Design and experimental investigation of radiators for antenna arrays based on EBG waveguides

The problems of the designs of elementary radiators for thinned antenna arrays based on the waveguides formed inside a microwave EBG structure are considered. Technical requirements on such radiators are formulated and it is shown that helical radiators satisfy these requirements. Theoretical (numerical) and experimental antenna characteristics of helical radiators excited by an EBG waveguide are obtained. Matching of a helical radiator to an EBG waveguide with the use of a probe coupling element and a microhelical coupling element is considered. Probe coupling elements are analyzed both numerically and experimentally and microhelical coupling elements are analyzed only numerically. It is shown that application of such elements substantially extends the matching band of the helical radiator.