A Decoupling Method for Tightly Coupled Dual-Polarized Filtenna with Restored Radiation Patterns

Aiming at the fact that a single decoupling method cannot address all types of coupling at the same time, this paper presents a decoupling method that can be used for tightly coupled dual-polarized filtenna arrays. The method employs partially reflective surfaces (PRSs) and semi-transmissive non-resonant square ring baffles to achieve the suppression of co-polarization and cross-polarization couplings, respectively. They are both composed of a periodic arrangement of sub-units printed with simple metal strips, and good decoupling can be achieved without careful design. In order to verify the decoupling effect of this method in the filtenna, <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$1\times 3$</tex> dual-polarized array antennas with a close distance of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$0.37\lambda_{0}$</tex> are implemented. The simulation results show that the isolation of the co-polarization and cross-polarization ports improves from 12 dB and 10 dB, respectively, to more than 18 dB, while the return loss in the antenna's operating band remains below −10 dB. Compared with the reference array without decoupling measures, the radiation pattern of the array has no distortion, and the cross-polarization ratio in the boresight direction is improved by more than 9.3 dB, achieving the restoration of radiation patterns and the enhancement of peakrealized gain. The above results indicate that the decoupling method has a promising application in BSG/6G massive MIMO tightly coupled arrays.