Frequency scanning long slots array in a ridge gap waveguide technology

Abstract

Two different radiating mechanisms are implemented using the ridge gap waveguide (RGW) technology for the design of a frequency scanning antenna with high gain; through a number of radiating slots array. A Quasi-TEM horn of a shaped ridge is designed as a guiding structure to direct the propagating waves in the enclosed air gap between the ridge and the top radiating metallic plate. The first well known mechanism is to introduce one guided wavelength separation between the slots to assure that the slots are in phase. The drawback of such mechanism is the presence of undesired grating lobe. In order to eliminate the grating lobe, another mechanism is introduced, which is newly implemented here in the RGW technology. A non-radiating longitudinal slot is used to split each slot into two halves. Each half is then displaced along the non-radiating slot by a half wavelength. At the feed end, a phase shifter of 180° is introduced. This new arrangements allows a distance of a half wavelength between each two neighboring slots and thus eliminating the grating lobe.