Physically-based approximation of electromagnetic field quantities

Mathematical and numerical analyses are necessary for analyzing error levels and convergence behavior of numerical algorithms, but they can be of limited usefulness in selecting or developing good representations for field or equivalent current quantities. The choice or development of basis/expansion functions is often best guided by applying physical principles. This presentation summarizes the development of various field and current approximations, and discusses principles guiding their development. The focus is on bases that model equivalent currents for integral equations solved by the method of moments.