Broadband Radiation Pattern Restoration of Self-Decoupled Metasurface Antenna by Balancing Common and Differential Modes

Non-uniform metasurface (MTS) antenna fed by an anti-TE20 slot is proposed to achieve broadband radiation pattern isolation by balancing common and differential modes. Based on characteristic mode analysis, the distorted active element pattern in a multi-antenna system is restored back to the isolated element pattern of a single antenna by maintaining common/differential modes balance and suppressing higher-order modes over a wide bandwidth using non-uniformly patterned MTSs. The distorted radiation pattern of a 1×2 MTS antenna system, as an example, is restored over a decoupling bandwidth of 28.6% from 3.14 to 4.19 GHz with port coupling below −25 dB, where the two antennas are spaced with an edge-to-edge spacing of 0.012 λ<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> in the H-planes. Furthermore, a 1×3 antenna system achieves corrected radiation patterns with consistent beam directions and half-power beamwidths of edge and center elements, suggesting that the proposed technique is valid for large-scale systems.