Dielectric Constant Ferrites and Loss Tangent of Microwave at Elevated Temperatures

Abstract

Measurements were made of the real part of the dielectric constant and loss tangent of 32 commercial ferrites at x-band at temperatures from 25 C to 250 C, but not exceeding the curie temperature. A modified perturbation technique was used for these measurements.' The principal modification included a correction based on the diameter and real part of the dielectric constant. For a sample diameter of 35 mils, the correction ranged from 4 to 10% for dielectric constants of 7 to 16, respectively. Expressions were also derived for'the correction due to the contribution of the irises and metal losses to the cavity Q, since the resonant frequency of the cavity changed when a sample was introduced. The accuracy in the measurement of the real part of the dielectric constant is ± 3%, where 1% is attributed to the taper and ellipticity of the samples and 2% to the electrical measurement. The accuracy in the measurement of the loss tangent is ± 0.0005. U. S. ARMY SIGNAL RESEARCH AND DEVELOPMENT LABORATORY FORT MONMOUTH, NEW JERSEY CONTENTS