Single frequency 2-D leaky-wave beam steering using an array of surface-wave launchers

A planar antenna that utilizes surface-waves (SWs) for leaky-wave (LW) excitation is presented for millimeter-wave applications. Specifically, a two element array of directive Yagi-Uda like surface-wave launchers (SWLs) is used as the antenna feed, exciting cylindrical SWs on a grounded dielectric slab. By varying the relative phase difference between elements, the excited SW field distribution can be controlled. With the addition of metallic circular strip gratings, suitable conditions for LW excitation can be achieved. Essentially cylindrical LWs can be steered to confined regions on the guiding surface. For instance, by changing the relative phase difference between SWL sources such aperture fields can produce pencil and conical-sector beam patterns that can be steered in the far field at a single frequency. To the authors knowledge this is the first time such a LWA has been designed, fabricated and measured.