Dual-Band Circular-Polarization Horn Antenna with Completely Inhomogeneous Corrugations

A dual-band circularly polarized horn antenna of completely inhomogeneous corrugations is efficiently designed for simultaneous good polarization, aperture efficiency (AE), sidelobe level (SLL), and symmetric radiation pattern (SRP). The method employs two steps to integrate a mode-matching method and a genetic algorithm by introducing a modal expansion of the aperture field as an intermediate interface for optimization, where the selected modes' weightings are first optimized to resemble the desirable far-field patterns. Afterward, the aperture distribution serves as the goal to subsequently optimize the entire corrugation structure by formatting related scattering matrices using the weighting coefficients of available modes on the aperture and inside the horn section. In the implementation of design, the developed corrugated horn comprises six and 19 completely inhomogeneous corrugations in mode conversion and radiation sections, respectively, providing sufficient design freedom. Simulated and measured results are shown to validate the optimized horn design, which simultaneously meets all above-mentioned requirements in both the K-band (19.6-21.2 GHz) and the Ka-band (29.4-31 GHz).