This paper presents a fully planar antenna based on a metamaterial consisting of a planar array of dogbones. The unit element of this high impedance surface (HIS) is composed of a layer with dogbone shaped conductors on top of a thin dielectric substrate backed by a metal ground plane. A HIS as an intermediate-gain antenna at C band is demonstrated. Previously, HISs have been employed in order to improve the radiation performance of antennas on top of them, this yields to low profile planar antenna applications. In this paper the idea is to eliminate the antenna above the HIS and instead use the HIS itself as an antenna. The direct use of a HIS as an antenna thus allows designing even thinner antennas. The leaky wave modes supported by this kind of metalayer have been previously demonstrated, and the main principle of this HIS antenna is the excitation of such modes in the finite array of dogbones to achieve broadside radiation. Various ways of exciting this antenna are explained and radiation patterns are given as simulation results. Also antennas in various sizes are compared with respect to the broadside gain. © 2011 IEEE.