FIELD DISTRIBUTIONS IN LOOP-GAP RESONATORS

Maxwell's equations for cylindrical loop-gap resonators used for EPR spectroscopy have been solved with the assumption of the existence of the magnetic z-component only. Resonant structures of the loop-gap resonators with one, two, and four gaps have been investigated. The formulae obtained were used to find the electric and magnetic field distributions numerically. Simple analytical formulae for the magnetic field inhomogeneity were also found and are in good agreement with the experimental observations that the magnetic field homogeneity is improved when the number of gaps is increased. Using the obtained E field distributions a quality factor and signal amplitude for the resonator containing a capillary filled with water were calculated numerically. In spite of neglecting the fringing electric field, the results obtained are in agreement with experiments.