Fast and accurate extraction of complex permittivity from surface imaging with SPDR scanner and hand-held VNAs

The work proposes and validates a methodology for efficient imaging of material samples with a recently developed portable 2D scanner incorporating a 10 GHz split-post dielectric resonator and driven by a low-form-factor vector or scalar network analyser. First, experimental studies are conducted to evaluate the influence of the network analyser operating parameters on the accuracy and stability of complex permittivity extraction. The settings of 1 kHz intermediate frequency bandwidth and 200 frequency points within the measured band are selected, as a cost-to-accuracy compromise. Then, a post-processing procedure based on Lorentzian curve fitting is applied to the raw response, to further enhance the measurement accuracy and stability. The methodology is applied to three materials, and a 2D scan of a laminate sample demonstrates the achieved efficiency.