Lipton, RobertSchweizer, Ben2017-03-062017-03-062016-12-19http://hdl.handle.net/2003/3584110.17877/DE290R-17865We analyze the time harmonic Maxwell's equations in a geometry containing perfectly conducting split rings. We derive the homogenization limit in which the typical size of the rings tends to zero. The split rings act as resonators and the assembly can act, effectively, as a magnetically active material. The frequency dependent effective permeability of the medium can be large and/or negative.en610preprintHomogenisierung <Mathematik>