When electromagnetic radiation interacts with microstructures (either isolated or located on a surface) whose size is of the order of the incident
wavelength, scattered radiation can be detected in all directions. Furthermore, the electromagnetic characteristics of the scattered wave in a given direction may be changed due to the interaction of the incident radiation with the microstructure. This constitutes an important electromagnetic problem since long time ago and, in order to solve it some information has to be obtained about the physical scattering structure (i.e. size, shape, optical properties,
etc).