A Wideband Sub-Wavelength-Thick Circularly Polarized Discrete Lens Using Dielectric-coated Polarization-Twisting ME-Dipole Elements

This letter presents a circularly polarized (CP) discrete lens with large operating bandwidth and optimized thickness. A wideband polarization-twisting unit cell, which enables polarization agility of the lens at pixel level, is developed using the magneto-electric (ME) 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-λ₀-thick, 256-element discrete lens.