Precision calculation of microwave cavity parameters using finite difference and finite element techniques

The properties of axially symmetric TM mode microwave resonant cavities are calculated by finite difference and finite element techniques. The methods used to achieve the highest accuracy from these techniques are described, and evidence is given that no significant systematic errors are present. The resonant frequencies of two standard cavities computed by the two techniques agree with the theoretical values to within 30 parts per million, and the agreement with measured resonant frequencies of three 9 GHz re-entrant cavities is within the limits set by surface finish and the uncertainty in the measurement of the dimensions of the cavities.