Scalar and Tensor Holographic Artificial Impedance Surfaces

Fong, Bryan H.; Colburn, J.S.; Ottusch, John J.; Visher, J.L.; Sievenpiper, Daniel F.

doi:10.1109/tap.2010.2055812

Cited by 684 publications

(472 citation statements)

References 13 publications

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“…In other cases, spatial dispersion can be treated approximately by evaluating the surface impedance for a fixed value of the wavenumber, corresponding to that of a suitable average field. This is a reliable approximation when the field excited by the source is dominated by a given leaky-wave or surface-wave field, as occurs in cylindrical LWAs [28] or holographic [45] antennas, respectively. Finally, the present MoM formulation can be used for the analysis of radially non-uniform metasurfaces, whose locally homogenized surface impedance is a step-wise function of the radial coordinate ρ (e.g., the surface impedance can vary between adjacent slots).…”

Section: Method-of-moments Approach For Truncated Structuresmentioning

confidence: 99%

Omnidirectional Radiation in the Presence of Homogenized Metasurfaces

Ruscio¹,

Burghignoli²,

Baccarelli³

et al. 2015

PIER

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Abstract-Analytical and numerical approaches are presented for modeling the interaction of azimuthally symmetric fields with omnidirectional metasurfaces, based on the use of locally homogenized equivalent sheet impedances. Radially uniform metasurfaces on layered dielectric media are described in terms of a spectral impedance dyadic, thus allowing for the derivation of the field excited by omnidirectional sources through a simple transmission-line model. In a first approximation, the effect of circular edges in laterally truncated structures is taken into account through an efficient physicaloptics method. Then, truncated and radially non-uniform homogenized layered structures are treated numerically with the method of moments, by suitably extending a recently developed spectral-domain formulation. Numerical results are presented for planar radiating structures based on omnidirectional metasurfaces, comparing the radiation patterns obtained through the proposed homogenized models with those calculated by means of full-wave simulations. The discussion emphasizes the validity of the proposed approaches and their usefulness in the analysis of two-dimensional leaky-wave antennas based on printed omnidirectional metasurfaces.

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Section: Method-of-moments Approach For Truncated Structuresmentioning

confidence: 99%

Omnidirectional Radiation in the Presence of Homogenized Metasurfaces

Ruscio¹,

Burghignoli²,

Baccarelli³

et al. 2015

PIER

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“…This choice leads to the formulation presented in [1]. However, this technique does not garentee a perfect match between (7) and (8) because a significant part of the tensor that ensures the exact phase (9) is neglected.…”

Section: Formulationmentioning

confidence: 99%

Implementation of Radiating Aperture Field Distribution Using Tensorial Metasurfaces

Teniou

Roussel

Capet

et al. 2017

IEEE Trans. Antennas Propagat.

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Abstract-This paper deals with the design of tensorial modulated metasurfaces able to implement a general radiating aperture field distribution. A new aperture synthesis approach is introduced, based on local holography and variable impedance modulation. In particular, it is shown that tensorial metasurfaces can be used to generate general radiating distribution (phase and amplitude). In addition, a step by step algorithm is presented. In order to validate the method, several solutions are presented at 20 GHz which implement aperture distributions able to radiate different beams with general polarization.Index Terms-Metasurface antenna, leaky-waves, periodic surface, surface-waves. I. INTRODUCTIONn recent years, metamaterials have become an appealing subject of research. They are synthetic materials that have exotic properties that cannot be found in nature: double negative materials, negative index materials, left-handed materials… Metasurfaces are the equivalent of metamaterials in the case of 2D structures. The properties of these surfaces are described in terms of tensorial or scalar surface impedances (analogous to the constitutive parameters for volumetric metamaterials). Metasurfaces [9], orbital angular momentum communication [10] or transformation optics [11]-[12].All these works are based on the propagation properties of waves over a sinusoidally modulated impedance [13]. By choosing an appropriate modulated surface impedance, it is possible to control the propagation of SW along a surface or to obtain the transition from SW to leaky wave (LW) modes in order to realize antennas [16], [17].Surfaces composed of sub-wavelength printed elements over grounded dielectric slabs were largely used in order to obtain modulated scalar impedances by locally changing the dimensions of the elements [1]- [15]. Symmetric elements are used to produce scalar impedances [1] [19]. However, the direction of the radiating aperture field (or the equivalent surface current) is dictated by the source [19]. This latter aspect limits the number of possible aperture field distributions that can be implemented.Recently, tensorial metasurfaces were successfully used in antenna design that can radiate CP waves [1], [20] and isoflux shaped beam antennas for space applications [20], [21].The additional degrees of freedom offered by tensorial metasurfaces could be used to overcome the limits of scalar solution by generalizing the procedure presented in [19].Our objective is to propose a systematic procedure for the design of metasurface antennas capable of implementing a general aperture field distribution (amplitude, phase and direction). The principal novelty of this approach is the independent control of the generated aperture field components. This important aspect (critical for general aperture implementation), is achieved by introducing independent modulations of the impedance tensorial components and a new exact holographic formulation. Moreover, average impedance variation along the propagation direction is introduced in ord...

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“…This understanding of subwavelength structures can be used to build new types of electromagnetic antennas such as tuneable impedance surface, 2 leaky-wave antenna, 3 and microwave holographic surface. 4 In addition, the concept of artificial impedance surfaces can be applied to acoustics by utilizing acoustic metasurfaces. [5][6][7][8][9][10][11][12] For example, a periodic array of Helmholtz resonators can be used to manipulate the reflection phase of incident sound waves.…”

confidence: 99%

Concentric artificial impedance surface for directional sound beamforming

et al. 2017

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Utilizing acoustic metasurfaces consisting of subwavelength resonant textures, we design an artificial impedance surface by creating a new boundary condition. We demonstrate a circular artificial impedance surface with surface impedance modulation for directional sound beamforming in three-dimensional space. This artificial impedance surface is implemented by revolving two-dimensional Helmholtz resonators with varying internal coiled path. Physically, the textured surface has inductive surface impedance on its inner circular patterns and capacitive surface impedance on its outer circular patterns. Directional receive beamforming can be achieved using an omnidirectional microphone located at the focal point formed by the gradient-impeding surface. In addition, the uniaxial surface impedance patterning inside the circular aperture can be used for steering the direction of the main lobe of the radiation pattern.

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Scalar and Tensor Holographic Artificial Impedance Surfaces

Cited by 684 publications

References 13 publications

Omnidirectional Radiation in the Presence of Homogenized Metasurfaces

Omnidirectional Radiation in the Presence of Homogenized Metasurfaces

Implementation of Radiating Aperture Field Distribution Using Tensorial Metasurfaces

Concentric artificial impedance surface for directional sound beamforming

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