Advances in EBG-resonator antenna research

Electromagnetic Band-Gap (EBG) materials can be successfully employed to improve the performances of antennas [1], [2]. When used as planar reflectors, as substrates, or as high-impedance ground-planes, they are able to eliminate the drawbacks of conducting ground-planes, to prevent the propagation of surface waves, also allowing a lowering of the antenna profile, and to improve the radiation efficiency. In EBG resonator antennas, instead, an EBG is employed as a superstrate on a primary radiator, backed with a ground plane, and its main effect is a considerable increase in the directivity [3]. It is also possible to obtain a highly-directive antenna by embedding a source in an EBG working near its band-gap edge, thanks to the limited angular propagation allowed.