Filter transformer section for wide broadband in coaxial couplers

The couplers play an important role in coupling the power in and out from the helical SWS of a TWT with minimum reflection. For a space helix TWT, coupler should be wide bandwidth and small size. The main objective of the paper is to design a wide band output coaxial coupler, and a filter consisting of different radius and different length of transformer section is optimized. The simulated reflection loss of filter transformer section is obtained by using Ansoft HFSS and compares with that of three-stage transformer section. The wide band matching properties of the transformer is better than the three-section transformer section.