An A6 relativistic magnetron with quasi-continuous frequency tunability

This is the authors' abstract. We don't add key points for this paper.

We numerically demonstrate quasi-continuous frequency tunability of an A6 relativistic magnetron (RM) using alternate cavities loaded with split-ring resonator (SRR) metamaterial slabs. The design employs SRRs fabricated on a dielectric substrate coated with a thin Mylar layer to suppress electrical breakdown at the capacitive points. To minimize the electric field concentration, the resonance frequency of the SRR is deliberately shifted away from that of the bare RM cavity. Full particle-in-cell (PIC) simulations using CST Studio Suite show that inserting the SRR slabs produces an initial frequency shift from 4.63 GHz to 4.58 GHz. The simulation results demonstrate that the orientation of metamaterial slabs significantly influences the S-parameter profile, affecting effective permittivity and permeability. These findings provide a promising framework for the design of high-performance metamaterials (MMs) in tunable frequency applications. By varying the rotation angle of the slabs inside the cavities, the effective permittivity and permeability are modulated, enabling a quasi-continuous frequency tuning. Acceptable RF output power (∼0.595 GW) and efficiencies (∼13 %) are achieved for most rotation angles, except at where mode competition prevents stable oscillation. This work introduces a compact, mechanically adjustable method for frequency tuning without altering the cavity volume, offering promising applications in high-power microwave (HPM) sources, frequency-agile communication systems, and radar.