Dual-Polarized Array of Triangular Leaky-Wave Antennas for Compact Water Radar Instruments

This paper presents a compact dual-polarized leaky-wave antenna array for water remote sensing. The antenna employs a triangular slotted waveguide to achieve high gain and slanted pointing. Its cross-section supports two orthogonal propagation modes to enable dual-linear polarization and a highly slanted beam without exciting higher-order modes. A tailored slot shape is introduced to provide high leakage for both modes while efficiently controlling the aperture illumination to reduce sidelobe levels. The antenna consists of a three-layer monolithic structure, where the array of triangular leaky waveguides supports two stacked beamforming networks (one per polarization). An array of orthomode transducers connects the beamformers to the radiating elements. Unconventional waveguide sections are employed to ensure self-supporting additive manufacturing. The design is validated through a progressive methodology that increases complexity in steps, allowing separate validation of key features and incorporating feedback from the manufacturing process to minimize deviations. Both the antenna concept and the experimental methodology are confirmed through prototyping of a 4-element array and a 32-element array. The final design achieves realized gains above 37 dB, high cross-polarization discrimination and isolation, and reduced sidelobe levels. Moreover, high slanted angles are attained without generating grating lobes or exciting higher-order modes, meeting the specifications of an airborne water monitoring radar instrument.