A NOVEL HIGH DIRECTIVE EBG STRUCTURE AND METAMATERIAL SUPERSTRATE FOR MICROSTRIP ANTENNA

In this paper a high gain and directive microstrip antenna made from metamatrial superstrate and an electromagnetic band-gap (EBG) substrate has been investigated. EBG structures have two main configurations, first EBG substrate and second EBG superstrate. In first case, the patch of antenna is surrounded with EBG structure that suppress the propagation of surface wave and in second case, layer of EBG structure that call EBG superstrate or metamaterial superstrate set above the patch of antenna. The layers of EBG superstrate have near zero refraction index that concentrate radiation energy normal to superstrate. A patch antenna surrounded with novel EBG structure is used for radiation. By choosing appropriate geometrical parameters of the structures we can obtain suitable impedance matching and negative refraction. The results show that the gain of the antenna with one layer of H-Doubled split ring EBG superstrate increase up to 16dB at 14.3 GHz. In addition, pattern of microstrip antenna with EBG superstrate is more narrower than simple microstrip antenna.