Design and development of 90 GHz backward-wave oscillator with staggered double-vane slow-wave structure

We designed a 90 GHz band backward-wave oscillator (BWO) with a double-vane slow-wave structure (SWS). A double periodic alignment of metal vanes serves as an SWS wherein electromagnetic waves propagate along a staggered path. We determined the scale parameters of the SWS by dispersion curves and calculated interaction impedance using CST Studio Suite simulation software. Using particle-in-cell (PIC) simulation, we observed the expected radiation with a frequency of 90 GHz, stimulated by a 10 keV electron beam with a 200 mA current. The output power was estimated to be level of Watt. The good agreements between the predictions, based on the interaction impedance and PIC calculation results, offer a key to a timesaving estimation of radiation from a BWO without using PIC simulation.