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Based on the reversed Cherenkov radiation excited in metamaterials, a novel S-band reversed Cherenkov radiation amplifier (RCRA) with two output ports is proposed in this paper. Its metamaterial slow-wave structure (MSWS) consists of a hollow circular waveguide periodically loaded with all-metal double-ridge complementary electric split-ring resonators (CeSRRs). The CeSRR exhibits subwavelength and strong resonance characteristics, which lead to miniaturization and high interaction impedance of the MSWS. The period of the MSWS is optimized using the phase velocity jump technique to further increase the output power and electronic efficiency. The simulation results demonstrate that when the microwave signal of 7.8 W at 2.286 GHz is inputted at port 2, the output power at port 1 is 307 W, and the saturated output power and saturated gain at port 3 are 5.48 kW and 28.47 dB, respectively. Notably, the total electronic efficiency of the RCRA is predicted as 33.84%. The RCRA features high electronic efficiency and miniaturization and may meet special application scenarios that require two output microwave signals at the same frequency. [ABSTRACT FROM AUTHOR]

An all-metal metamaterial slow-wave structure (MSWS), which comprises a hollow circular waveguide loaded by periodically arranged complementary electric split-ring resonators (CeSRRs), is proposed. Due to the CeSRRs with the characteristics of both subwavelength and strong resonance, the MSWS has both compact size and high interaction impedance relative to conventional SWS. Based on the reversed Cherenkov radiation in the MSWS, a compact reversed Cherenkov radiation oscillator (RCRO) with high efficiency is developed. The measured electronic efficiency is 19.54%, and measured output power is 10.16 kW at 2.221 GHz under the conditions that the beam voltage is 26 kV, the beam current is 2.0 A, and axial magnetic flux density is ∼962 G. The experimental results clearly show that the brand-new RCRO can be applied to large-scale scientific facilities, medical imaging, microwave heating, microwave disinfection and sterilization, and so on. [ABSTRACT FROM AUTHOR]

We proposed an all-metal metamaterial slow-wave structure (MSWS) that consists of a circular waveguide periodically loaded with complementary electric split-ring resonators (CeSRRs). We set up an equivalent circuit theoretical model of MSWS and analyzed its high-frequency characteristics. Also, based on the surface current distribution on the CeSRR obtained by using the eigenmode solver in the CST Microwave Studio, a method of calculating the resonant frequency of the CeSRR was proposed. Furthermore, an MSWS with RF coupling port was designed, simulated, fabricated, and experimentally characterized. The dispersion characteristics of MSWS obtained by interpreting the experimental transmission characteristics agreed well with those predicted by theory as well as simulation. Based on the results of simulation and experiment, a concept of “resonance-coupling” was proposed for the passband of MSWS for frequencies below the cutoff frequency of an empty circular waveguide. The role of the slot-line in the CeSRR in influencing the performance of MSWS was also analyzed. The proposed MSWS has wide potential applications in vacuum electron devices, such as backward-wave oscillator and extended interaction klystron. [ABSTRACT FROM AUTHOR]