two-ports siw array antenna with circular polarization for 5g base station

The demand for mobile communication systems with high data rate has drawn attention to the millimeter-wave frequencies to increases the channel capacity compared to current 4g cellular networks. so, the fifth generation (5g) mobile communications is presented which is to work in mm-wave frequency band to improve data rate, capacity and latency. one of the challenges of 5g application is the base station and mobile antennas which should be robust against fading. therefore, in this paper, a two port substrate integrated waveguide (siw) slot base station antenna for 5g application at 28 ghz is presented. the realized gain of the two-port antenna with a high isolation (20 db) and circular polarization is 6.35 dbi. the 5-element array of the two-port antenna with the same excitation can increase the gain 8 db, but it has some nulls. with phase shift for excitation ports, the nulls are cancelled