High-Efficiency Dual-Polarized Patch Antenna Array with Common Waveguide Feed

A concept for a dual-polarized patch antenna array with large bandwidth and high efficiency is proposed. A short overmoded waveguide section is connected to a square feed waveguide on one side, and to the common groundplane of a 2x2 or a 3x3 patch array on the other side. Each square-shaped patch is coupled to the waveguide by crossed slots in the groundplane. The coupled resonances of the patch and the slot result in large impedance bandwidth (at -10 dB) of more than 20%. Prototypes are realized at X band. At 9 GHz, the 2x2 array has a measured gain of 13.6 dBi, whereas the 3x3 array shows 15.2 dBi gain. Simulated efficiency of the 3x3 array is 98.5%.