Cross-Band Decoupling Method for Dual-Band Aperture-Shared Antenna Array Using Metasurfaces

One method of using a metasurface to reduce the cross-band mutual interference of the dual-band aperture-shared antenna array is proposed. A base-station dual-band antenna array is designed to validate the method and is composed of a lower-band (LB) antenna element,
$2\times2$
higher-band (HB) antenna elements, and a metasurface. The metasurface exhibits the bandstop characteristic in the HB and cancels the HB radiation from the LB antenna. Meanwhile, the metasurface absorbs part of the HB electromagnetic wave from the LB antenna. As a result, the mutual coupling between the LB and HB antennas is suppressed substantially. The metasurface causes little loss for the LB antenna. The dual-band aperture-shared antenna array covers the bands of 1.7–2.7 GHz (45.5%) and 3.3–3.8 GHz (14.1%). The simulated and measured results show that the proposed array has high port-to-port isolation, wide bandwidth, and stable radiation patterns in both the LB and HB.