Dielectric filter having adjacently-positioned resonators of dissimilar cross-sectional dimensions and notched side surface

In a radio transceiver having transmitter circuitry and receiver circuitry, the combination with the transmitter circuitry of a transmitter clean-up filter, said transmitter clean-up filter comprising:

• a dielectric block defining top, bottom, and at least first and second side surfaces;
• at least two longitudinally-extending resonators defined by sidewalls of cavities formed to extend longitudinally along longitudinal axes thereof between the top and bottom surfaces of the dielectric block, the at least two longitudinally-extending resonators including a pair of adjacently positioned resonators wherein a first resonator of the pair of adjacently positioned resonators is of a circular cross-section and a second resonator of the pair of adjacently positioned resonators is of a substantially elliptical cross-section;
• a coating of an electrically-conductive material substantially covering the bottom and the at least first and second side surfaces and the sidewalls of the cavities defining the at least two longitudinally-extending resonators thereby to permit electromagnetic coupling between adjacent ones of the at least two resonators;
• means forming a notch positioned to extend along at least one of the first and second side surfaces of the dielectric block at a location between the first resonator and the second resonator of the pair of adjacently positioned resonators for altering the electromagnetic coupling between the pair of adjacently positioned resonators of the at least two longitudinally-extending resonators.

A method for constructing a dielectric filter of a block of dielectric material having top, bottom, and at least first and second side surfaces, said method comprising the steps of:

• forming at least two longitudinally-extending resonators defined by sidewalls of cavities to extend longitudinally along longitudinal axes thereof between the top and bottom surfaces of the dielectric block, the at least two longitudinally-extending resonators including a pair of adjacently positioned resonators wherein a first resonator of the pair of adjacently positioned resonators is of a circular cross-section and a second resonator of the pair of adjacently positioned resonators is of a substantially elliptical cross-section;
• covering the bottom and the at least first and second side surfaces of the dielectric block and the sidewalls of the cavities defining the at least two longitudinally-extending resonators with a coating of an electrically-conductive material thereby to permit electromagnetic coupling between adjacent ones of the at least two resonators;
• and
• molding a longitudinally-extending notch in the dielectric material forming the dielectric filter at least one side surface of the first and second side surfaces of the dielectric block between the first resonator and the second resonator of the pair of adjacently positioned resonators to alter thereby the amount of dielectric material separating the first and resonator and the second resonator of the pair of adjacently positioned resonators to alter thereby the electromagnetic coupling between the individual ones of the resonators of the at least one pair of resonators.