Switchable Slant Polarization Filtering Antenna Using Two Inverted Resonator Structures for 5G Application

This study presents a novel design of two filtering antennas with a +45° and -45° slant polarization, using the co-design of a third-order filter and a rectangular patch antenna. Slant polarization is obtained by directing the surface current that flows to the radiator by applying two parallel inverted resonators in the transmission line. The resonators consist of two parallel strips with alternate open and short circuits at each end and the 45° and -45° polarization is determined from these short circuit positions. The rectangular patch antenna is fed using proximity coupling, and it is parallel to the resonators. The filtering antennas provide not only 45° slant polarization, a flat gain response but also a controllable bandwidth. Operating at 4.65 GHz for 5G application, the antennas have a controllable bandwidth range from 5.9% to 8.4% without affecting the polarization and center frequency. The gain responses are filter like and attain the maximum value of 6.82 and 6.69 dBi at 4.7 GHz. This design needs no extra component or rotation of the radiator and transmission line because the inverted resonators can switch the polarization to be +45° and -45°. The results of the 45° and -45° polarization filtering antenna simulation and experiments are consistent with each other.