Circularly Polarized Transmitarray Antennas at Ka-Band

This letter presents the simulation, optimization, and demonstration of a collimated-beam transmitarray and a quad-beam transmitarray operating at Ka-band. Both transmitarrays are based on a 3 bit unit cell implementing both phase-shift and linear-to-circular polarization conversion functions. The collimated-beam transmitarray presents a measured gain of 33.8 dBi (corresponding to an aperture efficiency of 51.2%) and a 3 dB gain bandwidth larger than 15.9%. The quad-beam transmitarray phase distribution has been optimized by a genetic algorithm code coupled with an analytical tool. The array is designed to radiate four beams at θ
₀
= ± 25° in the horizontal and vertical planes at the frequency of optimization.