Comparison the impedance calculation models of coil above conductive plates

In eddy current testing, coil carrying AC current is used as a sensor to detect defects in the conductor. It is an important problem to analyze the impedance variation of the coil when the probe scanning along the surface of conductor. The accurate expression for the impedance variation of the coil above conductive plates is derived in the integral form by means of the double Fourier transformation method. The same problem is also solved with the domain truncation method and the expression in the form of series is obtained. The two calculation methods are compared and found that the calculated results of the double Fourier transformation method are more accurate. When truncation radius and the number of summation terms are selected properly, the computation time of the domain truncation method can be reduced considerably and at the same time preserve the computation accuracy. The validity of the solutions is demonstrated by comparison to results obtained with the finite element method.