An X-band over-mode relativistic backward wave oscillator

An X-band over-mode high-efficiency relativistic backward wave oscillator (RBWO) is proposed. The main structure includes a dual resonant cavity reflector, a periodic slow wave structure and an inserted coaxial mode selector. The device uses an over-mode structure where the device operates using the pure TM 02 mode in the beam-wave interaction region and transmits a pure TM 01 mode in the output waveguide. The dual-mode reflection allows good isolation of the slow-wave structure from the diode region under over-mode conditions, while providing sufficient pre-modulation of the electron beam. The inclusion of the coaxial inner conductor allows the device to operate in pure TM 02 mode while eliminating other modes, and TM 02 has a higher power capacity. The device is capable of achieving higher microwave power output at low magnetic field conditions.