Isolation Improvement and Bandwidth Enhancement of Dual-Band MIMO Antenna Based on Metamaterial Wall

A new method of isolation improvement and bandwidth enhancement for the dual-band multiple-input–multiple-ouput (MIMO) antenna based on a metamaterial wall is proposed. The proposed antenna consists of a 2 × 1 dual-band antenna and a metal-line-based metamaterial wall (MLB-MW). On the one hand, the isolation improvement is achieved by the mu-negative metamaterial (MNG) characteristic of the MLB-MW. The isolation improved by 36 dB after loading the MLB-MW. On the other hand, the bandwidth enhancement is obtained by generating additional resonance by the MLB-MW. The operating bandwidths (|S₁₁| < −10 dB) have been increased from 3.54 GHz to 4.01 GHz and 4.72 GHz to 5.08 GHz to 3.41 GHz to 4.02 GHz and 4.67 GHz to 5.14 GHz, resulting in the bandwidth extensions of 32% and 30%, respectively. The dimension of the MIMO antenna is 0.70λ_L×0.29λ_L×0.23λ_L (λ_L is the wavelength of the lowest frequency). To validate the results, a prototype was fabricated and measured in an anechoic chamber, and the results show that the proposed antenna can be a candidate for 5G base station applications.