Microwave measurement of permittivity and tan ¿

A method of measuring the permittivity and loss tangent of dielectric specimens at 9375 Mc/s over a temperature range 20¿700°C is described. Circular specimens 0.900in in diameter and ¿/4 or 3¿/4 thick are measured in a 0.900in-diameter silver specimen chamber, using a slotted line, and in circular waveguide. The method is based on the short-circuited-line method and allows for the gaps produced by the differential expansion of the chamber and specimen and the variation in wavelength along the waveguide due to expansion. The effect of errors in the measurements is given. Typical measurements of permittivity and loss tangent of alumina and beryllium oxide specimens are given.