A Novel Waveguide Approach for Electromagnetic Characterization of Inhomogeneous Materials

In this paper, a novel approach is presented for determining the electromagnetic (EM) parameters of the lossy and dispersive inhomogeneous material loaded in the waveguide. The state-space approach is used for the parameter retrieval in the waveguide structure. In order to enhance the accuracy of reconstructing the inhomogeneity profile, a novel technique is suggested based on the hybrid of lateral dimension diversity and the Fourier series expansion. The validity of the proposed approach is verified for some applicable and practical types of the inhomogeneous material. The approach leads to a stable and unique converged solution due to the system of linear equations, which can be easily solved. Unlike the previous investigation based on the state space, the presented approach can determine the EM parameters of the lossy and dispersive inhomogeneous material in the wide microwave frequency range. The measurement setup is fabricated based on the presented approach in order to characterize the two-layered sample. From the practical point of view, the proposed waveguide characterization approach eliminates the common drawbacks in the free space system such as large sample size, fault in the calibration, and the common error due to the imperfectness of the anechoic chamber and environmental noise.