Determining polarizability tensors for an arbitrary small electromagnetic scatterer

• We propose a method to derive the polarizabilities of a meta-atom.
• The polarizabilities can be found also from experimentally measured cross sections.
• Decreasing the complexity of numerical calculations.
• Extracting polarizabilities of two bi-anisotropic particles.

In this paper, we present a method to retrieve tensor polarizabilities of general bi-anisotropic particles from their far-field responses to plane-wave illuminations. The necessary number of probing excitations and the directions where the scattered fields need to be calculated or measured have been found. When implemented numerically, the method does not require any spherical harmonic expansion nor direct calculation of dipole moments, but only calculations of co- and cross-polarized scattering cross sections for a number of plane-wave excitations. With this simple approach, the polarizabilities can be found also from experimentally measured cross sections. The method is exemplified considering two bi-anisotropic particles, a reciprocal omega particle and a non-reciprocal particle containing a ferrite inclusion coupled to metal strips.