3. Characterization techniques

3.1 Wave-matter interaction

When a microwave encounters a transition between two dielectric media, three types of effects are triggered, depending on the nature of the transition surface.

• Reflection and refraction: if the surface of the material is flat, the radiation is reflected according to the laws of geometrical optics. If the second medium is more or less transparent to waves, radiation can also be transmitted through it.

• Scattering: at the sub-wavelength scale, electromagnetic radiation can interact with particles (or the surface of the material). In this case, the microwave is redistributed in space following interaction with the particle (or surface). Scattering characteristics...