Broad-band characterization of magnetic and dielectric thin films using a microstrip line

A measurement method for the broad-band determination (100 MHz-10 GHz) of the permeability and permittivity of thin films with thicknesses of 1-10 μm has been developed. The technique is based on the measurement of the S parameters of a microstrip line loaded with the test sample. The S parameters are measured with a network analyzer. Besides its band width, the original feature of this method in comparison with existing techniques lies in the fact that the thin film does not entirely fill the cross section of the cell since it is directly laid on the substrate of the microstrip line. This leads to a simple and reproducible measurement process. It also permits the propagation of the electromagnetic wave along the film width of about a few millimeters, thus increasing the measurement accuracy. Moreover the method remains reliable for the characterization of bulk materials with the same cell and data processing program