Abstract：A finite-length wire source cannot be approximated as a point dipole when the distance between source and receiver is short. Usually, electromagnetic field calculation for finite-length wire sources can be achieved by two steps:discretize the wire into point dipole pieces, and evaluate several integrals to calculate each point dipole contribution. Although this is simple, the summation of point dipole fields entails significant computational cost. In this paper, we propose a fast and accurate calculation method for the electromagnetic response with finite-length wire sources. Based on the analytic solutions of electric dipole, the method solves the integral problem by discretizing the wire and constructing shape function on each element. The calculation accuracy and efficiency for both the proposed shape function integral algorithm and the point dipoles summation solution are shown on model tests. The results show that the shape function integral algorithm can achieve high accuracy even when the wire source is only divided into 2 elements. However, in order to reach the same relative error, the point dipoles summation solution needs many discrete elements. Therefore, we can conclude that shape function integral algorithm is a fast and accurate numerical method, especially when the source-receiver distances are short.
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