Broad-band measurement for determining the complex permeability of thin films using microstrip line method

A microstrip line method for making broad-band (0.5-5 GHz) and frequency-sweep measurement on complex permeability of thin magnetic films is presented. The theoretical formulas, in which S11 is expressed as the function of μr for short-circuited and inverted microstrip line network, are derived. A sample of the micros-trip line holder is designed. An automatic measurement system of virtual instrumentation, is developed for measuring complex permeability of nano-magnetic thin films materials under microwave frequency. Measured curves for μr of FeCo-based nano-magnetic thin granule films material are given. The measurement results demonstrate that the method proposed is of high accuracy and easy operation.