High-Gain Low Cross-Polarized Dual-Polarized Filtering Patch Antenna Without Extra Circuits

This letter presents a dual-polarized filtering patch antenna with high gain, low cross-polarization, and without extra filtering circuits. By etching the slots on the patch, a radiation null at the upper band edge is generated, while introducing an extra resonant mode to broaden the impedance bandwidth. In addition, four shorting pins are symmetrically loaded on the patch, which provides a radiation null at the lower band edge and the enhanced gain. Moreover, the cross-polarization level is reduced by adopting the symmetrical structure and a differential feeding scheme. For verification, a filtering antenna operating at 5G n77 band (3.3-4.2 GHz) is designed and fabricated. The measured 10 dB bandwidth is 29.7% (3.15-4.25 GHz) with a peak gain of 9.5 dBi, a cross-polarization level of less than -32 dB and an isolation of higher than 34 dB. The out-of-band suppression levels are more than 34 and 16 dB within the lower stopband (1-2.52 GHz) and the upper stopband (4.6-6.5 GHz), respectively.