A relativistic backward-wave oscillator with frequency-selectable across X- and Ku-bands

Abstract

The mechanism and realization of a relativistic backward-wave oscillator (RBWO) with frequency-selectable across X- and Ku-bands are presented. Both the transverse and the longitudinal mode selections contribute to the frequency-selectable across different bands. The transverse mode selection is achieved using the property of “surface wave” of the slow-wave structures to excite the coaxial TM01 mode (Ku-band) or the hollow TM01 mode (X-band) without exciting the higher TM modes. The longitudinal mode selection is achieved by the introduction of a coaxial extractor, which contributes to the compact structure and the restraints of the longitudinal mode competitions. In simulation, a Ku-band microwave with a frequency of 12.6 GHz and an X-band microwave with a frequency of 10.6 GHz are radiated when the inner-conductor length is 10.2 cm and 0 cm, respectively. The output power of both bands is above 2 GW. This technical route of RBWO with frequency-selectable across different bands is feasible and provide a guide to design other types of frequency tunable high power microwave sources operating at high frequency bands.