Differentially-Fed, Multi-Band Dual-Polarized Filtering Patch Antenna without Extra Circuits

In this paper, a multi-band patch antenna with bandpass filtering response is proposed. The antenna consists of two pairs of crossed dipoles, four F-shaped feedlines, and four steeped-impedance microstrip lines. With the introduction of F-shaped feedlines and U-shaped slots on the radiating patch, extra radiation nulls are induced, and four operation bands with band-pass filtering response are obtained. More importantly, the filtering response of the antenna is generated without any filtering circuits, which is easy to design for antenna engineers. Measured results of the prototype show that the proposed antenna has stable radiation patterns with low cross-polarization level of better than -26 dBi over the four operation bands. Good filtering response with deep roll-off can also be observed between different operation bands. Excellent radiating performances make it a promising candidate for 5G wireless communication systems.