# 28719 - Electromagnetic Fields T-1

### Course Unit Page

• Teacher Paolo Bassi

• Credits 9

• SSD ING-INF/02

• Language Italian

• Campus of Bologna

• Degree Programme First cycle degree programme (L) in Electronics and Telecommunications Engineering (cod. 0923)

## Learning outcomes

Understanding of phenomena concerning free and guided propagation of electromagnetic fields and their use in telecommunication systems. Knowledge of transmission lines and of the most used waveguides. Ability to solve matching problems.

## Course contents

1. Theoretical models to study electromagnetic fields

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 and Reciprocity Theorems.
Discontinuities and surface currents. Perfect electric and magnetic conductors. Duality principle.

Scalar theory

Geometical theory
Ray equation.
Optical path.
Limits in geometrical optics: Fresnel ellipsoid.

2. Maxwell's equation solution

Without sources
Helmholtz equation.
Solution of the Helmholtz equation in homogeneous media: Plane waves and their classification.
Effect of discontinuities. Reflection and refraction. Total reflection and refraction.
Stratified media.
Plane wave beams propagation. Parabolic approximation.

With sources.
Scalar and vector potentials.
Green function method.

3. Guided propagation

Transmission lines
Cylindrical structures.
TEM, TE, TM, Hybrid modes.
TEM modes: Basic equations
Low loss transmission lines.
Propagation and attenuation constants.
Mention of guiding structures: coaxial cable, dielectric slab, optical fibers.

Loaded lossless transmission lines: Voltage Standing Wave Ratio.
Smith chart
Impedance matching with distributed elements: single stub, double stub, quarter wavelength, principles of multisection transmission lines.

4. Free space propagation

Antennas
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

Friis formula.

Textbook : Paolo Bassi, Chiara Zaniboni, "Introduzione ai campi elettromagnetici", Bologna University Press, 2016

The textbook contains a rich list of references for further reading/study.

Further support material

Further lecture slides, external links relevant to the course, self evaluation tests, computer codes, etc available at http://iol.unibo.it (access with student's UniBo username and password)

## Teaching methods

During lecture hours, the general principles of free or guided propagation of electromagnetic fields in view of signal transmission are illustrated.

Practice hours show examples of application of the theoretical ideas illustrated during lectures. Solution of numerical exercises show how the theory can be used to solve simplified real problems. Examples of everyday life use of the theory and engineering applications described in future courses will be illustrated as well.

During the course, some tests are proposed in the classroom to verify the general level of understanding. Such tests can also be done autonomously for self evaluation purposes. They are intended as support to the students and have then no effect on the exam.

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 consists in a written and an oral part.

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.

The texts of the previous written part of the exams are available at http://iol.unibo.it (access with student's UniBo username and password).

## Teaching tools

Text book.

Further material available at: http://iol.unibo.it (access with student's UniBo username and password).

Use of Matlab codes made available to students. Matlab can be freely downloaded and installed by UniBo Students in the framework of the agreement between UniBo and Mathoworks at this link.

## Office hours

See the website of Paolo Bassi