Wideband High-Gain Circularly Polarized Antenna Using Artificial Anisotropic Polarizer

A novel wideband high-gain circularly polarized (CP) antenna is proposed and investigated for the 60 GHz high-throughput communication and the 77 GHz automobile radar system. The design consists of a rectangular horn, a hyperbolic lens, and an artificial anisotropic polarizer. To minimize the thickness of the polarizer, the properties of the artificial anisotropic material (AAM) for generating CP wave are discussed analytically. Minimal polarizer thickness and the corresponding component ratio are provided mathematically. In comparison with other approaches, the proposed design achieves a relatively high-gain and wideband performance with a minimal thickness. The antenna exhibits a wide impedance bandwidth of more than 39% (VSWR < 2) from 55 to 82 GHz and a wide axial ratio (AR) bandwidth of more than 32% (AR < 3 dB) from 56 to 77 GHz. The average gain is 17 dBic. Good unidirectional radiation characteristics are achieved with low fabrication cost. In addition, the off-body lens and the polarizer could be directly migrated to other radiating sources with the concrete analytical guidance for polarizer design.