A Wideband Subwavelength-Thick Circularly Polarized Discrete Lens Using Dielectric-Coated Polarization-Twisting ME-Dipole Elements

Abstract

This letter presents a circularly polarized (CP) discrete lens with large operating bandwidth and optimized thickness. A wideband polarization-twisting unit cell, which enables the polarization agility of the lens at a pixel level, is developed using the magnetoelectric-dipole-based transmissive element. By comprehensively utilizing the rotation freedom of the probes at the transmitting and the receiving layers as well as incorporating additional dielectric-coating layer, an over-2-bit CP discrete lens is achieved, demonstrating a wide axial ratio (AR) bandwidth, an improved antenna gain, and a well-controlled lens thickness. A maximum gain of 21.5 dBic and an overlapped 3 dB gain and AR bandwidth of 47% are experimentally achieved with the designed 0.66-λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> -thick, 256-element discrete lens.