Isolation and gain enhancement of patch antennas using EMNZ superstrate

A system comprising of multiple antennas demonstrate performance degradation due to the adverse effects of mutual coupling. This work describes an isolation enhancement technique using an Epsilon-And-Mu-Near-Zero (EMNZ) metamaterial as superstrate. The method is demonstrated for closely packed H-plane microstrip patch antennas. The EMNZ superstrate is placed at a height of 10 mm (equivalent to λ0/12) above the antennas which have an edge to edge separation of 4 mm (equivalent to λ0/30). The EMNZ superstrate enhances the isolation to −30 dB at the resonant frequency. At the same time metamaterial demonstrates NZRI (near zero refractive index) properties due to which the directivity of the antennas is enhanced. Additionally, the generation of cavity effect due to the placement of the superstrate leads to an increase in the gain and efficiency of the antenna by 3.4 dBi and 20% respectively. The overall design is very compact and can be easily incorporated in a multi antenna system.