Synthesis of dielectric resonator band-pass filters

A computer program for calculating bandpass filters, based on a procedure proposed by S.B. Cohn (1968), is presented. The filters are constructed with cylindrical dielectric resonators transverse oriented in a rectangular waveguide below cut-off. The required couplings between resonators are computed from a low-pass Chebyshev or Butterwork prototype filter. The distances between dielectric resonators are calculated and the theoretical response of the filter is plotted. The results obtained by the program have been confirmed by a four-stage bandpass Chebyshev filter. The accuracy of distances between dielectric resonators is better than 6%, and the measured center-frequency insertion loss is 1.9 dB compared with the computed 1.5 dB.