Comment I on “Resonant and antiresonant frequency dependence of the effective parameters of metamaterials”

Abstract

Noting that the imaginary parts of the permittivity and permeability of any linear, homogeneous, passive, dielectric-magnetic material are always positive, independent of the signs of their real parts, we conclude that recent claims by Koschny [Phys. Rev. E 68, 065602 (2003)] are unphysical. © 2004 The American Physical Society.