Analysis and Synthesis of Mirrors for High Divergence Microwave Beams

The Katzenelenbaum-Semenov-Algorithm for the analysis and synthesis of microwave beams is commonly used e.g. in transmission lines and gyrotrons for plasma heating. However, this algorithm is limited to flat mirrors (corresponding to thin lenses) and paraxial beams. The paper describes a method for the analysis and synthesis of deep mirrors (corresponding to thick lenses) as used e.g. for quasi-optical mode converters in gyrotrons. The opportunity to also sythesize deep mirrors gives an additional degree of freedom. It can improve the beam quality and/or reduces the required number of mirrors for a given beam transformation when non-paraxial beams are involved.