Non-Iterative Method for Extracting Complex Permittivity and Thickness of Materials From Reflection-Only Measurements

In this article, a non-iterative method is proposed to extract unique and stable complex permittivity of materials under test (MUT) from reflection-only measurements without the prior thickness knowledge of the MUT. And the thicknesses of the MUT can be determined by the proposed method. The derived formulas for the extraction are as simple as those of the well-known Nicolson–Ross–Weir (NRW) method. A silicon carbide (SiC) sample with thickness of 2.02 mm and a black Bakelite (BBL) sample with thickness of 6.03 mm are measured in the $X$ -band to validate the proposed method in complex permittivity determination without prior knowledge of the thickness of the samples. The thickness errors of the proposed method are similar with those of the methods in the literature. The low-loss material acrylonitrile butadiene styrene (ABS) with thickness of the 8.56 mm is fabricated to validate that the proposed method can overcome the resonance problem. Additionally, the simulations are also implemented to further validate the proposed method.