Object Identification With Minimal Precomputed Library Using Physical Aspect of Singularity Expansion Method

In this letter, we propose a method for estimating the circumferential length of metal objects without any
a priori
information regarding object shape and dimension. Object type can also be determined using this method with a reduced precomputed library consisting of the quality factor of fundamental natural resonance frequency and the ratio of second-order to first-order damped resonance frequency for each object type. The proposed method is applied to identify different canonical objects. Natural resonance frequencies, extracted using the matrix pencil method of singularity expansion from the scattered field from different metal objects, have been validated with physical reasoning. Simple methods for predicting the resonance frequency of triangular plates and discs have been proposed.