Radiative Deep-Subwavelength Frequency Selective Surface-Based Cross-Band Decoupling Method for Base Station Antenna

To address the bandwidth limitations encountered by existing decoupling methods during the global integration process of base station antennas, a radiative deep-subwavelength frequency selective surface (RFSS)-based cross-band decoupling method is proposed. The RFSS is formed by a deep-subwavelength FSS whose external profile is defined by a well-optimized narrow frame. It is implemented to not only be transparent for high-band (HB) electromagnetic waves, but also effectively radiates low-band (LB) ones. To validate this concept, a dual-band base station antenna which comprises an RFSS-based LB antenna and a 2×2 HB sub-array is proposed. Furthermore, we conduct a detailed analysis of the operational mechanism underlying the proposed RFSS-based LB antenna. In addition, a proof-of-concept prototype is fabricated and measured. The results demonstrate that the LB antenna operates within a relatively wideband of 1.4-2.7GHz (63.4%), featuring a low profile of 0.25λ_lc (at the center frequency of LB), and the HB antenna operates at 3.3-4.2GHz (24%).