A Novel Coupling Suppression Method Based on D-CM Path Synergy for Dual-Band Shared-Aperture Base Station Antenna Design

A novel coupling suppression method, namely Differential-Common Mode Path Synergy (D-CMPS) technique, is proposed for shared-aperture dual-band base station antennas. The D-CMPS method employs two key strategies: Elimination of Reverse-Flow Current Radiation and Mitigation of In-Phase Current Radiation. The strategies guide high-band (HB) induced currents into precisely engineered differential mode (DM) and common mode (CM) paths that are deliberately integrated within the low-band (LB) antenna structure. This approach provides an innovative perspective for effectively mitigating cross-band coupling. Specifically, the HB-induced currents generated by illumination from the HB antenna are strategically redirected and confined within the DM and CM paths. Through the synergistic interaction of the DM and CM pathways, coupling from the LB antenna onto the HB antenna is significantly reduced, ensuring that the HB antenna’s radiation patterns remain undistorted. Meanwhile, the additional DM and CM paths have negligible impact on the LB antenna’s inherent performance. To experimentally validate this concept, a shared-aperture dual-band antenna array incorporating the Differential-Common Mode Path (D-CMP) structure was designed, fabricated, and measured. The results demonstrate that, compared to existing the coupling-suppression techniques, D-CMPS approach not only achieves robust suppression of cross-band coupling but also streamlines the design and fabrication process, thereby reducing manufacturing costs.