Optimization of couplers of TWT using TDR method

This paper describes usefulness of time-domain method (TDR) for optimization of couplers of TWT. Initially the method is used for a coaxial transmission line having four sections. Due to the transitions between the sections there exist some reflections. By knowing exact position of reflections one can optimize for better VSWR by introducing compensating steps. This method has been extended for the optimization of output coupler of a TWT by estimating the positions of discontinuities and optimizing the design for better VSWR. This method can be extended for any type of couplers like waveguide-to-coaxial transitions, or any other microwave transmission lines.