Resonance based discrimination of targets with minor structural variations

An efficient and precise method to discriminate two radar targets with small structural variations is presented in this paper. Traditionally, target discrimination is carried out by processing the Radar Cross Section (RCS), to identify the Natural Resonant Frequencies (NRFs). The NRFs have the distinction of being aspect independent by nature. A library of distinction polynomials, based on the dominant NRFs of each known target, is built. The distinction polynomial of the known target and the RCS of the unknown target are used to complete the discrimination. In order to efficiently and accurately compute the NRFs, use of the Vector Fitting (VF) algorithm is proposed in this paper. Additionally, a refinement in the identification of the true NRFs has been carried out, by considering for the first time, the power contribution of each pole. The above modified method has been successfully validated by determining the discrimination of the three wire structures reported in literature. Subsequently, it has been applied to discriminate aircraft of size λ/2, with two locations of the tail plane. Modifications have been proposed in this paper in calculating the risk value, which helps in improving the discrimination at various aspect angles.