Development of W-Band Folded Waveguide TWT With Lowered Operating Voltage and Improved Gain Flatness

A W-band folded waveguide traveling wave tube (FWTWT) with lowered 19.4-kV operation voltage and improved gain flatness was investigated and developed. In this article, design methodology, fabrication, and test results were presented and discussed. Two kinds of slow-wave circuits with the positive and negative period stepping were chosen to carry out the contrastive study. A folded waveguide automatic measurement code was independently developed, and the FWTWT was fabricated by LIGA method. The test results showed that a saturated output power was greater than 87 W in the frequency range of 93–100 GHz and greater than 102 W in the frequency range of 95–98.3 GHz with the maximum output power of 123 W at 96.9 GHz. Within the frequency range of 93–100 GHz, saturated gains were higher than 30.05 dB, and gain fluctuation was 3.47 dB with the maximum gain of 33.52 dB at 96.9 GHz. The maximum electronic efficiency of 7.04% and the maximum total efficiency of 13.52% were obtained.