Temperature dependence of composite microwave cavities

Composite microwave resonant cavities contain several regions of different dielectric materials. The variation of the resonant frequency with temperature is described in terms of a linear model. One part of the frequency variation is caused by the physical expansion of material parts, and the other by the change in the relative dielectric constant. The frequency sensitivity coefficients for both types of variation are obtained with the use of a computer code for numerical analysis of the electromagnetic field inside bodies of revolution.