INVESTIGATION OF MICROWAVE DIELECTRIC -RESONATOR FILTERS.

摘要

The serious effect of air gaps on the measurement of high dielectric-constant values is discussed. Two measurement techniques are described in which air gaps are made to be insignificant sources of error. Both methods utilize resonant modes having zero electric field at dielectric-sample surfaces adjacent to metal walls. In the first method, a cylindrical sample is placed in a close-fitting metal waveguide and resonated in the TEsub01delta mode. The air-filled regions of the waveguide on each side of the sample are cut off for the TEsub01wave,so that inappreciable loss of resonant-mode energy occurs. In the second method, a cylindrical dielectric sample is placed at the center of a metallic radial-line pill box. The flat faces of the sample are in contact with the flat walls of the radial line. In this case,also, a circular-electric TEsub01mode resonance is excited,and the electric field is zero on the sample surfaces. Practical techniques of identifying and measuring the desired resonant frequencies are explained,and exact formulas yielding the dielectric constant are given for both methods. Data obtained by these methods are presented,and the effect of density variation is discussed. (Author)