Enhancement of gain and directivity for microstrip antenna using negative permeability metamaterial

A method to improve the gain and directivity of the patch antenna using permeability negative metamaterial (MTM) cells is proposed. Composing of dual-layer symmetry single ring resonator pair (D-SSRRP) embedded on both sides of the dielectric layer, the MTM cell is easy to integrate with a patch antenna and can be used as an insulator to reflect surface waves based on the μ-negative characteristic. By inserting the D-SSRRP-loaded MTM cells with different dimensions around the conventional patch antenna, a dual-band antenna with high gain and narrow beamwidth is designed, which operates at 5.2 GHz and 6.75 GHz for WLAN. As a result, both the numerical and experimental results illustrate that the μ-negative D-SSRRP-loaded MTM antenna achieves a good radiation performance: at both working frequencies, the antenna gain has increased at least 2.2 dB and the half-power beam width (HPBW) decreased around 20° compared with that of the conventional microstrip patch antenna.