Accurate Theoretical Model for the High-Frequency Characteristics of the Ladder Multigap Resonant Cavity

The ladder multigap resonant cavity finds wide application in the terahertz vacuum electric devices. It consists of a single slotted plate (called ladder) enclosed by a rectangular waveguide, which offers advantages in mechanical simplicity as well as the capability of high gain per circuit length and frequency tuning. The theoretical model for the high-frequency characteristics of such circuit was developed. The derivation of the characteristic impedance (R/Q) and the intrinsic quality factor (Q
₀
) in combination of the established dispersion relation enables a complete analysis for this circuit. Examples at the terahertz frequencies were used to demonstrate the usefulness of the theoretical model with the 3-D finite-element electromagnetic simulation as a benchmark. The formula system is described and the computational results are presented.