Circularly Polarized Metasurface Superstrate Slot Antenna Array Fed by PRGW

We present a wideband circularly-polarized 2-by-2 slot antenna array for X-band applications. The feeding network of the antenna is designed using printed ridge gap waveguide (PRGW) technology as a magnetic ground to suppress surface wave propagation and excite a quasi-TEM wave in the air along the ridge. Then, a single layer linear-to-circular polarization converter metasurface is designed and placed on top of the slot antenna array. The unit-cell of the converter contains two identical metallic layers with a combination of a connected Jerusalem cross (JC) and two parasitically coupled LC resonators. The antenna has a compact structure with a low profile, a -10-dB impedance bandwidth of 26% from 8.6 to 11.2 GHz, a 3-dB axial ratio bandwidth of 14% from 9.3 to 10.7 GHz, and an average gain of 13 dBi.