A Rectangular Metamaterial Structure for Sub-GHz Vacuum Electron Devices

This paper presents the design of a compact, metallic, rectangular complementary split-ring resonator (CeSRR) with a coaxial beam configuration. Eigenmode analysis on the unit cell shows a <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\pi$</tex> -mode frequency of 700MHz. Time-domain simulation is performed with a two-port input geometry of 8-cells, excited through magnetic coupling loops. The S-parameters show reflection below -35 dB at the resonant frequency. The permittivity and permeability are obtained from the S-parameters and show a double-negative response at the resonant frequency. Results indicate that such structures are applicable to sub-GHz vacuum electron devices with high operating power.