Stefano; Staniscia, F
2011-01-01
We show that, in the continuum limit, the dynamics of Hamiltonian systems defined on a lattice with long-range couplings is well described by the Vlasov equation. This equation can be linearized around the homogeneous state and a dispersion relation, that depends explicitly on the Fourier modes of the lattice, can be derived. This allows to compute the stability thresholds of the homogeneous state, which turn out to depend on the mode number. When this state is unstable, the growth rates are also function of the mode number. Explicit calculations are performed for the $\\alpha$-HMF model with $0 \\leq \\alpha <1$, for which the zero mean-field mode is always found to dominate the exponential growth. The theoretical predictions are successfully compared with numerical simulations performed on a finite lattice.
Vlasov equation for long-range interactions on a lattice.
Bachelard, R; Dauxois, T; De Ninno, G; Ruffo, S; Staniscia, F
2011-06-01
We show that, in the continuum limit, the dynamics of Hamiltonian systems defined on a lattice with long-range couplings is well described by the Vlasov equation. This equation can be linearized around the homogeneous state, and a dispersion relation, which depends explicitly on the Fourier modes of the lattice, can be derived. This allows one to compute the stability thresholds of the homogeneous state, which turns out to depend on the mode number. When this state is unstable, the growth rates are also functions of the mode number. Explicit calculations are performed for the α-Hamiltonian mean field model with 0≤α<1, for which the mean-field mode is always found to dominate the exponential growth. The theoretical predictions are successfully compared with numerical simulations performed on a finite lattice.
Capability of patch antennas in a portable harmonic radar system to track insects
Monitoring technologies are needed to track insects and gain a better understanding of their behavior, population, migration and movement. A portable microwave harmonic-radar tracking system that utilizes antenna miniaturization techniques was investigated to achieve this goal. The system mainly con...
A Coordinated Approach to Channel Estimation in Large-scale Multiple-antenna Systems
Yin, Haifan; Filippou, Miltiades; Liu, Yingzhuang
2012-01-01
This paper addresses the problem of channel estimation in multi-cell interference-limited cellular networks. We consider systems employing multiple antennas and are interested in both the finite and large-scale antenna number regimes (so-called "Massive MIMO"). Such systems deal with the multi-cell interference by way of per-cell beamforming applied at each base station. Channel estimation in such networks, which is known to be hampered by the pilot contamination effect, constitute a major bottleneck for overall performance. We present a novel approach which tackles this problem by enabling a low-rate coordination between cells during the channel estimation phase itself. The coordination makes use of the additional second-order statistical information about the user channels, which are shown to offer a powerful way of discriminating across interfering users with even strongly correlated pilot sequences. Importantly, we demonstrate analytically that in the large number of antennas regime the pilot contaminatio...
Multihop relaying and multiple antenna techniques: performance trade-offs in cellular systems
Directory of Open Access Journals (Sweden)
Jacobson Kevin
2011-01-01
Full Text Available Abstract Two very important and active areas of wireless research are multihop relaying and multiple antenna techniques. Wireless multihop relaying can increase the aggregate network data capacity and improve coverage of cellular systems by reducing path loss, mitigating shadowing, and enabling spatial reuse. In particular, multihop relaying can improve the throughput for mobiles suffering from poor signal to interference and noise ratio at the edge of a cell and reduce cell size to increase spectral efficiency. On the other hand, multiple antenna techniques can take advantage of scattering in the wireless channel to achieve higher capacity on individual links. Multiple antennas can provide impressive capacity gains, but the greatest gains occur in high scattering environments with high signal to interference and noise ratio, which are not typical characteristics of cellular systems. Emerging standards for fourth generation cellular systems include both multihop relaying and multiple antenna techniques, so it is necessary to study how these two work jointly in a realistic cellular system. In this paper, we look at the joint application of these two techniques in a cellular system and analyze the fundamental tradeoff between them. In order to obtain meaningful results, system performance is evaluated using realistic propagation models.
Adaptive antenna selection and Tx/Rx beamforming for large-scale MIMO systems in 60 GHz channels
Directory of Open Access Journals (Sweden)
Prasad Narayan
2011-01-01
Full Text Available Abstract We consider a large-scale MIMO system operating in the 60 GHz band employing beamforming for high-speed data transmission. We assume that the number of RF chains is smaller than the number of antennas, which motivates the use of antenna selection to exploit the beamforming gain afforded by the large-scale antenna array. However, the system constraint that at the receiver, only a linear combination of the receive antenna outputs is available, which together with the large dimension of the MIMO system makes it challenging to devise an efficient antenna selection algorithm. By exploiting the strong line-of-sight property of the 60 GHz channels, we propose an iterative antenna selection algorithm based on discrete stochastic approximation that can quickly lock onto a near-optimal antenna subset. Moreover, given a selected antenna subset, we propose an adaptive transmit and receive beamforming algorithm based on the stochastic gradient method that makes use of a low-rate feedback channel to inform the transmitter about the selected beams. Simulation results show that both the proposed antenna selection and the adaptive beamforming techniques exhibit fast convergence and near-optimal performance.
A Multiband Proximity-Coupled-Fed Flexible Microstrip Antenna for Wireless Systems
Directory of Open Access Journals (Sweden)
Giovanni Andrea Casula
2016-01-01
Full Text Available A multiband printed microstrip antenna for wireless communications is presented. The antenna is fed by a proximity-coupled microstrip line, and it is printed on a flexible substrate. The antenna has been designed using a general-purpose 3D computer-aided design software (CAD, CST Microwave Studio, and then realized. The comparison between simulated and measured results shows that the proposed antenna can be used for wireless communications for WLAN systems, covering both the WLAN S-band (2.45 GHz and C-band (5.2 GHz, and the Wi-Max 3.5 GHz band, with satisfactory input matching and broadside radiation pattern. Moreover, it has a compact size, is very easy to realize, and presents a discrete out-of-band rejection, without requiring the use of stop-band filters. The proposed structure can be used also as a conformal antenna, and its frequency response and radiated field are satisfactory for curvatures up to 65°.
Design of High Gain and Broadband Antennas at 60 GHz for Underground Communications Systems
Directory of Open Access Journals (Sweden)
Yacouba Coulibaly
2012-01-01
Full Text Available A new broadband and high gain dielectric resonator antenna for millimeter wave is presented. The investigated antenna configuration consists of a periodic square ring frequency selective surfaces on a superstrate, an aperture-coupled scheme feed, an intermediate substrate, and a cylindrical dielectric resonator. This antenna is designed to cover the ISM frequency band at 60 GHz (57 GHz–64 GHz. It was numerically designed using CST microwave Studio simulation software package. Another prototype with a plain dielectric superstrate is also studied for comparison purposes. A bandwidth of 13.56% at the centered frequency of 61.34 GHz and a gain of 11 dB over the entire ISM band have been achieved. A maximum gain of 14.26 dB is obtained at 60 GHz. This is an enhancement of 9 dB compared to a single DRA. HFSS is used to validate our antenna designs. Good agreement between the results of the two softwares is obtained. With these performances, these antennas promise to be useful in the design of future wireless underground communication systems operating in the unlicensed 60 GHz frequency band.
Terahertz MMICs and Antenna-in-Package Technology at 300 GHz for KIOSK Download System
Tajima, Takuro; Kosugi, Toshihiko; Song, Ho-Jin; Hamada, Hiroshi; El Moutaouakil, Amine; Sugiyama, Hiroki; Matsuzaki, Hideaki; Yaita, Makoto; Kagami, Osamu
2016-09-01
Toward the realization of ultra-fast wireless communications systems, the inherent broad bandwidth of the terahertz (THz) band is attracting attention, especially for short-range instant download applications. In this paper, we present our recent progress on InP-based THz MMICs and packaging techniques based on low-temperature co-fibered ceramic (LTCC) technology. The transmitter MMICs are based on 80-nm InP-based high electron mobility transistors (HEMTs). Using the transmitter packaged in an E-plane split-block waveguide and compact lens receiver packaged in LTCC multilayered substrates, we tested wireless data transmission up to 27 Gbps with the simple amplitude key shifting (ASK) modulation scheme. We also present several THz antenna-in-packaging solutions based on substrate integrated waveguide (SIW) technology. A vertical hollow (VH) SIW was applied to a compact medium-gain SIW antenna and low-loss interconnection integrated in LTCC multi-layer substrates. The size of the LTCC antennas with 15-dBi gain is less than 0.1 cm3. For feeding the antenna, we investigated an LTCC-integrated transition and polyimide transition to LTCC VH SIWs. These transitions exhibit around 1-dB estimated loss at 300 GHz and more than 35 GHz bandwidth with 10-dB return loss. The proposed package solutions make antennas and interconnections easy to integrate in a compact LTCC package with an MMIC chip for practical applications.
Directory of Open Access Journals (Sweden)
Mohammed Moulay
2015-01-01
Full Text Available A novel configuration of quad-band bowtie antenna suitable for wireless application is proposed based on accurate equivalent circuit model. The simple configuration and low profile nature of the proposed antenna lead to easy multifrequency operation. The proposed antenna is designed to satisfy specific bandwidth specifications for current communication systems including the Bluetooth (frequency range 2.4–2.485 GHz and bands of the Unlicensed National Information Infrastructure (U-NII low band (frequency range 5.15–5.35 GHz and U-NII mid band (frequency range 5.47–5.725 GHz and used for mobile WiMAX (frequency range 3.3–3.6 GHz. To validate the proposed equivalent circuit model, the simulation results are compared with those obtained by the moments method of Momentum software, the finite integration technique of CST Microwave studio, and the finite element method of HFSS software. An excellent agreement is achieved for all the designed antennas. The analysis of the simulated results confirms the successful design of quad-band bowtie antenna.
Terahertz MMICs and Antenna-in-Package Technology at 300 GHz for KIOSK Download System
Tajima, Takuro; Kosugi, Toshihiko; Song, Ho-Jin; Hamada, Hiroshi; El Moutaouakil, Amine; Sugiyama, Hiroki; Matsuzaki, Hideaki; Yaita, Makoto; Kagami, Osamu
2016-12-01
Toward the realization of ultra-fast wireless communications systems, the inherent broad bandwidth of the terahertz (THz) band is attracting attention, especially for short-range instant download applications. In this paper, we present our recent progress on InP-based THz MMICs and packaging techniques based on low-temperature co-fibered ceramic (LTCC) technology. The transmitter MMICs are based on 80-nm InP-based high electron mobility transistors (HEMTs). Using the transmitter packaged in an E-plane split-block waveguide and compact lens receiver packaged in LTCC multilayered substrates, we tested wireless data transmission up to 27 Gbps with the simple amplitude key shifting (ASK) modulation scheme. We also present several THz antenna-in-packaging solutions based on substrate integrated waveguide (SIW) technology. A vertical hollow (VH) SIW was applied to a compact medium-gain SIW antenna and low-loss interconnection integrated in LTCC multi-layer substrates. The size of the LTCC antennas with 15-dBi gain is less than 0.1 cm3. For feeding the antenna, we investigated an LTCC-integrated transition and polyimide transition to LTCC VH SIWs. These transitions exhibit around 1-dB estimated loss at 300 GHz and more than 35 GHz bandwidth with 10-dB return loss. The proposed package solutions make antennas and interconnections easy to integrate in a compact LTCC package with an MMIC chip for practical applications.
Wang, Ren; Wang, Bing-Zhong; Huang, Wei-Ying; Ding, Xiao
2016-04-16
A compact reconfigurable antenna with an omnidirectional mode and four directional modes is proposed. The antenna has a main radiator and four parasitic elements printed on a dielectric substrate. By changing the status of diodes soldered on the parasitic elements, the proposed antenna can generate four directional radiation patterns and one omnidirectional radiation pattern. The main beam directions of the four directional modes are almost orthogonal and the four directional beams can jointly cover a 360° range in the horizontal plane, i.e., the main radiation plane of omnidirectional mode. The whole volume of the antenna and the control network is approximately 0.70 λ × 0.53 λ × 0.02 λ, where λ is the wavelength corresponding to the center frequency. The proposed antenna has a simple structure and small dimensions under the requirement that the directional radiation patterns can jointly cover the main radiation plane of the omnidirectional mode, therefore, it can be used in smart wireless sensor systems for different application scenarios.
Directory of Open Access Journals (Sweden)
Ren Wang
2016-04-01
Full Text Available A compact reconfigurable antenna with an omnidirectional mode and four directional modes is proposed. The antenna has a main radiator and four parasitic elements printed on a dielectric substrate. By changing the status of diodes soldered on the parasitic elements, the proposed antenna can generate four directional radiation patterns and one omnidirectional radiation pattern. The main beam directions of the four directional modes are almost orthogonal and the four directional beams can jointly cover a 360° range in the horizontal plane, i.e., the main radiation plane of omnidirectional mode. The whole volume of the antenna and the control network is approximately 0.70 λ × 0.53 λ × 0.02 λ, where λ is the wavelength corresponding to the center frequency. The proposed antenna has a simple structure and small dimensions under the requirement that the directional radiation patterns can jointly cover the main radiation plane of the omnidirectional mode, therefore, it can be used in smart wireless sensor systems for different application scenarios.
Reconfigurable contour beam generation using a smart subreflector antenna system
Yoon, Hwan-Sik; Washington, Gregory N.; Theunissen, Wilhelmus H.
2000-06-01
A novel way to design, synthesize and adjust the reconfigurable dual offset contour beam reflector antenna employing an adjustable subreflector is presented. The work also presents a graphical user interface based computer code that connects the electro-magnetic effects to the mechanical surface deflections. The subreflector surface is described by using the finite element method and the far-field radiation pattern is calculated by reflector diffraction synthesis. The reflector surface shape is adjusted using a set of linear piezoelectric point actuators attached to its back surface, from which the diffraction synthesis code calculates the radiation pattern. An example of this method applied to the contiguous US is also presented. As a future work, a software package will be built where the finite element code and the diffraction synthesis code are combined, and it will be used for advanced actuator placement and reflector design problem.
Hossain, Robiul; Karmokar, Debabrata Kumar
2012-11-01
A design of single feed Dual Band Modified Inverted F-Antenna (IFA) operating at 4.45 GHz (4.4-4.7GHz) and 5.9 GHz (5.850-5.925 GHz) has been proposed in this paper. The design is initiated by trial and error method of Numerical Analysis and method of moments (MoMís) in Numerical Electromagnetic code (NEC) is used to design, simulate and analyze this antenna. The results exhibit a proper operation of the antenna in terms of return loss, bandwidth, efficiency, VSWR, and gain at both bands. Proposed antenna is designed to achieve multi-serving purposes. Military applications and applications in the Intelligent Transportation Systems (ITS) are the most important applications within the above mentioned frequency bands respectively. The simulated results including performance parameters of antenna are presented and all are acceptable for the standard antennas.
Design of a mechanically actuated RF grounding system for the ITER ICRH antenna
Hancock, D; Beaumont, B; Dumortier, P; Durodie, F; Kyrytsya, V; Louche, F; McKinley, R; Nicholls, K
2013-01-01
In the ITER equatorial ports containing ICRH antennas, parasitic electrical resonances can be excited in the nominal 20 mm clearance gap between the port walls and the plug contained within it. RF calculations have established that these resonances can be effectively mitigated by a series of suitably located electrically conducting contacts between the port and plug. These contacts must allow installation and removal of the antenna but must also make reliable electrical contact during antenna operation. In addition, the contacts must be compliant enough to survive deflection of the port during seismic and disruption events without transmitting large forces to the vacuum vessel. The distance to be spanned is subject to significant uncertainty, due to the large manufacturing tolerances of the surrounding components, and this also must be considered during the design process. This paper outlines progress made in the design of the grounding system, as well as detailing a number of concepts which have been investi...
Directory of Open Access Journals (Sweden)
Alessandra Costanzo
2014-08-01
Full Text Available In this paper, we describe some promising solutions to the modern need for wearable, energy-aware, miniaturized, wireless systems, whose typical envisaged application is a body area network (BAN. To reach this goal, novel materials are adopted, such as fabrics, in place of standard substrates and metallizations, which require a systematic procedure for their electromagnetic characterization. Indeed, the design of such sub-systems represents a big issue, since approximate approaches could result in strong deviations from the actual system performance. To face this problem, we demonstrate our design procedure, which is based on the concurrent use of electromagnetic software tools and nonlinear circuit-level techniques, able to simultaneously predict the actual system behavior of an antenna system, consisting of the radiating and of the nonlinear blocks, at the component level. This approach is demonstrated for the design of a fully-wearable tri-band rectifying antenna (rectenna and of a button-shaped, electrically-small antenna deploying a novel magneto-dielectric substrate. Simulations are supported by measurements, both in terms of antenna port parameters and far-field results.
Suppression of EM Fields using Active Control Algorithms and MIMO Antenna System
Directory of Open Access Journals (Sweden)
A. Mohammed
2004-09-01
Full Text Available Active methods for attenuating acoustic pressure fields have beensuccessfully used in many applications. In this paper we investigatesome of these active control methods in combination with a MIMO antennasystem in order to assess their validity and performance when appliedto electromagnetic fields. The application that we evaluated in thispaper is a model of a mobile phone equipped with one ordinarytransmitting antenna and two actuator-antennas which purpose is toreduce the electromagnetic field at a specific area in space (e.g. atthe human head. Simulation results show the promise of using theadaptive active control algorithms and MIMO system to attenuate theelectromagnetic field power density.
Circuit Methods for VLF Antenna Couplers. [for use in Loran or Omega receiver systems
Burhans, R. W.
1977-01-01
The limitations of different E-field antenna coupler or preamplifier circuits are presented. All circuits were evaluated using actual Loran or Omega signals. Electric field whip or wire antennas are the simplest types which can be used for reception of VLF signals in the 10 to 100 kHz range. JFET or MOSFET transistors provide impedance transformation and some voltage gain in simple circuits where the power for operating the preamplifier uses the same coaxial cable that feeds the signal back to the receiver. The circuit techniques provide useful alternative methods for Loran-Omega receiver system designers.
Institute of Scientific and Technical Information of China (English)
HU Bing; XU Xiao-wen; HE Mang
2008-01-01
An efficient hybrid method based on the method of moments (MOM) and physical optics (PO) for the analysis of radiation characteristics of an electrically large antenna-radome system is presented. Specifically, MOM is first applied to the antenna to find the current on its surface, and then the equivalent PO currents produced by the antenna radiation are assumed on the radome wall. When the coupling of the PO currents and antenna current is considered, the coupling matrix is divided into a series of partial matrices, in order to deduce the memory requirement and accelerate the evaluation process. Numerical results indicate that the proposed hybrid PO-MOM method is accurate and efficient.
Crouseilles, Nicolas; Faou, Erwan
2016-01-01
We consider the relativistic Vlasov--Maxwell (RVM) equations in the limit when the light velocity $c$ goes to infinity. In this regime, the RVM system converges towards the Vlasov--Poisson system and the aim of this paper is to construct asymptotic preserving numerical schemes that are robust with respect to this limit. Our approach relies on a time splitting approach for the RVM system employing an implicit time integrator for Maxwell's equations in order to damp the higher and higher frequencies present in the numerical solution. It turns out that the choice of this implicit method is crucial as even $L$-stable methods can lead to numerical instabilities for large values of $c$. A number of numerical simulations are conducted in order to investigate the performances of our numerical scheme both in the relativistic as well as in the classical limit regime. In addition, we derive the dispersion relation of the Weibel instability for the continuous and the discretized problem.
An asymptotic preserving scheme for the relativistic Vlasov-Maxwell equations in the classical limit
Crouseilles, Nicolas; Einkemmer, Lukas; Faou, Erwan
2016-12-01
We consider the relativistic Vlasov-Maxwell (RVM) equations in the limit when the light velocity c goes to infinity. In this regime, the RVM system converges towards the Vlasov-Poisson system and the aim of this paper is to construct asymptotic preserving numerical schemes that are robust with respect to this limit. Our approach relies on a time splitting approach for the RVM system employing an implicit time integrator for Maxwell's equations in order to damp the higher and higher frequencies present in the numerical solution. A number of numerical simulations are conducted in order to investigate the performances of our numerical scheme both in the relativistic as well as in the classical limit regime. In addition, we derive the dispersion relation of the Weibel instability for the continuous and the discretized problem.
Гребенюк, Олег Петрович
2014-01-01
The method of orientation of the antenna system of complex of radiomonitoring of satellite communication networks is offered. A method takes into account the features of construction and functional setting of a transport stream of standard of DVB ‑ S.
Control System and Tests for the 13.2-m RAEGE Antenna at Yebes
de Vicente, P.; Bolaño, R.; Barbas, L.
2014-12-01
The RAEGE network is being deployed. The antenna at the Yebes Observatory is the first one in the network, and its construction finished in October 2013. During the construction phase, the remote control system for the antenna and the receivers was developed, and during the commisioning time the software was tested by MT-Mechatronics. As a result, both the control system from MT-Mechatronics and the remote control system by the IGN-CDT were debugged. We have tested the basic functionality of the antenna operated as a single dish telescope. First light at S, X, and Ka band was achieved on February 10^{th}. Afterwards a pointing model for the whole sky was determined, together with an optimum focus position as a function of elevation. Commisioning is not finished yet, and the antenna will be totally delivered to the IGN-CDT in the next weeks. VLBI equipment will be installed within three months, and VLBI observations are foreseen by the end of 2014. In this paper, we provide an overview of the control system and of the main results achieved.
Reflex feed system for dual frequency antenna with frequency cutoff means
Hartop, R. W. (Inventor)
1978-01-01
A reflex feed system is described for a dual frequency antenna such as one which transmits and receives both S and X band signals. The dichroic plate, normally employed for directing X band radiation away from the X band horn, is replaced by a flange about the opening of the X band horn.
Radio/Antenna Mounting System for Wireless Networking under Row-Crop Agriculture Conditions
Directory of Open Access Journals (Sweden)
Daniel K. Fisher
2015-07-01
Full Text Available Interest in and deployment of wireless monitoring systems is increasing in many diverse environments, including row-crop agricultural fields. While many studies have been undertaken to evaluate various aspects of wireless monitoring and networking, such as electronic hardware components, data-collection procedures, power management, and communication protocols, little information related to physical deployment issues has been reported. To achieve acceptable wireless transmission capability, the radio/antenna must be positioned properly relative to the ground surface or crop canopy to minimize degradation of the radio signal, usually requiring the mounting of the radio/antenna above the canopy. This results in the presence of obstacles to normal agricultural equipment traffic and production operations and potential damage to the wireless monitoring system. A simple and rugged radio/antenna mounting system was designed which could be subjected to encounters with agricultural equipment without suffering physical damage. The mounting system was deployed and tested, and operated successfully following repeated encounters with various agricultural machines and implements. The radio/antenna mount is simple and inexpensive to fabricate using locally available components.
Simulation of a ring resonator-based optical beamformer system for phased array receive antennas
Tijmes, M.R.; Meijerink, Arjan; Roeloffzen, C.G.H.; Bentum, Marinus Jan
2009-01-01
A new simulator tool is described that can be used in the field of RF photonics. It has been developed on the basis of a broadband, continuously tunable optical beamformer system for phased array receive antennas. The application that is considered in this paper is airborne satellite reception of di
Simulation of a ring-resonator based optical beamformer system for phased array receive antennas
Tijmes, M.R.; Meijerink, A.; Bentum, M.J.; Roeloffzen, C.G.H.
2009-01-01
A new simulator tool is described that can be used in the field of RF photonics. It has been developed on the basis of a broadband, continuously tunable optical beamformer system for phased array receive antennas. The application that is considered in this paper is airborne satellite reception of di
Kartsan, I. N.; Tyapkin, V. N.; Dmitriev, D. D.; Goncharov, A. E.; Zelenkov, P. V.; Kovalev, I. V.
2016-11-01
This paper considers the simulation of adaptive nulling mechanism patterns in hybrid reflector antenna systems with a 19-element feed element, in which the radiation pattern is formed as a cluster. Incidents of broadband and narrowband interference are studied in the article.
Dong, Danan; Chen, Wen; Cai, Miaomiao; Zhou, Feng; Wang, Minghua; Yu, Chao; Zheng, Zhengqi; Wang, Yuanfei
2016-12-01
The multi-antenna synchronized global navigation satellite system receiver is a high precision, low cost, and widely used emerging receiver. Using this type of receiver, the satellite and receiver clock errors can be eliminated simultaneously by forming between antenna single-differences, which is equivalent to the conventional double-difference model. However, current multi-antenna synchronized global navigation satellite system receiver products have not fully realized their potential to achieve better accuracy, efficiency, and broader applications. This paper introduces the conceptual design and derivable products of multi-antenna synchronized global navigation satellite system receivers involving the aspects of attitude determination, multipath effect mitigation, phase center variation correction, and ground-based carrier phase windup calibration. Through case studies, the advantages of multi-antenna synchronized global navigation satellite system receivers in high-precision positioning applications are demonstrated.
One-dimensional Vlasov-Maxwell equilibria
Greene, John M.
1993-06-01
The purpose of this paper is to show that the Vlasov equilibrium of a plasma of charged particles in an electromagnetic field is closely related to a fluid equilibrium, where only a few moments of the velocity distribution of the plasma are considered. In this fluid equilibrium the electric field should be calculated from Ohm's law, rather than the Poisson equation. In practice, only one-dimensional equilibria are treated, because the symmetry makes this case tractable. The emphasis here is on gaining a better understanding of the subject, but an alternate way of doing the calculations is suggested. It is shown that particle distributions can be found that are consistent with any reasonable electromagnetic field profile.
Entropy production in coarse grained Vlasov equations
Energy Technology Data Exchange (ETDEWEB)
Morawetz, K. [Grand Accelerateur National d' Ions Lourds (GANIL), LPC-ISMRA, 14 - Caen (France); Walke, R. [Rostock Univ., Fachbereich Physick (Germany)
2000-07-01
The Vlasov equation is analyzed for coarse grained distributions. This coarse graining resembles a finite width of test-particles as used in numerical implementations. It is shown that this coarse grained distribution obeys a kinetic equation similar to the Vlasov equation, but with additional terms. These terms give rise to entropy production indicating dissipative features. The reason is a nonlinear mode coupling due to the finite width of the test-particles. The interchange of coarse graining and dynamical evolution is discussed with the help of an exactly solvable model and practical consequences are worked out. By calculating analytically the stationary solution we can show that a sum of modified Boltzmann-like distributions is approached dependent on the initial distribution. This behavior is independent of degeneracy and only controlled by the width of test-particles. The condition for approaching a stationary solution is derived in that the coarse graining energy given by momentum coarse graining should be smaller than a quarter of the kinetic energy. Observable consequences of this coarse graining are: (i) In the thermodynamics the coarse graining leads to spatial correlations in observables. (ii) Too large radii of nucleus in self-consistent treatments are observed and an explicit correction term appears in the Thomas Fermi equation. (iii) The momentum coarse graining translates into a structure term in the response function and resembles to a certain extent vertex correction correlations or internal structure effects. (iv) The coarse graining which is numerically unavoidable leads to a modified centroid energy and higher damping width of collective modes. The numerical codes should be revised in that a refolding is proposed. (author)
CSIR Research Space (South Africa)
Bembe, MJ
2010-11-01
Full Text Available single device. In this study the focus is on the modification of the antenna designs for dual-band functionality which is limited on the ESPAR antenna’s structural parameter. This modification should result in an antenna system which operates in both 2...
Development and Field Testing of a Multi- Antenna GPS System for Deformation Monitoring
Institute of Scientific and Technical Information of China (English)
Ding Xiao-li; Huang Ding-fa; Yin Jian-hua; Chen Yong-qi; C. K. Lau; Yang Yu-wen; Sun Yong-rong; Chen Wu; He Xiu-feng
2003-01-01
GPS has become an important technology for monitoring deformations of structures and the crust of the Earth. A limiting factor for large-scale use of GPS in such applications is however its high hardware cost. For automatic monitoring of deformations, each point to be monitored needs equipped with a set of GPS instruments. This makes many applications such as routine monitoring of landslides too expensive in most cases. A multi-antenna GPS system has been developed and tested aiming at significantly reducing the cost of GPS when used for monitoring deformations of objects such as slopes. The system uses special hardware and software to allow one GPS receiver to be used with a number of GPS antennas. One set of such equipment can therefore be used to monitor a number of points. The system normally reduces the cost of GPS hardware by a number of folds. Besides, such a system design also eases the tasks of data communication, management and system control. This paper describes the design and system configurations of the multi-antenna GPS system that has been developed by the research team. The system consists of integrated hardware and software components for data acquisition, transmission, processing, analysis and visualization. Integration of the GPS system with conventional slope monitoring systems will also be discussed in brief.
A Huygens Surface Approach to Antenna Implementation in Near-Field Radar Imaging System Simulations
2015-08-01
critical geometrical details; re- casting the FDTD update equations on a grid conformal to a curvilinear coordinate system (e.g., cylindrical); and...Imaging System Simulations by Traian Dogaru and DaHan Liao Approved for public release; distribution unlimited...A Huygens Surface Approach to Antenna Implementation in Near-Field Radar Imaging System Simulations by Traian Dogaru and DaHan Liao Sensors
Nonlinear wave evolution in VLASOV plasma: a lie-transform analysis
Energy Technology Data Exchange (ETDEWEB)
Cary, J.R.
1979-08-01
Nonlinear wave evolution in Vlasov plasma is analyzed using the Lie transform, a powerful mathematical tool which is applicable to Hamiltonian systems. The first part of this thesis is an exposition of the Lie transform. Dewar's general Lie transform theory is explained and is used to construct Deprit's Lie transform perturbation technique. The basic theory is illustrated by simple examples.
Discrete Time McKean–Vlasov Control Problem: A Dynamic Programming Approach
Energy Technology Data Exchange (ETDEWEB)
Pham, Huyên, E-mail: pham@math.univ-paris-diderot.fr; Wei, Xiaoli, E-mail: tyswxl@gmail.com [Laboratoire de Probabilités et Modèles Aléatoires, CNRS, UMR 7599, Université Paris Diderot (France)
2016-12-15
We consider the stochastic optimal control problem of nonlinear mean-field systems in discrete time. We reformulate the problem into a deterministic control problem with marginal distribution as controlled state variable, and prove that dynamic programming principle holds in its general form. We apply our method for solving explicitly the mean-variance portfolio selection and the multivariate linear-quadratic McKean–Vlasov control problem.
Convergence analysis of Strang splitting for Vlasov-type equations
Einkemmer, Lukas
2012-01-01
A rigorous convergence analysis of the Strang splitting algorithm for Vlasov-type equations in the setting of abstract evolution equations is provided. It is shown that under suitable assumptions the convergence is of second order in the time step h. As an example, it is verified that the Vlasov-Poisson equation in 1+1 dimensions fits into the framework of this analysis. Also, numerical experiments for the latter case are presented.
The Hamiltonian Structure of the Maxwell-Vlasov Equations.
1981-02-01
principle of Percival [1979). 4. By using an appropriate Darboux theorem, (see Marsden [1981], lecture 1), one can show that Of admits canonically...get the Vlasov-Poisson equation. It would also be of interest to realize both the Vlasov-Maxwell and MHD equations as limiting cases of a grand...de Vries equation, Springer Lecture Notes, #755, 1-15 and Inv. Math. 50, 219-248. J. Arms (1979]. Linearization stability of gravitational and gauge
Energy-Efficient Large-Scale Antenna Systems with Hybrid Digital-Analog Beamforming Structure
Institute of Scientific and Technical Information of China (English)
Shuangfeng Han; ChihLin I; Zhikun Xu; Qi Sun; Haibin Li
2015-01-01
A large⁃scale antenna system (LSAS) with digital beamforming is expected to significantly increase energy efficiency (EE) and spectral efficiency (SE) in a wireless communication system. However, there are many challenging issues related to calibration, en⁃ergy consumption, and cost in implementing a digital beamforming structure in an LSAS. In a practical LSAS deployment, hybrid digital⁃analog beamforming structures with active antennas can be used. In this paper, we investigate the optimal antenna configu⁃ration in an N × M beamforming structure, where N is the number of transceivers, M is the number of active antennas per trans⁃ceiver, where analog beamforming is introduced for individual transceivers and digital beamforming is introduced across all N transceivers. We analyze the green point, which is the point of maximum EE on the EE⁃SE curve, and show that the log⁃scale EE scales linearly with SE along a slope of ⁃lg2/N. We investigate the effect of M on EE for a given SE value in the case of fixed NM and independent N and M. In both cases, there is a unique optimal M that results in optimal EE. In the case of independent N and M, there is no optimal (N, M) combination for optimizing EE. The results of numerical simulations are provided, and these re⁃sults support our analysis.
Link adaptation strategies for multi-antenna assisted WiMAX-like system
DEFF Research Database (Denmark)
Rahman, Muhammad Imadur; Das, Suvra Sekhar; Wang, Yuanye;
2007-01-01
. Contrary to this popular belief, we have found that in some scenarios and in some system conditions, bit and power allocations across OFDM sub-channels are required together for efficient system performance. We have studied a novel link adaptation algorithm in different multi-antenna systems. We have found......In this work, we have studied bit and power allocation strategies for multi-antenna assisted Orthogonal Frequency Division Multiplexing (OFDM) systems. Popularly it is believed that simultaneous bit and power allocation at the same rate is not very much useful in terms of system throughput...... that, if we cannot find the exact Signal to Noise Ratio (SNR) thresholds due to different reasons, such as reduced Link Adaptation (LA) rate, Channel State Information (CSI) error, feedback delay etc., it is better to fix the transmit power across all sub-channels to guarantee the target Frame Error...
Collisional effects on the numerical recurrence in Vlasov-Poisson simulations
Pezzi, Oreste; Valentini, Francesco
2016-01-01
The initial state recurrence in numerical simulations of the Vlasov-Poisson system is a well-known phenomenon. Here we study the effect on recurrence of artificial collisions modeled through the Lenard-Bernstein operator [A. Lenard and I. B. Bernstein, Phys. Rev. 112, 1456-1459 (1958)]. By decomposing the linear Vlasov-Poisson system in the Fourier-Hermite space, the recurrence problem is investigated in the linear regime of the damping of a Langmuir wave and of the onset of the bump-on-tail instability. The analysis is then confirmed and extended to the nonlinear regime through a Eulerian collisional Vlasov-Poisson code. It is found that, despite being routinely used, an artificial collisionality is not a viable way of preventing recurrence in numerical simulations without compromising the kinetic nature of the solution. Moreover, it is shown how numerical effects associated to the generation of fine velocity scales, can modify the physical features of the system evolution even in nonlinear regime. This mean...
Collisional effects on the numerical recurrence in Vlasov-Poisson simulations
Energy Technology Data Exchange (ETDEWEB)
Pezzi, Oreste; Valentini, Francesco [Dipartimento di Fisica and CNISM, Università della Calabria, 87036 Rende (CS) (Italy); Camporeale, Enrico [Center for Mathematics and Computer Science (CWI), 1090 GB Amsterdam (Netherlands)
2016-02-15
The initial state recurrence in numerical simulations of the Vlasov-Poisson system is a well-known phenomenon. Here, we study the effect on recurrence of artificial collisions modeled through the Lenard-Bernstein operator [A. Lenard and I. B. Bernstein, Phys. Rev. 112, 1456–1459 (1958)]. By decomposing the linear Vlasov-Poisson system in the Fourier-Hermite space, the recurrence problem is investigated in the linear regime of the damping of a Langmuir wave and of the onset of the bump-on-tail instability. The analysis is then confirmed and extended to the nonlinear regime through an Eulerian collisional Vlasov-Poisson code. It is found that, despite being routinely used, an artificial collisionality is not a viable way of preventing recurrence in numerical simulations without compromising the kinetic nature of the solution. Moreover, it is shown how numerical effects associated to the generation of fine velocity scales can modify the physical features of the system evolution even in nonlinear regime. This means that filamentation-like phenomena, usually associated with low amplitude fluctuations contexts, can play a role even in nonlinear regime.
Campbell, T. G.; Bailey, M. C.; Belvin, W. K.
1986-01-01
This paper presents the technical results obtained during the development and engineering tests of a 15-Meter Hoop Column deployable antenna system. An important element of the 15-meter antenna program was the structural tests and the characterization of the surface accuracy of the deployed mesh surface. The overall system performance of the 15-meter antenna was obtained during radio frequency tests conducted in the Martin Marietta Near Field Test Laboratory in Denver, CO. The near field tests verified the electromagnetic performance of the structure which exhibited a surface accuracy of 0.061 in (RMS). Radio frequency tests were conducted at 2.3, 4.3, 7.7, and 11.6 GHz. The experiment and analytical results obtained through the 15-meter antenna program will provide new opportunities for the application of large space antennas for future missions.
On the Required Number of Antennas in a Point-to-Point Large-but-Finite MIMO System
Makki, Behrooz
2015-11-12
In this paper, we investigate the performance of the point-to-point multiple-input-multiple-output (MIMO) systems in the presence of a large but finite numbers of antennas at the transmitters and/or receivers. Considering the cases with and without hybrid automatic repeat request (HARQ) feedback, we determine the minimum numbers of the transmit/receive antennas which are required to satisfy different outage probability constraints. We study the effect of the spatial correlation between the antennas on the system performance. Also, the required number of antennas are obtained for different fading conditions. Our results show that different outage requirements can be satisfied with relatively few transmit/receive antennas. © 2015 IEEE.
Tsai, Cheng-Ying; Li, Rui; Tennant, Chris
2015-01-01
As is known, microbunching instability (MBI) has been one of the most challenging issues in designs of magnetic chicanes for short-wavelength free-electron lasers or linear colliders, as well as those of transport lines for recirculating or energy recovery linac machines. To more accurately quantify MBI in a single-pass system and for more complete analyses, we further extend and continue to increase the capabilities of our previously developed linear Vlasov solver [1] to incorporate more relevant impedance models into the code, including transient and steady-state free-space and/or shielding coherent synchrotron radiation (CSR) impedances, the longitudinal space charge (LSC) impedances, and the linac geometric impedances with extension of the existing formulation to include beam acceleration [2]. Then, we directly solve the linearized Vlasov equation numerically for microbunching gain amplification factor. In this study we apply this code to a beamline lattice of transport arc [3] following an upstream linac...
Vlasov simulations of self generated strong magnetic fields in plasmas and laser-plasma interaction
Directory of Open Access Journals (Sweden)
Inglebert A.
2013-11-01
Full Text Available A new formulation based on Hamiltonian reduction technique using the invariance of generalized canonical momentum is introduced for the study of relativistic Weibel-type instability. An example of application is given for the current filamentation instability resulting from the propagation of two counter-streaming electron beams in the relativistic regime of the instability. This model presents a double advantage. From an analytical point of view, the method is exact and standard fluid dispersion relations for Weibel or filamentation instabilies can be recovered. From a numerical point of view, the method allows a drastic reduction of the computational time. A 1D multi-stream Vlasov-Maxwell code is developed using such dynamical invariants in the perpendicular momentum space. Numerical comparison with a full Vlasov-Maxwell system has also been carried out to show the efficiency of this reduction technique.
Williams, W. F.
1983-01-01
The Networks Consolidation Program (NCP) will utilize 34-meter shaped dual-reflector Cassegrain antennas. The shaping calculations, the X/S-band feedhorn to be used, and the predicted RF performance of this antenna system are discussed.
Mixer-Duplexer-Antenna Leaky-Wave System Based on Periodic Space-Time Modulation
Taravati, Sajjad
2016-01-01
We present a mixer-duplexer-antenna leaky-wave system based on periodic space-time modulation. This system operates as a full transceiver, where the upconversion and downconversion mixing operations are accomplished via space-time transitions, the duplexing operation is induced by the nonreciprocal nature of the structure, and the radiation operation is provided by the leaky-wave nature of the wave. A rigorous electromagnetic solution is derived for the dispersion relation and field distributions. The system is implemented in the form of a spatio-temporally modulated microstrip leaky-wave structure incorporating an array of sub-wavelengthly spaced varactors modulated by a harmonic wave. In addition to the overall mixer-duplexer-antenna operation, frequency beam scanning at fixed input frequency is demonstrated as one of the interesting features of the system. A prototype is realized and demonstrated by full-wave and experimental results.
A satellite-tracking millimeter-wave reflector antenna system for mobile satellite-tracking
Densmore, Arthur C. (Inventor); Jamnejad, Vahraz (Inventor); Woo, Kenneth E. (Inventor)
1995-01-01
A miniature dual-band two-way mobile satellite tracking antenna system mounted on a movable ground vehicle includes a miniature parabolic reflector dish having an elliptical aperture with major and minor elliptical axes aligned horizontally and vertically, respectively, to maximize azimuthal directionality and minimize elevational directionality to an extent corresponding to expected pitch excursions of the movable ground vehicle. A feed-horn has a back end and an open front end facing the reflector dish and has vertical side walls opening out from the back end to the front end at a lesser horn angle and horizontal top and bottom walls opening out from the back end to the front end at a greater horn angle. An RF circuit couples two different signal bands between the feed-horn and the user. An antenna attitude controller maintains an antenna azimuth direction relative to the satellite by rotating it in azimuth in response to sensed yaw motions of the movable ground vehicle so as to compensate for the yaw motions to within a pointing error angle. The controller sinusoidally dithers the antenna through a small azimuth dither angle greater than the pointing error angle while sensing a signal from the satellite received at the reflector dish, and deduces the pointing angle error from dither-induced fluctuations in the received signal.
Satellite-Tracking Millimeter-Wave Reflector Antenna System For Mobile Satellite-Tracking
Densmore, Arthur C. (Inventor); Jamnejad, Vahraz (Inventor); Woo, Kenneth E. (Inventor)
2001-01-01
A miniature dual-band two-way mobile satellite-tracking antenna system mounted on a movable vehicle includes a miniature parabolic reflector dish having an elliptical aperture with major and minor elliptical axes aligned horizontally and vertically, respectively, to maximize azimuthal directionality and minimize elevational directionality to an extent corresponding to expected pitch excursions of the movable ground vehicle. A feed-horn has a back end and an open front end facing the reflector dish and has vertical side walls opening out from the back end to the front end at a lesser horn angle and horizontal top and bottom walls opening out from the back end to the front end at a greater horn angle. An RF circuit couples two different signal bands between the feed-horn and the user. An antenna attitude controller maintains an antenna azimuth direction relative to the satellite by rotating it in azimuth in response to sensed yaw motions of the movable ground vehicle so as to compensate for the yaw motions to within a pointing error angle. The controller sinusoidally dithers the antenna through a small azimuth dither angle greater than the pointing error angle while sensing a signal from the satellite received at the reflector dish, and deduces the pointing angle error from dither-induced fluctuations in the received signal.
Directory of Open Access Journals (Sweden)
Md. Moidul Islam
2016-03-01
Full Text Available This Paper presents Microstrip patch antenna for WiMAX communication system which operate at 5.8 GHz frequency band. The main objective of this paper is to design and observe the performance of the designed microstrip patch antenna for different dielectric materials. The size of the designed antenna has been also miniaturized. Better performance is observed for FR4 and dupont-951 dielectric material. For FR4 radiation efficiency is-2.776 dB and total efficiency is -3.026 dB at 5.8 GHz, this indicates better performance. And for dupont-951 the return loss is much lower comparing to the other dielectric materials used in this research, which is -16.609 dB. Also for dupont-951 and FR4, VSWR is found 1.35 and 1.7 respectively which is desirable. Also the size of the antenna has been reduced. In this paper we also observed and analyzed the radiation pattern of far field region, gain, radiation efficiency and total efficiency for different dielectric materials.
On the diversity enhancement and power balancing of per-subcarrier antenna selection in OFDM systems
Park, Kihong
2010-09-01
In this paper, we consider multi-carrier systems with multiple transmit antennas under a power balancing constraint. Applying transmit antenna selection and discrete rate adaptive modulation using M-ary quadrature amplitude modulation (QAM) according to the channel variation per subcarrier, we develop an optimal antenna selection scheme in terms of maximum spectral efficiency where all the possible grouping to send the same information bearing signals in a group of subcarriers are searched and the groups of subcarriers to provide the frequency diversity gain are formed. In addition, we propose a suboptimal method to reduce the computational complexity of the optimal method. The suboptimal scheme consider only the subcarriers under outage and those are combined sequentially until it meets a required SNR. Numerical results show that the proposed suboptimal method with diversity combining outperforms the optimal antenna selection without diversity combining introduced in [1], especially for low SNR region and offers the spectral efficiency close to that of the optimal method with diversity combining, while maintaining lower complexity. ©2010 IEEE.
Abutarboush, Hattan
2012-08-01
This paper presents the design of a low-profile compact printed antenna for fixed frequency and reconfigurable frequency bands. The antenna consists of a main patch, four sub-patches, and a ground plane to generate five frequency bands, at 0.92, 1.73, 1.98, 2.4, and 2.9 GHz, for different wireless systems. For the fixed-frequency design, the five individual frequency bands can be adjusted and set independently over the wide ranges of 18.78%, 22.75%, 4.51%, 11%, and 8.21%, respectively, using just one parameter of the antenna. By putting a varactor (diode) at each of the sub-patch inputs, four of the frequency bands can be controlled independently over wide ranges and the antenna has a reconfigurable design. The tunability ranges for the four bands of 0.92, 1.73, 1.98, and 2.9 GHz are 23.5%, 10.30%, 13.5%, and 3%, respectively. The fixed and reconfigurable designs are studied using computer simulation. For verification of simulation results, the two designs are fabricated and the prototypes are measured. The results show a good agreement between simulated and measured results. © 1963-2012 IEEE.
Design of a mechanically actuated RF grounding system for the ITER ICRH antenna
Energy Technology Data Exchange (ETDEWEB)
Hancock, David, E-mail: david.hancock@ccfe.ac.uk [EURATOM/CCFE Fusion Association, Culham Science Centre, Abingdon, OX14 5ER (United Kingdom); Shannon, Mark [EURATOM/CCFE Fusion Association, Culham Science Centre, Abingdon, OX14 5ER (United Kingdom); Beaumont, Bertrand [ITER Organisation, Route de Vinon sur Verdon, 13115 Saint Paul Lez Durance (France); Dumortier, Pierre; Durodie, Frederic; Kyrytsya, Volodymyr; Louche, Fabrice [LPP/ERM-KMS, Association EURATOM-Belgian State, Brussels (Belgium); McKinley, Robert; Nicholls, Keith [EURATOM/CCFE Fusion Association, Culham Science Centre, Abingdon, OX14 5ER (United Kingdom)
2013-10-15
Highlights: ► The requirements for RF grounding of the ITER ICRH antenna are outlined. ► A number of early concepts are presented and reasons given for their rejection. ► The current grounding contact design is presented and its operation explained. ► Analysis and testing have been undertaken and these results are outlined. -- Abstract: In the ITER equatorial ports containing ICRH antennas, parasitic electrical resonances can be excited in the nominal 20 mm clearance gap between the port walls and the plug contained within it. RF calculations have established that these resonances can be effectively mitigated by a series of suitably located electrically conducting contacts between the port and plug. These contacts must allow installation and removal of the antenna but must also make reliable electrical contact during antenna operation. In addition, the contacts must be compliant enough to survive deflection of the port during seismic and disruption events without transmitting large forces to the vacuum vessel. The distance to be spanned is subject to significant uncertainty, due to the large manufacturing tolerances of the surrounding components, and this also must be considered during the design process. This paper outlines progress made in the design of the grounding system, as well as detailing a number of concepts which have been investigated and abandoned, leading up to the current reference design. The current reference design is a simple and robust mechanical solution consisting of sprung Copper-plated Inconel flaps which use part of the range of the shimming system included in the antenna design as the actuation mechanism. This paper also details practical testing of a number of aspects of the design, including building and testing a prototype to validate mechanical and thermal analyses.
Yuan, Xiaoyan
2009-01-01
This thesis work builds upon the theoretical studies and full-wave analysis of radio frequency micro- and nano-electromechanical systems (RF M/NEMS) integrated multi-functional reconfigurable antennas(MRAs). This is a part of the overall M/NEMS research efforts performed in the RF NEMS Laboratory at USU, which includes design, microfabrication, test, and characterization of M/NEMS integrated congitive wireless communication systems (fig. A.1). The thesis work focuses on two MRAs. 1) A tri...
Vidal, E. V. S.; Ishitsuka, J. I. I.; Koyama, K. Y.
2006-08-01
We are in the process to transform a 32m antenna in Peru, used for telecommunications, into a Radio Telescope to perform Radio Astronomy in Peru. The 32m antenna of Peru constructed by NEC was used for telecommunications with communications satellites at 6 GHz for transmission, and 4 GHz for reception. In collaboration of National Institute of Information and Communications Technology (NICT) Japan, and National Observatory of Japan we developed an Antenna Control System for the 32m antenna in Peru. It is based on the Field System FS9, software released by NASA for VLBI station, and an interface to link PC within FS9 software (PC-FS9) and Antenna Control Unit (ACU) of the 32 meters antenna. The PC-FS9 controls the antenna, commands are translated by interface into control signals compatibles with the ACU using: an I/O digital card with two 20bits ports to read azimuth and elevation angles, one 16bits port for reading status of ACU, one 24bits port to send pulses to start or stop operations of antenna, two channels are analogic outputs to drive the azimuth and elevation motors of the antenna, a LCD display to show the status of interface and error messages, and one serial port for communications with PC-FS9,. The first experiment of the control system was made with 11m parabolic antenna of Kashima Space Research Center (NICT), where we tested the right working of the routines implemented for de FS9 software, and simulations was made with looped data between output and input of the interface, both test were done successfully. With this scientific instrument we will be able to contribute with researching of astrophysics. We expect to into a near future to work at 6.7GHz to study Methanol masers, and higher frequencies with some improvements of the surface of the dish.
Kelly, Kenneth C.; Huang, John
2000-01-01
A highly successful Earth orbiting synthetic antenna aperture radar (SAR) system, known as the SIR-C mission, was carried into orbit in 1994 on a U.S. Shuttle (Space Transportation System) mission. The radar system was mounted in the cargo bay with no need to fold, or in any other way reduce the size of the antennas for launch. Weight and size were not limited for the L-Band, C-Band, and X-Band radar systems of the SIR-C radar imaging mission; the set of antennas weighed 10,500 kg, the L-Band antenna having the major share of the weight. This paper treats designing an L-Band antenna functionally similar to that used for SIR-C, but at a fraction of the cost and at a weight in the order of 250 kg. Further, the antenna must be folded to fit into the small payload shroud of low cost booster rocket systems. Over 31 square meters of antenna area is required. This low weight, foldable, electronic scanning antenna is for the proposed LightSAR radar system which is to be placed in Earth orbit on a small, dedicated space craft at the lowest possible cost for an efficient L- Band radar imaging system. This LightSAR spacecraft radar is to be continuously available for at least five operational years, and have the ability to map or repeat-map any area on earth within a few days of any request. A microstrip patch array, with microstrip transmission lines heavily employed in the aperture and in the corporate feed network, was chosen as the low cost approach for this active dual-polarization, 80 MHz (6.4%) bandwidth antenna design.
Novel time-frequency differential space-time modulation for multi-antenna OFDM systems
Institute of Scientific and Technical Information of China (English)
Tian Jifeng; Jiang Haining; Song Wentao; Luo Hanwen; Xu Youyun
2006-01-01
Differential space-time (DST) modulation has been proposed recently for multiple-antenna systems over Rayleigh fading channels, where neither the transmitter nor the receiver knows the fading coefficients. Among existing schemes, differential modulation is always performed in the time domain and suffers performance degradations in frequency-selective fading channels. In order to combat the fast time and frequency-selective fading, a novel time-frequency differential space-time (TF-DST) modulation scheme, which adopts differential modulation in both time and frequency domains, is proposed for multi-antenna orthogonal frequency division multiplexing (OFDM) system. A corresponding suboptimal yet low-complexity non-coherent detection approach is also proposed. Simulation results demonstrate that the propped system is robust for time and frequency-selective Rayleigh fading channels.
Reverse Compute and Forward: A Low-Complexity Architecture for Downlink Distributed Antenna Systems
Hong, Songnam
2012-01-01
We consider a distributed antenna system where $L$ antenna terminals (ATs) are connected to a Central Processor (CP) via digital error-free links of finite capacity $R_0$, and serve $L$ user terminals (UTs). This system model has been widely investigated both for the uplink and the downlink, which are instances of the general multiple-access relay and broadcast relay networks. In this work we focus on the downlink, and propose a novel downlink precoding scheme nicknamed "Reverse Quantized Compute and Forward" (RQCoF). For this scheme we obtain achievable rates and compare with the state of the art available in the literature. We also provide simulation results for a realistic network with fading and pathloss with $K > L$ UTs, and show that channel-based user selection produces large benefits and essentially removes the problem of rank deficiency in the system matrix.
Directory of Open Access Journals (Sweden)
Xiaoyu Dang
2012-01-01
Full Text Available By combining adaptive modulation and automatic repeat request, a cross-layer design (CLD scheme for MIMO system with antenna selection (AS and imperfect feedback is presented, and the corresponding performance is studied. Subject to a target packet loss rate and fixed power constraint, the variable switching thresholds of fading gain are derived. According to these results, and using mathematical manipulation, the average spectrum efficiency (SE and packet error rate (PER of the system are further derived. As a result, closed-form expressions of the average SE and PER are obtained, respectively. These expressions include the expressions under perfect channel state information as special cases and provide good performance evaluation for the system. Numerical results show that the proposed CLD scheme with antenna selection has higher SE than the existing CLD scheme with space-time block coding, and the CLD scheme with variable switching thresholds outperforms that with conventional-fixed switching thresholds.
Dynamic Optimal CCI Weight Channel Pre-evaluative Assignment in Adaptive Array Antenna System
Institute of Scientific and Technical Information of China (English)
MENG Weixiao; ZHANG Naitong
2001-01-01
Dynamic Channel Assignment (DCA)together with Adaptive Array Antenna (AAA) takes an important part in cellular mobile communication system. In this paper, a conception of co-channel in terference (CCI) quantification is advanced in multicell 8-element circular adaptive array antenna system.Normalized CCI weight relational expression, which is concerned in distance and look angle difference is sublimed from experiential sampling, induction and non-linear fitting. Then an algorithm of optimal CCI weight channel pre-evaluation is proposed as a solution of dynamic channel assignment. The least sum of weight value before assignment is used to pre-evaluate the performance of all the channels. Based on an approached practical cellular model, a series of systemclassed simulations are accomplished. Simulation resuits show that this algorithm is quite effective: system capacity is increased greatly; traffic block probabilities are decreased remarkably; nice channel quality is maintained; the reliability of DCA is enhanced; the higher frequency utilization efficiency is also obtained.
An arc control and protection system for the JET lower hybrid antenna based on an imaging system
Figueiredo, J.; Mailloux, J.; Kirov, K.; Kinna, D.; Stamp, M.; Devaux, S.; Arnoux, G.; Edwards, J. S.; Stephen, A. V.; McCullen, P.; Hogben, C.
2014-11-01
Arcs are the potentially most dangerous events related to Lower Hybrid (LH) antenna operation. If left uncontrolled they can produce damage and cause plasma disruption by impurity influx. To address this issue an arc real time control and protection imaging system for the Joint European Torus (JET) LH antenna has been implemented. The LH system is one of the additional heating systems at JET. It comprises 24 microwave generators (klystrons, operating at 3.7 GHz) providing up to 5 MW of heating and current drive to the JET plasma. This is done through an antenna composed of an array of waveguides facing the plasma. The protection system presented here is based primarily on an imaging arc detection and real time control system. It has adapted the ITER like wall hotspot protection system using an identical CCD camera and real time image processing unit. A filter has been installed to avoid saturation and spurious system triggers caused by ionization light. The antenna is divided in 24 Regions Of Interest (ROIs) each one corresponding to one klystron. If an arc precursor is detected in a ROI, power is reduced locally with subsequent potential damage and plasma disruption avoided. The power is subsequently reinstated if, during a defined interval of time, arcing is confirmed not to be present by image analysis. This system was successfully commissioned during the restart phase and beginning of the 2013 scientific campaign. Since its installation and commissioning, arcs and related phenomena have been prevented. In this contribution we briefly describe the camera, image processing, and real time control systems. Most importantly, we demonstrate that an LH antenna arc protection system based on CCD camera imaging systems works. Examples of both controlled and uncontrolled LH arc events and their consequences are shown.
An arc control and protection system for the JET lower hybrid antenna based on an imaging system
Energy Technology Data Exchange (ETDEWEB)
Figueiredo, J., E-mail: joao.figueiredo@jet.efda.org [Associação EURATOM/IST, Instituto de Plasmas e Fusão Nuclear, Instituto Superior Técnico, Universidade de Lisboa, 1049-001 Lisboa, Portugal and EFDA-CSU, Culham Science Centre, Abingdon OX14 3DB (United Kingdom); Mailloux, J.; Kirov, K.; Kinna, D.; Stamp, M.; Devaux, S.; Arnoux, G.; Edwards, J. S.; Stephen, A. V.; McCullen, P.; Hogben, C. [EURATOM/CCFE Fusion Association, Culham Science Center, Abingdon OX14 3DB (United Kingdom)
2014-11-15
Arcs are the potentially most dangerous events related to Lower Hybrid (LH) antenna operation. If left uncontrolled they can produce damage and cause plasma disruption by impurity influx. To address this issue an arc real time control and protection imaging system for the Joint European Torus (JET) LH antenna has been implemented. The LH system is one of the additional heating systems at JET. It comprises 24 microwave generators (klystrons, operating at 3.7 GHz) providing up to 5 MW of heating and current drive to the JET plasma. This is done through an antenna composed of an array of waveguides facing the plasma. The protection system presented here is based primarily on an imaging arc detection and real time control system. It has adapted the ITER like wall hotspot protection system using an identical CCD camera and real time image processing unit. A filter has been installed to avoid saturation and spurious system triggers caused by ionization light. The antenna is divided in 24 Regions Of Interest (ROIs) each one corresponding to one klystron. If an arc precursor is detected in a ROI, power is reduced locally with subsequent potential damage and plasma disruption avoided. The power is subsequently reinstated if, during a defined interval of time, arcing is confirmed not to be present by image analysis. This system was successfully commissioned during the restart phase and beginning of the 2013 scientific campaign. Since its installation and commissioning, arcs and related phenomena have been prevented. In this contribution we briefly describe the camera, image processing, and real time control systems. Most importantly, we demonstrate that an LH antenna arc protection system based on CCD camera imaging systems works. Examples of both controlled and uncontrolled LH arc events and their consequences are shown.
An arc control and protection system for the JET lower hybrid antenna based on an imaging system.
Figueiredo, J; Mailloux, J; Kirov, K; Kinna, D; Stamp, M; Devaux, S; Arnoux, G; Edwards, J S; Stephen, A V; McCullen, P; Hogben, C
2014-11-01
Arcs are the potentially most dangerous events related to Lower Hybrid (LH) antenna operation. If left uncontrolled they can produce damage and cause plasma disruption by impurity influx. To address this issue an arc real time control and protection imaging system for the Joint European Torus (JET) LH antenna has been implemented. The LH system is one of the additional heating systems at JET. It comprises 24 microwave generators (klystrons, operating at 3.7 GHz) providing up to 5 MW of heating and current drive to the JET plasma. This is done through an antenna composed of an array of waveguides facing the plasma. The protection system presented here is based primarily on an imaging arc detection and real time control system. It has adapted the ITER like wall hotspot protection system using an identical CCD camera and real time image processing unit. A filter has been installed to avoid saturation and spurious system triggers caused by ionization light. The antenna is divided in 24 Regions Of Interest (ROIs) each one corresponding to one klystron. If an arc precursor is detected in a ROI, power is reduced locally with subsequent potential damage and plasma disruption avoided. The power is subsequently reinstated if, during a defined interval of time, arcing is confirmed not to be present by image analysis. This system was successfully commissioned during the restart phase and beginning of the 2013 scientific campaign. Since its installation and commissioning, arcs and related phenomena have been prevented. In this contribution we briefly describe the camera, image processing, and real time control systems. Most importantly, we demonstrate that an LH antenna arc protection system based on CCD camera imaging systems works. Examples of both controlled and uncontrolled LH arc events and their consequences are shown.
Joint switched multi-spectrum and transmit antenna diversity for spectrum sharing systems
Sayed, Mostafa M.
2013-10-01
In spectrum sharing systems, a secondary user (SU) is allowed to share the spectrum with a primary (licensed) network under the condition that the interference observed at the receivers of the primary users (PU-Rxs) is below a predetermined level. In this paper, we consider a secondary network comprised of a secondary transmitter (SU-Tx) equipped with multiple antennas and a single-antenna secondary receiver (SU-Rx) sharing the same spectrum with multiple primary users (PUs), each with a distinct spectrum. We develop transmit antenna diversity schemes at the SU-Tx that exploit the multi-spectrum diversity provided by the existence of multiple PUs so as to optimize the signal-to-noise ratio (SNR) at the SU-Rx. In particular, assuming bounded transmit power at the SU-Tx, we develop switched selection schemes that select the primary spectrum and the SU-Tx transmit antenna that maintain the SNR at the SU-Rx above a specific threshold. Assuming Rayleigh fading channels and binary phase-shift keying (BPSK) transmission, we derive the average bit-error-rate (BER) and average feedback load expressions for the proposed schemes. For the sake of comparison, we also derive a BER expression for the optimal selection scheme that selects the best antenna/spectrum pair that maximizes the SNR at the SU-Rx, in exchange of high feedback load and switching complexity. Finally, we show that our analytical results are in perfect agreement with the simulation results. © 2013 IEEE.
Pethe, Kaiwalya; Galande, Shridhar; Jamadar, Sachin; Mahajan, S. P.; Patil, R. A.; Joshi, B. C.; Manoharan, P. K.; Roy, Jayashree; Kate, G.
2016-03-01
Low frequency Radio Experiment (LORE) is a proposed space payload for space weather observations from space, operating between few kHz to 30 MHz. This paper presents preliminary design and practical implementation of LORE antenna systems, which consist of three mutually orthogonal mono-poles. Detailed computational electromagnetic simulations, carried out to study the performance of the antenna systems, are presented followed up by laboratory tests of the antennas as well as radiation tests with a long range test range, designed for this purpose. These tests form the first phase of the design and implementation of the full LORE prototype later in the year.
Design of a Dual-Band On-Body Antenna for a Wireless Body Area Network Repeater System
Directory of Open Access Journals (Sweden)
Kyeol Kwon
2012-01-01
Full Text Available A dual-band on-body antenna for a wireless body area network repeater system is proposed. The designed dual-band antenna has the maximum radiation directed toward the inside of the human body in the medical implantable communication service (MICS band in order to collect vital information from the human body and directed toward the outside in the industrial, scientific, and medical (ISM band to transmit that information to a monitoring system. In addition, the return loss property of the antenna is insensitive to human body effects by utilizing the epsilon negative zeroth-order resonance property.
A spectral analysis of an integrated photomixer/antenna in a homodyne terahertz photomixing system
Ryu, Han-Cheol; Park, Seong-Ook; Kang, Kwang-Yong
2013-01-01
An analysis has been carried out to estimate the spectral characteristics of an integrated photomixer/antenna in a homodyne photomixing system. The analysis adopts the impedance mismatch factor and Friis power transmission formula used in communication links based on the conventional analysis theory of a terahertz photomixer. The analysis and experimental results have proved that an impedance matching condition between the impedance of a photomixer and the input impedance of an antenna is directly related with photomixing terahertz wave generation. The Friis formula is introduced to calculate the propagation loss of the wave from a transmitter to a receiver in a homodyne photomixing system. A log-periodic antenna was used to ensure a high dynamic range in a broad frequency region. The dynamic range of the homodyne terahertz photomixing system was about 60 dB near 100 GHz and decreased with an increasing frequency from 10 GHz to 1000 GHz. The measured results agree well with the theoretically analyzed results and prove that the terahertz photomixing power is closely related to impedance mismatch factor and it could be estimated in the homodyne terahertz photomixing system without a terahertz power detector.
System-level integrated circuit (SLIC) development for phased array antenna applications
Shalkhauser, K. A.; Raquet, C. A.
1991-01-01
A microwave/millimeter wave system-level integrated circuit (SLIC) being developed for use in phased array antenna applications is described. The program goal is to design, fabricate, test, and deliver an advanced integrated circuit that merges radio frequency (RF) monolithic microwave integrated circuit (MMIC) technologies with digital, photonic, and analog circuitry that provide control, support, and interface functions. As a whole, the SLIC will offer improvements in RF device performance, uniformity, and stability while enabling accurate, rapid, repeatable control of the RF signal. Furthermore, the SLIC program addresses issues relating to insertion of solid state devices into antenna systems, such as the reduction in number of bias, control, and signal lines. Program goals, approach, and status are discussed.
A new approach to design of quasi-isotropic antenna systems for satellite applications
DEFF Research Database (Denmark)
Schjær-Jacobsen, Hans; Hansen, J.E.
1976-01-01
The new approach considered takes into account the maximum error of the quasi-isotropic radiation pattern relative to the ideal pattern. A design example involving a spherical satellite with quarter wave monopoles is used to demonstrate the effectiveness of the new approach. An investigation...... is conducted concerning the minimax optimization of power radiation patterns. It is shown that the minimax objective represents a useful alternative to the isotropy concept in the design of quasi-isotropic antenna systems for satellite applications....
A new approach to design of quasi-isotropic antenna systems for satellite applications
DEFF Research Database (Denmark)
Schjær-Jacobsen, Hans; Hansen, J.E.
1976-01-01
The new approach considered takes into account the maximum error of the quasi-isotropic radiation pattern relative to the ideal pattern. A design example involving a spherical satellite with quarter wave monopoles is used to demonstrate the effectiveness of the new approach. An investigation...... is conducted concerning the minimax optimization of power radiation patterns. It is shown that the minimax objective represents a useful alternative to the isotropy concept in the design of quasi-isotropic antenna systems for satellite applications....
Multihop relaying and multiple antenna techniques: performance trade-offs in cellular systems
Jacobson Kevin; Krzymień Witold
2011-01-01
Abstract Two very important and active areas of wireless research are multihop relaying and multiple antenna techniques. Wireless multihop relaying can increase the aggregate network data capacity and improve coverage of cellular systems by reducing path loss, mitigating shadowing, and enabling spatial reuse. In particular, multihop relaying can improve the throughput for mobiles suffering from poor signal to interference and noise ratio at the edge of a cell and reduce cell size to increase ...
Integrated Antenna Solutions for Wireless Sensor and Millimeter-Wave Systems
2009-01-01
This thesis presents various integrated antenna solutions for different types of systems and applications, e.g. wireless sensors, broadband handsets, advanced base stations, MEMS-based reconfigurable front-ends, automotive anti-collision radars, and large area electronics. For wireless sensor applications, a T-matched dipole is proposed and integrated in an electrically small body-worn sensor node. Measurement techniques are developed to characterize the port impedance and radiation propertie...
Cui, Xiao; Chen, Gang; Wang, Jin; Song, Huan; Gong, Wanlin
2016-06-15
The Wuhan Ionospheric Oblique Backscattering Sounding System with the addition of an antenna array (WIOBSS-AA) is the newest member of the WIOBSS family. It is a multi-channel radio system using phased-array antenna technology. The transmitting part of this radio system applies an array composed of five log-periodic antennas to form five beams that span an area to the northwest of the radar site. The hardware and the antenna array of the first multi-channel ionosonde in the WIOBSS family are introduced in detail in this paper. An ionospheric detection experiment was carried out in Chongyang, Hubei province, China on 16 March 2015 to examine the performance of WIOBSS-AA. The radio system demonstrated its ability to obtain ionospheric electron density information over a wide area. The observations indicate that during the experiment, the monitored large-area ionospheric F2-layer was calm and electron density increased with decreasing latitude.
Application of MMIC modules in future multiple beam satellite antenna systems
Smetana, J.
1982-01-01
Multiple beam antenna systems for advanced communication satellites operating in the 30/20 GHz frequency bands (30 GHz uplink, 20 GHz downlink) were developed. Up to twenty 0.3 deg HPBW fixed spot beams and six 0.3 deg HPBW scanning spot beams will be required. Array-fed dual reflector antenna systems in which monolithic microwave integrated circuit (MMIC) phase shift and amplifier modules are used with each radiating element of the feed array for beam pointing and power gain were developed. The feasibility of distributed power amplification and beam pointing with MMIC modules in the elements of an array and to develop a data base for future development were demonstrated. The technical discussion centers around the potential advantages of ""monolithic'' antennas for specific applications as compared to systems using high powered TWT's. These include: reduced losses in the beam forming network; advantage of space combining and graceful degradation; dynamic control of beam pointing and illumination contour; and possibilities for cost and weight reduction.
Practical and Simple Wireless Channel Models for Use in Multipolarized Antenna Systems
Directory of Open Access Journals (Sweden)
KwangHyun Jeon
2014-01-01
Full Text Available The next-generation wireless systems are expected to support data rates of more than 100 Mbps in outdoor environments. In order to support such large payloads, a polarized antenna may be employed as one of the candidate technologies. Recently, the third generation partnership standards bodies (3GPP/3GPP2 have defined a cross-polarized channel model in SCM-E for MIMO systems; however, this model is quite complex since it considers a great many channel-related parameters. Furthermore, the SCM-E channel model combines the channel coefficients of all the polarization links into one complex output, making it impossible to exploit the MIMO spatial multiplexing or diversity gains in the case of employing polarized antenna at transmitter and receiver side. In this paper, we present practical and simple 2D and 3D multipolarized multipath channel models, which take into account both the cross-polarization discrimination (XPD and the Rician factor. After verifying the proposed channel models, the BER and PER performances and throughput using the EGC and MRC combining techniques are evaluated in multipolarized antenna systems.
Joint Angle and Delay Estimation (JADE) in Antenna Array CDMA Systems
Institute of Scientific and Technical Information of China (English)
无
2002-01-01
The estimate of signals parameters is very important in wireless communications. In this paper, we combine subspace-based blind channel estimation algorithm with the extension of the JADE-WSF algorithm to jointly estimate the Angles-of-Arrival (AOAs) and delays of multipath signals arriving at an antenna array in Code Division Multiple Access (CDMA) systems. Our approach uses a collection of estimates of a consistent chip-sample of space-time vector channel. The channel estimates are assumed to have constant path AOA and delay over a finite number of symbols. Unlike the traditional MUltiple SIgnal Classification (MUSIC) and Estimation of Signal Parameters via Rotational Invariance Techniques (ESPRIT) algorithms for the estimation of signals parameters, the proposed method can work when the number of paths exceeds the number of antennas. The Cramer-Rao Bound (CRB) and simulations are provided.
CHANNEL ESTIMATION TECHNIQUE IN MULTI-ANTENNA AF RELAY COMMUNICATION SYSTEMS
Institute of Scientific and Technical Information of China (English)
Chen Mingxue; Xu Chengqi
2011-01-01
The channel estimation technique is investigated in OFDM communication systems with multi-antenna Amplify-and-Forward (AF) relay.The Space-Time Block Code (STBC) is applied at the transmitter of the relay to obtain diversity gain.According to the transmission characteristics of OFDM symbols on multiple antennas,a pilot-aided Linear Minimum Mean-Square-Error (LMMSE) channel estimation algorithm with low complexity is designed.Simulation results show that,the proposed LMMSE estimator outperforms least-square estimator and approaches the optimal estimator without error in the performance of Symbol Error Ratio (SER) under several modulation modes,and has a good estimation effect in the realistic relay communication scenario.
Planar antenna for system Wi-Fi on dielectric resonators
Directory of Open Access Journals (Sweden)
A. A. Trubin
2007-10-01
Full Text Available The results of research of the aerial for system without of the conductor access are given which has of the single diagram of an orientation, plate and consists from 4 of the dielectric resonators.
Optimised inductively coupled reader antennas for smart HF RFID systems.
Soodmand, Soheyl
2015-01-01
The Internet of things (IoT) refers to uniquely identifiable objects and their virtual representations in an Internet-like structure to be managed and inventoried by computers. Radio-frequency identification (RFID) - a prerequisite for the IoT - is an automatic way for data transaction in object identification and is used to improve automation, inventory control and checkout operations. An RFID system consists of a reader device and one or several tags. Smart reader systems are...
Simple ML Detector for Multiple Antennas Communication System
Directory of Open Access Journals (Sweden)
Ahmad Taqwa
2010-10-01
Full Text Available In order to support providing broadband wireless communication services against limited and expensive frequency bandwidth, we have to develop a bandwidth efficient system. Therefore, in this paper we propose a closed-loop MIMO (Multiple-Input-Multiple-Output system using ML (Maximum Likelihood detector to optimize capacity and to increase system performance. What is especially exciting about the benefits offered by MIMO is that a high capacity and performance can be attained without additional frequency-spectral resource. The grand scenario of this concept is the attained advantages of transformation matrices having capability to allocate transmitted signals power suit to the channel. Furthermore, product of these matrices forms parallel singular channels. Due to zero inter-channels correlation, thus we can design ML detector to increase the system performance. Finally, computer simulations validates that at 0 dB SNR our system can reach optimal capacity up to 1 bps/Hz and SER up to 0.2 higher than opened-loop MIMO.
Artemenko, A. A.; Mal'tsev, A. A.; Maslennikov, R. O.; Sevastyanov, A. G.; Ssorin, V. N.
2013-01-01
We consider the development of an integrated lens antenna for LAN radio communication systems operated in the 60 GHz frequency band. The antenna is an extended hemispherical silicon lens. On its flat surface, a microstrip antenna element is located. The use of silicon, which has a dielectric permittivity ɛ = 11.7, as the lens material ensures the maximum range of scanning angles for the minimum axial size of the lens. The approximate analytical formulas, which are used for initial calculations of the lens parameters, allow one to evaluate the basic parameters of the lens antenna integrated with the microstrip antenna element. For further optimizing the parameters of the lens and the antenna element, 3D simulation of the electromagnetic-field distribution was performed. Based on its results, we have developed and manufactured extended hemispherical silicon lenses, which had radii of 6 and 12 mm. The planar microstrip antenna element was manufactured by the low temperature co-fired ceramics (LTCC) technology. The results of simulation and experimental studies of the manufactured prototypes demonstrate that the developed lens antennas has directivities of 17.6 and 23.1 dBi for lenses with radii of 6 and 12 mm, respectively. In this case, the maximum beam deflection angle is achieved, which is equal to 55°, while the permissible decrease in the directivity is no more than 6 dBi compared with the case of a non-deflected beam. The obtained results show that the developed integrated lens antennas can find applications in high-speed radio communication systems operated in the millimeter-wave range.
Multi-feed System for a Variable Profile Antenna
Pinchuk, G. A.; Majorova, E. K.; Berlizev, I. V.
A new design for the RATAN-600 radio telescope is discussed. A multi-channel receiving system, using the principles of phased feed arrays, is suggested for installation in the focal region of the secondary mirror. In such a hybrid system, the main reflecting surface with its rather large collecting area would provide the sensitivity and resolving power of the telescope, and the feed array would give a considerable increase in field of view. Several advantages of such a system, widely used in radar technique, could be applied to radio astronomy. Two version of the array configuration are considered: a one-dimensional version, using the existing secondary reflector, and a more complicated but more powerful two- or three-dimensional configuration. For the latter, we propose to use either the existing secondary reflector, or a new, specially shaped secondary.
The influence of nonlinear effects on the spectral efficiency of multiinput antenna systems
Directory of Open Access Journals (Sweden)
Vishniakova J. V.
2015-08-01
Full Text Available The analysis technique and design algorithm are proposed for multiinput antenna systems, based on the mathematical model developed. The technique and algorithm described allow the analysis of a wide class of multiinput systems, in particular, MIMO systems, reconfigurable multiantenna systems, multiinput systems with nonlinear components and devices. The paper presents numerical analysis results of the intermodulation interference effect on the spectral efficiency of a multiinput system with nonlinear elements in receiving antennas, obtained using the methods, algorithms and software products developed. It is shown that in the nonlinear system intermodulation interferences appear, and the spectral efficiency of the data transmission system decays near the operating frequency due to the appearance of additional combinational components in the frequency response of the system. This effect depends on the degree of nonlinearity, radiated power, the level of interfering signals. Based on the results obtained, it was concluded that the presence of nonlinear elements and devices must be taken into account in the design and analysis processes of multiinput multiantenna systems, considering the specific types of those nonlinearities.
Feedback Control System for Antenna Phase Difference in the LHCD Experiments
Institute of Scientific and Technical Information of China (English)
Jiang Min; Kuang Guangli; Shan Jiafang; Lin Jian'an; Kong Jun; HT-7 Team
2005-01-01
It is well accepted that lower hybrid current drive (LHCD) is the most efficient method for non-inductive current drive in fusion devices and the effect of the current drive is dependent on not only microwave power but also its grill phase shift. This paper presents a new kind of feedback control system for antenna phase difference in LHCD experiments. In this high-speed control system, a lot of new technologies and methods are incorporated. The results of the experiments show a very good agreement with the system design.
Increasing the Performance of OFDM-OQAM Communication Systems through Smart Antennas Processing
Zorba, Nizar; Pfletschinger, Stephan; Bader, Faouzi
A novel filter bank based multicarrier (FBMC) transmission scheme is proposed, where the transmit antennas are employed to substantially reduce the inherent inter-carrier and inter-symbol interference. Since FBMC systems do not apply a guard interval, they can achieve higher spectral efficiencies than OFDM systems, although at the cost of additional inter-symbol interference (ISI). In this paper, we present a method which reduces the number of interference terms by employing a multiantenna precoding scheme based on spatial diversity, and the system can benefit from the multiuser gain, through an opportunistic scheduler at the transmitter side.
Excitation migration in fluctuating light-harvesting antenna systems
Chmeliov, J.; Trinkunas, G.; Amerongen, van H.; Valkunas, L.
2016-01-01
Complex multi-exponential fluorescence decay kinetics observed in various photosynthetic systems like photosystem II (PSII) have often been explained by the reversible quenching mechanism of the charge separation taking place in the reaction center (RC) of PSII. However, this description does not ac
Cognitive Multiple-Antenna Network with Outage and Rate Margins at the Primary System
DEFF Research Database (Denmark)
Maham, Behrouz; Popovski, Petar
2015-01-01
In the common model for spectrum sharing, cognitive users can access the spectrum as long as the target performance in the legitimate primary system is not violated. In this paper, we consider a downlink primary multiple-inputsingle- output (MISO) system which operates under a controlled interfer......In the common model for spectrum sharing, cognitive users can access the spectrum as long as the target performance in the legitimate primary system is not violated. In this paper, we consider a downlink primary multiple-inputsingle- output (MISO) system which operates under a controlled...... interference from the downlink MISO cognitive radio, also called secondary system. We derive exact expressions for outage probability of the primary user under Rayleigh fading, when the primary system is exposed to interference from a secondary base station. We treat three different operating modes...... of the adaptive-rate transmit-beamforming primary system and the adaptive-rate transmit antenna-selection primary system. The analytical results are confirmed by simulations, in which we analyze the impact of different parameters, such as the number of antennas and the amount of the interference on the system...
Advanced Radio Resource Management for Multi Antenna Packet Radio Systems
Nonchev, Stanislav; 10.5121/ijwmn.2010.2201
2010-01-01
In this paper, we propose fairness-oriented packet scheduling (PS) schemes with power-efficient control mechanism for future packet radio systems. In general, the radio resource management functionality plays an important role in new OFDMA based networks. The control of the network resource division among the users is performed by packet scheduling functionality based on maximizing cell coverage and capacity satisfying, and certain quality of service requirements. Moreover, multiantenna transmit-receive schemes provide additional flexibility to packet scheduler functionality. In order to mitigate inter-cell and co-channel interference problems in OFDMA cellular networks soft frequency reuse with different power masks patterns is used. Stemming from the earlier enhanced proportional fair scheduler studies for single-input multiple-output (SIMO) and multiple-input multipleoutput (MIMO) systems, we extend the development of efficient packet scheduling algorithms by adding transmit power considerations in the ove...
Advanced Radio Resource Management for Multi Antenna Packet Radio Systems
Stanislav Nonchev; Mikko Valkama
2010-01-01
In this paper, we propose fairness-oriented packet scheduling (PS) schemes with power-efficientcontrol mechanism for future packet radio systems. In general, the radio resource managementfunctionality plays an important role in new OFDMA based networks. The control of the networkresource division among the users is performed by packet scheduling functionality based on maximizingcell coverage and capacity satisfying, and certain quality of service requirements. Moreover, multiantennatransmit-r...
ADI type preconditioners for the steady state inhomogeneous Vlasov equation
Gasteiger, Markus; Ostermann, Alexander; Tskhakaya, David
2016-01-01
The purpose of the current work is to find numerical solutions of the steady state inhomogeneous Vlasov equation. This problem has a wide range of applications in the kinetic simulation of non-thermal plasmas. However, the direct application of either time stepping schemes or iterative methods (such as Krylov based methods like GMRES or relexation schemes) is computationally expensive. In the former case the slowest timescale in the system forces us to perform a long time integration while in the latter case a large number of iterations is required. In this paper we propose a preconditioner based on an ADI type splitting method. This preconditioner is then combined with both GMRES and Richardson iteration. The resulting numerical schemes scale almost ideally (i.e. the computational effort is proportional to the number of grid points). Numerical simulations conducted show that this can result in a speedup of close to two orders of magnitude (even for intermediate grid sizes) with respect to the not preconditio...
Circular Microstrip Patch Array Antenna for C-Band Altimeter System
Directory of Open Access Journals (Sweden)
Asghar Keshtkar
2008-01-01
Full Text Available The purpose of this paper is to discuss the practical and experimental results obtained from the design, construction, and test of an array of circular microstrip elements. The aim of this antenna construction was to obtain a gain of 12 dB, an acceptable pattern, and a reasonable value of SWR for altimeter system application. In this paper, the cavity model was applied to analyze the patch and a proper combination of ordinary formulas; HPHFSS software and Microwave Office software were used. The array includes four circular elements with equal sizes and equal spacing and was planed on a substrate. The method of analysis, design, and development of this antenna array is explained completely here. The antenna is simulated and is completely analyzed by commercial HPHFSS software. Microwave Office 2006 software has been used to initially simulate and find the optimum design and results. Comparison between practical results and the results obtained from the simulation shows that we reached our goals by a great degree of validity.
EMC, RF, and Antenna Systems in Miniature Electronic Devices
DEFF Research Database (Denmark)
Ruaro, Andrea
Advanced techniques for the control of electromagnetic interference (EMI) and for the optimization of the electromagnetic compatibility (EMC) performance has been developed under the constraints typical of miniature electronic devices (MED). The electromagnetic coexistence of multiple systems...... and their mutual interaction have been the underlying theme of the work. The research results concern different aspects related to the integration of radio-frequency (RF) electronics in MEDs and hearing instruments (HI). To control internal EMI, a novel near-field parasitic resonator (NFPR) has been researched...
Scanning beam antenna conceptual design for 20/30 GHz satellite systems
Smetana, J.; Sorbello, R.; Crosswell, W. F.
1983-01-01
The configuration described is one of four antenna system configurations developed using a variety of monolithic microwave integrated circuit module arrangements and optical systems. A parametric analysis is expected to produce a data base for the selection of design points for a variety of applications. Soon to be accomplished is the design concept of the active (lens) array, which will take into consideration such factors as, coupling effects, the space-fed power divider network design, input bias and control layout, investigation of thermal distribution, and analysis of module failure (graceful degradation).
Doppler Navigation System with a Non-Stabilized Antenna as a Sea-Surface Wind Sensor.
Nekrasov, Alexey; Khachaturian, Alena; Veremyev, Vladimir; Bogachev, Mikhail
2017-06-09
We propose a concept of the utilization of an aircraft Doppler Navigation System (DNS) as a sea-surface wind sensor complementary to its normal functionality. The DNS with an antenna, which is non-stabilized physically to the local horizontal with x-configured beams, is considered. We consider the wind measurements by the DNS configured in the multi-beam scatterometer mode for a rectilinear flight scenario. The system feasibility and the efficiency of the proposed wind algorithm retrieval are supported by computer simulations. Finally, the associated limitations of the proposed approach are considered.
High Gain Antenna System Deployment Mechanism Integration, Characterization, and Lessons Learned
Parong, Fil; Russell, Blair; Garcen, Walter; Rose, Chris; Johnson, Chris; Huber, Craig
2014-01-01
The integration and deployment testing of the High Gain Antenna System for the Global Precipitation Measurement mission is summarized. The HGAS deployment mechanism is described. The gravity negation system configuration and its influence on vertical, ground-based, deployment tests are presented with test data and model predictions. A focus is made on the late discovery and resolution of a potentially mission degrading deployment interference condition. The interaction of the flight deployment mechanism, gravity negation mechanism, and use of dynamic modeling is described and lessons learned presented.
Institute of Scientific and Technical Information of China (English)
CHEN Peng; WU Wei-ling
2005-01-01
The impact of imperfect channel estimation on the forward-link performance in CDMA distributed antenna systems in multi-path fading environment is investigated.A detailed analytical model based on a hybrid signal combining method is presented and exact outage probability expression is derived.The investigation shows that the effect of imperfect channel estimates varies with system load.Furthermore,if simulcasting is employed,macro-diversity can decrease the sensitivity of forward-link to channel estimation errors and increase the forward-link outage performance,which is contrary to the conclusion drawn based on the ideal channel estimation assumption.
Beam Switching Cylindrical Array Antenna System for Communication
Directory of Open Access Journals (Sweden)
V. C. Misra
1998-10-01
Full Text Available The beam switching cylindrical array, which is a unique system, has been designed and developed to cover 360° in azimuth plane by generating 16 beams with specified elevation coverage.In this design, the concept of fast aperture selection (4 x 4 in microseconds from the total cylindrical array has been realised successfully to meet the requirement of point-to-multipoint communication. The components of the array, viz., radiating elements, powder dividers, switches, etc., are designed in printed circuit type, and hence, objectives of lightweight and ease of reproducibility are achieved. The lightweight of the array makes it accessible for easy mounting at a specified height for achieving longer communication range. Finally, a low-loss radome is incorporated to protect the array from environmental conditions. The various parameters, viz., return loss, gain, and switched-beam radiation patterns were measured over a bandwidth of 300 MHz in L- band and typical measured results are presented in this paper.
Directory of Open Access Journals (Sweden)
Jun Suk Kim
2014-01-01
Full Text Available The use of a millimeter-wave band defined as a 30–300 GHz range is significant element for improving performance of 5th generation (5G mobile communication systems. However, since the millimeter-wave signal has peculiar propagation characteristics especially toward non-line-of-sight regions, the system architecture and antenna structure for 5G mobile communications should be designed to overcome these propagation limitations. For realization of the 5G mobile communications, electronics and telecommunications research institute (ETRI is developing central network applying various massive antenna structures with beamforming. In this paper, we have introduced the central network and evaluated the system coverage and capacity through C++ language-based simulations with real geospatial information.
Near Field UHF RFID Antenna System Enabling the Tracking of Small Laboratory Animals
Directory of Open Access Journals (Sweden)
Luca Catarinucci
2013-01-01
Full Text Available Radio frequency identification (RFID technology is more and more adopted in a wide range of applicative scenarios. In many cases, such as the tracking of small-size living animals for behaviour analysis purposes, the straightforward use of commercial solutions does not ensure adequate performance. Consequently, both RFID hardware and the control software should be tailored for the particular application. In this work, a novel RFID-based approach enabling an effective localization and tracking of small-sized laboratory animals is proposed. It is mainly based on a UHF Near Field RFID multiantenna system, to be placed under the animals’ cage, and able to rigorously identify the NF RFID tags implanted in laboratory animals (e.g., mice. Once the requirements of the reader antenna have been individuated, the antenna system has been designed and realized. Moreover, an algorithm based on the measured Received Signal Strength Indication (RSSI aiming at removing potential ambiguities in data captured by the multiantenna system has been developed and integrated. The animal tracking system has been largely tested on phantom mice in order to verify its ability to precisely localize each subject and to reconstruct its path. The achieved and discussed results demonstrate the effectiveness of the proposed tracking system.
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
2003-01-01
Wideband antennas with omnidirectional coverage have both military and commercial applications. In one embodiment, the Planar Inverted Cone Antenna (PICA) is composed of a single flat element vertically mounted above a ground plane. A geometry of Planar Inverted Cone Antenna (PICA) is based on the conventional circular-disc antenna with trimmed top part having the shape of a planar-inverted cone, in a second embodiment, the Fourpoint antenna also provides balanced impedance over the operating...
Institute of Scientific and Technical Information of China (English)
无
2002-01-01
The multicarrier code division multiple access (MC-CDMA) systems without cyclic prefix (CP) hold a finespectral efficiency though they are unavoidably corrupted by the intersymbol interference (ISI) over the finite impulseresponse (FIR) channel. We call MC-CDMA systems without CP the ISI-corrupted MC-CDMA systems in some sense.Considering the fact that combining antenna arrays with so-called ISI-corrupted MC-CDMA systems is advantageous insuppressing cochannel interference in cellular communication systems, this paper investigates ISI-corrupted MC-CDMAsystems with base station antenna arrays. Joint space-time multiuser detection (MUD) schemes for DS-CDMA systemswith antenna arrays have drawn much attention recently. Based upon them, we can derive the equivalent joint spatial-temporal MUD scheme for ISI-corrupted MC-CDMA systems with antenna arrays. In order to achieve this goal, anequivalent space-time estimation method of uplink vector channel is first derived for the ISI-corrupted MC-CDMA systemwith the arbitrary antenna array over frequency-selective fading channels. Then, based on the estimated equivalent space-time channel, an equivalent joint space-time multiuser detector is constructed. Computer simulations illustrate that ouralgorithm is more robust against noise and can well mitigate multiple access interference (MAI) in multiuser scenarios.
Cognitive multiple-antenna network in outage-restricted primary system
DEFF Research Database (Denmark)
Maham, Behrouz; Popovski, Petar
2013-01-01
In the commons model for the spectrum sharing, cognitive users can access the spectrum as long as the target performance in the legitimate primary system is not violated. In this paper, we consider a downlink primary multiple-input-single-output (MISO) system which operates under a controlled...... interference from the downlink MISO cognitive radio, also called secondary system. We derive exact expressions for outage probability of the primary user under Rayleigh fading, when the primary system is exposed to interference from a secondary base station. Moreover, in high-SNR scenario, a closed...... there is an outage constraint at the primary system, and a simple solution is proposed. Finally, the analytical results are confirmed by simulations, in which we analyze the impact of different parameters, such as the number of antennas and the amount of the interference on the system performance; these could...
Hong, Y-W Peter; Kuo, C-C Jay
2013-01-01
This book introduces various signal processing approaches to enhance physical layer secrecy in multi-antenna wireless systems. Wireless physical layer secrecy has attracted much attention in recent years due to the broadcast nature of the wireless medium and its inherent vulnerability to eavesdropping. While most articles on physical layer secrecy focus on the information-theoretic aspect, we focus specifically on the signal processing aspects, including beamforming and precoding techniques for data transmission and discriminatory training schemes for channel estimation. The discussions will c
Low complexity antenna selection for V-BLAST systems with OSIC detection
Directory of Open Access Journals (Sweden)
Bae Youngtaek
2011-01-01
Full Text Available Abstract Multiple-input multiple-output (MIMO systems have an advantage of spectral efficiency compared to single-input single-output systems, which means that the MIMO systems have significantly higher data throughput. The V-BLAST (Vertical Bell Laboratories Layered Space Time scheme is a popular transceiver structure which has relatively good performance. In the V-BLAST scheme, ordered successive interference cancellation (OSIC technique was proposed as a possible efficient detection method in terms of performance and complexity. However, MIMO systems suffer from high complexity and implementation cost. As a practical solution, a technique called antenna selection has been introduced. Since the existing literature considered only the capacity-based selection, we develop an optimal selection method for V-BLAST scheme using OSIC detection with respect to error rate performance in this article. Its complexity is shown to be proportional to the fourth power of the number of transmit antennas. To reduce the complexity without significant performance degradation compared to the optimal selection method, a near-optimal selection method is also proposed. Simulation results show that the proposed selection method is very close to the performance of optimal selection.
Multi-Antenna System Design with Bright Transmitters and Blind Receivers
Li, Liangbin
2012-01-01
This paper considers a scenario for multi-input multi-output (MIMO) communication systems when perfect channel state information at the transmitter (CSIT) is given while the equivalent channel state information at the receiver (CSIR) is not available. Such an assumption is valid for the downlink multi-user MIMO systems with linear precoders that depend on channels to all receivers. We propose a concept called dual systems with zero-forcing designs based on the duality principle, originally proposed to relate Gaussian multi-access channels (MACs) and Gaussian broadcast channels (BCs). For the two-user N*2 MIMO BC with N antennas at the transmitter and two antennas at each of the receivers, we design a downlink interference cancellation (IC) transmission scheme using the dual of uplink MAC systems employing IC methods. The transmitter simultaneously sends two precoded Alamouti codes, one for each user. Each receiver can zero-force the unintended user's Alamouti codes and decouple its own data streams using two ...
From the Hartree dynamics to the Vlasov equation
DEFF Research Database (Denmark)
Benedikter, Niels Patriz; Porta, Marcello; Saffirio, Chiara;
2016-01-01
We consider the evolution of quasi-free states describing N fermions in the mean field limit, as governed by the nonlinear Hartree equation. In the limit of large N, we study the convergence towards the classical Vlasov equation. For a class of regular interaction potentials, we establish precise...... bounds on the 0rate of convergence....
Energy Technology Data Exchange (ETDEWEB)
Suzuki, Y.; Kanao, K. [Sumitomo Heavy Industries Ltd., Tokyo (Japan); Ehata, K.; Kusunoki, M.; Mukaida, M.; Oshima, S. [Yamagata Univ., Yamagata (Japan)
1999-06-07
Though the performance of the high temperature superconductivity device is improved, cooling system by small refrigerating machine is necessary in order to use this practically. This time, as high temperature superconductivity patch antenna cooling system, we constituted the system of the small transportability level by small Stirling refrigerating machine and vacuum vessel with the microwave introduction window, and we examined the performance. We constructed the cooling system with the aim of 60 K so that we may be able to keep superconductive state in which a high temperature superconductivity film is stable. As the result, we achieved goal temperature 60 K of high temperature superconductivity patch antenna. (NEDO)
Combining the switched-beam and beam-steering capabilities in a 2-D phased array antenna system
Tsai, Yi-Che; Chen, Yin-Bing; Hwang, Ruey-Bing
2016-01-01
This paper presents the development, fabrication, and measurement of a novel beam-forming system consisting of 16 subarray antennas, each containing four aperture-coupled patch antennas, and the application of this system in smart wireless communication systems. The beam patterns of each of the subarray antennas can be switched toward one of nine zones over a half space by adjusting the specific phase delay angles among the four antenna elements. Furthermore, when all subarrays are pointed at the same zone, slightly continuous beam steering in around 1° increments can be achieved by dynamically altering the progressive phase delay angle among the subarrays. Phase angle calibration was implemented by coupling each transmitter output and down converter into the in-phase/quadrature baseband to calculate the correction factor to the weight. In addition, to validate the proposed concepts and the fabricated 2-D phased array antenna system, this study measured the far-field radiation patterns of the aperture-coupled patch array integrated with feeding networks and a phase-calibration system to carefully verify its spatially switched-beam and beam-steering characteristics at a center frequency of 2.4 GHz which can cover the industrial, scientific, and medical band and some long-term evolution applications. In addition, measured results were compared with calculated results, and agreement between them was observed.
A General Closed-Form Solution for the Lunar Reconnaissance Orbiter (LRO) Antenna Pointing System
Shah, Neerav; Chen, J. Roger; Hashmall, Joseph A.
2010-01-01
The National Aeronautics and Space Administration s (NASA) Lunar Reconnaissance Orbiter (LRO) launched on June 18, 2009 from the Cape Canaveral Air Force Station aboard an Atlas V launch vehicle into a direct insertion trajectory to the Moon LRO, designed, built, and operated by the NASA Goddard Space Flight Center in Greenbelt, MD, is gathering crucial data on the lunar environment that will help astronauts prepare for long-duration lunar expeditions. During the mission s nominal life of one year its six instruments and one technology demonstrator will find safe landing site, locate potential resources, characterize the radiation environment and test new technology. To date, LRO has been operating well within the bounds of its requirements and has been collecting excellent science data images taken from the LRO Camera Narrow Angle Camera (LROC NAC) of the Apollo landing sites have appeared on cable news networks. A significant amount of information on LRO s science instruments is provided at the LRO mission webpage. LRO s Attitude Control System (ACS), in addition to controlling the orientation of the spacecraft is also responsible for pointing the High Gain Antenna (HGA). A dual-axis (or double-gimbaled) antenna, deployed on a meter-long boom, is required to point at a selected Earth ground station. Due to signal loss over the distance from the Moon to Earth, pointing precision for the antenna system is very tight. Since the HGA has to be deployed in spaceflight, its exact geometry relative to the spacecraft body is uncertain. In addition, thermal distortions and mechanical errors/tolerances must be characterized and removed to realize the greatest gain from the antenna system. These reasons necessitate the need for an in-flight calibration. Once in orbit around the moon, a series of attitude maneuvers was conducted to provide data needed to determine optimal parameters to load onboard, which would account for the environmental and mechanical errors at any
Directory of Open Access Journals (Sweden)
Yu-Chun Liu
2015-08-01
Full Text Available An implantable wireless system with on-chip antenna for cardiovascular pressure monitor is studied. The implantable device is operated in a batteryless manner, powered by an external radio frequency (RF power source. The received RF power level can be sensed and wirelessly transmitted along with blood pressure signal for feedback control of the external RF power. The integrated electronic system, consisting of a capacitance-to-voltage converter, an adaptive RF powering system, an RF transmitter and digital control circuitry, is simulated using a TSMC 0.18 μm CMOS technology. The implanted RF transmitter circuit is combined with a low power voltage-controlled oscillator resonating at 5.8 GHz and a power amplifier. For the design, the simulation model is setup using ADS and HFSS software. The dimension of the antenna is 1 × 0.6 × 4.8 mm3 with a 1 × 0.6 mm2 on-chip circuit which is small enough to place in human carotid artery.
Capacity Optimized CDMA-MIMO Antenna System for Spectral-Efficient Wireless Networks
Directory of Open Access Journals (Sweden)
Nirmalendu Bikas Sinha and Abhishek Mitra
2011-03-01
Full Text Available With the explosion of wireless data traffic there is an increasing emphasis on techniques that can enhance the spectral efficiency and utilization of scarce wireless bandwidth. The future generation (4G Wireless Networks aim at offering very high data rates and flexibility by supporting multiple users by adopting multicarrier (MC transmissions. Multi-Input Multi-Output (MIMO has emerged as a hot topic in wireless communications during the last decade. This is due to possible dramatic increase in reliability and capacity as compared to single-antenna solutions. In this study, an attempt has been made to increase the capacity of a CDMA-based MIMO system by exploiting the frequency selectivity of the channel. The proposed system turns a MIMO frequency selective channel to a set of parallel multiplexing sub-channels in space and time domain. Numerical results show that the proposed CDMA MIMO antenna systems further increase the number of subchannels by exploiting the frequency selectivity of the channel, which leads to a significant increase in both the average capacity and the outage capacity.
Directory of Open Access Journals (Sweden)
Castañeda-Camacho Josefina
2015-03-01
Full Text Available The smart antenna technology has received increasing interest due to its capability for improving the performance of wireless radio systems. In this work, we studied the throughput maximization in a digital cellular system when a smart antenna array is implemented. We focus, in the study of the downlink of a 3G cellular system and consider a packet data direct-sequence code division, multiple access (DS-CDMA. Our methodology is based on the Monte Carlo simulation technique, and it is used to show that it is possible to obtain a significant increment in the throughput of the system due to the switched beam smart antenna array. From our results we conclude that it is feasible to consider the application of this technology in 4G environments.
Semiclassical Vlasov and fluid models for an electron gas with spin effects
Hurst, Jerome; Manfredi, Giovanni; Hervieux, Paul-Antoine
2014-01-01
We derive a four-component Vlasov equation for a system composed of spin-1/2 fermions (typically electrons). The orbital part of the motion is classical, whereas the spin degrees of freedom are treated in a completely quantum-mechanical way. The corresponding hydrodynamic equations are derived by taking velocity moments of the phase-space distribution function. This hydrodynamic model is closed using a maximum entropy principle in the case of three or four constraints on the fluid moments, both for Maxwell-Boltzmann and Fermi-Dirac statistics.
Self-similar analysis of Vlasov-Einstein equations in spherical symmetry
Energy Technology Data Exchange (ETDEWEB)
Munier, A.; Burgan, J.R.; Feix, M.; Fijalkow, E.
1980-03-15
The Vlasov-Einstein system of equations is studied from the point of view of group transformations. Continuous groups are shown to generalize the usual infinitesimal treatment of the metric tensor to the case of a distribution function. Reduced equations are obtained, leading to a time-dependent analytical solution, which yields as a limiting case the Schwarzchild metric. The problem of a purely radial motion of null particles is discussed and leads to an expression for the redshift in a nonstatic, inhomogeneous spacetime.
Zhang, Jun; Tian, Gui Yun; Marindra, Adi M. J.; Sunny, Ali Imam; Zhao, Ao Bo
2017-01-01
In recent few years, the antenna and sensor communities have witnessed a considerable integration of radio frequency identification (RFID) tag antennas and sensors because of the impetus provided by internet of things (IoT) and cyber-physical systems (CPS). Such types of sensor can find potential applications in structural health monitoring (SHM) because of their passive, wireless, simple, compact size, and multimodal nature, particular in large scale infrastructures during their lifecycle. The big data from these ubiquitous sensors are expected to generate a big impact for intelligent monitoring. A remarkable number of scientific papers demonstrate the possibility that objects can be remotely tracked and intelligently monitored for their physical/chemical/mechanical properties and environment conditions. Most of the work focuses on antenna design, and significant information has been generated to demonstrate feasibilities. Further information is needed to gain deep understanding of the passive RFID antenna sensor systems in order to make them reliable and practical. Nevertheless, this information is scattered over much literature. This paper is to comprehensively summarize and clearly highlight the challenges and state-of-the-art methods of passive RFID antenna sensors and systems in terms of sensing and communication from system point of view. Future trends are also discussed. The future research and development in UK are suggested as well. PMID:28146067
Rossi, Marco; Stockman, Gert-Jan; Rogier, Hendrik; Vande Ginste, Dries
2016-07-19
The efficiency of a wireless power transfer (WPT) system in the radiative near-field is inevitably affected by the variability in the design parameters of the deployed antennas and by uncertainties in their mutual position. Therefore, we propose a stochastic analysis that combines the generalized polynomial chaos (gPC) theory with an efficient model for the interaction between devices in the radiative near-field. This framework enables us to investigate the impact of random effects on the power transfer efficiency (PTE) of a WPT system. More specifically, the WPT system under study consists of a transmitting horn antenna and a receiving textile antenna operating in the Industrial, Scientific and Medical (ISM) band at 2.45 GHz. First, we model the impact of the textile antenna's variability on the WPT system. Next, we include the position uncertainties of the antennas in the analysis in order to quantify the overall variations in the PTE. The analysis is carried out by means of polynomial-chaos-based macromodels, whereas a Monte Carlo simulation validates the complete technique. It is shown that the proposed approach is very accurate, more flexible and more efficient than a straightforward Monte Carlo analysis, with demonstrated speedup factors up to 2500.
Zhang, Jun; Tian, Gui Yun; Marindra, Adi M J; Sunny, Ali Imam; Zhao, Ao Bo
2017-01-29
In recent few years, the antenna and sensor communities have witnessed a considerable integration of radio frequency identification (RFID) tag antennas and sensors because of the impetus provided by internet of things (IoT) and cyber-physical systems (CPS). Such types of sensor can find potential applications in structural health monitoring (SHM) because of their passive, wireless, simple, compact size, and multimodal nature, particular in large scale infrastructures during their lifecycle. The big data from these ubiquitous sensors are expected to generate a big impact for intelligent monitoring. A remarkable number of scientific papers demonstrate the possibility that objects can be remotely tracked and intelligently monitored for their physical/chemical/mechanical properties and environment conditions. Most of the work focuses on antenna design, and significant information has been generated to demonstrate feasibilities. Further information is needed to gain deep understanding of the passive RFID antenna sensor systems in order to make them reliable and practical. Nevertheless, this information is scattered over much literature. This paper is to comprehensively summarize and clearly highlight the challenges and state-of-the-art methods of passive RFID antenna sensors and systems in terms of sensing and communication from system point of view. Future trends are also discussed. The future research and development in UK are suggested as well.
Avser, Bilgehan
The thesis presents three dual-band frequency tunable antennas for carrier aggregation systems and two new feeding networks for reducing the number of phase shifters in limited-scan arrays. First, single- and dual-feed, dual-frequency, low-profile antennas with independent frequency tuning using varactor diodes are presented. The dual-feed planar inverted F-antenna (PIFA) has two operating frequencies which are independently tuned at 0.7--1.1 GHz and at 1.7--2.3 GHz with better than 10 dB impedance match. The isolation between the high-band and the low-band ports is > 13 dB; hence, one resonant frequency can be tuned without affecting the other. The single-feed contiguous-dual-band antenna has two resonant frequencies, which are independently tuned at 1.2--1.6 GHz at 1.6--2.3 GHz with better than 10 dB impedance match for most of the tuning range. And the single-feed dual-band antenna has two resonant frequencies, which are independently tuned at 0.7--1.0 GHz at 1.7--2.3 GHz with better than 10 dB impedance match for most of the tuning range. The tuning is done using varactor diodes with a capacitance range from 0.8 to 3.8 pF, which is compatible with RF MEMS devices. The antenna volumes are 63 x 100 x 3.15 mm3 on epsilon r = 3.55 substrates and the measured antenna efficiencies vary between 25% and 50% over the tuning range. The application areas are in carrier aggregation systems for fourth generation (4G) wireless systems. Next, a new phased array feeding network that employs random sequences of non-uniform sub-arrays (and a single phase shifter for each sub-array) is presented. When these sequences are optimized, the resulting phased arrays can scan over a wide region with low sidelobe levels. Equations for analyzing the random arrays and an algorithm for optimizing the array sequences are presented. Multiple random-solutions with different number of phase shifters and different set of sub-array groups are analyzed and design guidelines are presented. The
Iupikov, O
2016-01-01
A method for accurate modeling of a reflector antenna system with a wideband phased array feed is presented and used to study the effects of the number of active antenna elements and associated receiving channels on the receiving sensitivity of the antenna system. Numerical results are shown for a practical design named APERTIF that is currently under developed at The Netherlands Institute for Radio Astronomy (ASTRON).
Institute of Scientific and Technical Information of China (English)
方勇; 朱耀麟
2006-01-01
In this paper, the antenna selection problem for spatial multiplexing systems in a BLAST receiver is investigated. In order to search the optimal antenna subset, a selection criterion is proposed, which is able to obtain the largest minimum post-detection SNR.The number of required antennas is deduced, which is determined by the system performance requirement for the existing RF chains. Simulation result shows that the optimal subset in a BLAST receiver has higher minimum sub-channel SNR than that in a ZF receiver. Computation of system performance can be fitted to a simple function, and it is simpler for the proposed algorithm to compute the required antenna number.
Bhardwaj, Dheeraj; Saraswat, Shriti; Gulati, Gitansh; Shekhar, Snehanshu; Joshi, Kanika; Sharma, Komal
2016-03-01
In this paper a dual band planar antenna has been proposed for IEEE 802.16 Wi-MAX /IEEE 802.11 WLAN/4.9 GHz public safety applications. The antenna comprises a frequency bandwidth of 560MHz (3.37GHz-3.93GHz) for WLAN and WiMAX and 372MHz (4.82GHz-5.192GHz) for 4.9 GHz public safety applications and Radio astronomy services (4.8-4.94 GHz). The proposed antenna constitutes of a single microstrip patch reactively loaded with three identical steps positioned in a zig-zag manner towards the radiating edges of the patch. The coaxially fed patch antenna characteristics (radiation pattern, antenna gain, antenna directivity, current distribution, S11) have been investigated. The antenna design is primarily focused on achieving a dual band operation.
Energy Technology Data Exchange (ETDEWEB)
Bhardwaj, Dheeraj, E-mail: dbhardwaj.bit@gmail.com [Department of Physics, BIT-Mesra-Jaipur Campus, Jaipur 302017 (India); Saraswat, Shriti, E-mail: saraswat.srishti@gmail.com; Gulati, Gitansh, E-mail: gitanshgulati@gmail.com; Shekhar, Snehanshu, E-mail: snehanshushekhar.bit@gmail.com; Joshi, Kanika, E-mail: kanika.karesh@gmail.com [Department of Electronics & Communication, BIT-Mesra-Jaipur Campus, Jaipur 302017 (India); Sharma, Komal, E-mail: kbhardwaj18@gmail.com [Department of Physics, Swami Keshvanand Institute of Technology, Jaipur 302017 (India)
2016-03-09
In this paper a dual band planar antenna has been proposed for IEEE 802.16 Wi-MAX /IEEE 802.11 WLAN/4.9 GHz public safety applications. The antenna comprises a frequency bandwidth of 560MHz (3.37GHz-3.93GHz) for WLAN and WiMAX and 372MHz (4.82GHz-5.192GHz) for 4.9 GHz public safety applications and Radio astronomy services (4.8-4.94 GHz). The proposed antenna constitutes of a single microstrip patch reactively loaded with three identical steps positioned in a zig-zag manner towards the radiating edges of the patch. The coaxially fed patch antenna characteristics (radiation pattern, antenna gain, antenna directivity, current distribution, S{sub 11}) have been investigated. The antenna design is primarily focused on achieving a dual band operation.
Power duality for multi-antenna OFDM system in broadcast channel with user scheduling
Institute of Scientific and Technical Information of China (English)
无
2008-01-01
This paper deals with design and analysis of user scheduling and power allocation for multi-antenna OFDM systems with DPC, ZF-DPC, ZF-BF and TDMA transmit strategies. We consider the general multi-user downlink scheduling problem and power minimization with multi-user rate constraints. According to the channel state, it is shown that there is a power optimal policy which selects a subset of users in each scheduling interval. We present user selection algorithms for DPC, ZF-DPC, ZF-BF and TDMA for multi-antenna OFDM system in broadcast channels, and we also present the practical water-filling solution in this paper. By the selected users with the consideration of fairness, we derive the power optimization algorithm with multi-user rate constraints. We also analyze the power duality of uplink-downlink for the transmit strategies of DPC, ZF-DPC and ZF-BF. Simulation results show that the present user-scheduling algorithm and power minimization algorithm can achieve good power performance, and that the scheduling algorithm can guarantee fairness.
Directory of Open Access Journals (Sweden)
M Chakraborty
2012-10-01
Full Text Available Interfering, clutter and jamming systems are becoming an increasing concern to the military and security industries worldwide. To overcome these problems phase array antennas and adaptive beam forming systems offers a potential solution. STAP is an application of optimum and adaptive array processing algorithms to the radar problem of target detection in ground clutter and interference with pulse-Doppler waveforms.In this paper we have presented our work of designing a MVDR beam former receiver using AWG and VSA. The minimumvariance distortion less response (MVDR approach is very popular technic in array processing that generates some mean square error or values. When these values fed to the phase array antenna system results in electronic steering of antenna beam according to the weight vector generated.
Hu, Chia-Chang; Su, Hao-Hsian; Tang, Kang-Tsao
2014-09-01
This paper considers a two-way multiple-input multiple-output (MIMO) relaying system with multiple relays between two terminals nodes. The relay antenna selection scheme based on channel singular valued decomposition (SVD) is used to reduce energy consumption. To enhance the system performance, we apply a SVD-based algorithm with MSE criterion which calculates optimal linear transceivers precoding jointly at the source nodes and relay nodes for amplify-and-forward (AF) protocols. In computer simulations, we use an iteration method to compute the non-convex function of joint source and relays power allocation. The simulation results show the SVD-based precoding design with SVD-based relay and antenna selection scheme can achieve a superior system bit error rate (BER) performance and reduce the power consume of relay antennas.
Shin, H. J.; Hong, S. C.; Lee, J. R.; Kim, J. H.
2016-10-01
Most of aircraft antennas usually have various types of radome made of composite materials for protecting antenna structures. However, these antenna radome structures, which are installed on the outside of airplane, are easy to be damaged by external forces such as drag, foreign object, bird strike and others. In this study, full-field pulse-echo ultrasonic propagation imaging (PE UPI) system is proposed as the non-destructive inspection technique to visualize manufacturing defects in composite antenna radome. Based on the results of the sample case study, it is shown that the ultrasonic wave propagation imaging (UWPI) that is generated by the proposed full-field PE UPI system is able to highlight the intact internal condition of antenna structure and its defect area. Additional damage visualization techniques like ultrasonic energy mapping (UEM), variable time window amplitude map (VTWAM) and also ultrasonic spectral imaging (USI) algorithms are applied to improve the reliability of the damage visualization. It can be concluded that the proposed PE UPI system is an effective non-destructive inspection technique for the composite radome structures.
On the Security of Millimeter Wave Vehicular Communication Systems Using Random Antenna Subsets
Eltayeb, Mohammed E.
2017-03-20
Millimeter wave (mmWave) vehicular communication systems have the potential to improve traffic efficiency and safety. Lack of secure communication links, however, may lead to a formidable set of abuses and attacks. To secure communication links, a physical layer precoding technique for mmWave vehicular communication systems is proposed in this paper. The proposed technique exploits the large dimensional antenna arrays available at mmWave systems to produce direction dependent transmission. This results in coherent transmission to the legitimate receiver and artificial noise that jams eavesdroppers with sensitive receivers. Theoretical and numerical results demonstrate the validity and effectiveness of the proposed technique and show that the proposed technique provides high secrecy throughput when compared to conventional array and switched array transmission techniques.
Directory of Open Access Journals (Sweden)
Feng Zhao
2015-01-01
Full Text Available Multi-input multioutput (MIMO technique provides a promising solution to enhance the performance of wireless communication systems. In this paper, we consider antenna correlation at the transmitter in practical cognitive MIMO systems. What is more, a game-theoretic framework is conducted to analyze the optimum beamforming and power allocation such that each user maximizes its own rate selfishly under the transmitting power constraint and the primary user (PU interference constraint. The design of the cognitive MIMO system is formulated as a noncooperative game, where the secondary users (SUs compete with each other over the resources made available by the PUs. Interestingly, as the correlation parameter grows, the utility degrades. Nash equilibrium is considered as the solution of this game. Simulation results show that the proposed algorithm can converge quickly and clearly outperforms the strategy without game.
Characterization of Hardware Impairments in Multiple Antenna Systems for DoA Estimation
Directory of Open Access Journals (Sweden)
Daniele Inserra
2011-01-01
Full Text Available We consider the effects introduced by hardware impairments on the estimation of the direction of arrival (DoA deploying a multiple antenna radio system. We derive a system model from experimental measurements of a state-of-the-art hardware test bed based on an RF direct-conversion architecture. The system model includes DC offsets, carrier frequency and phase offsets, and the phase noise. Then, we propose a simple digital compensation algorithm of the impairments for bidimensional DoA estimation (azimuth and elevation with a 3D orthogonal linear array. The robustness of the algorithm in terms of minimum-mean-squared error as a function of the hardware impairments is evaluated and compared with that achieved using the root-MUSIC algorithm.
Experiments with Dipole Antennas
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…
Directory of Open Access Journals (Sweden)
Ludwig Ilnytskyi
2015-12-01
Full Text Available The article is devoted to current issues in the field of radio monitoring. In this article was considered the antenna of radio control, which represents a grid from three vibrators. Threelement antenna array provides simultaneous control of two radio electronic devices that radiates at frequencies that are close to each other. Antenna system using simple technical means provides noise suppression, even if noise will have the same frequency as useful signal. This makes it possible to use the antenna system in conditions of multibeam wave propagation under the adjustment on the most intense by the power beam. Antenna system makes it possible to measure the electromagnetic field intensity, congestion of the frequency spectrum, direction of noise electromagnetic waves incidence, noise electric field intensity.
De Hoop, A.T.; Lager, I.E.; Tomassetti, V.
2009-01-01
A novel time-domain approach to the derivation of the pulsed electromagnetic field multiport antenna system reciprocity theorem is presented. The theorem interrelates the field and system properties in two states: the transmitting state and the receiving state. General time-domain Thevenin (voltage-
Boudin, Laurent; Grandmont, Céline; Moussa, Ayman
2017-02-01
In this article, we prove the existence of global weak solutions for the incompressible Navier-Stokes-Vlasov system in a three-dimensional time-dependent domain with absorption boundary conditions for the kinetic part. This model arises from the study of respiratory aerosol in the human airways. The proof is based on a regularization and approximation strategy designed for our time-dependent framework.
Timing-Free Blind Multiuser Detection for Multicarrier DS/CDMA Systems with Multiple Antennae
Directory of Open Access Journals (Sweden)
Stefano Buzzi
2004-05-01
Full Text Available The problem of blind multiuser detection for an asynchronous multicarrier DS-CDMA system employing multiple transmit and receive antennae over a Rayleigh fading channel is considered in this paper. The solutions that we develop require prior knowledge of the spreading code of the user to be decoded only, while no further information either on the user to be decoded or on the other active users is required. Several combining rules for the observables at the output of each receive antenna are proposed and assessed, and the implications of the different options are studied in depth in terms of both detection performance and computational complexity. A closed form expression is also derived for the conditional error probability and a lower bound for the near-far resistance is provided. Results confirm that the proposed blind receivers can cope with both multiple access interference suppression and channel estimation at the price of a limited performance loss as compared to the ideal linear receivers which assume perfect channel state information.
N M Vijay
2014-01-01
The fundamental base of plasma antenna is the use of an ionized medium as a conductor. The plasma antenna is a radiofrequency antenna formed by a plasma columns, Filaments or sheets, which are excited by a surface wave. The relevance of this device is how rapidly it can be turned on and off, only applying an electrical pulse. Besides its wide carrier frequency, the great directivity and controllable antenna shape. Otherwise a disadvantage is that it needs energy to be ionized....
FPGA-Based Communications Receivers for Smart Antenna Array Embedded Systems
Directory of Open Access Journals (Sweden)
Millar James
2006-01-01
Full Text Available Field-programmable gate arrays (FPGAs are drawing ever increasing interest from designers of embedded wireless communications systems. They outpace digital signal processors (DSPs, through hardware execution of a wide range of parallelizable communications transceiver algorithms, at a fraction of the design and implementation effort and cost required for application-specific integrated circuits (ASICs. In our study, we employ an Altera Stratix FPGA development board, along with the DSP Builder software tool which acts as a high-level interface to the powerful Quartus II environment. We compare single- and multibranch FPGA-based receiver designs in terms of error rate performance and power consumption. We exploit FPGA operational flexibility and algorithm parallelism to design eigenmode-monitoring receivers that can adapt to variations in wireless channel statistics, for high-performing, inexpensive, smart antenna array embedded systems.
FPGA-Based Communications Receivers for Smart Antenna Array Embedded Systems
Directory of Open Access Journals (Sweden)
James Millar
2006-10-01
Full Text Available Field-programmable gate arrays (FPGAs are drawing ever increasing interest from designers of embedded wireless communications systems. They outpace digital signal processors (DSPs, through hardware execution of a wide range of parallelizable communications transceiver algorithms, at a fraction of the design and implementation effort and cost required for application-specific integrated circuits (ASICs. In our study, we employ an Altera Stratix FPGA development board, along with the DSP Builder software tool which acts as a high-level interface to the powerful Quartus II environment. We compare single- and multibranch FPGA-based receiver designs in terms of error rate performance and power consumption. We exploit FPGA operational flexibility and algorithm parallelism to design eigenmode-monitoring receivers that can adapt to variations in wireless channel statistics, for high-performing, inexpensive, smart antenna array embedded systems.
2012-03-01
system. . . . . . . . . . . . . . . . . . . . 8 2.2. 4QAM decision boundaries. . . . . . . . . . . . . . . . . . . . . 10 2.3. Multipath in SIMO system...11 2.4. SISO antenna model. . . . . . . . . . . . . . . . . . . . . . . . 14 2.5. SIMO antenna model...12 SNR Signal-to-Noise Ratio . . . . . . . . . . . . . . . . . . . . . 13 SIMO Single-Input and Multiple-Output
Dubey,R.K.; Inan, D.; Sengupta, S.; Sudhölter,E.J.R.; Grozema, F.C.; Jager, W.F.
2016-01-01
We report the synthesis and excited-state dynamics of a series of five bichromophoric light-harvesting antenna systems, which are capable of efficient harvesting of solar energy in the spectral range of 350–580 nm. These antenna systems have been synthesized in a modular fashion by the covalent
Medway Tunnel Road Pavement Survey Using Different Frequency GPR Antenna Systems - A Case Study
Alani, Morteza Amir; Banks, Kevin
2015-04-01
This presentation reports on an extensive survey carried out on a section (just outside the westbound end of the tunnel portal) of the Medway Tunnel in North Kent, UK. The Medway Tunnel provides a dual carriageway road crossing under the River Medway between Chatham and Strood. It is 725 metres long from portal to portal and consists of three sections. The appearance of repeated cracking of the road surface in this particular section of the tunnel suggested either a steady movement of the ground or possible undermining due to an underground watercourse. Ironically, the design and construction of the road had been realised to prevent any form of structural movement. It was deemed necessary to perform a Ground Penetrating Radar (GPR) survey in order to confirm underground construction details of the road in this section of the tunnel. This presentation reports on the detailed survey and the challenges encountered during the operation, which utilised four different frequency GPR systems including 2GHz, 900MHz, 600MHz and 200MHz antennas. The presentation will also describe how decisions were made to carry out supplementary surveys based on results obtained on-site (via primary data processing) and observations made during the survey. A summary of results will be presented individually for each antenna system used, as well as comparisons between each antenna system. Results will then be mapped against the design drawings available for confirmation of construction configurations. In conclusion, the presentation will demonstrate that the tunnel road pavement is not constructed as per the information provided (design drawings). Results will clearly indicate that there is no second reinforced concrete layer present in this particular section of the road pavement (contrary to what was originally believed) and will present the actual road construction in comparison with the design drawings. The results will confirm that there is no underground watercourse present in this
Block-Structured Adaptive Mesh Refinement Algorithms for Vlasov Simulation
Hittinger, J A F
2012-01-01
Direct discretization of continuum kinetic equations, like the Vlasov equation, are under-utilized because the distribution function generally exists in a high-dimensional (>3D) space and computational cost increases geometrically with dimension. We propose to use high-order finite-volume techniques with block-structured adaptive mesh refinement (AMR) to reduce the computational cost. The primary complication comes from a solution state comprised of variables of different dimensions. We develop the algorithms required to extend standard single-dimension block structured AMR to the multi-dimension case. Specifically, algorithms for reduction and injection operations that transfer data between mesh hierarchies of different dimensions are explained in detail. In addition, modifications to the basic AMR algorithm that enable the use of high-order spatial and temporal discretizations are discussed. Preliminary results for a standard 1D+1V Vlasov-Poisson test problem are presented. Results indicate that there is po...
Vlasov Analysis of Microbunching Gain for Magnetized Beams
Energy Technology Data Exchange (ETDEWEB)
Tsai, Cheng Ying [Virginia Polytechnic Inst. and State Univ. (Virginia Tech), Blacksburg, VA (United States); Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Derbenev, Yaroslav [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Douglas, David R. [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Li, Rui [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Tennant, Christopher D. [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)
2016-10-01
For a high-brightness electron beam with low energy and high bunch charge traversing a recirculation beamline, coherent synchrotron radiation and space charge effect may result in the microbunching instability (MBI). Both tracking simulation and Vlasov analysis for an early design of Circulator Cooler Ring for the Jefferson Lab Electron Ion Collider reveal significant MBI. It is envisioned these could be substantially suppressed by using a magnetized beam. In this work, we extend the existing Vlasov analysis, originally developed for a non-magnetized beam, to the description of transport of a magnetized beam including relevant collective effects. The new formulation will be further employed to confirm prediction of microbunching suppression for a magnetized beam transport in a recirculating machine design.
Varela, P.; Belo, J. H.; Quental, P. B.
2016-11-01
The design of the in-vessel antennas for the ITER plasma position reflectometry diagnostic is very challenging due to the need to cope both with the space restrictions inside the vacuum vessel and with the high mechanical and thermal loads during ITER operation. Here, we present the work carried out to assess and optimise the design of the antenna. We show that the blanket modules surrounding the antenna strongly modify its characteristics and need to be considered from the early phases of the design. We also show that it is possible to optimise the antenna performance, within the design restrictions.
Varela, P; Belo, J H; Quental, P B
2016-11-01
The design of the in-vessel antennas for the ITER plasma position reflectometry diagnostic is very challenging due to the need to cope both with the space restrictions inside the vacuum vessel and with the high mechanical and thermal loads during ITER operation. Here, we present the work carried out to assess and optimise the design of the antenna. We show that the blanket modules surrounding the antenna strongly modify its characteristics and need to be considered from the early phases of the design. We also show that it is possible to optimise the antenna performance, within the design restrictions.
Antenna Selection for Full-Duplex MIMO Two-Way Communication Systems
Wilson-Nunn, Daniel
2017-03-11
Antenna selection for full-duplex communication between two nodes, each equipped with a predefined number of antennae and transmit/receive chains, is studied. Selection algorithms are proposed based on magnitude, orthogonality, and determinant criteria. The algorithms are compared to optimal selection obtained by exhaustive search as well as random selection, and are shown to yield performance fairly close to optimal at a much lower complexity. Performance comparison for a Rayleigh fading symmetric channel reveals that selecting a single transmit antenna is best at low signal-to-noise ratio (SNR), while selecting an equal number of transmit and receive antennae is best at high SNR.
Bin, W.; Alessi, E.; Bruschi, A.; D'Arcangelo, O.; Figini, L.; Galperti, C.; Garavaglia, S.; Granucci, G.; Moro, A.
2014-05-01
The algorithm for the automatic control of the new front steering antenna of the Frascati Tokamak Upgrade device has been improved, in view of forthcoming experiments aimed at testing the mode conversion of electron cyclotron waves at a frequency of 140 GHz. The existing antenna system has been prepared to provide two-point real-time measurements of electron Bernstein waves and to allow real-time tracking of the optimal conversion region. This required an accurate analysis of the antenna to minimize the risk of a mechanical damage of the movable launching mirrors, when accessing the high toroidal launching angles needed for this kind of experiment. A detailed description is presented of the work carried out to safely reach and validate the desired range of steering angles, which include the region of interest, and a technique is proposed to track and chase the correct line of sight for electron Bernstein waves detection during the shot.
Hu, Chia-Chang
2005-12-01
A novel space-time adaptive near-far robust code-synchronization array detector for asynchronous DS-CDMA systems is developed in this paper. There are the same basic requirements that are needed by the conventional matched filter of an asynchronous DS-CDMA system. For the real-time applicability, a computationally efficient architecture of the proposed detector is developed that is based on the concept of the multistage Wiener filter (MWF) of Goldstein and Reed. This multistage technique results in a self-synchronizing detection criterion that requires no inversion or eigendecomposition of a covariance matrix. As a consequence, this detector achieves a complexity that is only a linear function of the size of antenna array ([InlineEquation not available: see fulltext.]), the rank of the MWF ([InlineEquation not available: see fulltext.]), the system processing gain ([InlineEquation not available: see fulltext.]), and the number of samples in a chip interval ([InlineEquation not available: see fulltext.]), that is,[InlineEquation not available: see fulltext.]. The complexity of the equivalent detector based on the minimum mean-squared error (MMSE) or the subspace-based eigenstructure analysis is a function of[InlineEquation not available: see fulltext.]. Moreover, this multistage scheme provides a rapid adaptive convergence under limited observation-data support. Simulations are conducted to evaluate the performance and convergence behavior of the proposed detector with the size of the[InlineEquation not available: see fulltext.]-element antenna array, the amount of the[InlineEquation not available: see fulltext.]-sample support, and the rank of the[InlineEquation not available: see fulltext.]-stage MWF. The performance advantage of the proposed detector over other DS-CDMA detectors is investigated as well.
Directory of Open Access Journals (Sweden)
Chia-Chang Hu
2005-04-01
Full Text Available A novel space-time adaptive near-far robust code-synchronization array detector for asynchronous DS-CDMA systems is developed in this paper. There are the same basic requirements that are needed by the conventional matched filter of an asynchronous DS-CDMA system. For the real-time applicability, a computationally efficient architecture of the proposed detector is developed that is based on the concept of the multistage Wiener filter (MWF of Goldstein and Reed. This multistage technique results in a self-synchronizing detection criterion that requires no inversion or eigendecomposition of a covariance matrix. As a consequence, this detector achieves a complexity that is only a linear function of the size of antenna array (J, the rank of the MWF (M, the system processing gain (N, and the number of samples in a chip interval (S, that is, Ã°ÂÂ’Âª(JMNS. The complexity of the equivalent detector based on the minimum mean-squared error (MMSE or the subspace-based eigenstructure analysis is a function of Ã°ÂÂ’Âª((JNS3. Moreover, this multistage scheme provides a rapid adaptive convergence under limited observation-data support. Simulations are conducted to evaluate the performance and convergence behavior of the proposed detector with the size of the J-element antenna array, the amount of the L-sample support, and the rank of the M-stage MWF. The performance advantage of the proposed detector over other DS-CDMA detectors is investigated as well.
Variational formulations of guiding-center Vlasov-Maxwell theory
Brizard, Alain J.; Tronci, Cesare
2016-06-01
The variational formulations of guiding-center Vlasov-Maxwell theory based on Lagrange, Euler, and Euler-Poincaré variational principles are presented. Each variational principle yields a different approach to deriving guiding-center polarization and magnetization effects into the guiding-center Maxwell equations. The conservation laws of energy, momentum, and angular momentum are also derived by Noether method, where the guiding-center stress tensor is now shown to be explicitly symmetric.
Coupled Vlasov and two-fluid codes on GPUs
Rieke, M; Grauer, R
2014-01-01
We present a way to combine Vlasov and two-fluid codes for the simulation of a collisionless plasma in large domains while keeping full information of the velocity distribution in localized areas of interest. This is made possible by solving the full Vlasov equation in one region while the remaining area is treated by a 5-moment two-fluid code. In such a treatment, the main challenge of coupling kinetic and fluid descriptions is the interchange of physically correct boundary conditions between the different plasma models. In contrast to other treatments, we do not rely on any specific form of the distribution function, e.g. a Maxwellian type. Instead, we combine an extrapolation of the distribution function and a correction of the moments based on the fluid data. Thus, throughout the simulation both codes provide the necessary boundary conditions for each other. A speed-up factor of around 20 is achieved by using GPUs for the computationally expensive solution of the Vlasov equation and an overall factor of a...
Vlasov models for kinetic Weibel-type instabilities
Ghizzo, A.; Sarrat, M.; Del Sarto, D.
2017-02-01
The Weibel instability, driven by a temperature anisotropy, is investigated within different kinetic descriptions based on the semi-Lagrangian full kinetic and relativistic Vlasov-Maxwell model, on the multi-stream approach, which is based on a Hamiltonian reduction technique, and finally, with the full pressure tensor fluid-type description. Dispersion relations of the Weibel instability are derived using the three different models. A qualitatively different regime is observed in Vlasov numerical experiments depending on the excitation of a longitudinal plasma electric field driven initially by the combined action of the stream symmetry breaking and weak relativistic effects, in contrast with the existing theories of the Weibel instability based on their purely transverse characters. The multi-stream model offers an alternate way to simulate easily the coupling with the longitudinal electric field and particularly the nonlinear regime of saturation, making numerical experiments more tractable, when only a few moments of the distribution are considered. Thus a numerical comparison between the reduced Hamiltonian model (the multi-stream model) and full kinetic (relativistic) Vlasov simulations has been investigated in that regime. Although nonlinear simulations of the fluid model, including the dynamics of the pressure tensor, have not been carried out here, the model is strongly relevant even in the three-dimensional case.
Energy Technology Data Exchange (ETDEWEB)
Vdovin, V.; Watari, T.; Fukuyama, A.
1996-12-01
We develop the theory for the wave excitation, propagation and absorption in 3-dimensional (3D) stellarator equilibrium high beta plasma in ion cyclotron frequency range (ICRF). This theory forms a basis for a 3D code creation, urgently needed for the ICRF heating scenarios development for the constructed LHD and projected W7-X stellarators and for the stellarators being at operation (like CHS, W7-AS, etc.). The theory solves the 3D Maxwell-Vlasov antenna-plasma-conducting shell boundary value problem in the non - orthogonal flux coordinates ({psi}, {theta}, {phi}), {psi} being magnetic flux function, {theta} and {phi} being the poloidal and toroidal angles, respectively. All basic physics, like wave refraction, reflection and diffraction are firstly self consistently included, along with the fundamental ion and ion minority cyclotron resonances, two ion hybrid resonance, electron Landau and TTMP absorption. Antenna reactive impedance and loading resistance are also calculated and urgently needed for an antenna -generator matching. This is accomplished in a real confining magnetic field being varying in a plasma major radius direction, in toroidal and poloidal directions, through making use of the hot dense plasma dielectric kinetic tensor. The theory is developed in a manner that includes tokamaks and magnetic mirrors as the particular cases through general metric tensor (provided by an equilibrium solver) treatment of the wave equations. We describe the structure of newly developed stellarator ICRF 3D full wave code STELION, based on theory described in this report. (J.P.N.)
Handbook of antenna technologies
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.
Directory of Open Access Journals (Sweden)
Marco Rossi
2016-07-01
Full Text Available The efficiency of a wireless power transfer (WPT system in the radiative near-field is inevitably affected by the variability in the design parameters of the deployed antennas and by uncertainties in their mutual position. Therefore, we propose a stochastic analysis that combines the generalized polynomial chaos (gPC theory with an efficient model for the interaction between devices in the radiative near-field. This framework enables us to investigate the impact of random effects on the power transfer efficiency (PTE of a WPT system. More specifically, the WPT system under study consists of a transmitting horn antenna and a receiving textile antenna operating in the Industrial, Scientific and Medical (ISM band at 2.45 GHz. First, we model the impact of the textile antenna’s variability on the WPT system. Next, we include the position uncertainties of the antennas in the analysis in order to quantify the overall variations in the PTE. The analysis is carried out by means of polynomial-chaos-based macromodels, whereas a Monte Carlo simulation validates the complete technique. It is shown that the proposed approach is very accurate, more flexible and more efficient than a straightforward Monte Carlo analysis, with demonstrated speedup factors up to 2500.
Recent Advances on OTA Testing for 5G Antenna Systems in Multi-probe Anechoic Chamber Setups
DEFF Research Database (Denmark)
Fan, Wei; Pedersen, Gert F.; Kyösti, Pekka
2017-01-01
Over-the-air (OTA) testing is seen as an essential method for evaluating 5G antenna systems, since conventional cable testing are no longer applicable. In the paper, we discussed the similarities and discrepancies of OTA testing in the multiprobe anechoic chamber (MPAC) setups for 4G user equipment...
Belfiori, F.; Monni, S.; Rossum, W.L. van; Hoogeboom, P.
2012-01-01
The design of passive coherent location radar, which exploits broadcasting transmitters of opportunity in the very high frequency (VHF) radio bandwidth, is presented. Here, the authors primarily focus on the system set-up and on the digital pre-processing steps. Emphasis is given to the antenna sect
Marpaung, D.A.I.; Roeloffzen, C.G.H.; Beeker, W.P.; Beeker, Willem; Noharet, Bertrand; Verpoorte, Jaco; Baggen, Rens
Novel avionic communication systems are required for various purposes, for example to increase the flight safety and operational integrity as well as to enhance the quality of service to passengers on board. To serve these purposes, a key technology that is essential to be developed is an antenna
The research of the maximum wind speed in Tomsk and calculations of dynamic load on antenna systems
Belan, B.; Belan, S.; Romanovskiy, O.; Girshtein, A.; Yanovich, A.; Baidali, S.; Terehov, S.
2017-01-01
The work is concerned with calculations and analysis of the maximum wind speed in Tomsk city. The data for analysis were taken from the TOR-station located in the north-eastern part of the city. The TOR-station sensors to measure a speed and a direction of wind are installed on the 10-meter meteorological mast. Wind is measured by M-63, which uses the standard approach and the program with one-minute averaging for wind gusts recording as well. According to the measured results in the research performed, the estimation of the dynamic and wind load on different types of antenna systems was performed. The work shows the calculations of wind load on ten types of antenna systems, distinguished by their different constructions and antenna areas. For implementation of calculations, we used methods developed in the Central Research and Development Institute of Building Constructions named after V.A. Kucherenko. The research results could be used for design engineering of the static antenna systems and mobile tracking systems for the distant objects.
Reconfigurable antenna pattern verification
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.
Low temperature growth of diamond films on optical fibers using Linear Antenna CVD system
Ficek, M.; Drijkoningen, S.; Karczewski, J.; Bogdanowicz, R.; Haenen, K.
2016-01-01
It is not trivial to achieve a good quality diamond-coated fibre interface due to a large difference in the properties and composition of the diamond films (or use coating even) and the optical fibre material, i.e. fused silica. One of the biggest problems is the high temperature during the deposition which influences the optical fibre or optical fibre sensor structure (e.g. long-period gratings (LPG)). The greatest advantage of a linear antenna microwave plasma enhanced chemical vapor deposition system (LA MW CVD) is the fact that it allows to grow the diamond layers at low temperature (below 300°C) [1]. High quality nanocrystalline diamond (NCD) thin films with thicknesses ranging from 70 nm to 150 nm, were deposited on silicon, glass and optical fibre substrates [2]. Substrates pretreatment by dip-coating and spin coating process with a dispersion consisting of detonation nanodiamond (DND) in dimethyl sulfoxide (DMSO) with polyvinyl alcohol (PVA) has been applied. During the deposition process the continuous mode of operation of the LA MW CVD system was used, which produces a continuous wave at a maximum power of 1.9 kW (in each antenna). Diamond films on optical fibres were obtained at temperatures below 350°C, providing a clear improvement of results compared to our earlier work [3]. The samples were characterized by scanning electron microscopy (SEM) imaging to investigate the morphology of the nanocrystalline diamond films. The film growth rate, film thickness, and optical properties in the VIS-NIR range, i.e. refractive index and extinction coefficient will be discussed based on measurements on reference quartz plates by using spectroscopic ellipsometry (SE).
Design of an electric power system with incorporation of a phased array antenna for OLFAR
Klein, J.M.; Budianu, A.; Bentum, M.J.; Engelen, S.; Verhoeven, C.J.M.
2013-01-01
The Orbiting Low Frequency Antennas for Radio Astronomy (OLFAR) project is investigating the feasibility of an orbiting low frequency radio telescope. The radio telescope is formed using a swarm of nano-satellites equipped with astronomical antennas, conceivably orbiting the Moon or the second Lagra
Leaky-Wave Slot Array Antenna Fed by a Dual Reflector System
Ettorre, M.; Neto, A.; Gerini, G.; Maci, S.
2008-01-01
Planar leaky-wave antennas (LWAs) have received much attention in the recent years [1] for applications in the millimeter-wave ranges. In particular the compatibility with printed circuit board technology (PCB) and the low profile are the strongest features of these antennas. Mono dimensional planar
Wearable Fabric Reconfigurable Beam-Steering Antenna for On/Off-Body Communication System
Directory of Open Access Journals (Sweden)
Seonghun Kang
2015-01-01
Full Text Available This paper presents a comparison of on-body performances between omnidirectional (loop antenna and reconfigurable beam-steering antennas. Both omnidirectional and reconfigurable antennas were manufactured on the same fabric substrate and operated at the frequency band of the WLAN 802.11a (5.725–5.85 GHz. The reconfigurable antenna was designed to steer the beam directions. In order to implement the beam-steering capability, the antenna used two PIN diodes. The maximum beam directions of three states (states 0, 1, and 2 were steerable in the YZ-plane (h=2°, 28°, and 326°, resp.. The measured peak gains were 5.9–6.6 dBi and the overall half power beam width (HPBW was 102°. The measured results of total radiated power (TRP and total isotropic sensitivity (TIS indicated that the communication efficiency of the reconfigurable beam steering antenna was better than that of the loop antenna. When the input power was 0.04 W (16 dBm, the simulated specific absorption rate (SAR values of the reconfigurable beam steering antenna on the body were less than 0.979 W/kg (1 g tissue in all states, satisfying the SAR criteria of the US.
A High-Efficiency Compact Planar Antenna for ISM Wireless Systems
Directory of Open Access Journals (Sweden)
Tao Zhou
2017-01-01
Full Text Available A novel high-efficiency compact planar antenna at 433 MHz with minimized size and low-cost and easy to integrate into the ISM wireless applications is designed, fabricated, and measured. Capacitive strips that are formed by cutting inter-digital slots and the meander lines on both sides are introduced to greatly reduce the antenna size yet maintain the high efficiency. The proposed antenna has a simple planar structure and occupies a small area (i.e., 45 × 30 mm2. This novel electrically small antenna can be operated well without any lumped elements for impedance matching. Details of the antenna design and experimental results are presented and discussed.
Simons, Rainee N.
2002-01-01
A nearly square patch antenna with a contact actuator along a radiating edge for polarization reconfiguration was demonstrated at Ka-band frequencies at the NASA Glenn Research Center. The layout of the antenna is shown in the following sketch. This antenna has the following advantages: 1) It can be dynamically reconfigured to receive and transmit a linearly polarized signal or a circularly polarized signal. This feature allows the substitution of multiple antennas on a satellite by a single antenna, thereby resulting in significant cost savings. 2) In our approach, the polarization is switched between the two states without affecting the frequency of operation; thus, valuable frequency spectrum is conserved. 3) The ability to switch polarization also helps mitigate propagation effects due to adverse weather on the performance of a satellite-to-ground link. Hence, polarization reconfigurability enhances link reliability.
Microwave Ablation of Pulmonary Malignancies Using a Novel High-energy Antenna System
Energy Technology Data Exchange (ETDEWEB)
Little, Mark W.; Chung, Daniel; Boardman, Philip; Gleeson, Fergus V.; Anderson, Ewan M., E-mail: ewan.anderson@ouh.nhs.uk [Churchill Hospital, Department of Radiology (United Kingdom)
2013-04-15
To evaluate the technical success, safety, and imaging follow-up of malignant pulmonary nodules treated with a novel high-energy percutaneous microwave ablation (MWA) system. Between July 2010 and September 2011, a total of 23 patients, 12 men, mean age 68 (range 30-87) years with 29 pulmonary malignancies of median diameter 19 (range 8-57) mm, underwent computed tomography (CT)-guided MWA with a 16G microwave needle antenna enabling power up to 180 W. Technical success was defined as needle placement in the intended lesion without death or serious injury. Adequacy of ablation was assessed at 24 h on contrast-enhanced CT. Circumferential solid or ground glass opacification >5 mm was used to define an ideal ablation. Local tumor recurrence was assessed at 1, 3, and 6 months after ablation on contrast-enhanced CT. MWA was technically successful in 93 % (n = 27). Mean ablation duration was 3.6 (range 1-9) min. Ten patients (43 %) developed a pneumothorax as a result of the MWA; only 3 (13 %) required placement of a chest drain. Thirty-day mortality rate was 0 %. The mean hospital stay was 1.5 (range 1-7) days. A total of 22 lesions (75 %) were surrounded by {>=}5 mm ground glass or solid opacification after the procedure. At a median follow-up of 6 months, local recurrence was identified in 3 out of 26 lesions, giving a local control rate of 88 %. MWA using a high-power antenna of pulmonary malignancies is safe, technically achievable, and enables fast ablation times.
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 ...
Ragona, R.; Messiaen, A.
2016-07-01
For the central heating of a fusion reactor ion cyclotron radio frequency heating (ICRH) is the first choice method as it is able to couple RF power to the ions without density limit. The drawback of this heating method is the problem of excitation of the magneto-sonic wave through the plasma boundary layer from the antenna located along the wall, without exceeding its voltage standoff. The amount of coupling depends on the antenna excitation and the surface admittance at the antenna output due to the plasma profile. The paper deals with the optimization of the antenna excitation by the use of sections of traveling-wave antennas (TWAs) distributed all along the reactor wall between the blanket modules. They are mounted and fed in resonant ring system(s). First, the physics of the coupling of a strap array is studied by simple models and the coupling code ANTITER II. Then, after the study of the basic properties of a TWA section, its feeding problem is solved by hybrids driving them in resonant ring circuit(s). The complete modeling is obtained from the matrices of the TWA sections connected to one of the feeding hybrid(s). The solution is iterated with the coupling code to determine the loading for a reference low-coupling ITER plasma profile. The resulting wave pattern up to the plasma bulk is derived. The proposed system is totally load resilient and allows us to obtain a very selective exciting wave spectrum. A discussion of some practical implementation problems is added.
Picard, Dominique
2010-01-01
Currently it is possible to measure all the characteristics of an antenna with a good accuracy. Far-field ranges do not have a very good accuracy, due to parasitic reflections for the outdoor ranges and because of the limited distance between the source antenna and the tested antenna for the indoor ranges. The compact range allows one to obtain a direct farfield cut in a relatively short time. The near-field techniques are the most accurate and the most convenient for global antenna radiation...
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
On-chip micromachined dipole antenna with parasitic radiator for mm-wave wireless systems
Sallam, Mai O.
2016-12-19
In this paper, we present a micromachined dipole antenna with parasitic radiator. The antenna is designed for operation at 60 GHz. It consists of two I
Sastry, Amit V; Swet, Jacob H; Murphy, Keith J; Baker, Erin H; Vrochides, Dionisios; Martinie, John B; McKillop, Iain H; Iannitti, David A
2017-09-13
Failure to locate lesions and accurately place microwave antennas can lead to incomplete tumor ablation. The Emprint™ SX Ablation Platform employs real-time 3D-electromagnetic spatial antenna tracking to generate intraoperative laparoscopic antenna guidance. We sought to determine whether Emprint™ SX affected time/accuracy of antenna-placement in a laparoscopic training model. Targets (7-10 mm) were set in agar within a laparoscopic training device. Novices (no surgical experience), intermediates (surgical residents), and experts (HPB-surgeons) were asked to locate and hit targets using a MWA antenna (10-ultrasound only, 10-Emprint™ SX). Time to locate target, number of attempts to hit the target, first-time hit rate, and time from initiating antenna advance to hitting the target were measured. Participants located 100% of targets using ultrasound, with experts taking significantly less time than novices and intermediates. Using ultrasound only, successful hit-rates were 70% for novices and 90% for intermediates and experts. Using Emprint™ SX, successful hit rates for all 3-groups were 100%, with significantly increased first-time hit-rates and reduced time required to hit targets compared to ultrasound only. Emprint™ SX significantly improved accuracy and speed of antenna-placement independent of experience, and was particularly beneficial for novice users. Copyright © 2017 International Hepato-Pancreato-Biliary Association Inc. Published by Elsevier Ltd. All rights reserved.
Handbook of reflector antennas and feed systems v.3 applications of reflectors
Rao, Sudhakar; Sharma, Satish K
2013-01-01
This is the first truly comprehensive and most up-to-date handbook available on modern reflector antennas and feed sources for diversified space and ground applications. There has never been such an all-encompassing reflector handbook in print, and no currently available title offers coverage of such recent research developments. The Handbook consists of three volumes. Volume III focuses on the range of reflector antenna applications, including space, terrestrial, and radar. The intent of this book volume is to provide practical applications and design information on reflector antennas used fo
A Novel and Compact Multi Frequency-Agile Slot Antenna for Cognitive Radio Systems
Directory of Open Access Journals (Sweden)
Rajeev Kumar
2015-10-01
Full Text Available A novel and compact frequency- agile slot antenna is presented. The antenna is switchable between 5.03-6.90GHz at twenty four different frequencies and is capable to operate multi frequency at a time. The proposed antenna has two slots etched out, one in the ground plane and another in the patch. To attain frequency agility, the effective lengths of these slots are altered by use of four p-i-n diodes which are placed within these slots at predetermined positions. Results such as return losses, gain, bandwidth and radiation patterns are presented in this paper.
Liquid Crystal Polymer (LCP) based antenna for flexible system on package (SoP) applications
Marnat, Loic
2012-06-01
The design, fabrication and measurement of a bowtie antenna on a flexible Liquid Crystal Polymer (LCP) substrate is reported in this paper. The antenna is fed by a balun transition which helps improve the gain up to 5.1 dB. The antenna performance is analyzed for both planar and curved substrates. The comparison between simulation and measurements shows a good agreement. This structure can either be used to sense the bending of the substrate or use the bending to tilt the beam. © 2012 IEEE.
Antenna Parts and Waveguide Transmission Line of Short Pulse Radar System Design
Directory of Open Access Journals (Sweden)
M. E. Golubcov
2014-01-01
Full Text Available The main point of this research was работы являлось to create a stand to explore the application of short pulse radio signals in radar. The stand consists of antenna and waveguide elements. Each element out to guarantee operation in X-band with 10 percent working bank and 5 percent instantaneous bandwidth and the power output gotta be 1.5 kW. The form of the antenna beam patten need to be similar to cosecant pattern Side-lobe level need to be less than -25 dB. Background level got to be at least -30 dB. Wave friction, which is radiated from the antenna aperture, got to simultaneous formed in a space.As the most easily realizing variant of such antenna cutting parabolic mirror antenna with offset irradiator was chosen. The irradiator phase centre is shifted from the focal point of the paraboloid to form a cosecant pattern. Method of physical optics is used for the analysis of antennas. Calculating pattern of horn irradiator and mirror antenna which were met the requirements was received. The construction choice was limited by the preproduction possibilities, mass and dimensions. Mirror antenna consists of skeleton framing with mirroring elements which are fixing on it. Mirroring plane is multiplex and consists off rectangular planes made by hydroforming method. Antenna was tested and adjusted at the antenna darkroom after fabricating. The results were meted requirements.Besides the mirror antenna and the horn antenna waveguide elements, waveguide bends and rotating joints were calculated, manufactured and researched. All calculations included the manufacturers tolerances, technological corner R etc. As the construction base of rotating joint coaxial waveguide was chosen. The decision on the one hand: let keep the axial symmetry of excited wave at rotating part of the waveguide, on the other hand there’s no necessary to apply resonant rings, which are plug into dielectric beads for the transition from rotating ring part to
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....
Determining properties of the Antennae system - Merging ability for restricted N-body
Petsch, Hanns P
2008-01-01
Motivated by the closest major merger, the Antennae Galaxies (NGC4038/4039), we want to improve our genetic algorithm based modeling code Minga (Theis 1999). The aim is to reveal the major interaction and galaxy parameters, e.g. orbital information and halo properties of such an equal mass merger system. Together with the sophisticated search strategy of Minga, one needs fast and reliable models in order to investigate the high dimensional parameter space of this problem. Therefore we use a restricted N-body code which is based on the approach by Toomre & Toomre (1972), however with some refinements like consistent orbits of extended dark matter halos. Recently also dynamical friction was included to this code (Petsch 2007). While a good description for dynamical friction was found for mass ratios up to q = 1/3 (Petsch & Theis 2008), major merger systems were only imperfectly remodeled. Here we show recent improvements for a major merger system by including mass-loss and using NFW halos.
Determining properties of the Antennae system - Merging ability for restricted N-body
Petsch, H. P.; Theis, C.
2011-01-01
Motivated by the closest major merger, the Antennae Galaxies (NGC4038/4039), we want to improve our genetic algorithm based modeling code Minga (Theis 1999). The aim is to reveal the major interaction and galaxy parameters, e.g. orbital information and halo properties of such an equal mass merger system. Together with the sophisticated search strategy of Minga, one needs fast and reliable models in order to investigate the high dimensional parameter space of this problem. Therefore we use a restricted N-body code which is based on the approach by Toomre & Toomre (1972), however with some refinements like consistent orbits of extended dark matter halos. Recently also dynamical friction was included to this code (Petsch 2007). While a good description for dynamical friction was found for mass ratios up to q = 1/3 (Petsch & Theis 2008), major merger systems were only imperfectly remodeled. Here we show recent improvements for a major merger system by including mass-loss and using NFW halos.
Development of High-Throughput Liquid Treatment System using Slot Antenna Excited Microwave Plasma
Takitou, Sho; Ito, Michiko; Takashima, Seigou; Nomura, Norio; Kitagawa, Tominori; Toyoda, Hirotaka
2015-09-01
Recently, much attention has been given to plasma production under liquid and its industrial applications as well as investigation of chemical reactions as a result of plasma-liquid interactions. In various kinds of plasma production techniques, we have proposed pulsed microwave excited plasma using slot antenna, where damage to the slot electrode can be minimized and plasma volume can be increased. Furthermore, we have proposed an in-line microwave plasma system where plasma is efficiently produced under reduced pressures using Venturi effect, and have demonstrated enhancement of organic decomposition efficiency. For practical use of the plasma liquid treatment, however, cost-effective and more efficient treatment system with high treatment capability is required. In this study, we propose further enhancement of the treatment speed by designing four-parallel-type liquid treatment device where four discharges for the treatment are performed using one microwave power source. Decomposition speed of newly-developed plasma system is investigated. Not only high decomposition rate but also enhanced energy efficiency is realized.
Institute of Scientific and Technical Information of China (English)
Zhang Hong-Lin; Hu Bin-Jie; Zhang Xiu-Yin
2012-01-01
A compact and broadband circularly polarized (CP) annular ring antenna with wide beam-width is proposed for multiple global navigation satellite systems (GNSS) in the L1 band.The annular ring is excited by two modified L-probes with quadrature phase difference.It has a 36.3％ 10-dB return loss bandwidth and a 13％ 3-dB axial ratio bandwidth,because of the orthogonal L-probes with 90° phase difference.The measured peak gain of the antenna is 3.9 dBic.It can detect the satellites at lower elevation as its half power beam-width (HPBW) is 113° in both the x-z and y-z planes,achieving a cross-polarization level of larger than 25 dB.Noticeably,the antenna achieves 89％ size reduction compared with the conventional half wavelength patch antennas.It can be used in hand-held navigation devices of multiple GNSS such as COMPASS,Galileo,GPS and GLONASS.
Sayed, Mostafa
2012-12-01
In spectrum sharing systems, a secondary user (SU) is allowed to share the spectrum with a primary licensed user under the condition that the interference at the the primary user receiver (PU-Rx) is below a predetermined threshold. Joint primary spectrum and transmit antenna selection diversity schemes can be utilized as an efficient way to meet the quality of service (QoS) demands of the SUs while satisfying the interference constraint. In this paper, we consider a secondary link comprised of a secondary transmitter (SU-Tx) equipped with multiple antennas and a single-antenna secondary receiver (SU-Rx) sharing the same spectrum with a number of primary users (PUs) operating at distinct spectra. We present a performance analysis for two primary spectrum and transmit antenna switched selection schemes with different amount of feedback requirements. In particular, assuming Rayleigh fading and BPSK transmission, we derive approximate BER expressions for the presented schemes. For the sake of comparison, we also derive a closed-form BER expression for the optimal selection scheme that selects the best pair in terms of the SU-Rx signal-to-noise ratio (SNR) which has the disadvantage of high feedback requirements. Finally, our results are verified with numerical simulations. © 2012 IEEE.
Park, Kihong
2011-01-01
In this paper, we consider multicarrier systems with multiple transmit antennas under a power-balancing constraint. Applying transmit antenna selection and discrete rate-adaptive modulation using M-ary quadrature-amplitude modulation (QAM) according to the channel variation per subcarrier, we develop an optimal transmit antenna selection scheme in terms of the maximum spectral efficiency, where all the possible groupings for sending the same information-bearing signals in a group of subcarriers are searched, and the groups of subcarriers for providing the frequency diversity gain are formed. In addition, we propose a suboptimal method for reducing the computational complexity of the optimal method. The suboptimal scheme considers only the subcarriers under outage, and these subcarriers are sequentially combined until the required signal-to-noise ratio (SNR) is met. Numerical results show that the proposed suboptimal method with diversity combining outperforms the optimal antenna selection without diversity combining, as introduced in the work of Sandell and Coon, particularly for low-SNR regions, and offers the spectral efficiency close to the optimal method with diversity combining while maintaining lower complexity. © 2011 IEEE.
Hamiltonian particle-in-cell methods for Vlasov-Maxwell equations
He, Yang; Sun, Yajuan; Qin, Hong; Liu, Jian
2016-09-01
In this paper, we study the Vlasov-Maxwell equations based on the Morrison-Marsden-Weinstein bracket. We develop Hamiltonian particle-in-cell methods for this system by employing finite element methods in space and splitting methods in time. In order to derive the semi-discrete system that possesses a discrete non-canonical Poisson structure, we present a criterion for choosing the appropriate finite element spaces. It is confirmed that some conforming elements, e.g., Nédélec's mixed elements, satisfy this requirement. When the Hamiltonian splitting method is used to discretize this semi-discrete system in time, the resulting algorithm is explicit and preserves the discrete Poisson structure. The structure-preserving nature of the algorithm ensures accuracy and fidelity of the numerical simulations over long time.
Adaptive multiresolution semi-Lagrangian discontinuous Galerkin methods for the Vlasov equations
Besse, N.; Deriaz, E.; Madaule, É.
2017-03-01
We develop adaptive numerical schemes for the Vlasov equation by combining discontinuous Galerkin discretisation, multiresolution analysis and semi-Lagrangian time integration. We implement a tree based structure in order to achieve adaptivity. Both multi-wavelets and discontinuous Galerkin rely on a local polynomial basis. The schemes are tested and validated using Vlasov-Poisson equations for plasma physics and astrophysics.
Li, Xinying; Yu, Jianjun; Zhang, Junwen; Dong, Ze; Chi, Nan
2013-06-15
We experimentally demonstrate 2×56 Gb/s two-channel polarization-division-multiplexing quadrature-phase-shift-keying signal delivery over 80 km single-mode fiber-28 and 2 m Q-band (33-50 GHz) wireless link, adopting antenna horizontal- (H-) and vertical-polarization (V-polarization) multiplexing. At the wireless receiver, classic constant-modulus-algorithm equalization based on digital signal processing can realize polarization demultiplexing and remove the crosstalk at the same antenna polarization. By adopting antenna polarization multiplexing, the signal baud rate and performance requirements for optical and wireless devices can be reduced but at the cost of double antennas and devices, while wireless transmission capacity can also be increased but at the cost of stricter requirements for V-polarization. The isolation is only about 19 dB when V-polarization deviation approaches 10°, which will affect high-speed (>50 Gb/s) wireless delivery.
COMBINED TRANSMIT ANTENNA SELECTION AND DETECTION OVER SPATIAL CORRELATED MIMO SYSTEMS
Institute of Scientific and Technical Information of China (English)
无
2007-01-01
In this paper a method that combines transmit antenna selection and reduced-constellation detection in spatially correlated Multi-Input Multi-Output (MIMO) fading channels is presented. To mitigate the performance degradation caused by the use of antenna selection that is based on correlation among columns, an iterative receiver scheme that uses only a subset of the constellation points close to the expected symbol value estimated in the previous iteration is proposed. The size of the subset can adapt to the maximum correlation of the sub-matrix after the simple antenna selection. Furthermore, the error rate performance of the scheme under linear Minimum Mean Square Error (MMSE) or Ordered Successive Interference Cancellation (OSIC) for the first run detection and different interleaver lengths is investigated while the transmit antenna selection is considered. The simulation results show a significant advantage both for implementation complexity and for error rate performance under a fixed data rate.
Antenna Calibration and Measurement Equipment
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.
Placement insensitive antenna for RFID, sensing, and/or communication systems
Bernhard, Jennifer T.; Ruyle, Jessica E.
2014-06-10
An antenna includes a ground plane having a slot. The slot may be miniaturized using a meandered slot structure or other appropriate reactive loading method as an end load to one or both ends of the slot. An edge treatment may be included on one or more edges of the ground plane or a closely spaced reflecting plane. The antenna is structured to transmit or receive a signal independently or in response to electromagnetic radiation.
Placement insensitive antenna for RFID, sensing, and/or communication systems
Energy Technology Data Exchange (ETDEWEB)
Bernhard, Jennifer T.; Ruyle, Jessica E.
2014-06-10
An antenna includes a ground plane having a slot. The slot may be miniaturized using a meandered slot structure or other appropriate reactive loading method as an end load to one or both ends of the slot. An edge treatment may be included on one or more edges of the ground plane or a closely spaced reflecting plane. The antenna is structured to transmit or receive a signal independently or in response to electromagnetic radiation.
System-Level Integrated Circuit (SLIC) Technology Development for Phased Array Antenna Applications
Windyka, John A.; Zablocki, Ed G.
1997-01-01
This report documents the efforts and progress in developing a 'system-level' integrated circuit, or SLIC, for application in advanced phased array antenna systems. The SLIC combines radio-frequency (RF) microelectronics, digital and analog support circuitry, and photonic interfaces into a single micro-hybrid assembly. Together, these technologies provide not only the amplitude and phase control necessary for electronic beam steering in the phased array, but also add thermally-compensated automatic gain control, health and status feedback, bias regulation, and reduced interconnect complexity. All circuitry is integrated into a compact, multilayer structure configured for use as a two-by-four element phased array module, operating at 20 Gigahertz, using a Microwave High-Density Interconnect (MHDI) process. The resultant hardware is constructed without conventional wirebonds, maintains tight inter-element spacing, and leads toward low-cost mass production. The measured performances and development issues associated with both the two-by-four element module and the constituent elements are presented. Additionally, a section of the report describes alternative architectures and applications supported by the SLIC electronics. Test results show excellent yield and performance of RF circuitry and full automatic gain control for multiple, independent channels. Digital control function, while suffering from lower manufacturing yield, also proved successful.
Vedenyapin, V. V.; Negmatov, M. A.; Fimin, N. N.
2017-06-01
We give a derivation of the Vlasov-Maxwell and Vlasov-Poisson-Poisson equations from the Lagrangians of classical electrodynamics. The equations of electromagnetic hydrodynamics (EMHD) and electrostatics with gravitation are derived from them by means of a `hydrodynamical' substitution. We obtain and compare the Lagrange identities for various types of Vlasov equations and EMHD equations. We discuss the advantages of writing the EMHD equations in Godunov's double divergence form. We analyze stationary solutions of the Vlasov-Poisson-Poisson equation, which give rise to non-linear elliptic equations with various properties and various kinds of behaviour of the trajectories of particles as the mass passes through a critical value. We show that the classical equations can be derived from the Liouville equation by the Hamilton-Jacobi method and give an analogue of this procedure for the Vlasov equation as well as in the non-Hamiltonian case.
A Vlasov equation with Dirac potential used in fusion plasmas
Energy Technology Data Exchange (ETDEWEB)
Bardos, Claude [Universite Paris-Diderot, Laboratoire J.-L. Lions, BP187, 4 Place Jussieu, 75252 Paris Cedex 05 (France); Nouri, Anne [Laboratoire d' Analyse, Topologie et Probabilites (UMR 6632), Aix-Marseille Universite, 39 Rue Joliot-Curie, 13453 Marseille Cedex 13 (France)
2012-11-15
Well-posedness of the Cauchy problem is analyzed for a singular Vlasov equation governing the evolution of the ionic distribution function of a quasineutral fusion plasma. The Penrose criterium is adapted to the linearized problem around a time and space homogeneous distribution function showing (due to the singularity) more drastic differences between stable and unstable situations. This pathology appears on the full nonlinear problem, well-posed locally in time with analytic initial data, but generally ill-posed in the Hadamard sense. Eventually with a very different class of solutions, mono-kinetic, which constrains the structure of the density distribution, the problem becomes locally in time well-posed.
Lindsey, J. F.
1976-01-01
The isolation between the upper S-band quad antenna and the S-band payload antenna on the shuttle orbiter is calculated using a combination of plane surface and curved surface theories along with worst case values. A minimum value of 60 db isolation is predicted based on recent antenna pattern data, antenna locations on the orbiter, curvature effects, dielectric covering effects and edge effects of the payload bay. The calculated value of 60 db is significantly greater than the baseline value of 40 db. Use of the new value will result in the design of smaller, lighter weight and less expensive filters for S-band transponder and the S-band payload interrogator.
Fetherman, Eric R.; Avila, Brian W.; Winkelman, Dana L.
2016-01-01
Portable radio frequency identification (RFID) PIT tag antenna systems are increasingly being used in studies examining aquatic animal movement, survival, and habitat use, and their design flexibility permits application in a wide variety of settings. We describe the construction, use, and performance of two portable floating RFID PIT tag antenna systems designed to detect fish that were unavailable for recapture using stationary antennas or electrofishing. A raft antenna system was designed to detect and locate PIT-tagged fish in relatively long (i.e., ≥10 km) river reaches, and consisted of two antennas: (1) a horizontal antenna (4 × 1.2 m) installed on the bottom of the raft and used to detect fish in shallower river reaches (<1 m), and (2) a vertical antenna (2.7 × 1.2 m) for detecting fish in deeper pools (≥1 m). Detection distances of the horizontal antenna were between 0.7 and 1.0 m, and detection probability was 0.32 ± 0.02 (mean ± SE) in a field test using rocks marked with 32-mm PIT tags. Detection probability of PIT-tagged fish in the Cache la Poudre River, Colorado, using the raft antenna system, which covered 21% of the wetted area, was 0.14 ± 0.14. A shore-deployed floating antenna (14.6 × 0.6 m), which covered 100% of the wetted area, was designed for use by two operators for detecting and locating PIT-tagged fish in shorter (i.e., <2 km) river reaches. Detection distances of the shore-deployed floating antenna were between 0.7 and 0.8 m, and detection probabilities during field deployment in the St. Vrain River exceeded 0.52. The shore-deployed floating antenna was also used to estimate abundance of PIT-tagged fish. Results suggest that the shore-deployed floating antenna could be used as an alternative to estimating abundance using traditional sampling methods such as electrofishing.
Campbell, T. G.; White, W. E.; Gilreath, M. C.
1976-01-01
The Research Support Flight System, a modified Boeing 737, was used to evaluate the performance of several aircraft antennas and locations for the Time Reference Scanning Beam (TRSB) Microwave Landing System (MLS). These tests were conducted at the National Aviation Facilities Experimental Center (NAFEC), Atlantic City, New Jersey on December 18, 1975. The flight tests measured the signal strength and all pertinent MLS data during a straight-in approach, a racetrack approach, and ICAO approach profiles using the independent antenna-receiver combinations simultaneously on the aircraft. Signal drop-outs were experienced during the various approaches but only a small percentage could be attributed to antenna pattern effects.
DEFF Research Database (Denmark)
Thaysen, Jesper; Jakobsen, Kaj Bjarne
2007-01-01
The influence of mutual coupling on the envelope correlation between two identical planar inverted F-antennas (PIFA) are investigated. The capacity of a multiple-input multiple-output (MIMO) antenna system strongly depends on the correlation between the antennas. By placing two antennas in a fixe...
Nganou, C; David, L; Adir, N; Mkandawire, M
2016-01-01
We applied a femtosecond flash method, using induced transient absorption changes, to obtain a time-resolved view of excitation energy transfer in intact phycobilisomes of Thermosynechococcus vulcanus at room temperature. Our measurement of an excitation energy transfer rate of 888 fs in phycobilisomes shows the existence of ultrafast kinetics along the phycocyanin rod subcomplex to the allophycocyanin core that is faster than expected for previous excitation energy transfer based on Förster theory in phycobilisomes. Allophycocyanin in the core further transfers energy to the terminal emitter(s) in 17 ps. In the phycobilisome, rod doublets composed of hexameric phycocyanin discs and internal linker proteins are arranged in a parallel fashion, facilitating direct rod-rod interactions. Excitonic splitting likely drives rod absorption at 635 nm as a result of strong coupling between β84 chromophores (20 ± 1 Å) in adjacent hexamers. In comparison to the absorbance of the phycobilisome antenna system of the cyanobacterium Acaryochloris marina, which possesses a single rod structure, the linkers in T. vulcanus rods induce a 17 nm red shift in the absorbance spectrum. Furthermore, the kinetics of 888 fs indicates that the presence of the linker protein induces ultrafast excitation energy transfer between phycocyanin and allophycocyanin inside the phycobilisome, which is faster than all previous excitation energy transfer in phycobilisome subunits or sub-complexes reported to date.
Alvarez, L. S.; Moore, M.; Veruttipong, W.; Andres, E.
1994-01-01
The design and implementation of an antenna beam-waveguide (BWG) mirror position control system at the DSS-13 34-m antenna is presented. While it has several potential applications, a positioner on the last flat-plate BWG mirror (M6) at DSS 13 is installed to demonstrate the conical scan (conscan) angle-tracking technique at the Ka-band (32-GHz) operating frequency. Radio frequency (RF) beam-scanning predictions for the M6 mirror, computed from a diffraction analysis, are presented. From these predictions, position control system requirements are then derived. The final mechanical positioner and servo system designs, as implemented at DSS 13, are illustrated with detailed design descriptions given in the appendices. Preliminary measurements of antenna Ka-band beam scan versus M6 mirror tilt made at DSS 13 in December 1993 are presented. After reduction, the initial measurements are shown to be in agreement with the RF predicts. Plans for preliminary conscan experimentation at DSS 13 are summarized.
Vlasov analysis of microbunching instability for magnetized beams
Directory of Open Access Journals (Sweden)
C.-Y. Tsai
2017-05-01
Full Text Available For a high-brightness electron beam with high bunch charge traversing a recirculation beam line, coherent synchrotron radiation and space charge effects may result in microbunching instability (MBI. Both tracking simulation and Vlasov analysis for an early design of a circulator cooler ring (CCR for the Jefferson Lab Electron Ion Collider (JLEIC reveal significant MBI [Ya. Derbenev and Y. Zhang, Proceedings of the Workshop on Beam Cooling and Related Topics, COOL’09, Lanzhou, China, 2009 (2009, FRM2MCCO01]. It is envisioned that the MBI could be substantially suppressed by using a magnetized beam. In this paper we have generalized the existing Vlasov analysis, originally developed for a nonmagnetized beam (or transversely uncoupled beam, to the description of transport of a magnetized beam including relevant collective effects. The new formulation is then employed to confirm prediction of microbunching suppression for a magnetized beam transport in the recirculation arc of a recent JLEIC energy recovery linac (ERL based cooler design for electron cooling. It is found that the smearing effect in the longitudinal beam phase space originates from the large transverse beam size as a nature of the magnetized beams and becomes effective through the x-z correlation when the correlated distance is larger than the microbunched scale. As a comparison, MBI analysis of the early design of JLEIC CCR is also presented in this paper.
Existence of Global Weak Solutions to a Hybrid Vlasov-MHD Model for Magnetized Plasmas
Cheng, Bin; Tronci, Cesare
2016-01-01
We prove the global-in-time existence of large-data finite-energy weak solutions to an incompressible hybrid Vlasov-magnetohydrodynamic model in three space dimensions. The model couples three essential ingredients of magnetized plasmas: a transport equation for the probability density function, which models energetic rarefied particles of one species; the incompressible Navier--Stokes system for the bulk fluid; and a parabolic evolution equation, involving magnetic diffusivity, for the magnetic field. The physical derivation of our model is given. It is also shown that the weak solution, whose existence is established, has nonincreasing total energy, and that it satisfies a number of physically relevant properties, including conservation of the total momentum, conservation of the total mass, and nonnegativity of the probability density function for the energetic particles. The proof is based on a one-level approximation scheme, which is carefully devised to avoid increase of the total energy for the sequence...
Description of the evolution of inhomogeneities on a dark matter halo with the Vlasov equation
Domínguez-Fernández, Paola; Jiménez-Vázquez, Erik; Alcubierre, Miguel; Montoya, Edison; Núñez, Darío
2017-09-01
We use a direct numerical integration of the Vlasov equation in spherical symmetry with a background gravitational potential to determine the evolution of a collection of particles in different models of a galactic halo in order to test its stability against perturbations. Such collection is assumed to represent a dark matter inhomogeneity which is represented by a distribution function defined in phase-space. Non-trivial stationary states are obtained and determined by the virialization of the system. We describe some features of these stationary states by means of the properties of the final distribution function and final density profile. We compare our results using the different halo models and find that the NFW halo model is the most stable of them, in the sense that an inhomogeneity in this halo model requires a shorter time to virialize.
A Full Eulerian Vlasov-Maxwell Study of Turbulent Dynamics and Dissipation
TenBarge, J. M.; Juno, J.; Hakim, A.
2016-12-01
The development of a detailed understanding of turbulence in magnetized plasmas has been a long standing goal of the broader scientific community, both as a fundamental physics process and because of its applicability to a wide variety of phenomena. Turbulence in a magnetized plasma is the primary mechanism responsible for transforming energy at large injection scales into small-scale motions, which are ultimately dissipated as heat in systems such as the solar corona and wind. At large scales, the turbulence is well described by fluid models of the plasma; however, understanding the processes responsible for heating a weakly collisional plasma such as the solar wind requires a kinetic description. We present the first fully kinetic Eulerian Vlasov-Maxwell study of turbulence using the Gkeyll simulation code. We focus on the pristine distribution function dynamics that are possible with the Eulerian approach. We also present the signatures and form of dissipation as diagnosed via field-particle correlation functions.
Enabling Technologies for Fabrication of Large Area Flexible Antennas Project
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...