Annular Beam Driven Metamaterial Backward Wave Oscillator

Metamaterials (MTMs) are synthetic materials designed to have characteristics that "may not be readily available in nature," such as negative permittivity, reversed Doppler Effect, reversed Cherenkov Effect, and negative Refractive Index. These characteristics have motivated researchers to analyze and investigate the use of MTMs for modelling high-power microwave (HPM) radiation sources. One of the most potential HPM sources is an annular beam-driven Backward-Wave Oscillator (BWO) based on the Cerenkov mechanism. The devices that use the Cerenkov mechanism are preferred due to their larger bandwidth. Its high output power and repetition operations make it a promising source. In this paper, an annular beam-loaded metamaterial BWO is simulated in order to investigate and comment on the possibility of metamaterial or metamaterial-inspired structures replacing the slow-wave structures (SWSs) in vacuum tube devices. Performance parameters of several BWO configurations loaded with different metamaterial-inspired conductor rings are compared to rippled SWS-based BWOs. The results suggest that fewer metamaterial rings with solid cross-section (CS) inside the BWO lead to a closer match in generated output power and frequency with the output power generated using a rippled SWS.