Leaky‐Wave Antennas
13 Aug 2008-pp 325-367
TL;DR: In this paper, an introduction history classification of leaky wave antennas is presented, along with a detailed discussion of the physics of Leaky Waves Radiation properties of one-dimensional and two-dimensional Leaky wave antenna.
Abstract: This chapter contains sections titled: Introduction History Classification of Leaky‐Wave Antennas Physics of Leaky Waves Radiation Properties of One‐Dimensional Leaky‐Wave Antennas Radiation Properties of Two‐Dimensional Leaky‐Wave Antennas Conclusions Acknowledgment References
Citations
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TL;DR: This paper gives a basic review and a summary of recent developments for leaky-wave antennas (LWAs), a guiding structure that supports wave propagation along the length of the structure, with the wave radiating or “leaking” continuously along the structure.
Abstract: This paper gives a basic review and a summary of recent developments for leaky-wave antennas (LWAs). An LWA uses a guiding structure that supports wave propagation along the length of the structure, with the wave radiating or “leaking” continuously along the structure. Such antennas may be uniform, quasi-uniform, or periodic. After reviewing the basic physics and operating principles, a summary of some recent advances for these types of structures is given. Recent advances include structures that can scan to endfire, structures that can scan through broadside, structures that are conformal to surfaces, and structures that incorporate power recycling or include active elements. Some of these novel structures are inspired by recent advances in the metamaterials area.
988 citations
01 Nov 1984
TL;DR: In this article, a substrate-superstrate printed antenna geometry which allows for large antenna gain is presented, asymptotic formulas for gain, beamwidth, and bandwidth are given, and the bandwidth limitation of the method is discussed.
Abstract: Resonance conditions for a substrate-superstrate printed antenna geometry which allow for large antenna gain are presented. Asymptotic formulas for gain, beamwidth, and bandwidth are given, and the bandwidth limitation of the method is discussed. The method is extended to produce narrow patterns about the horizon, and directive patterns at two different angles.
568 citations
TL;DR: In this paper, a planar antenna based on modulated metasurfaces (MTSs) is proposed for the first time for space applications, where an impedance-based amplitude synthesis of the aperture field distribution is presented.
Abstract: This paper presents design and analysis methods for planar antennas based on modulated metasurfaces (MTSs). These antennas operate on an interaction between a cylindrical surface-wave (SW) excited by an isotropic TM radiator, and an MTS having a spatially modulated equivalent impedance. The MTS is realized by using sub-wavelength patches printed on a grounded slab, thus resulting in a structure with light weight and compact volume. Both features are appealing characteristics for space applications. This paper introduces for the first time an impedance-based amplitude synthesis of the aperture field distribution and shows several new examples of antennas for space applications obtained in recent research projects financed by the European Space Agency.
337 citations
Cites methods from "Leaky‐Wave Antennas"
...This can be done by using an extension of the formula derived by Oliner in [20] and based on power conservation....
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TL;DR: In this article, a novel technique for the elimination of the open stopband in one-dimensional periodic printed leaky-wave antennas is presented, where a quarter-wave transformer, or alternatively a matching stub, is introduced into the unit cell of the antenna, which forces the Bloch-wave impedance of the structure to remain real and non-zero at broadside.
Abstract: A novel technique for the elimination of the open stopband in one-dimensional periodic printed leaky-wave antennas is presented. A quarter-wave transformer, or alternatively a matching stub, is introduced into the unit cell of the antenna, which forces the Bloch-wave impedance of the structure to remain real and non-zero at broadside. The effectiveness of the proposed technique is first demonstrated on a printed periodic microstrip leaky-wave antenna consisting of a single radiating stub per unit cell, which exhibits a significant stopband at broadside. The technique is then also applied to a structure consisting of two radiating stubs per unit cell, which is capable of mitigating, but not eliminating, the open stopband. In both cases the open stopband at broadside is completely suppressed.
237 citations
Cites background from "Leaky‐Wave Antennas"
...standing-wave phenomenon occurs and hence radiation is not possible exactly at broadside [2]....
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...employ a series of resonant patch antennas connected by a microstrip line or a series of array elements coupled by proximity to a microstrip line [2], [6]....
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...It should be noted that, instead of the expression for the beamwidth in (1), which is valid for a semi-infinite aperture, the following one has to be used [2]:...
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...AND PREDICTED BY MEANS OF LEAKY-WAVE THEORY AS IN [2]...
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...The radiation is due to a leaky mode that leaks power into free space, with radiation occurring from the fast space harmonic [1], [2]....
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TL;DR: In this paper, an effective synthesis procedure for planar antennas realized with nonuniform metasurfaces (MTSs) excited by a point source is presented, which enhances previous formulations by introducing a control of the amplitude of the aperture field while improving the polarization and phase performances.
Abstract: An effective synthesis procedure for planar antennas realized with nonuniform metasurfaces (MTSs) excited by a point source is presented. This synthesis potentiates previous formulations by introducing a control of the amplitude of the aperture field while improving the polarization and phase performances. The class of MTS antennas we are dealing with is realized by using subwavelength patches of different dimensions printed on a grounded slab, illuminated by a transverse magnetic point source. These antennas are based on the interaction between a cylindrical surface-wave and the periodic modulation of the MTS, which leads to radiation through a leaky-wave (LW) effect. This new design method permits a systematic and simple synthesis of amplitude, phase, and polarization of the aperture field by designing the boundary conditions imposed by the MTS. The polarization control is based on the local value of the MTS anisotropy, the phase is controlled by the shape and periodicity of the modulation, and the amplitude is controlled by the local leakage attenuation parameter of the LW. The synthesis is based on analytical formulas derived by an adiabatic Floquet-wave expansion of currents and fields over the surface, which are simultaneously published in this journal issue. The effectiveness of the procedure is tested through several numerical examples involving realistic structures.
197 citations
Cites background from "Leaky‐Wave Antennas"
...Using (15), (12), and (6) in the BCs, (1) identifies the adiabatic form of the electric field integral equation for the local periodic problem [23], [24]...
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References
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TL;DR: In this article, the authors proposed an alternate perspective on the design and function of such materials that exploits the well-known L-C distributed network representation of homogeneous dielectrics.
Abstract: Recent demonstrations of negative refraction utilize three-dimensional collections of discrete periodic scatterers to synthesize artificial dielectrics with simultaneously negative permittivity and permeability. In this paper, we propose an alternate perspective on the design and function of such materials that exploits the well-known L-C distributed network representation of homogeneous dielectrics. In the conventional low-pass topology, the quantities L and C represent a positive equivalent permeability and permittivity, respectively. However, in the dual configuration, in which the positions of L and C are simply interchanged, these equivalent material parameters assume simultaneously negative values. Two-dimensional periodic versions of these dual networks are used to demonstrate negative refraction and focusing; phenomena that are manifestations of the fact that such media support a propagating fundamental backward harmonic. We hereby present the characteristics of these artificial transmission-line media and propose a suitable means of implementing them in planar form. We then present circuit and full-wave field simulations illustrating negative refraction and focusing, and the first experimental verification of focusing using such an implementation.
1,439 citations
02 Aug 2005
TL;DR: In this article, the authors proposed a planar guided-wave structure with double-negative (DNG) and single-negative (SNG) layers, and showed the properties of the planar guide-wave structures with DNG and SNG layers.
Abstract: Contributors. Preface. 1. Negative-Refractive-Index Transmission-Line Metamaterials (A. Iyer & G. Eleftheriades). 2. Passive Microwave Devices and Antennas Using Negative-Refractive-Index Transmission-Line Metamaterials (G. Eleftheriades). 3. Super Resolving Negative-Refractive-Index Transmission-Line Lenses (A. Grbic & G. Eleftheriades). 4. Gaussian Beam Interactions with DNG Metamaterials (R. Ziolkowski). 5. Negative Index Lenses (D. Schurig & D. Smith). 6. Planar Anisotropic Resonance-Cone Metamaterials (K. balmain & A. Luttgen). 7. Negative Refraction and Subwavelength Imaging in Photonic Crystals (C. Luo & J. Joannopoulos). 8. Plasmonic Nanowire Metamaterials (A. Sarychev & V. Shalaev). 9. An Overview of Salient Properties of Planar Guided-Wave Structures with Double-Negative (DNG) and Single-Negative (SNG) Layers (A Alu and N. Engheta). 10. Dispersion Engineering: The Use of Abnormal Velocities and Negative Index of Refraction to Control the Dispersive Effects (M. Mojahedi & G. Eleftheriades). Index.
1,050 citations
TL;DR: In this paper, the authors investigated the effect of placing a partially reflecting sheet in front of an antenna with a reflecting screen at a wavelength of 3.2 cm and showed that large arrays produce considerably greater directivity but their efficiency is poor.
Abstract: Multiple reflections of electromagnetic waves between two planes are studied, and the increase in directivity that results by placing a partially reflecting sheet in front of an antenna with a reflecting screen is investigated at a wavelength of 3.2 cm. The construction and performance of various models of such arrays is discussed. Thus, for example, a "reflex-cavity antenna" with an outer diameter of 1.88 \lambda and an over-all length of only 0.65 \lambda is described which has half-power beamwidths of 34\deg and 41\deg in the E and H planes, respectively, and a gain of approximately 14 db. It is shown that larger systems produce considerably greater directivity but that their efficiency is poor.
977 citations
01 Dec 2001
TL;DR: In this paper, a high gain planar antenna with an optimized partially reflecting surface (PRS) placed in front of a waveguide aperture in a ground plane was investigated, where the antenna performance was initially related to the reflection characteristics of the PRS array following an approximate analysis.
Abstract: A high gain planar antenna has been investigated, using an optimised partially reflecting surface (PRS) placed in front of a waveguide aperture in a ground plane. The antenna performance is initially related to the reflection characteristics of the PRS array following an approximate analysis. The array geometry is optimised using an analytical formula. The optimisation results are verified using a full wave model taking into account the edge effects. The array size for maximum antenna efficiency has also been investigated.
611 citations
TL;DR: The method is extended to produce narrow patterns about the horizon, and directive patterns at two different angles, and the bandwidth limitation of the method is discussed.
Abstract: Resonance conditions for a substrate-superstrate printed antenna geometry which allow for large antenna gain are presented. Asymptotic formulas for gain, beamwidth, and bandwidth are given, and the bandwidth limitation of the method is discussed. The method is extended to produce narrow patterns about the horizon, and directive patterns at two different angles.
594 citations