A Study of an In-line Slot Array Antenna Fed by a Zigzag Ridge Waveguide

We propose a novel in-line slot array antenna on broad wall of a ridge waveguide. A conventional broad wall slotted waveguide array requires alternating slot displacement from the waveguide centerline, which generates undesirable high sidelobe in skewed direction. In order to overcome the problem, we apply a configuration that all slot elements are placed in line along a centerline of a waveguide. In this case, asymmetry inside of the waveguide is necessary so that we achieve radiation from slot elements. To this end, we propose a waveguide structure with a bent ridge and grooves with different depths with respect to the ridge. Simulation and experimental results are presented.