5. Conclusion

In this article, we presented the main methods used to characterize composite materials: guided and free-space methods. We have seen that these relatively classic methods are now being joined by near-field mapping methods, which enable us to explore the physics of how these composite materials operate near their surface, as well as methods for measuring the heterogeneity of these materials. Guide methods enable rapid testing of small material samples. They are, however, sensitive to contact between the material and the guide, and do not allow incidence testing. They are relatively inexpensive. Free-space methods require a greater investment, but have many advantages. They enable non-contact testing of large structures with variable incidence and polarization. For two-dimensional structures, near-field testing and field mapping enable us to characterize the physics of the devices and make...