Objectives of the course
The contents of the course are organized in such a way to fit the actual position of a communication engineer. As a consequence, the course is not too applicative (useful in practice, but limited in education) neither too theoretical (specific topics can be investiagated in the scientific literature). The result is a course where, first, the physical aspects of the phenomena are duly introduced and, second, the theory behind them is addressed.
Introduction: the main protagonists in the history of electromagnetic propagation.
The electromagnetic spectrum: frequency bands and spectrum management.
Main features of electromagnetic waves (frequency, wavelength, polarization, ...) and electromagnetic characterizations of materials (electric permittivity and magnetic permeability, condictivity, ...).
Characterization of the radio channel in terms of single and multiple wave components: direct, reflected, diffracted and diffused waves.
Wave propagation in real environment. The ionosphere, the non-ionized atmosphere, and the ground. Physical characterization of the medium and electromagnetic description.
Propagation in the ionosphere and impact on Global Navigation Satellite Systems (GNSS). Refraction, attenuation, Faraday rotation, phase and group delay.
Propagation in the presence of ground. The ground wave: direct, reflected, surface and evanescent wave components, knife edge diffraction, Fresnel ellipsoids.
Propagation in the non-ionized atmosphere (troposphere) and impact on radio relay links, and Earth to space (HAPs, LEO, MEO, GEO satellites, Deep Space probes) links. Clear air propagation: refraction, attenuation and scintillation. Propagation through clouds. Adverse weather disturbances: attenuation, depolarization, electromagnetic interference due to hydrometeors.
Atmospheric and extra-atmospheric noise sources: impact on the signal detection and some concepts on passive remore sensing .
Statistical characterization of the radio channel and system design: the link budget. Fade mitigation techniques (i.e. site, frequency and time diversity, link power control).
Free space optical wave propagation: the optical channel, transmitters and receivers. Advantages and limitations of FSO. Impairments due to hydrometeors (fog and clouds), and to clear air (turbulence). Applications: ground links and Earth to space links.