High Gain and Dual Circularly Polarized SIW Slotted Antenna

A dual circularly polarized (CP) substrate integrated waveguide (SIW) slotted antenna is proposed. The antenna is composed of a CP SIW slotted antenna and a big reflected ground (Gnd.). The CP is realized by bending a straight SIW to a circular shape. The Gnd. is set at the bottom of the antenna with a quarter wavelength distance, which will improve the antenna gain with about 2 dB. Left-handed circular polarization (LHCP) and righthanded circular polarization (RHCP) can be achieved by feeding 2 different ports. The proposed antenna has good performance. The -10 dB impendence band is 9.6~10.5 GHz. The 3 dB axial ratio band is 9.6~10.1 GHz where the average realized gains are around 10 dB.