Low-Profile Polarization-Twisting Cassegrain Antenna for Generating Dual Circularly Polarized Multibeam Radiation in Ku-Band

Abstract

In this paper, a low-profile polarization-twisting Cassegrain antenna (LPPTCA) is proposed to generate dual circularly polarized (CP) multi-beam radiation by integrating multifunctional metasurface (MM), polarization conversion metasurface (PCM), and multiple microstrip feeds. Considering that the LPPTCA removes the occlusion effect from the traditional Cassegrain antenna, the profile height of LPPTCA will be chosen as 1/3 focal length of PCM and can also be freely adjusted when employing corresponding phase gradient over the MM to mimic the hyperbolic reflector of the traditional Cassegrain antenna. The MM is capable of achieving the functionality of reflecting co-LP waves with performing diverged wave-fronts and transmitting cross-LP waves with linear-to-dual-circular polarization conversion. Based on the MM and PCM, the LPPTCA is designed and fabricated, then measurement results illustrate that the LPPTCA is capable of realizing dual CP multi-beam radiation in the range of 13.7 - 14.7 GHz when employing multiple microstrip antennas as feeds. In the meanwhile, the scanning range of multi-beams is ±20° with the minimum feed isolation of 15 dB. The proposed dual CP multi-beam LPPTCA integrating the MM and PCM should thus pave the way for building up current and future wireless communication systems with millimeter-wave MIMO applications in Ku-band.