Special Beams to Low-RCS Beam Scanning: Multifunctional Leaky-Wave Antennas

Leaky-wave antennas provide a promising platform for integrating special-beam generation, frequency-controlled beam scanning, and radar-cross-section reduction within a low-profile structure. This presentation introduces three representative designs based on traveling-wave radiation and dispersion engineering. First, a substrate-integrated-waveguide leaky-wave antenna is developed to generate a near-field Airy beam through continuous phase accumulation. The prototype achieves a measured radiation efficiency of approximately 64% with a profile of only 0.039 free-space wavelengths. Second, a circular leaky-wave array is proposed to generate multiple circularly polarized orbital-angular-momentum modes. The frequency-dependent phase progression enables four OAM states, with measured main-mode purity exceeding 75%. Third, a dielectric-image-line leaky-wave array is integrated with a resistively loaded periodic surface, enabling in-band frequency-controlled beam scanning and out-of-band absorption for RCS reduction within a single-layer aperture. These studies demonstrate that the propagation constant, leakage rate, polarization, and surface impedance can be jointly engineered to achieve multiple radiation and scattering functions. The results provide a unified design framework for compact multifunctional antenna systems in communication, sensing, imaging, and low-observable applications.