A 3-D-Printed UHF Dual-Polarized Dielectric-Loaded Waveguide Horn Antenna for CATR Applications

This communication presents a 3-D-printed dielectric-loaded waveguide antenna with a wideband dual-polarized wide-beam radiation. First, this communication derives the analytical solution for the propagation modes in a three-layer dielectric-filled circular waveguide. With the mode equations guiding the geometric structure, broadband single-mode operation is achieved, and the broadband distribution characteristics of the dominant HE₁₁ mode are analyzed—these distribution features serve as the foundation for stable broadband radiation. To effectively excite the dominant mode, this communication proposes a balanced probe structure with ridge loading. This probe guides electromagnetic waves along the high-permittivity dielectric core toward the aperture, providing an effective feeding solution for fully dielectric-filled enclosed structures. Then, leveraging 3-D-printed geometric shaping, a spline-based aspheric dielectric tip is introduced to stabilize the phase center and provide a smooth permittivity transition from the dielectric to free space. The fabricated antenna achieves a 66.7% relative bandwidth (0.5–1 GHz) with a compact size of 0.54λ × 0.54λ × 0.66λ, exhibiting a peak gain > 6 dBi, phase center variation < 0.1λ, and stable symmetric radiation patterns featuring a 70°–85° half-power beamwidth (HPBW) for dual polarizations.