A Complex Permittivity Extraction Method Based on Anomalous Dispersion

A novel method to extract dielectric material parameters from the anomalous phase response is theoretically investigated and experimentally verified. A microstrip resonance circuit that operates in the anomalous dispersion spectrum is constructed by employing the material sample as the substrate. This topology results in a strongly dispersive transmission phase having a slope opposite to the case in normal dispersion. This unique phase reversal property facilitates the detection of the resonance frequency with higher accuracy. Furthermore, since the transmission phase and magnitude in the anomalous dispersive region are related through Kramers-Kronig-like equations, one phase measurement is sufficient to completely characterize a dielectric material. Five known dielectric samples are characterized and the extracted parameters are compared with the known parameters. The extracted dielectric constants are found to be within a 10% error range. The extracted resonant parameters are utilized in reconstructing the magnitude and phase spectra in off-resonance regions. The reconstructed and measured curves bear close resemblance.