This course addresses the fundamentals of radiowave propagation, with particular emphasis on wireless and mobile systems. An engineering approach is adopted: excessive formalism is avoided while theoretical instruments are given, so that the student can address real problems starting from a solid background.

DoD 1: Knowledge and understanding

Students will learn:

- the fundamental physical principles of electromagnetic wave propagation 

- the fundamental properties and parameters of antennas (as transducers)

- the effects of the interaction of electromagnetic waves with the environment in a nomadic/mobile scenario

DoD 2: Applying knowledge and understanding

Students will be able to:

- identify the most relevant propagation modes for a given scenario

- select and apply the correct empirical/statistical and physical/deterministic prediction models 

- predict system performance

DoD 3: Making judgements

Students will be able to:

- identify the most important design parameters of the air-segment of a wireless communication system

- choose and apply the most effective methods to counteract propagation impairments

Introduction.

Electromagnetic waves (frequency, wavelength, polarization). Nature of the waves: direct wave, reflected wave, diffracted wave, scattered wave. Multipath radio channel; mean delay and delay spread.

Antennas.

Antennas as transducers. Antenna parameters: directivity, gain, directivity function, effective area, effective length, impedance. Equivalent circuit. Link budget in free space (Friis equation). EIRP.

Nomadic systems.

Time dispersion; wideband and narrowband channel; LOS (Rice distribution) and NLOS (Rayleigh distribution); space correlation. Fading countermeasures (multiple antennas, frequency hopping, etc.). Applications: civic WiFi networks, digital broadcasting, etc.

Mobile systems.

Frequency dispersion; Doppler effect and Doppler shift; correlation in time and frequency; fading countermeasures. Applications: mobile cellular networks, inter-vehicular networks, etc.

Indoor propagation.

Reverberating environment; penetration through walls, floor and ceiling made of common indoor materials (marble, glass, concrete, wood, etc.); dependence on frequency; fading countermeasures. Applications: WiFi, domotics, UWB systems, sensor networks, etc.

Models and methods.

Optical geometry; empirical propagation models; deterministic models (ray tracing and launching, etc.); radio coverage prediction; numerical tools (examples).

Students are required to have a good knowledge of complex numbers, phasors and vector fields. Basic knowledge of electromagnetic theory can help in the learning process.

The assessment will be based on a written exam at the end of the course. The written exam consists of three numerical exercises that must be solved in two hours. Copies of past exams texts can be found on BeeP.

The objective of the exam is to assess the student's ability to:

- identify the most relevant propagation mode(s) for the given scenario

- quantitatively describe the interaction of electromagnetic rays with the environment

- quantitatively evaluate the effects of the interaction of direct, reflected and/or diffracted electromagnetic rays

- quantitatively assess the impact of countermeasures on system's performance

 The written exam is "open book", i.e. during the exam the student can freely consult textbooks, notes, etc.

In italiano - in Italian