Wideband Slot Array Antenna Fed by Gap Waveguide with Right-Handed Circular Polarization and High Gain

Abstract

A wideband and high-gain circularly polarized (CP) 16 × 16 array antenna based on gap waveguide technology is presented for millimeter-wave applications at 28 GHz frequency range. Four cavity-backed slots with linear polarized (LP) radiation are used as the subarray. CP is obtained by a 4 × 4 sequential feeding network which is also expanded to achieve high gain. The feeding network of the final array antenna consists of two layers based on the ridge gap waveguide (RGW), and it has four unconnected metal layers. It is shown by simulation that the proposed antenna has 20.5% impedance bandwidth over 25.8-31.7 GHz and 3 dB axial ratio bandwidth near 10% over 27.2-30 GHz. In addition, the maximum gain value for this antenna is 31.6 dBi at a frequency of 29 GHz, which shows good performance compared to other structures.