“…Moreover, compound exponential (CE) PDFs arose in [14] (see that paper for definitions of α i and β i ), on the basis of partial 3D polarization of random EM free fields. While CE PDFs also produce better agreement with experiment compared to χ 2 6 PDFs at relative long wavelengths, their origin lies instead in the statistical anisotropy in random fields (especially near deterministic [16,[40][41][42] and stochastic [43][44][45][46][47] EM boundaries), unlike Bessel K PDFs that do not discriminate between spatial directions (although a generalization to statistically anisotropic fields exists [32, App. III]).…”