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

A Ka-band Serpentine Folded Waveguide Travelling Wave Tube (TWT) has been designed. The imposed design parameters values in terms of high power, high load, wide bandwidth, low weight, along with a structure manufactured with planar technique or by means of a micro milling process, have been obtained. Small signal simulations have been carried out with an in-house software for interaction impedance evaluation. The commercial electromagnetic simulation code CST Suite has been used for dispersion diagram prediction. An optimization of the one-dimensional software, normally used for large-signal simulation in coupled cavity TWTs (“Computer Program for Analysis of Coupled-cavity Travelling-wave-tube”, by Cosmic) has been carried out, by reducing processing time and by achieving results found in a close agreement compared with the ones obtained by the Particle In Cell suite of CST. In this paper, the design theory of a 1 kW output power Ka-band Folded Waveguide TWT, will be explained and predicted data for the dispersion diagram and interaction impedance as well as “cold test” results, in good agreement with each other, will be shown.