17938 - Electromagnetic Fields Propagation (L-A)

Learning outcomes

This course aims to illustrate the basic principles of electromagnetic waves propagation and apply them to design a free space transmission system. To this purpose, also the main parameters of antennas will be introduced, considering only very simple cases.

Course contents

• Theories to study electromagnetic fields propagation
• Vector theory
  Basic principles. material constitutive relations.
  Poynting and Uniqueness Theorems (in the time domain).
  Field polarization. Time harmonic fields and complex vector quantities.
  Harmonic regime fields. Poynting, Uniqueness, Equivalence Reciprocity Theorems.
  Discontinuities and surface currents. Perfect electric and magnetic conductors. Duality principle.
  Propagation in homogeneous media: Helmholtz equation.
  Solution of the Helmholtz equation in domains without field sources. Plane waves and their classification.
  Effect of discontinuities. Reflection and refraction. Total reflection and refraction.
  Stratified media.
  Plane wave beams propagation. Parabolic approximation.
• Scalar theory
• Geometrical theory
  Ray equation.
  Optical path.
  Reflection and refraction explained using Fermat principle.
  Limits in geometrical optics: Fresnel ellipsoid.
• Antennas
  Solution of Maxwell equation when sources are present. Scalar and vector potentials. Green function method.
  General features of antennas.
  Elemental current. Field radiated by an elemental current. Near and far field approximations.
  Antenna equivalent moment.
  Fundamental parameters of an antenna: radiation intensity, radiation function, directivity and gain. Effective area.
  Composite antennas and arrays.
• Link power budget
  Friis formula.
  RADAR equation.

Readings/Bibliography

Texbook : Paolo Bassi, Lara Scolari, Rossella Zoli, "Propagazione di onde elettromagnetiche", CLUEB 2006, http://www.clueb.com/servlet/SchedaArticolo?cat_id=2645

Further reading : websites   http://elearning.ing.unibo.it   and http://pbassi.deis.unibo.it/Avvisi_agli_studenti.htm (in italian, access restricted to students of the course)

 

Teaching methods

During lecture hours, the general pinciples of electromagnetic fields propagation in free space and the main features of antennas are illustrated. 

Practice hours (in the classroom or in the laboratory, taking advantage of dedicated software) illustrate examples of application of the theoretical ideas illustrated during lectures, showing how they are useful in practice to solve real problems.

At the end of the course, students will know the general principles of electromagnetic theory, the main features of the different models developed to study electromagnetic propagation and the relevant limits. They will then be both able to critically evaluate the most suitable model to apply and the precision of the results it may provide and to apply them to solve problems of technical interest.

Assessment methods

The exam consistes in a written and an oral part.

The written part may be split in two parts (the former during the course, the latter after its end) or a single one (after the end of the course).

Once the written part is passed, the oral part takes place and concludes the exam.

The written parts aims to check that the student can apply the studied theory solving some exercises.
The oral part aims to check the knowledge and the understanding of the general principles of the studied theory and his ability of discuss them with propriety of language.

Teaching tools

Perconal Computer with dedicated software.

Office hours

See the website of Paolo Bassi