Design Guidelines and Performance Analysis of a Wideband Coaxial Horn Antenna Fabricated via Additive Manufacturing

This work introduces a Ka-band coaxial horn antenna that incorporates a specialized dielectric supporting structure and a transition to a 2.4 mm connector. The inner and outer radii of the coaxial aperture were sized using an approximated model for an open-ended coaxial waveguide. The theory of small reflections was then used to account for the reflection coefficient resulting from an additional cascading cylindrical-conical section. A refined numerical model, representing more accurately a prototype, featured a transition region to standardized connectors and a dielectric structure that offers mechanical support for the inner conductor and impedance matching. Ansys HFSS full-wave electromagnetic finite-element method solver was used to compute the parameters of the antenna, and a genetic algorithm optimizer was employed to improve the performance of the complete coaxial horn. A prototype was fabricated using metal additive manufacturing for the inner and outer horn conductors, while the dielectric support was created using 3D polymer printing. Experimental measurements demonstrate that the prototyped antenna has an impedance bandwidth of above 79.36% (19-44 GHz), a peak realized gain of 11.53 dBi, and a maximum efficiency of 89.83%. Additionally, a sensitivity analysis was conducted to evaluate the potential impact of additive manufacturing imperfections and assembly errors on the antenna's performance.