High Port-to-Port Isolation Dual-Polarized Antenna Array Dedicated for Full-Duplex Base Stations

This letter discusses the design of a dual-polarized four-element linear antenna array with increased port-to-port isolation, intended for base stations of single-channel full-duplex systems. The antenna is designed for the U-NII 5.15-5.925 GHz frequency band and is characterized by port-to-port isolation higher than 57 dB and cross polarization better than -27 dB within the mainlobe. An electromagnetically coupled microstrip antenna is used as a single element of the antenna array. Enhanced isolation is obtained owing to the multilayer antenna structure and special feeding network utilizing the pairwise antiphased feeding technique combined with a careful selection of phase-shifters and power dividers. The antenna parameters are optimized with the use of full-wave simulations, while the scattering parameters and radiation characteristics are verified by measurements.