Improved Technique for Extracting Parameters of Low-Loss Dielectrics on Printed Circuit Boards

The paper is devoted to a methodology and an improved technique of characterization of low-loss dielectrics on printed circuit boards. The technique is based on measuring S-parameters and recalculating them into complex propagation constant. Phase correction is proposed to assure that the phase constant passes through zero at zero frequency. An effect of dielectric loss upon a dielectric constant is considered in the analytical model for dielectric parameter extraction. Dielectric and conductor losses are separated using a model, which includes surface roughness of conductors. Network asymmetry is taken into account in the model. Extracted parameters for frequency-dispersive dielectrics satisfy Kramers-Krönig causality relations. The proposed model allows for extracting dielectric constant and dissipation factor with an increased accuracy.