The eigenvalue spectrum of rectangular waveguide with two symmetrically placed double ridges has been determined by formulating an integral eigenvalue problem and solving by Ritz-Galerkin method. The bandwidth characteristic is found to be adequate for varactor-tuned solid-state microwave oscillator applications requiring ridge structure for resonator. There remains some ambiguity in the designati...

Experimentally-determined tuning characteristics are presented for a long cylindrical re-entrant cavity having dimensions similar to those used for Gunn oscillators and for studies on semiconductors. The results indicate the simultaneous existence of the dominant TEM and the fundamental TE modes of resonance. A perturbation technique is given for the identification of the modes. Theoretical calculations of the resonant frequencies using simple models are presented. Experimental values of the Q-factors of the resonator for both the modes of resonance are also given.

A new cavity perturbation technique is presented for microwave measurement of dielectric constant, which uses a modified cylindrical reentrant cavity. Though suitable for only low dielectric constants, the method has the advantages, (a) sample area does not appear in the calculations, (b) only the ratio of frequency shifts due to two samples of same area and different thickness is involved, and (c) calibration of the measuring system with known dielectric is not necessary.

A bridge method of determining the loaded Q-factor and coupling coefficient of single-ended cavity resonators is described. The measuring system consists of a hybrid-T or ’’magic T’’ bridge with one of the collinear arms terminated by the cavity and the other by a precision attenuator followed by a variable precision short. The experimental procedure essentially measures the reflection coefficient of a cavity resonator as a function of frequency by balancing the bridge, using an oscillator with variable frequency amplitude modulation as the source.