Low-profile antennas with 100% aperture efficiency based on cavity-excited omega-type biansiotropic metasurfaces

Abstract

We propose a novel concept for highly-directive lowprofile antennas, based on a single localized source embedded in a cavity, covered by an omega-type bianistoropic metasurface (BMS). We show that such metasurfaces, which include subwavelength particles with electric and magnetic polarizabilities, and magnetoelectric coupling, allow control of both the aperture field phase and the BMS reflection coefficient, without requiring active or lossy components. Subsequently, we use this degree of freedom to exclusively excite the highest-order fast lateral mode, guaranteeing optimal aperture illumination efficiency for arbitrarily-large apertures, without incurring edge-taper losses. We verify our semianalytical calculations with full-wave simulations, showing that the proposed antenna can outperform our previously-introduced cavity-excited Huygens' metasurface antenna, offering a simple and efficient design for compact highgain antennas.

Arbitrary Power-Conserving Field Transformations With Passive Lossless Omega-Type Bianisotropic Metasurfaces

“…Consequently, the source position is set such that β 7 (z + d) = π, guaranteeing that the terms corresponding to the 7th mode will vanish in (20) due to destructive interference between the source and its image; specifically, z = −0.267λ. To reduce the quality factor of the cavity as much as possible, we set the reflection coefficient of the (2N − 1)th mode (22) to Γ 2N −1 = 0 (a higher value was explored in [48]). This fixes the last degree of freedom in the design, and the required O-BMS constituents can be evaluated by substituting (23) and (25), with (26) and the prescribed values of d, z , and Γ 2N −1 , into (5).…”

A Rigorous Approach to Designing Reflectarrays

“…Another application of metasurfaces is in enhanced antenna design. For example, in [53], [111], [112], a metasurface antenna is designed to achieve perfect (100%) aperture efficiency. In [49], the metasurface antenna consists of a patterned metallic cladding supported by a grounded dielectric substrate and fed by an infinite electric line source placed within the substrate, as seen in Fig.…”