All-metal corrugated antenna with optimized leaky-wave feeder. Far- and near-field properties

All-metal corrugated leaky-wave antennas lend themselves to the realization of efficient and low-profile radiating devices thanks to their low material losses, compactness, and robust structure. Using leaky-wave theory, this work investigates the unique far-field and near-field radiation characteristics of annular, radially periodic corrugated configurations. The antenna design is based on a state-of-the-art dispersive analysis of the leaky-wave mode supported by the corresponding linearized structure, which allows direct determination of the antenna aperture size and optimization of both gain and bandwidth of the broadside radiation. We propose the study and design of an optimized leaky-wave launcher to significantly improve both near- and far-field radiation performance. Two different feeders incorporating a metallic covering structure are introduced, which effectively suppress direct feed radiation into free space, thereby enhancing the excitation of the intended leaky mode. Following this approach, the analysis confirms enhanced, high-gain, and wideband broadside radiation, and demonstrates the possibility of generating a non-diffracting beam in the form of a zeroth-order Bessel beam. This opens new and promising opportunities for generating focused beams using compact and efficient devices at millimeter-wave frequencies and beyond.