A WIDE-BAND WHISPERING-GALLERY MODE DIELECTRIC RESONATOR HAVING MULTIPLE HIGH-Q CAVITIES FOR HIGH-FIELD ESR SPECTROSCOPY

The behaviour of a disc-shaped dielectric resonator made of sintered a lumina and working in the Whispering Gallery Mode (WGM) has been studi ed in the frequency interval from about 8 up to about 26 GHz. Many equ idistant resonances have been detected in this frequency interval each of which being characterized by a satisfactory g-value due to the ver y good self-confinement of the microwave field which is typical of WGM propagation. Particular care has been devoted to the optimization of the coupling between the resonating disc and the microwave source. Exa mples of ESR spectra obtained on each of the detected resonances are r eported which show the variation of the lineshape with the increase of the frequency. The obtained results allow one to foresee that the sam e dielectric disc can be used for ESR spectroscopy also at frequencies much higher than those up to now exploited.