Chirality in the Maxwell Equations by the Dipole Approximation

In this paper, we show how chiral materials are realized by embedding chiral objects (helices) in an isotropic medium. More precisely, we derive the Drude-Born-Fedorov constitutive relations, governing the propagation of electromagnetic waves in chiral media, from the standard constitutive relations for a homogeneous, isotropic medium by embedding in the medium a large number of regularly spaced, ramdomly oriented helical conductors, each modeled as a dipole.