Low-Interacted Multiple Antenna Systems Based on Metasurface-Inspired Isolation Approach for MIMO Applications

This paper investigates a simple method based on the metasurface concept to suppress the mutual-coupling between the radiation parts of a 2 x 2 antenna-arrays. The array-antennas have constructed of four circular-patches implemented on the FR-4 substrate, so each patch has separately excited by a waveguide-port. The proposed decoupling-approach inspired the metasurface principle has applied by realizing the rectangular-slots in a linear and series configuration incorporated between the antennas to decrease their interaction and reduce the surface-waves. The proposed slots act like series left-handed capacitors. To achieve more isolation, the metallic via-holes have employed between the rectangular-slots across the substrate-layer, which has caused to suppress the substrate-losses. The via-holes behave like shunt left-handed inductors. By incorporating series slots and via-holes, the metasurafce-inspired decoupling-slab has realized without increasing the physical dimensions. The results show that by the proposed method the substrate-loses, surface-waves, and interaction between the radiation elements have significantly diminished and as resultant the array's performances such as impedance bandwidth, fractional bandwidth, impedance matching, isolation between antennas radiation gain, and efficiency have improved by 2.1 GHz, 21.2%, 4 dB, 12 dB, 16 dB, 13 dB, 3.2 dBi, and 23%, respectively, which exhibit the effectiveness of the proposed metasurface-based isolation-slab. The fabricated proposed 2 x 2 array-antennas with compact dimensions of 40 x 40 x0.8 mm(3) and edge-to-edge distance between the radiation components of 0.16 lambda(0) operates over approximately entire X-band spectrum of 8.2-12 GHz, which corresponds to 37.62% practical bandwidth. The array antennas exhibit an average efficiency and gain of 76% and 8.5dBi, which enable it to be applicable for MIMO systems.