Abstract: A dielectric resonator filter having at least two poles for filtering a frequency band from an input frequency spectrum, which filter comprises (i) a body (2a, 2b) formed of electrically conductive material, which body (2a, 2b) defines a cavity (13) therein; (ii) a dielectric resonator element (1) enclosed in said cavity (13), (iii) a deformable member (6) located outside said cavity, and (iv) a metal member (4) located within said cavity (13) that is connected to said deformable member (6), the arrangement being such that, in use, said deformable member (6) is deformable to move said metal member (4) toward and/or away from said dielectric resonator element (1) to effect adjustment of a said frequency band.