Low-Profile Polarization-Adjustable Ring Slot Antenna for Millimeterwave Applications

In this paper, a dual-port antenna with polarization adjustability is proposed for millimeter-wave applications. The loading effect of four ring slots stimulates a hybrid mode in the cylindrical cavity that generates eight magnetic monopoles with high gain in boresight. Through controlling the phase difference between the two ports, six types of polarization can be demonstrated. Simulation results in 28 GHz show a maximum gain of 13 dBi, 10% bandwidth, and a good cross-polarization level in all polarization states. Distinct features including low-profile, low-cost, single-layer, and simple feeding network make the antenna a suitable candidate for upcoming millimeter-wave and 5G applications.