Leaky-mode generation by means of all-metal corrugated slotted parallel-plate waveguides

Periodic leaky-wave antennas can be realized with planar low-profile structures supporting the generation of highly directional beams with frequency backward-to-forward scanning. Fast scanning rates in a wide field of view are notably desirable for applications to passive direction-of-arrival detection. We propose a method to generate leaky modes with continuous scanning through broadside with an all-metal periodic parallel-plate waveguide. Periodic corrugations are introduced to support a slow wave, which is transformed into a fast radiating wave with periodic slots etched on the top plate. Suitable choices of the corrugation and slot parameters lead to a single fast spatial harmonic being responsible for well-defined and directional radiation. An original unit cell, properly optimized to suppress the open stop band, is designed with this method. The analysis and the design is accomplished with a rigorous in-house periodic method-of-moment code, allowing for the computation of complex modes in open 2-D waveguides. The leaky-wave antenna is validated by means of full-wave simulations in Ka band. The structure features continuous beam scanning with broadside radiation at 29.7 GHz with scanning rate comparable to different antenna technologies having much larger thickness.