A lowloss bandpass filter using electrically coupled highQ TM(01 delta) dielectric rod resonators
Abstract
For a TM(01 delta) mode dielectric rod resonator placed coaxially in a TM(01) cutoff circular waveguide, characteristics such as the resonant frequency, its temperature coefficient, the unloaded Q, and the other resonances are discussed on the basis of accurate calculations using the modematching method. The results show that this resonator compares favorably with a conventional TE(01 delta) mode dielectric resonator, particularly for realization of a high unloaded Q. Analytical results also verify that interresonator coupling between these two resonators can be expressed equivalently by a capacitively coupled LC resonant circuit. A fourstage Chebyshev filter having a ripple of 0.035 dB and an equiripple bandwidth of 27 MHz at a center frequency of 11.958 GHz was fabricated using these resonators. Its insertion loss is 0.5 dB, which corresponds to an unloaded Q of 17,000, and no spurious response appears in the frequency range below 17 GHz.
 Publication:

IEEE Transactions on Microwave Theory Techniques
 Pub Date:
 December 1988
 DOI:
 10.1109/22.17406
 Bibcode:
 1988ITMTT..36.1727K
 Keywords:

 Bandpass Filters;
 Circular Waveguides;
 Coupled Modes;
 Dielectrics;
 Q Factors;
 Resonators;
 Bessel Functions;
 Chebyshev Approximation;
 Design Analysis;
 Maxwell Equation;
 Rods;
 Electronics and Electrical Engineering