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

Abstract

This paper investigates a simple method based on the metasurface concept to suppress the mutual-coupling between the radiation parts of a 2 × 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 #1&#2, #1&#3, #1&#4, 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 × 2 array-antennas with compact dimensions of 40 $$\times $$ 40 $$\times $$ 0.8 mm3 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.