Dual-Band Dual-Circularly Polarized Shared-Aperture mmWave Antenna

In this paper, a substrate integration waveguide (SIW) dual-band dual-circularly polarized (CP) antenna is proposed. The antenna is composed of three components i.e., low-frequency feed structure, SIW cavity, and polarization converter. In the high-frequency band, the TM010 mode of the SIW cylindrical cavity is excited by a probe. A slot is etched on the top of the SIW cavity and the linear-circular polarization converter is top-loaded to generate right-handed circularly polarized (RHCP) radiation. In the low-frequency band, the SIW cavity operates as a circular patch. The patch is excited by two branches of the Y-shaped slot to generate left-handed circularly polarized (LHCP) radiation. The simulated results show that the proposed antenna obtains −10 dB impedance bandwidths of 18.65-21.15 GHz and 30.1-31.3 GHz. The 3 dB axial ratio (AR) bandwidths are 18.85-21.15 GHz and 29.8-31.8 GHz with the peak gains of 6 dBi and 3 dBi at the corresponding bandwidths. The isolations of input ports are better than 34 dB and 20 dB, for the dual operating frequencies, respectively.