Abstract: A re-entrant dielectric ceramic resonator and filters incorporating a plurality thereof are suitable for use in mobile and portable radio transmitting and receiving devices. The inventive re-entrant dielectric ceramic resonator comprises a dielectric means comprised of a dielectric ceramic material having a top surface, a bottom surface and outer side surfaces, the top and bottom surfaces being flat and parallel to each other, the dielectric means further having a cylindrical hole extending partially from the top surface toward the bottom surface thereby forming an inner side surface and an inner bottom surface, the inner bottom surface being flat and parallel to the bottom surface.