Direct Use of the High Impedance Surface as an Antenna Without Dipole on Top

High impedance surfaces (HISs) have been proposed and used as substrate for dipoles for realizing low-profile antennas. Here, we show that HISs can be used directly as low-profile antennas with a single feed point, without any dipole on top. The structure is made of only two metallic layers, the patterned surface and the ground plane below, at a subwavelength distance. We analyze two possible feeding mechanisms of an HIS made of dogbone-shaped conductors, though the ideas proposed here can be applied also to other HIS structures. We show that broadside gain of the order of 7-11 dBi can be obtained. We also explain that radiation of the HIS is in part related to a TM-like leaky wave with attenuation constant that is not as small in contrast to other standard high-gain leaky-wave antennas.