Chirality in the Maxwell equations by the dipole approximation

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