A 2.5D Broadband Non-Reciprocal Metasurface Based on Aperture-Coupled Feed Structures

Abstract

In traditional non-reciprocal metasurfaces based on antenna-circuit-antenna structure, the radiation module and the non-reciprocal circuit module are coplanar, which occupies extra surface area and has the inherent defect of narrow operating bandwidth. Therefore, a new 2.5D non-reciprocal metasurface based on the aperture coupling structure is proposed to realize the separate design and broad operating bandwidth, in which the non-reciprocal circuit module is perpendicular to the radiation module. In addition, this work improves isolation to over 35 dB without affecting the radiation mode and resonance frequency. Based on multimode resonance theory, a broadband microstrip antenna is further presented to obtain a broader operating bandwidth. By exciting multiple resonant modes with similar frequencies in the resonant cavity, the relative bandwidth reaches up to 38.2%. The experimental results coincide well with the simulation results, which fully demonstrate the validity of the proposed design.