Multilayer antennas for directive beam steering broadside radiation and circular polarization

Multilayer antennas that utilize surface-waves launchers (SWLs) for leaky wave (LW) excitation are presented for microwave and millimeter-wave applications. Specifically, by placing two superstrate dielectric layers on top of a base grounded dielectric slab, a resonant cavity structure can be realized, and the bound field distributions can be transformed into LWs for radiation into the far field. For verification of the multilayer designs a single antenna structure is fabricated using commercially available substrates. A pencil beam can be observed at 17.4 GHz with measured gain values of >10.5 dBi at broadside. In addition, by using an array of such SWL sources, beam steering can be achieved as well as circular polarization.