An EPR resonator is constructed by inserting a pair of. dielectric ceramic rings in an unmodified rectangular TE102 cavity. It is tuneable over the range of 8.0-10.0 GHz. Therefore, existing EPR cavities can be easily converted to resonators with superior signal-to-noise ratios that are at least 24 times larger than the original ones in this extended frequency range. The resonator's performance is tested using DPPH, TEMPONE, MnO and Cu2+ complexes and displays excellent resolution and sensitivity. Thus EPR spectra of small paramagnetic organic and inorganic samples and spin labeled biomolecules may be obtained without resorting to loop gap resonators. (C) 2003 Elsevier Science B.V. All rights reserved.