Error mitigation of cross-polarization suppression component for large-scale slot array with high-gain horn

Parallel metallic plates and a high-gain horn are widely applied to large-scale rectangular waveguide slot array antennas to obtain pure linear polarization and satisfying radiation performance. The two components form horn waveguides to suppress cross-polarization with cut-off modes. However, it is found that they can also influence co-polarization with band-notched performance. When engineering errors are under consideration, the condition becomes worse. Transmission line theory is utilized to explain the notched performance with resonant mechanism. Engineering errors are comprehensively estimated. The results show that several errors influence the band-notched performance, which causes a wide potential notched band. Based on simulation and measurement, the horn waveguides are found to be non-closed and have two adjacent notched bands caused by the characteristics of parallel-plate and horn waveguides. Mitigation methods are proposed and validated for these errors. The error estimation and mitigation give guidance to the process from design to practice, which is useful for similar projects.