Simulation of 650 GHz sine waveguide backward wave oscillator

A 650 GHz watt-class backward wave oscillator has been proposed by using a sine waveguide slow-wave structure which possesses low loss and low reflection. In this letter, the three-dimensional particle-in-cell method is applied to predict the output performance of the backward wave oscillator. The investigation results show that, the backward wave oscillator can produce 1.55 W peak power output at 645.9 GHz under 20 kV operating voltage and 5 mA beam current. Its output mode is the TE10 mode. By tuning the operating voltage from 15 kV to 25 kV, the backward wave oscillator has over 1 W peak power output with a tuning bandwidth of 80 GHz.