A broad-band technique for determining the electromagnetic properties of isotropic film-shaped materials, which uses a microstrip line, is presented. Complex permittivity and permeability are computed from analytical equations and S-parameter measurements of microstrip cells propagating the dominant mode, Measured epsilon (r) and mu (r) data for several materials are presented between 0.05 GHz and 40 GHz, This technique shows a good agreement between measured and predicted data.