Technical Approach

Target classification using standard physics-based processing of EMI data collected over a target entails inverting the data to determine the target’s location, orientation, and three principal axis polarizability curves. The inversion is based on a dipole response model in which the polarizabilities specify the target’s intrinsic electromagnetic response. In order for this procedure to yield accurate results, measurements of the response at many locations or from many directions are needed, and the locations of the sensor readings relative to each other must be precisely known. However, it turns out that the shapes of the principal axis response curves can be recovered from data collected by a small array of reciprocal transmit/receive (Tx/Rx) coil pairs without using full dipole inversion. The shapes of the response curves contain much of the information currently used for target classification. The researchers will evaluate the feasibility of employing a compact, three-element handheld EMI array that can simply be held over a suspected target location and can then classify the target on the basis of its intrinsic EMI response in real time.