Broad-Band Measurements of Electromagnetic Properties of Film-Shaped Materials Using Striplines

Two broad-band techniques for measuring the electromagnetic properties of isotropic film-shaped materials are presented. The electromagnetic properties are computed from S-parameter measurements of coplanar and microstrip lines. These lines can be used as cells, propagating the quasi-TEM mode. The measurements are easy to be implemented. They are carried out with a network analyzer and on-wafer systems covering 0.05–40 GHz. The quasi-TEM dispersion is very low for a coplanar cell shape such as h>W+2S. Thus, an extraction method of the coplanar substrate properties (εr,μr) has been developed from analytical relationships. It is faster than the microstrip extraction method, which requires a numerical analysis method of the propagation in order to take into account the quasi-TEM dispersion. Moreover, a theoretical study of the electromagnetic propagation through these cells is presented. It has allowed us to determinate the best cell to be used according to the material properties to be characterized. Measured εr and μr data for several materials are presented in the 0.05–40 GHz frequency range. These techniques show good agreement between measured and predicted values. However, the loss tangent measurements of low-loss materials are not possible with these techniques.