Title: Introduction to Electromagnetic Compatibility,
2nd Edition
Author: Clayton R. Paul
Publisher: Wiley Interscience
Publication Date: 2006
Number of Pages: 983
This review addresses the second edition (2006)
of the well-known book by Prof. Clayton Paul, Introduction to
Electromagnetic Compatibility, which first appeared in 1992. Though
I had personally read his first book, I decided to read the new
book, all over again. It took me about one month, in my spare
time, to read the almost 1000 pages of this new text (previous
edition was about 750 pages). As I was reading the text I tried
to put myself in the shoes of a senior undergraduate or first
year graduate student and ask myself the question, “Would
I understand this if it were my first experience with the subject?”
In the same spirit, I also worked a problem from each chapter
of the book and asked myself the same question. The answer to
both questions was indeed YES. The attention to all the technical
details in this book is extraordinary. The harmonization of the
contents among all the chapters to provide a progressive theme
in EMI and its control is amazing. This book was truly written
with the student in mind. It is indeed a classic in terms of the
undergraduate teaching of EMC at the college level.
The second edition of this book has been substantially revised
and re-written from the first edition. For example, the student
will enjoy a large number of worked examples in just about every
section of each chapter in the book. Each section of each chapter
also has a review exercise for the student to test the knowledge
of what the important technical points for that section is about.
Just about every problem in the back of each chapter has the answers
given, so the student can corroborate his/her effort. Most of
the problems are new. Chapters have also been repositioned (from
the first edition), which allow the flow of knowledge to build
up in a more uniform and logical fashion. Another thing the student
will enjoy is the use of PSPICE in many of the worked examples
as well as in many assignments of several chapters. PSPICE is
introduced, in a given chapter, to corroborate the theory the
students have learned and how the PSPICE modeling tool can be
used to model more complicated examples; hence, the book emphasizes
the use of PSPICE to simulate all areas of EMC analysis. The students
will also see that the book contains a CD ROM with OrCAD PSPICE
version 10 and MicroSim PSPICE version 8 (student versions) as
well as several FORTRAN programs written by the author to compute
per-unit-length parameters and also programs for the analysis
of crosstalk in multiconductor transmission lines. Though I did
not have time to try it, it would not be difficult to convert
these programs to VBasic and run using Excel. Faculty will also
enjoy this book because it simply makes teaching EMC much easier;
it is that simple. Because of my limited amount of space in the
Newsletter, as I review each chapter, the emphasis will be on
addressing the content (i.e. what is covered in the chapter; I
will leave the discussions of EMC and the technical issues to
the reader). Nevertheless, I must emphasize that the explanations
of all the EMC principles are presented in satisfying detail.
The book is made up of nine chapters and four appendices. Appendix
C is of special interest because it describes seven FORTRAN programs
in the CD for calculating per-unit-length parameters and crosstalk
analysis (with the help of PSPICE).
Chapter 1 titled Introduction to Electromagnetic Compatibility
is an introduction to the reader to the concepts of electromagnetic
compatibility; the how and why EMI happens, some history of EMC,
an introduction to electromagnetic waves, and a discussion on
how we arrive at the common EMC units (dB, dBuV, dBuA, dBmW, etc.)
with some practical examples (e.g. the treatment of power loss
in cables, and signal source specifications). Chapter 2 titled
EMC Requirements for Electronic Systems is a highly revamped version
from the first edition and it addresses the EMC requirements for
electronic systems. This was highly necessary since there has
been a lot of US and other governmental changes in EMC requirements
since the first edition was published. Therefore, the chapter
contains the latest conducted and radiated emission requirements
for US (FCC) and European (CISPR 22) commercial computing devices,
and also the latest conducted and radiated emission requirements
for US military standards (MIL-STD-461E). In addition to the requirements,
the chapter covers measurements methods for radiated emissions
(using OATS, semi-anechoic chambers) and conducted emissions (using
the LISN) measurements. The chapter briefly covers susceptibility
and ESD requirements. The chapter ends with some qualitative analysis
of the importance of EMC in the design process of a product and
some of the constraints and considerations that arise during that
process.
Chapter 3 titled Signal Spectra—The Relationship between
Time and Frequency Domain is one of those repositioned chapters
I talked about before. It went from Chapter 7 in the first edition
to now Chapter 3. The author was correct. This is the right location
for this chapter since the material in it serves as the backbone
for the rest of the book. The material of this chapter is similar
to what a junior electrical engineer student will see in a Signals
& Systems course (i.e. spectra of periodic and non-periodic
and random signals). However, the material is tailored to the
type of signals present in typical digital products. One unique
feature of this chapter (and to me the most important) is that
it develops “bounds” for the different types of spectra
which facilitates the analysis of the effects of these signals
(several good examples are given), a concept that most EMC engineers
must grasp if one wants to make quick assessments of what types
of EMI violations might be present in a given product. The chapter
also addresses measurement equipment such as the spectrum analyzer
and how it works in light of the material covered in this chapter.
The chapter ends with the use of PSPICE in Fourier analysis and
several very illustrative examples are provided.
Chapter 4 is titled Transmission Lines and Signal Integrity. This
chapter has been significantly revised when compared to the first
edition because it now includes signal integrity. This chapter,
together with Chapter 3, are a must for future EMC engineers to
master, and the rest of the book really depends upon the concepts
developed in these two chapters. I believe these are the two most
important chapters in the book. The treatment of signal integrity
is necessary because at today’s computing device frequencies,
the physical size of transmission lines (wiring, traces, etc.)
are now comparable in size to the wavelength of the circuits’
operating frequencies (or at least the wavelengths of the harmonics).
Therefore, these physical transmission lines must now be treated
as true transmission lines. The chapter starts with the general
two-conductor transmission line and then goes on to address how
to derive the per unit length parameters (inductive and capacitive)
and the characteristic impedance of such a transmission line.
Information is provided for different physical topologies such
as round wires (next two each, above ground, and shielded) and
printed circuit board lands (stripline, microstrip, PCB strips).
The two-conductor transmission line is analyzed in the time domain
and frequency domain. The analysis in the time domain includes
the graphical solution approach (basically an analytical approach)
and the SPICE model. The time domain analysis is extended to address
the development of transmission lines models for signal integrity
purposes. Both analytical and SPICE modeling examples are illustrated.
The chapter ends with modeling the two-conductor transmission
line also in the frequency domain, which allows a better introduction
for modeling the effect of losses in signal integrity. The chapter
ends with the usage of SPICE for modeling the transmission line
in the frequency domain as well as using the lumped circuit approximate
model.
Chapter 5 is titled Nonideal Behavior of Components and it has
been expanded from the first edition. This chapter develops mathematical
models that provide considerable information on the nonideal behavior
of components (resistors, capacitors, inductors) and conductors
(PCB lands, component leads) at higher frequencies (frequencies
that may go beyond the applicable government regulations but still
must be accounted for because of the needed self compatibility
of the product). It is here that the chapter introduces several
concepts (e.g. skin depth, internal inductance, external inductance,
line capacitance, characteristic impedance, loss tangent) for
wires and PCB lands that will be used later in subsequent chapters.
The nonideal behavior of certain components actually provides
advantages in reducing noise. To that end, the chapter provides
techniques for either diverting or diminishing noise at these
higher frequencies. For example, the chapter addresses in detail
the principles of using capacitance to divert noise for high impedance
loads (it does not work for low impedance loads) and the use of
ferromagnetic materials (ferromagnetic cores, ferrite beads, common
mode chokes) for diminishing noise, especially common mode noise.
It is during the discussion of common mode chokes that the book
discusses, for the first time, the concepts of differential mode
and common mode currents, a concept that is explained in more
detail again in Chapters 6 and 8. I thought the introduction of
common mode currents in this chapter was strategically correct
and well placed. The chapter ends by addressing the noise from
electromechanical devices (motors, solenoids, and mechanical switches).
Chapter 6 is titled Conducted Emissions and Susceptibility and
is essentially the same as the first edition of the book. The
purpose of the chapter is to investigate the ways by which emissions
are generated and propagated through conducted paths along the
product’s ac power cord. Conducted emissions from power
distribution systems can also radiate and make such cabling behave
as antennas. The main emphasis in the chapter is the measurement
and control of conducted emissions. A more detailed explanation
of the LISN is given. The chapter also addresses in more detail
the concepts of common mode and differential mode currents. From
the control of emissions point of view, the author discusses the
basic design, topology, workings, and EMI suppressing features
of power supply filters. Now the two concepts of common mode currents
and conduction EMI filtering come together in the chapter, as
the effects of filter elements are studied with respect to common
mode and differential mode currents, and how to separate the conducted
emissions measurements into common mode and differential mode.
Example measurements are given. The chapter ends with a discussion
on the topology and designs of different types of common power
supplies (linear and switching mode), and how the common mode
currents can manifest themselves in these types of power supplies.
Chapter 7 titled Antennas is essentially the same as the first
edition of the book. This chapter is addressed because the reader
needs to be familiar with the typical antennas used in EMC measurements.
This will provide the ability to calculate the electromagnetic
field levels in the vicinity of the product that will be used
to determine its susceptibility to interference. This topic is
also addressed because of the fact that radiated emissions are
produced by unintentional antennas and there is a need to understand
how to approximately model these antennas. The material starts
with the coverage of the simplest of all radiating elements, the
Hertzian and the magnetic dipoles, followed by the half-wave dipole
and the quarter-wave monopole. All analysis is presented in the
far field and includes the calculation of the radiated electric/magnetic
fields, average radiated power, and radiation resistance. The
analysis for general antennas is extended also to antenna arrays.
The chapter then addresses other types of antenna parameters such
as directivity, gain, effective aperture, and antenna factors
(a terminology very familiar to EMC test engineers). There are
a few examples presented on the usage of antenna factors. A very
simple model on the coupling of two antennas is addressed using
the Friis model. Because it is important to EMC testing, the effect
of reflections of EM waves and multipath effects is also addressed.
The chapter ends with an overview of the biconical and log periodic
antennas (the mainstay antennas for EMC testing).
Chapter 8 has been slightly revised in this second edition. The
chapter is titled Radiated Emissions and Susceptibility. The objective
of the chapter is to use some of the modeled radiated electric
fields presented in Chapter 7 (Hertzian and half-wave dipole)
to postulate radiated emissions models (far field only) from simple
unintentional radiating elements like wires (e.g. those found
in I/O cabling) and PCB lands. This chapter expands upon the concepts
of differential mode and common mode currents addressed in previous
chapters. The chapter presents models for radiating wires/lands
where the currents are initially differential mode and then are
common mode. Through several examples, the chapter shows that
common mode currents often are the culprits in radiating structures
producing the majority of radiated emissions, even though the
common mode current themselves may be small. The chapter shows
how to measure the common mode and differential mode currents
using current probes. Several examples are also given. The chapter
ends with simple field-to-wire coupling models and a few examples
of such.
Chapter 9 is the largest chapter in the book and is titled Crosstalk.
The chapter has been substantially revised from the first edition.
Crosstalk is a near field-coupling problem. The material in this
chapter is very detailed. This chapter, as important as it is,
is an extension of previous chapters dealing with 2-conductor
transmissions lines; whereas in crosstalk we deal with a 3-conductor
transmission line where the third conductor is the “receptor”
or victim of the crosstalk; and the objective is to calculate
the induced near-end and far-end voltages given the line cross-sectional
dimensions and the termination characteristics of the line. The
MTL lossless equations are again developed with assumed TEM propagation.
The next step is to develop all the per unit length parameters.
The chapter uses both, closed form expressions (wires are separated
sufficiently) and numerical methods (method of moments) for closely
spaced wires. The chapter does a very detailed job in this area
and includes FORTRAN programs that compute the per unit length
parameters for ribbon cables, PCB lands, coupled microstrip lines,
and coupled strip lines. The chapter develops, in the frequency
and time domains, the inductive-capacitive coupling model in a
very elegant way (intuitively and mathematically), and this is
done for unshielded and shielded conductors. Throughout this development,
the chapter presents numerous examples and provides corroboration
with experimental results. The chapter also contains a FORTRAN
program (on the CD) that contains an exact PSPICE subcircuit model
for a coupled transmission line and it is used in numerical and
experimental examples.
Chapter 10 is titled Shielding. It is essentially the same as
in the first edition. The chapter addresses the subject form an
“enclosure” point of view and the main objective is
how to calculate the shielding effectiveness of a shielded structure
under different conditions (far field, near field) and also the
effects of apertures on the shielding effectiveness.
There is a new final Chapter in this edition. Chapter 11 is titled
System Design for EMC. This chapter encourages the engineer to
take a systems approach to addressing EMC in a product design.
The objective of this final chapter is to provide applications
of the material learned in previous chapters. I find the contents
of Chapter 11 to be relatively pleasant reading after the technical
rigorousness of previous chapters. Of extreme importance, and
almost required reading, is the section on grounding. I found
this section to be one of the most insightful in the entire book.
I would certainly use this book for the teaching of EE undergraduates
or first year EE graduate students on the subject of EMC. I highly
recommend this book. EMC
Book
Review