Relative Permittivity Measurement of Square Copper-Laminated Substrates Using theFull-Sheet Resonance Technique

摘要

The full sheet resonance (FSR) technique has been available a number of years formeasuring the relative permittivity of microwave circuit board substrates. A measurement program has been undertaken at NIST to evaluate this technique, and consistent values for the relative permittivity have been obtained. Here, we present an analysis of the theory underlying the FSR technique, along with a theoretical formulation described in the literature for related measurements, which when implemented with the FSR technique should improve the technique's absolute measurement accuracy. A theoretical analysis is presented both for the FSR technique assuming these improvements have been implemented and for the standard FSR technique. Numerical uncertainty estimates are presented for the standard FSR technique. Our measured results are compared against re-entrant cavity measuremnets for the substrate material, and it shows that both the FSR and re-entrant cavity measurements agree within expected uncertainty limits. We also present FSR measurement results for a circular cavity measurements agree within expected uncertainty limits. We also present FSR measurement results for a circular disk, fed at the center of the disk, which tend to be substantiated by the re-entrant cavity measurements.