Finite element modeling and identification of metallic materials step responses

The paper deals with the numerical analysis of a gradiometric coil arrangement excited by bandwidth limited step function and the identification of responses of metallic targets placed into the vicinity of the coil system. The simulations have been executed for different target materials, i.e. aluminum, steel, stainless steel and for four fictive materials differing systematically from the three real target materials in their magnetic permeability and the electrical conductivity. It was found that the changing of the magnetic permeability has a significant influence to the step response when the electrical conductivity of the target material is low, however it has a less influence to the response of the target for high-conductivity materials. It has been proved that the step response of a metallic target contains relevant information about the target material and the distance between the coil system and the target