84240 - Electromagnetic Compatibility M

Course Unit Page

Academic Year 2018/2019

Learning outcomes

The course provides the basic knowledge of electromagnetic compatibility of electric and/or electronic devices. Crosstalk, conducted and radiated emission and immunity are examined, with models for the analysis. Competence is developed in order to solve problems of conducted and radiated interference, with particular reference to EMI filters, methods and techniques for electromagnetic shielding and measurement in reverberation chambers. Moreover, knowledge of electromagnetic wave propagation in unbounded and guided media is provided. Particular emphasis is given to practical aspects and the classes are supported by computer and laboratory demos.

Course contents

Introduction to electromagnetic compatibility

History of electromagnetic compatibility (EMC). Basic definitions. Requirements of EMC according to the EMC Directive 2014/30/EU: emission and immunity. Electromagnetic interference model. Decibel and electric length. Choice of the electromagnetic model for an EMC problem: quasistationary and non stationary electrodynamics.

Crosstalk

Capacitive (electric) coupling. Inductive (magnetic) coupling. Capacitive-inductive coupling. Circuit models for crosstalk.

Conducted emission and immunity

Common mode and differential-mode conducted emissions. Measurement of conducted emissions: LISN and EMI receiver. Model for the assessment of conducted emissions in SMPS power converters. EMI filters. Immunity to transients and voltage variations.

Basic antennas

Electromagnetic field radiated by elemental dipoles. Electric and magnetic dipoles. Near- and far-field approximation. Near-field impedance. High and low field impedance.

Radiated emission and immunity

Models for the evaluation of radiated emissions from wires and PCB lands. Radio frequency immunity. Model for the evaluation of immunity of wires and PCB lands.

Waves in an unbounded medium

Uniform plane waves (TEM) in a lossless medium. Uniform plane waves in a lossy medium. Uniform plane waves in a conductor and in a lossy dielectric. Dispersive materials. Analogy between transmission lines and uniform plane waves. Normal incidence of uniform plane waves to a surface.

Electromagnetic shielding

Shielding effectiveness. Methods for the calculation of shielding effectiveness. Shielding of uniform plane waves. Study of an electrically short structure with the diffusion equation of magnetic vector potential and application to multilayered shielding. Shields with apertures. Transfer impedance of enclosures, cables, connectors, junctions. Techniques for the measurement of the shielding effectiveness. Shielding materials.

Rectangular waveguides

Solution of the wave equation in a rectangular waveguide filled with a lossless dielectric. Transverse magnetic (TM) and transverse electric (TE) modes. Wave propagation in a guide.

Reverberation chambers

Generalities. Resonant frequencies. Application to EMC measurement. Test equipment. Mode stirring and mode tuning. Validation of the chamber. Measurement of shielding effectiveness of materials, enclosures, cables, connectors, gaskets.

Readings/Bibliography

C. R. Paul, Introduction to Electromagnetic Compatibility, Wiley, 2006

H. W. Ott, Electromagnetic Compatibility Engineering, John Wiley & Sons, 2009

P. A. Chatterton, M. A. Houlden, EMC Electromagnetic Theory to practical design, John Wiley & Sons, 1991

Teaching methods

Laboratory demos will help students to better understand the material covered in the lessons.

Assessment methods

Oral exam.

Teaching tools

Handouts of slides are available to students.

Office hours

See the website of Leonardo Sandrolini