A modified dipole model for target discrimination in EMI sensing

As an inverse problem, UXO (unexploded ordnance) discrimination requires fast forward models to estimate the response of target to sensor sources. In EMI sensing, the most well developed models approximate an object using frequency (or time) dependent magnetic dipoles. If the dipole moments at each frequency are independent model parameters, the number of unknowns in the inverse problem will be very large, particularly when multiple dipoles are required. Here we introduce a modified dipole model, in which a small number of model parameters are needed to describe each element of magnetization tensor. The modified model simplifies the inversion process, which makes it more suitable for real field applications, especially for highly contaminated UXO sites.