Design of SWS for a Ku-band 140W short-length TWT

Helical slow wave structure (SWS) for Ku-band 140 W short length space TWT has been designed in a single section to achieve the desired saturated RF output power 140 W, gain 25 dB and electronic efficiency more than 28% over the frequency band of 10.9 to 11.7 GHz. This short-length TWT has been designed for a microwave power module (MPM). In-house developed one-dimensional large signal model (SUNRAY-1D) and 2.5-dimensional large signal model (SUNRAY-2.5D) along with the commercial code CST-MWS have been used for the design of helix SWS assembly. Dependency of helix tape and APBN support rod dimensions on the SWS dispersion and impedance characteristics over the desired frequency band of 10.9 to 11.7 GHz has also been analyzed.