Space-harmonic analysis of multidepth corrugated waveguides

Multidepth corrugated and ring-loaded waveguides are analysed in terms of space-harmonics. A general eigenvalue equation for the corrugated waveguide with M different slot depths in one corrugation period, is derived under the assumption of thin corrugations. The theory is then applied to corrugated waveguides possessing one to four different slot depths. Dispersion curves for tri-depth corrugated guides are calculated and propagation characteristics in dual-depth corrugated and ring-loaded guides are compared with each other. Frequency band properties of these guides and the accuracies of some more approximative methods for the tri-depth guide analysis are discussed.