Electromagnetic characterization of rectangular ferroelectric resonators

An optimized geometry for a rectangular ferroelectric resonator (FR) is proposed to increase signal-to-noise ratio in EPR spectroscopy. To develop optimization criteria, the distribution of the microwave electromagnetic field in the FR is computed and analyzed. The computations, based on solution of Maxwell's field equations, were made for two types of rectangular FRs-a FR with a hollow sample hole and a FR with a blind sample hole. To introduce the samples, a hole was drilled through the resonator with its axis aligned to the axis of the FR. We computed and studied the spatial distributions of H- and E-components of the microwave electromagnetic field for two rectangular FRs, made of single-crystal potassium tantalate, with the following sizes: 1.9 × 1.9 × 1.4 mm3 and 1.7 × 1.7 × 3.1 mm3. As analysis of the obtained data indicated, in both resonators, the lowest mode was TE11δ. By analyzing the distribution of the microwave field in the FR and comparing it with the experimental result, we developed optimization criteria for the geometry of a rectangular FR.