Magnetic polarizability tensors for low frequency object classification and detection

There is considerable interest in obtaining a low-cost mathematical description, which describes the interaction between a low frequency alternating magnetic field and a conducting object. Electrical engineers have proposed that the voltage perturbation in a coil placed in the field can be described in terms of a tensor that characterises its shape and material properties. In previous work [4], [6], we have obtained an explicit expression for the tensor's computation. This presentation extends on this to include a Bayesian inverse solution for the tensor coefficients of different objects. This has important applications in metal detectors for landmine clearance and airport security.