Performance of spiral antenna over broadband uniform-height progressive EBG surface

This paper presents the performance of a spiral antenna over an electromagnetic band-gap (EBG) surface that is designed to operate over a broadband that matches the bandwidth of the spiral antenna. The broadband EBG uses unit cells arranged in a concentric pattern with progressively increasing dimensions that correspond to the decreasing frequencies of the spiral antenna regions. The EBG cells are based on the mushroom structure with a uniform height over all regions of the surface. The reflection off the broadband EBG surface enhances the radiation of the spiral antenna and produces a higher gain, unidirectional pattern with a high front-to-back ratio. The result is a low-profile, high-gain, octave-bandwidth spiral antenna.