Abstract

In this paper, we take a fresh look at the determination of the transition matrix for a homogeneous, biisotropic particle employing the Null-field approach. The condition for passivity of the material is discussed. In particular, we focus on some previously unproved properties of the Beltrami spherical vector waves, such as completeness, orthogonality, and linear independence, which are all instrumental in the analysis of the scattering problem with the Null-field approach. Some numerical examples illustrate the approach.