We report on the magnetic-field dependent surface resistance of polycrystalline YBa2Cu3O7 (Tc ≃ 92 K), measured using a brass cylindrical cavity resonator, operating at 16.5 GHz in the TE011 mode. A de magnetic field Happ is applied parallel to the superconducting sample surface, and the temperature dependence of the surface resistance is measured for four different values of Happ (0 T, 0.22 T, 1 T, 5 T). An effective medium theory and the two-fluid model are used to fit the surface resistance versus temperature measurements both in zero field and for various applied fields. These results are applied to characterize the microwave properties of a polycrystalline ceramic superconductor.
