Mode Conversion for Broadband Mutual Coupling Suppression of a Slot-Fed Metasurface Mosaic Antenna

A method of mode conversion from the anti-TE20 mode to TE20 mode is proposed to suppress the H-plane mutual coupling of slot-fed metasurface mosaic antennas over a broad bandwidth. The proposed method is first studied using a pair of side-by-side slot antennas arranged in their H-planes. The investigation reveals that when the excited microstrip-fed slot antenna is operating at an anti-TE20 mode, the coupled microstrip-fed slot antenna undergoes a mode conversion to a TE20 mode due to the boundary conditions of the slot. As a result, the pair of slot antennas achieves high self-decoupling. Then, a pair of side-by-side microstrip-slot-fed metasurface mosaic antennas operating at the anti-TE20 mode is further presented. With the mode conversion, the 1 x 2 mosaic antenna system with optimized metasurfaces achieves the H-plane port isolation of more than 25 dB over a broad bandwidth of 18.9% or a range from 3.20 to 3.88 GHz with an edge-to-edge spacing of 0.012 wavelength at 3.6 GHz. The proposed decoupling method has the potential for performance enhancement of multiple and beamforming antenna systems.