Study of 220GHz relativistic BWO with phase velocity taper

In this paper, a 220GHz relativistic backward wave oscillator (RBWO) with phase velocity taper is studied. The RBWO with phase velocity taper consists of five parts, including two parts of slow wave structures (SWS) which have different dispersion characteristics, the cathode, the resonant reflector and the output waveguide. The single-grating rectangular waveguide is selected as the SWS. Based on an RBWO without phase velocity taper, another part of SWS with different dispersion characteristic is added to build an RBWO with phase velocity taper. With the phase velocity taper, the output power of RBWO achieves 9.68MW at 220GHz, which increases 20% by the RBWO without phase velocity taper.