A Ka-band Beam-Steering Transmitarray Achieving Dual-Circular Polarization

This contribution describes a versatile and technologically simple approach for the design of polarization-agile beam-steering transmitarray antennas. The array interleaves two types of electronically reconfigurable unit cells which receive the same linear polarization but radiate horizontally and vertically polarized waves, respectively. The phase shift introduced by each cell can be varied with a resolution of about 90° (2-bit phase quantization) controlling the bias state of two pairs of p-i-n diodes. Dual-circular polarization can be obtained by enforcing the proper phase shift among orthogonally polarized cells. As a proof of concept, a 24×24 transmitarray for Ka-band satellite communications is designed and tested. The experimental results demonstrate beam-steering up to 60° and polarization switching capability. For broadside radiation, an axial ratio lower than 1 dB is measured over the entire operating band (29.5-31 GHz).