In this article, we proposed a novel metamaterial (MTM) inspired interaction structure for high-power microwave backward-wave oscillator (BWO). The proposed structure is an all-metallic MTM slow wave structure (MSWS) which comprises of a number of broadside-coupled split ring resonator (BCSRR) pairs, arranged periodically in the axial direction and repeated azimuthally. Each pair of oppositely oriented split ring resonator (SRR) provides negative mu and the cylindrical waveguide generates negative e medium for below cutoff TEmodes propagation. The full wave cold simulation analysis of the proposed structure, using computer simulation technique (CST)microwave studio, has been carried out with the objectives of double-negative medium (DNM) optimization, dispersion, and interaction characterization, and S-parameter validation. For the particle-in-cell (PIC) simulation analysis, the CST-particle studio (CST-PS) has been used. In this work, we report an operation of the proposed MTM-loaded BWO (MTM-BWO) employing a beam potential and total beam current of 340 kV and 1.2 kA, respectively, generating an output power of 175 MW within 22-24 ns with an efficiency of 43% using the four-beam MSWS. As compared to its three-beam counterpart, the fourbeam structure generates higher power with better efficiency.
