Dual-circularly polarized flat-top-beam transmitarray antenna with flexible energy allocations.

To fulfill the continuously developing requirements of satellite communications and radar detection, this paper demonstrates a theoretical and experimental investigation of dual-circularly polarized (CP) transmitarray antennas (TAs) capable of generating spin-decoupled flat-top beams with customized gain differences. The constituent element for the transmitarray is a high-efficiency receiver-transmitter structure composed of a CP receiving antenna and a polarization-adjustable transmitting antenna. By rotating these two antennas jointly and modifying dimensions of transmitting patch, independent phase shifts and flexible energy allocations can be imparted to dual-CP transmitting waves, respectively. Then, a circular array is implemented by using the proposed element, specifically, a modified intersection approach is employed to synthesis a fan-shaped and a circular-shaped flat-top beam for the left-handed CP (LHCP) and right-handed CP (RHCP) channels, respectively. Three TAs, achieving -6, 0, 6 dB realized gain differences between the fan-shaped and circular-shaped beams, are separately implemented and verified through full-wave simulations, while the 6 dB-case TA is also fabricated, assembled and validated through experimental tests. All the simulated and measured results verify the high-quality flat-top beam, tailorable energy allocation and wide-angle beam-scanning properties for the dual-CP TAs.