EFFECTIVE-MEDIUM APPROACH TO THE MICROWAVE PROPERTIES OF THE HIGH-T(C) SUPERCONDUCTOR-INSULATOR COMPOSITES

We study microwave transmission through composites consisting of small YBaCuO (BiSrCaCuO) grains embedded in a polymer host. For these compo sites we evaluate: (a) the effective dielectric constant epsilon, (b) the effective magnetic permeability mu, and (c) the losses. We demonst rate that epsilon almost does not change upon transition to the superc onducting state while mu changes considerably. The dependence of mu on the volume fraction of superconductor is well described by the Clausi us-Mossotti approximation.