3. Imaging. Goniometry of coherent sources

3.1 Antenna, spatial frequency filter

All imaging methods are based on the following fundamental property: in relation to an "object" distribution of external radiant sources, coherent or otherwise (stars, for example), a receiving antenna behaves like an angular signal filter. It provides a filtered "image". In this section, we'll look at how this filtering limits the qualities of precision and angular resolution, and how these can be improved using algorithms that take into account a priori information about the objects observed. This section is concerned with the imaging of an "object" distribution of radiant sources characterized not only by amplitudes and possibly polarizations, but also by phases.

Let's consider a directional antenna, such as that of an...