A novel closed-form synthesis approach for band-pass filters with arbitral end-coupled-reactances

摘要

Nowadays most BPF's from MHz to tens-GHz are designed with the application of J/K-inverters. It is however desirable to find such way of filter realization which can be arbitrary modified through adding reactances among filter and termination as additional physical connection to obtain simplest possible recalculations of the networks. This paper presents analytical method of synthesis for BPF with consideration of arbitrarily reactance-parts entered into the real terminations - called coupled-reactances. Presented method gives opportunity to apply any immittances of resonators and coupled-reactances inserted in such way that J0,1/Jn,n+1-admittance end-inverters remain unchanged. Therefore, considered filter networks employ novel asymmetric inverters with single shunt negative element proposed by Zaradny & Rymarz, which are more effective than widely known symmetrical inverters. Calculations and measurements of S21-responses with novel inverters confirm theoretical assumptions. One example of laboratory model of filter with favorable results confirming the theory has been presented experimentally in the paper. The method at present has applications in thick-film MIC's to several GHz.