Microwave filter including a plurality of cross-coupled dielectric resonators

A band pass filter for high frequency signals, said filter having a very high quality factor, high selectivity and transmission zeroes, the filter comprising:

• a filter body having several cavities:
• respective dielectric resonators housed in corresponding ones of said several cavities;
• and output connectors in said filter body;
• a cover on said filter body;
• screw stems projecting from an inner surface of said cover and extending inside said filter body;
• respective plates facing but at respective distances from a top surface of corresponding ones of said dielectric resonators, and attached to respective ones of said screw stems which regulate said respective distance and, thereby the tuning frequency of the filter;
• walls of adjacent cavities having openings therein to provide a cross-coupling therebetween;
• control elements having free ends, and the free ends of the control elements penetrating within respective ones of said openings to control said cross-coupling between adjacent ones of said cavities;
• adjusting elements on an outer surface of said cover to displace respective tuning regulating stems, as well as respective stem ends associated with and extending in said corresponding, openings between adjacent cavity walls;
• and
• means to cross-couple non-adjacent cavities, wherein each said non-adjacent cavity cross-coupling means includes a respective bridge element having a base which penetrates and rests in a slit of an electrically insulated holder disposed in a corresponding node between non-adjacent cavities, and said respective bridge element having corresponding wings which are disposed in positions of optimal coupling with the dielectric resonators associated therewith, at least one of said respective bridge elements being conductively connected to the filter cover, whereas an other one of respective bridge element being associated with the filter body from which it is electrically insulated.