Radiofrequency Sensing Method and Algorithm of Inhomogeneous Conductive Structures

Abstract

The paper proposes a method and algorithm for frequency probing of the internal inhomogeneous structure of electrically conductive objects based on the skin effect for diagnostics and control. The essence of the method consists in frequency control of electromagnetic field penetration depth into an electrically conductive object, and according to the measured frequency characteristic of the surface impedance, the profiles of electrophysical parameters characterizing the structural properties of the medium under study. An electrical model of an inhomogeneous medium with distributed RL parameters has been developed on the basis of electrodynamic presentations. The relationship of resistance and inductance linear parameters of the electrical model with the local parameters of the conductive medium results from their relationship with the electrical resistivity and magnetic permeability of the medium. The mathematical model of an inhomogeneous conducting medium is based on the Riccati equation with respect to the impedance characteristics of the medium. The mathematical statement of the probing problem is formulated as an inverse operator problem solution of mathematical physics. A numerical iterative algorithm for inhomogeneous medium frequency sensing based on Tikhonov regularized solution of the inverse problem is proposed. The proposed algorithm can also be extended to probe the internal structure of semiconductor and low-conducting objects containing a capacitive component in the impedance. The results of numerical simulation of the proposed algorithm for various distributions of inhomogeneity in the frequency characteristics of the impedance, measured with a known error, are presented. Solutions to various control and measurement problems in thermophysical applications based on the proposed method are given in the patents of the authors.