Investigations on EM field coupling in dielectric resonator

A structure consisting of a dielectric resonator (DR) placed on a substrate with a spacer in between is considered. The axisymmetric mode of coupling is considered. The theoretical expressions for the resonance fields are derived. The coefficient of coupling between the DR and the microstrip line is numerically evaluated for the limiting case where the height of the spacer goes to zero and with the assumption that the fields in the free space region outside the body of the DR and at the top of the substrate is negligibly small. The numerical results show excellent agreement with the experimental results. The effects of the substrate thickness on the coupling coefficient are also examined