Synthesis of irregular waveguide field transformation elements using a multi-resolution algorithm

We propose a way to synthesize field transformation elements by optimizing the irregular scattering surface of a conducting wall waveguide structure. Our approach, based on a multi-resolution algorithm, shows that, in addition to reaching a high transformation efficiency in a short distance, a local optimizer is good enough to find a solution with reasonable computational effort. This approach has been used to design several mode conversion structures involving multiple modes and up to two frequencies.