RF Output Window Design for HELIX TWT

An output circuit of a helix traveling wave tube was modeled in High Frequency Structure Simulation (HFSS) 3D software.

The challenge was to first determine how to model the circuit in HFSS and later match the model results to real measurements made with hardware. Upon the agreement of the model and hardware results a design change was attempted to make the circuit have a better VSWR than 1.5:1 in the frequency range of 12-18GHz. After making few changes in the geometry the circuit was able to give a VSWR less than 1.5:1.