Novel metamaterial insulator for compact array isolation

A single-negative (SNG) metamaterial insulator is designed to reduce coupling between two closely-spaced antennas. The proposed single-negative (SNG) metamaterial-inspired resonator is formed by connective and symmetrical placed spirals to have small size (0.03λ₀×0.14λ₀). The designed SNG structure functions as insulator in certain frequencies to efficiently reduce mutual coupling between two closely-spaced antennas. Nearly 20 dB isolation bandwidth from 2.83 GHz to 3.08 GHz is obtained (8.4% at 2.96 GHz), and it is 7 dB better than the array without the proposed structure. The SNG MTM-resonator is electrically small, therefore, enabling the resultant antenna array to have small separation (λ₀/5 at operating wavelength).