Automatic Computer-Controlled Tuning System for Microwave Filters

This paper presents an algorithm for automatic tuning of microwave filters. The method is based on an approximate filter model which is made accurate during measurements. The filter under test is measured and analyzed in terms of scattering parameters and filter element sensitivities. The so obtained filter characteristics are then mapped into the approximate filter model providing an exact model. The corrected filter model is then tuned on the computer to the desired frequency response. During this process, the mechanical tuning elements of the filter are set accordingly. Only a few measurements are necessary to update the model. This process is suitable for production as well as laboratory tuning of filters.