A Low-Cost Differentially Driven Dual-Polarized Patch Antenna by Using Open-Loop Resonators

A novel differentially driven dual-polarized patch antenna is presented in this communication. The proposed antenna is a low-cost design with a simple configuration, which avoids using the conventional high-cost multilayer PCB technology. The antenna is composed of two intersected open-loop resonators, which are connected to each other at the center. By using the electric coupling from the intersected resonators, two orthogonal radiating modes are excited from the top radiating patch. With the even- and odd-mode current distributions on the intersected resonators, high port isolation and low cross-polarization level are obtained. The external quality factor of the resonator is illustrated by using the analytical model of a double-loaded resonator. To demonstrate the design method, the proposed antenna and array are designed, fabricated, and measured. Compared to the traditionally designed capacitively coupled antenna, two times wider impedance bandwidth is obtained for the proposed antenna with high isolation (>38.5 dB) and low cross-polarization level (<; -33 dB). The antenna array is designed for 5G base stations, which features the compact size and low reflection coefficient (<; -15 dB). In addition, beam scanning performance of the antenna array is also investigated for base-station applications.