70119 - Guided Propagation

Learning outcomes

After completing the course the student will have the basic tools for understanding the propagation phenomena of the electromagnetic field, with particular attention to  emission,  free space propagation and reception of radio signals. In particular, the student: - will know the basic fundamentals of electromagnetism, the  formulation of Maxwell equations and of the corresponding equations which yield the propagation of waves (wave equations, Helmholtz equation)s - will know the general techniques for solving the problem of Maxwell in the presence or absence of sources of the electromagnetic field; - will know the most important characteristics of an antenna (directivity and gain, efficiency, radiation surface and radiation diagram) and their meaning; - will be able to design a simple radio link with antennas optimized in polarization using the equation of Friis.

Course contents

Basic postulates of Maxwell's theory. Maxwell's Equations (ME) in integral and differential form and interpretations. Field continuity over a plane surface. Time-harmonic fields: complex vector formulation of ME. The basic theorems: Unicity and Poynting's theorems.
Solution of the Maxwell's problem in free space: wave equations in the time and frequency domain. Helmholtz equation and plane wave expansion of the field. Analysis of a TEM plane wave: characteristics, reflection on a perfectly conducting or dieletric surface. Guided propagation principles.
Maxwell's problem in presence of a generic current source. The magnetic vector potential procedure. Solution in the case of a linear current element, and integral solution in the case of an extended source. The near field and the far field concepts. The radiation vector of an antenna. Far field approximations and interpretation as a spherical wave: energy conservation, attenuation with distance, local plane wave approximation.
Basic antenna characteristics: radiation pattern, gain, efficiency, directivity etc. Emission and reception: effective area and gain. Friis equation and its applications. Radio link design fundamentals.
Complementary and practical
Polarization. Visualization of the e.m. field through software tools.
The electric and magnetic potentials. Quasi-static regime: circuit model approximation. Lumped constants circuits. The Kirkhhoff current and voltage laws, the generalized Ohm law. Distribuited constants circuits.
Practical examples. Examples of examination written test.

Readings/Bibliography

- Duplicated lecture notes ( available on my website: http://www.elettra2000.it/vdegliesposti/  )
- P. Bassi et alii, "Propagazione di onde elettromagnetiche", Ed. CLUEB, 2006
- V. Rizzoli, Lezioni di Campi Elettromagnetici, Propagazione libera e antenne, Ed. Progetto Leonardo, Bologna
- G. Conciauro - Introduzione alle onde elettromagnetiche, Mc. Graw Hill (English version available)

 

Teaching methods

The teaching method is inductive: from practical problems and experiments to theorization.  Some parts are deductive.
The course mostly consists of direct lessons with the aid of a blackboard. Active participation of the students in the solution of theoretical and practical problems is encouraged throughout the course.

 

Assessment methods

The exam consists of an a one-hour written test and of an oral test. The final mark is the synthetic evaluation of both written and oral tests. Students are allowed to vision and discuss the written test manuscript only during the oral test. If written test average mark is insufficient (below 18 out of 30) the candidate must skip the oral exam and take the whole test again on a successive exam date.
Exceptions to the above mentioned rules will be considered and discussed case by case.

Teaching tools

Blackboard. PC. Projector.
Didactic antenna set including generator, sample antennas, receiver and tools .

 

Office hours

See the website of Giovanni Tartarini

See the website of Franco Fuschini