Analysis and design of planar metallic surface lenses for controlled wave guidance

Surface waves (SWs) on planar substrates are generally considered an adverse effect that can degrade the performance of printed circuits and antenna arrays. However, with appropriate conditions, these SW fields can be employed for controlled propagation along a planar guiding surface. For example, by the addition of a periodic configuration of microstrip lines printed on top of a grounded dielectric slab, an effective phase constant can be achieved, refracting cylindrical SWs transmitted from a slot source etched in the ground plane. A design approach for these surface lenses is presented as well as a specific structure that can generate a bound and guided plane-wave. Applications for these printed metallic lenses include new quasi-optical circuits, novel planar feeds, as well as lowcost leaky-wave antennas for microwave and millimeter-wave frequencies.