The launching of surface waves by an end-fire array of slots

An end-fire array of slots suitable for launching a surface wave on a dielectric-coated metal sheet is described and analysed. The analysis is based on the representation of the slots as magnetic dipoles in the plane of the sheet, their axes being perpendicular to the line of the array. In a practical embodiment of the scheme the elements take the form of slots fed by quarter-wavelength branch guides series fed from a waveguide partially filled with dielectric mounted beneath the metal sheet. Experimental results are given which support the theoretical conclusion that a high launching efficiency is possible. A launching efficiency of 95% is obtained theoretically for a 12-slot array launching a surface wave on a metal sheet coated with dielectric of relative permittivity 2.56 and of thickness 0.125 in at a frequency of 9.38 Gc/s.