Simultaneous Suppression of Cross-Band Scattering and Coupling Between Closely Spaced Dual-Band Dual-Polarized Antennas

When two antennas working in different frequency bands are placed in proximity, they suffer from strong cross-band interactions that degrade their radiation performance and reduce the isolation between them. This paper presents holistic methods to simultaneously suppress cross-band scattering and coupling. Specifically, we develop a systematic solution to suppress the scattering of low-band (LB) antennas to high-band (HB) radiation as well as the scattering of HB antennas to LB radiation using three new techniques. This leads to much reduced cross-band coupling between the LB and HB antennas. The proposed methods are applied to a "1 LB + 1 HB" dual-band array configuration with only one LB cross-dipole and one HB cross-dipole placed side-by-side to exclude the effects of the array topology. The robustness of the proposed methods is comprehensively verified for different scenarios by simulations and experiments. Furthermore, the methods are evaluated in a "1 LB + 4 HB" array configuration. In addition to effectively suppressing cross-band scattering and coupling, the proposed methods also demonstrated a significant reduction in in-band coupling between adjacent HB antennas.