A comparison of two spherical wave expansion techniques

A comparison of two spherical wave expansion techniques, the first a mature technique based on scalar spherical wave mode coefficients (SSWMC)/vector spherical wave functions (VSWF) and, the second, a recently proposed technique based on vector spherical wave mode coefficients (VSWMC)/scalar spherical wave functions (SSWF), is presented. A qualitative discussion comparing the relative efficiency, complexity, and applicability of the two techniques is offered. Numerical results for a circular aperture are given to support a quantitative comparison. The two spherical wave techniques are found to be essentially equivalent with the first technique benefiting from its maturity.