Physical optics analysis of multiple interactions in large scatters using current modes

An efficient scheme based on physical optics (PO) to analyze the mutual interactions between the parts of large bodies is presented. The PO current is approximated by current modes, defined as complex exponential functions. Both the body geometry and the current modes are represented by means of nonuniform rational bi-spline surfaces functions. The current modes are computed by extrapolation considering the current values in a set of sampling points. A new interpolation scheme to obtain the phase of the current modes using samples of the spatial frequency is presented. The field due to the current modes is calculated efficiently using analytical expressions. Some results are also presented that show the performances of the method.