A well‐posed problem for electromagnetic media with quadrupoles

In this paper, we consider a non‐local electromagnetic medium for which the quadrupole term in the electric induction is not negligible. After giving an outline of the physical model, the problem of Maxwell equations for such a medium is addressed by proving existence and uniqueness of solutions and a principle of constrained minimum is shown to hold as a consequence of some thermodynamical restrictions. Copyright © 2003 John Wiley & Sons, Ltd.