A High-Gain Aperture-Shared Dual-Band Circularly Polarized Antenna Using Polarizer Integrated Dual-Functional Surface

An aperture-shared dual-band circularly polarized (CP) antenna is proposed. It is the first attempt to propose a polarizer integrated dual-functional surface (PIDFS), enabling the co-designing of a CP reflectarray (RA) and a CP Fabry-Perot cavity (FPC) antenna while keeping wideband and high-gain performances. The proposed work divides a traditional polarizer into two distinct parts with a dual-function reflective surface sandwiched in between. The proposed PIDFS provides wave reflection with polarization rotation at higher-frequency band, contributing to the realization of a millimeter-wave (mm-wave) CP RA. At the same time, it also functions as CP partially reflective surface (PRS) for a high-gain FPC antenna designed at lower-frequency spectrum. For validation, a prototype of the aperture-shared dual-band CP antenna operating at 7 and 30 GHz bands is designed, fabricated, and measured. The 3-dB gain bandwidths of 14% and 26% with peak gains of 17.3 and 20.5 dBic over two bands are achieved, respectively. The proposed design demonstrates a new design method/scheme to construct a high-gain, aperture-shared antenna with large frequency ratio, superior bandwidth, and CP radiation characteristics. With these, it is a good candidate for future communications system that requires high integration, wideband, and high-CP-gain.