Investigation on the design method of TEM transition

The design method of TEM transition from circular section to rectangle section is presented. To achieve good transition two design principles are constructed. Firstly, the section shape between circle and rectangle section should change slowly. Secondly, impedance of transmission line with arbitrary section between circle and rectangle coaxial transmission line should be kept exactly same impedance. The VSWR computing result validate the method of TEM transition from circular section to rectangle section.