Novel Indeterminate EM Scattering Solver for Impenetrable Noncooperative Targets With Shape Variation

An efficient computation solver of radar cross section (RCS) is combined with asymptotic waveform evaluation (AWE) for impenetrable noncooperative targets with variable geometric shapes. Unlike traditional applications of AWE in the scalar field, involving angles and frequencies, this technique extends AWE to the vector field, allowing the combined field integral equation (CFIE) and the moment vector to be considered as functions of the shape vector. To simplify the calculation of shape vectors in the integral equation, the pseudospectral derivative method (PSDM) utilizing Chebyshev–Gauss–Lobatto (CGL) nodes is generalized to the AWE. Subsequently, coefficients of the Padé rational function are obtained, a computation that needs only be done once. Finally, the bistatic RCS is computed separately under different shape vectors. For electrically large-scale targets, the multilevel fast multipole algorithm (MLFMA) can accelerate the computation. The proposed novel indeterminate method combined with AWE (NI-AWE) is validated with numerical examples, demonstrating its accuracy. A greater perturbation radius can be obtained than the traditional perturbation method based on a Taylor series expansion. NI-AWE achieves greater efficiency than the traditional Monte Carlo (MC) method.