Enhancing the Power Capabilities of the Stepped Septum Using an Optimized Smooth Sigmoid Profile

The typical septum polarizer that has gained popularity in the literature may be unsuitable for high-power applications, due to the sharp corners in the design. In order to address this issue, the fundamentals of the septum operation are first revisited, using a graphical visualization through full-wave analysis. A septum profiled with smooth edges is next presented, with enhanced power-handling capabilities in comparison to the stepped-septum polarizer. In this work, the sigmoid function is introduced to represent the smooth contour of the septum, and to enable diverse configurations without any discontinuities. The smooth and stepped profiles are optimized using the Particle Swarm Optimization (PSO) technique. The maximum electric-field intensity around the smooth edges is investigated using a full-wave simulator, HFSS. Our observations show that the maximum electric field is reduced by 40% in comparison to the stepped septum. In Appendix 1, the numerical approach is evaluated by comparing the exact series solution for the half-plane scattering problem with the simulated results in HFSS. In Appendix 2, a septum design with rounded edges is also studied as another possible design to reduce the maximum fields.