Substrate Integrated Waveguide-Based Dual-Polarized Self-Diplexing Antenna Array

Substrate Integrated Waveguide (SIW) cavity backed self-diplexing slot antenna array is proposed with dual-polarized capability. The antenna array is composed of four linearly placed full-duplex elements operating at 3.5 and 4 GHz independently. The antennas are designed inside a Half Mode SIW (HMSIW) cavity, and two capacitive slots adjust the resonant frequencies. Furthermore, two 1 by 4 power dividers all including 50-ohm transmission lines are designed to feed the radiators, thus resulting in a single layer antenna array integrated with feeding networks. Upon evaluating the simulated and measured results, the minimum reflection coefficients of −25 dB were observed at both operating frequencies. In addition, the data showed that the suggested structure brings about a high isolation level of more than 23 dB between two bands. It is also worth expressing that maximum gains of 10 and 11.5 dBi are obtained at 3.5 and 4 GHz, respectively. And, the radiation efficiencies are 0.78 and 0.9 for the low and high frequency bands.