Abstract: A method and apparatus for reducing the size of microwave (or millimeter wave) dielectric resonator filters and for tuning the filter by inserting tuning screw within the dielectric itself. The filter includes a metallic housing that encloses a plurality of cavities, and each cavity contains a dielectric resonator whose top and bottom surfaces are flush with the top and bottom walls of the metallic structure. Due to the continuity and uniformity of the electric field generated in the y-axis of the dielectric, the filter's performance response becomes independent of height. This novel design allows for substantial reduction in cavity size without appreciably dropping the Q factor. Such continuity and uniformity of the electric field also allows for openings to be made parallel to the y-axis and inside the dielectric resonator, wherein tuning screws are inserted to selectively adjust the frequency.