Differential-Fed Patch Antenna Arrays With Low Cross Polarization and Wide Bandwidths

In this letter, two differential-fed Ku-band 2 x 2 patch antenna arrays with low cross polarization and wide bandwidths were developed using multilayer printed circuit board (PCB) technology. The patch elements in Design I were fed differentially, whereas the patches in Design II were single-ended. However, Design II is differential if the array is considered as a whole. The experimental demonstration revealed that Design I achieved a 10-dB impedance bandwidth of 15.3%. The measured gain was 10.41 dBi at 12.62 GHz with low cross polarization of -17.5 dB in the E-plane and -20.2 dB in the H-plane. Design II exhibited a 10-dB impedance bandwidth of 12.8%. The measured gain was 12.32 dBi at 13 GHz with cross polarization of -17.7 and -17 dB in the E-plane and H-plane, respectively. Design II achieves performance levels similar to that of Design I, but comprises a simple and compact feed network.