The eddy current testing (ECT) technique enables efficient and non-destructive conductivity measurement. However, conventional ECT is significantly influenced by the thickness of the material, often resulting in the arbitrary selection of excitation frequency. In addition, complex inverse calculations in the eddy current analytical model pose challenges for practical application. This paper proposes a method for measuring the conductivity of non-ferromagnetic materials based on a simplified analytical model. Firstly, the classical Dodd–Deeds analytical model is simplified based on the electromagnetic properties of materials under high-frequency conditions, resulting in a simplified model that directly relates the coil impedance phase to the material’s conductivity. Furthermore, in combination with a finite element method (FEM) analysis, a frequency selection criterion is proposed, and a corresponding measurement method is developed. This method enables direct conductivity calculation by substituting the measured coil impedance phase into the simplified model. Finally, experiments were conducted to verify the effectiveness of the proposed method. The results demonstrate that the proposed method accurately measures the conductivity of non-ferromagnetic materials over a range of 0.5–58.5 MS/m, achieving absolute and relative errors less than 1.05 MS/m and 1.83%, respectively, without requiring complex inversion calculations or multiple calibrations. This advancement in measurement principles provides a new theoretical foundation and technical pathway for developing online inspection systems and portable instrumentation.

The conductivity and thickness of metallic materials are crucial parameters for evaluating performance and quality. However, the eddy current (EC) method for measuring conductivity and thickness faces challenges, such as the need for multiple calibrations and complex inversion calculations. In this paper, a new simplified model and measurement method are proposed. First, according to the electromagnetic properties of non-magnetic materials at low and high frequencies, the classical Dodd-Deeds analytical model is simplified and analyzed. This derivation establishes a relationship between the phase feature of the impedance variation of the EC sensor and both conductivity and thickness, while also providing a basis for frequency selection. Additionally, a measurement method based on the simplified model is designed, which enables the simultaneous measurement of both conductivity and thickness in a single test. Finally, experiments verify the effectiveness of the proposed model and measurement method. The experimental results indicate that the relative errors in measuring conductivity and thickness are within 2.57% and 2.8%, respectively. The method directly calculates conductivity and thickness from the measured phase of the coil impedance variation, without the need for calibration or complex inversion processes, making the calculations simple, fast and accurate. These qualities make it ideal for online measurements or the design of portable measuring instruments.