The contents of this book “PRINCIPLES OF RADIO FREQUENCY ANALYSIS with emphasis on computer simulations of satellite constellations” will be of great help on the design and detailed visualization of any satellite constellation in geometrical orbits of any type. The MATLAB files (Examples), referred in the Chapters, may all of them be downloaded from www.bubok.es in the “pdf” file “EXECUTABLE PROGRAMS-Principles of RF Interference Analysis”. In summary, in Chapter 1 this book will give a general introduction to the uses of the electromagnetic spectrum, not only those related to the emissions of human origin but also the observations of those produced by Nature. In Chapters 2 to 4 the introduction and programs (Examples) related to directive antennas, the process of signal detection and different types of modulation are given. These Chapters also provide a valuable introduction to the actual design of digital systems. A classic definition of interference, I/No, as well as the analysis of different interference scenarios between wide and narrow-band modulations is given on Chapters 5 and 6. The modeling of near-Earth circular and elliptical orbits, interference scenarios with these satellite constellations as well as with the geostationary orbit and space-to-space links will complete Chapters 7 to 11. Finally in Chapter 12 the Moon is used as an illustrative example to the application of the previous Examples to other celestial bodies.