Split Slots Array for Grating Lobe Suppression in Ridge Gap Guide

Abstract

A frequency scanning antenna array of nonresonant slots with uniform slot field distribution is designed using the ridge gap waveguide (RGW) technology. The slots are separated by one wavelength, which cause the presence of undesired grating lobe. In order to eliminate the grating lobe, the structure is splitted by a non-radiating longitudinal slot, which splits each slot into two halves. Each half is displaced along the non-radiating slot by a separation of half wavelength. In order for each of the two halves to be excited in phase, a phase shifter of 180 o is introduced to one side of the two halves. Such arrangement caused elimination of the grating lobes. The proposed configuration is fabricated and measurement results are provided to prove the concept.Index Terms-Ridge Gap Waveguide (RGW), Phase Shifter, Splitted, and Uniform Field Distribution.

A flat aperture antenna composed of a series fed H‐plane horn array excited by a ridge gap waveguide horn

“…The split configuration of the transverse slots alongside with a dielectric slab in the RGW air gap as a 180° phase shifter is applied to deal with the grating lobe problem associated with the array of transverse slots. The antenna presented in [19] shows the frequency scanning performance of over 19% bandwidth with the maximum gain of 14 dBi and high side lobes (up to −5 dB) in E‐plane.…”

“…In [16][17][18], the array of series fed longitudinal slot columns is used to form the antenna aperture in which the feed network is associated with lower complexity compared to that presented in [14] but at the cost of providing lower bandwidth. In [19], the array of long transverse slots is applied to form the antenna aperture presenting a quite simple structure with low fabrication complexity. The split configuration of the transverse slots alongside with a dielectric slab in the RGW air gap as a 180°phase shifter is applied to deal with the grating lobe problem associated with the array of transverse slots.…”

“…Different techniques including conventional metallic waveguides [8][9][10], substrate integrated waveguides [11][12][13], and gap waveguides [14][15][16][17][18][19] have been applied to implement slot arrays. Metallic waveguides are low loss and efficient structures, however, they suffer from fabrication cost and complexity at mm-wave ranges as fine electrical contact between their metal blocks is required.…”

“…Until now, different aperture array antennas with directive radiation have been designed and implemented using the gap waveguide technology [14][15][16][17][18][19]. In [14], the array of parallel fed slots is applied in the antenna radiating layer and 14% bandwidth with maximum gain and efficiency of 26 dBi and 80% is provided but at the cost of being associated with a quite complicated corporate feed network, which enhances the fabrication complexity and cost especially for higher gains.…”