A NEW TYPE BAND-PASS FILTERS USING DIELECTRIC RESONATORS

Miniature narrow band filters with high performance can be formed by means of high Q and low temperature coefficient dielectric resonators, such as barium titanate, which are reasonably placed in a cut-off waveguide and properly excited. This paper describes a new type dielectric resonator band-pass filter which can be combined with MIC. At present, this kind of filter is the best one of the filters used in MIC. It has been shown, for example, that a 5 cm band-pass filter using three dielectric resonators with relative bandwidth of 0.2% has an insertion loss of about 0.8 dB, the attenuation outside the band over 50 dB, and the ratio of 30 dB to 3 dB bandwidth approximately 3.3. This filter has been theoretically analysed, and some interesting formulae are derived. The practical measured performances for 1-to 4-resonator band-pass filters are presented.