A 20/30GHz Dualband Dual Circularly Polarized Folded Transmitarray Antenna for Satellite Communications

A design of 20/30GHz high-gain circularly polarized folded transmitarray antenna (CPFTA) is presented in this paper for satellite communications systems. The dualband antenna mainly consists of a polarization-sensitive frequency selective surface (FSS) as the subreflector, a printed reflectarray as the main reflector and a double-ridged waveguide horn antenna as the wideband feed antenna. Based on antenna-filter-antenna (AFA) technology, the polarization-sensitive FSS is realized with linearly-polarized antennas as receive antennas, circularly-polarized antennas as transmit antennas and through-hole vias as its connecting circuits. Phase compensation to obtain a broadside radiation beam can be done by adjusting the proper angular rotation of the upper circularly polarized antenna at the dualband frequencies. The printed reflectarray that is composed of crossed dipole array made on a single-layer substrate is used to achieve 90degree polarization rotation at the center frequencies of around 20 and 30GHz. Simulated results also show that the proposed dualband CPFTA can realize the 3-dB gain bandwidth of 7.6% and 3.5% for the lower and upper band, respectively. Besides, wide 3db axial ratio (AR) bandwidths have been obtained at the dualband frequencies. The antenna gains are 23.7 and 25.9dBic with the high aperture efficiency of 33.4% and 21% at 20 and 29.5GHz, respectively.