Accurate Prediction, Validation of Ambient Microwave Breakdown Threshold in High Power Very Narrowband Microwave Filters and Novel Design Techniques to Establish Sufficient Margins

This paper describes the method to accurately predict air breakdown threshold in high power microwave filters using theoretical analysis carried out in 3D FEM electromagnetic field solver. The effects of various factors like atmospheric pressure, relative humidity, output VSWR on the air breakdown threshold are also evaluated. Predicted air breakdown threshold is experimentally verified. Details of High power tests required to demonstrate air breakdown are included in the paper. The impacts of air breakdown on RF parameters of the filter during and after breakdown have been discussed and visual signatures of breakdown on filter surface have been included in the paper. Novel methods to improve air breakdown margin without compromising on other performance parameters, have been discussed. Moreover, necessary precautions required for carrying out high power test in ambient environment on such very narrow band filters have also been detailed.