In the initial stage of research on MMs emphasis was put on exploring materials that potentially lead to a biaxial anisotropic (linear dichroism) effective material response [1–6]. Recently research was also extended toward the exploration of meta-atoms that affect off-diagonal elements of the effective material tensors (elliptical dichroism). It expands the number of observable optical phenomena, leading to, e.g., optical activity [7–11] bidirectional and asymmetric transmission [12–14] or chirality-induced negative refraction [15–17]. In general, investigating the geometry of the MM (the meta-atoms geometry and their arrangement) allows us to determine the form of the effective material tensors in the quasistatic limit as extensively discussed in . From such considerations it is possible to conclude on the symmetry of the plasmonic eigenmodes sustained by the MAs and on the polarization of the eigenmodes allowed to propagate in the effective medium . But in order to determine the actual frequency dependence of the tensor elements, more extended models are needed which start in their description of the MA properties from scratch .