Dielectric filter having resonators aligned to effect zeros of the frequency response

A radio frequency filter comprising:

• a dielectric block having a first end and a second end, the dielectric block having an outer surface extending between the first end and the second end, and the outer surface having a coating of an electrically conductive material disposed thereon;
• at least two holes disposed in the first end of said dielectric block, each said hole defining a respective line extending through the open end of each of the at least two holes as a first axis, the at least two holes respectively having an inner surface portion extending from the first end toward the second end and having a coating of the electrically conductive material disposed thereon to define respective transmission line resonators;
• and
• at least one hole disposed in the first end between the at least two holes, each said at least one hole defining a respective line extending through the open end of the at least one hole as a second axis substantially parallel to the first axis, the at least one hole having an inner surface portion extending from the first end toward the second end and having a coating of the electrically conductive material to define another transmission line resonator, the first and second axis being spaced a predetermined distance from each other so that adjacent resonators are spaced an equal distance from one another and the spacing between non-adjacent resonators is determinative of the frequency response of the zeros in the frequency response of the filter.