R.I.356 Title: R\'esonances pour les \'Equations de Maxwell dans une Structure P\'eriodique Authors: H. Ammari, J. C. N\'ed\'elec et N. Vialle Abstract: This paper deals with the existence and the distribution of the resonances associated to the Maxwell system in a periodic infinite structure. By boundary integral operators method, we reduce our problem to the existence and distribution of the characteristic values of a family of periodic non-self adjoint integral operators. The distribution of resonances is completely shown. The whole paper is available as a compressed Postscript file by internet procedure FTP anonymous on host barbes.polytechnique.fr ( 129.104.4.100) in the directory pub/RI/1996 under the name ammari.nedelec.vialle_356.oct.ps.gz or by Netscape or any other www client via the CMAP www server "http://www.cmap.polytechnique.fr/"