Compact Dual-Polarized Antenna for Dual-Band Full-Duplex Base Station Applications

A compact single-radiator microstrip patch antenna with highly integrated duplexing and filtering functions is proposed for dual-band dual-polarized (DBDP) base-station applications, and the center frequency ratio of the upper and the lower operation band is just 1.14. The single radiation patch with four high isolation channels is oriented along the 45° diagonal of the ground plane to achieve the ±45° dual linearly polarizations (LP) at each of the two operation bands. For each polarization, the dual-band full-duplex characteristic is obtained by conceiving the strong mutual coupling between the combined resonator and the radiation path, and the mutual coupling then couples to two groups of resonator-based channels with different working frequencies. Therefore, high channel isolation is achieved, without resorting extra decoupling structures. Moreover, the mutual coupling of each resonator-based channel can help to improve its corresponding operation band and produce the third-order filtering feature, leading to enhancement of the full-duplex characteristic for the proposed antenna. Such a single-patch four-port DBDP antenna could significantly reduce the complexity and volume of the RF frontend of the base station. The removal of the bandpass filters and duplexers in the design could also reduce the potential cost of the RF frontend. The measured results agree well with the simulations, showing an excellent performance in terms of bandwidths, channel isolations, polarization isolations, radiation patterns, and gains.