Preface xv
substantially revamped (twice), more new product standards have been published, new
test methods have become established and much has been learned to improve old tests.
Although Maxwell’s laws haven’t changed, there is more understanding of how best to
apply them to maximize the compatibility of individual products. The onward and
upward march of clock speeds and the shrinking of product, package and interconnect
dimensions has continued. And so, even if you were familiar with earlier editions, you
will find quite a lot of new material in this one.
This book is intended to help the work of the company’s EMC centre. It seems to
be serving its purpose: I have been pleasantly surprised by how widely earlier editions
have been recommended. It can be used as a reference for the EMC engineer, as
background reading for designers and technicians new to the subject, or as part of the
armoury of the development group tackling a new project. It is structured into three
parts. The first part (Chapters 1–6) discusses the legislative and standards framework
now erected to encompass EMC. These chapters are mainly non-technical in nature.
Chapter 1 introduces the subject of interference, and Chapter 2 goes on to discuss the
provisions of the EMC Directive and its new partner, the Radio Equipment Directive,
and the means of achieving compliance with them. Chapter 3 looks at the major EMC
compliance regimes outside Europe. Chapter 4 details the standards-making structure
and describes the various standards that are now in existence and which are relevant for
compliance with the Directive. Chapter 5 covers requirements for those sectors that are
only peripherally affected by the RED and EMCD: automotive, military, aerospace and
rail transport. A new Chapter 6 reviews the increasingly important subject of the
electromagnetic compatibility aspects of functional safety.
Both design engineers and project managers need to have a feel for the tests to
which their products will be submitted. As well as witnessing tests carried out by third
party test houses, it is likely that many will be doing pre-compliance and full
compliance tests themselves. The second part of the book looks at these areas. Chapter
7 covers the test methods for RF emissions that are laid down in the standards and
which have to be followed both in-house and by external test houses. Chapter 8 does
the same for the immunity tests: RF immunity, ESD and transient immunity. Chapter 9
considers the low frequency techniques, both mains input harmonics and flicker
emissions, and immunity to magnetic field and voltage dips and interruptions. Finally,
the tests do not happen by themselves: they must be planned, and Chapter 10 looks at
this sadly neglected aspect of EMC compliance.
The third part of the book discusses techniques for achieving an acceptable EMC
performance at minimum extra cost, at the design stage. It is usually possible to add
screening and suppression components to an existing design to enable it to meet EMC
standards. This brute force method is expensive, time-consuming and inefficient. Far
better is to design to the appropriate principles from the start, so that the product has a
good chance of achieving compliance first time, or if it doesn’t then modifications are
made easy to implement.
Chapter 11 covers the basic principles involved in coupling electromagnetic
interference from a source to a victim. Chapter 12 looks at the techniques which can be
applied before resorting to the more traditional methods of screening and suppression:
attention to equipment and PCB layout and grounding, and Chapter 13 discusses choice
of circuit configuration, components and software features. Chapter 14 carries on to
detail the accepted “special” EMC techniques, which include cable configuration and
termination, and filtering methods and components. Shielding theory and practice – the
two are not always related – are covered in Chapter 15. Many products are used within