Differentially-Fed, Wideband Dual-Polarized Filtering Antenna With Novel Feeding Structure for 5G Sub-6 GHz Base Station Applications

In this paper, a differentially fed, wideband dual-polarized patch antenna with filtering response is proposed. A novel E-shaped feeding structure with one end shorted to the ground is proposed to excite a square patch antenna, and an extra resonant mode is induced, which leads to a wider operation band. Besides, symmetric open/short-circuited stepped impedance resonators (O/SCSIRs) are proposed to generate the third resonant mode. And the bandwidth is further improved. Moreover, the gain-suppression level outside the operation bands is greatly enhanced as the introduction of O/SCSIRs. A prototype of the proposed antenna is fabricated and tested. Measured results show that the proposed antenna has a wide operation band of 22.2% (3.12-3.9 GHz) for active VSWR <; 1.5. Stable in-band gains of 8.1 ± 0.3 dBi and unidirectional radiation patterns are also obtained. Moreover, the out-of-band gain suppression level is better than 18.5 dB. A 1 × 4 liner array is also developed to validate our design. Good radiating performance of the proposed antenna makes it a promising candidate for 5G Sub-6 GHz base station applications.