Design of a 1 kW output power Folded Waveguide TWT operating in Ka-band

A Ka-band Serpentine Folded WaveguideTravelling Wave Tube (TWT) has been designed. The imposeddesign parameters values in terms of high power, high load,wide bandwidth, low weight, along with a structuremanufactured with planar technique or by means of a micromilling process, have been obtained. Small signal simulationshave been carried out with an in-house software for interactionimpedance evaluation. The commercial electromagneticsimulation code CST Suite has been used for dispersiondiagram prediction. Optimization of the one-dimensionalsoftware, normally used for large-signal simulation in coupledcavity TWTs (“Computer Program for Analysis of Coupled-cavityTravelling-wave-tube”, by Cosmic) has been carried out,reducing processing time and achieving results found ina close agreement compared with the ones obtained by theParticle In Cell suite of CST. In this paper, the design theory ofa 1 kW output power Ka-band Folded Waveguide TWT, willbe explained and predicted data for the dispersion diagramand interaction impedance as well as “cold test” results, ingood agreement with each other will be shown.