BOOK REVIEWBOOK REVIEWRay Perez,
Associate Editor
In this book review, we address an introductory EMC book written for the undergraduate level of teaching. This book has been well researched and well written by the author. The material of the book seems to have originated from many technical papers published by the EMC community over the last 15 years (I recognize much of this material). The author has done a good job in compiling all this material together in a concise and understandable manner. The book is made up of 13 chapters and 4 appendices and covers the fundamentals of a senior level EMC engineering course.
Chapter 1 is introductory in nature and outlines some of the early history of EMC as an art and science from the pre-W.W.II era to today’s modern standards. The chapter also describes some basic definitions and provides some examples of practical experiences concerning EMI situations such as high voltage transmission lines, switches/relays, biological effects, aircraft navigation, etc. Some discussion concerning the present and future demands of frequency spectrum and the EMI implications are also discussed. Chapter 2 addresses some natural and quasi-natural sources of EMI; specifically, the work is dedicated to lightning, electrostatic discharge (ESD), and electromagnetic pulse. Each of these subjects are introduced briefly but with sufficient detail for a good conceptual understanding. It includes also some models representing the effect of the phenomena.
Chapter 3 provides a description of several sources of electromagnetic noise in electrical, electromechanical, and electronic apparatus. The electromagnetic noise accounted for is the one originated within these apparatus. Among the noise sources described are: systems (e.g. radar, aircraft, communications systems, mobile transmitters, power lines), relays and switches, including those in telephone equipment, and nonlinear sources such as rectifiers, mixer, logic in digital circuits. Simple noise models for amplifiers and modulation techniques are introduced. The chapter next explores the well-known subject of interference coupling through crosstalk for multi-conductor lines. Finally, the chapter ends with an introduction on the subject of field to wire coupling.
Chapter 4 follows an alternate approach in describing electromagnetic interference using analytical macromodels of statistical nature when EMI is assumed not to be of a deterministic nature but instead random and non-Gaussian. In such an approach, EMI is expressed as a function of random variables or stochastic variables. Analytical models that are based on statistical physical information combine the physical and statistical description of general EMI.
Chapters 5 through 7 are dedicated to EMI measurements. Actually, in this reviewer’s opinion, these are the best chapters in the book where the subject of measurements is well discussed. Chapter 5 addresses open area test site (OATS) measurements for radiated emissions and radiated susceptibility. Several important issues related to OATS are discussed, such as: a) the type of test antennas, b) measurement considerations such as the electromagnetic environment, scatterers and power cable connections, c) the shape and proper sizes of OATS, d) measurement configurations (the stationary EUT vs the stationary antenna), and e) terrain roughness. The chapter then addresses the very important subject of OATS and normalized site attenuation measurements (for far zone electric field). Using calculations of the maximum electric field possible in the presence of a conducting plane, the horizontal half-wavelength dipole, the vertical half-wavelength dipole, and a general antenna electric field expressions are calculated. Several sections are also dedicated to the concept of site attenuation, measurement test site imperfections and antenna factor measurements. Chapter 6 covers the material of radiated emission measurements using other facilities besides OATS. Among the facilities discussed are the anechoic chamber, the TEM cell, the reverberating chamber and the GTEM cell. For each of these testing facilities, the chapter describes the physical fundamentals of such facilities and how measurements are usually performed in them. The chapter ends with a brief comparison among the testing facilities. Chapter 7, which is the last of the measurement chapters, addresses the subject of conducted interference measurements. Among the subjects discussed are: a) electrical transients and other disturbances carried by electrical power supply lines, their characterization, and approaches to measurements, b) procedures for the measurements of conducted EMI (power line or signal line) originating from the operation of electronic equipment, and c) procedures for determining the immunity of equipment under test to conducted interferences. It is this chapter where the concepts of differential mode and common mode currents are discussed and how to perform such measurements.
In Chapter 8 the book addresses the concept of interference due to pulse interference or interference caused by pulses or transients. There are three types of pulses covered in the chapter: electrostatic discharge, fast electrical transients/burst, and electrical surges. Most of the chapter is dedicated to ESD and it includes the physics of ESD and the proper way of doing ESD testing (there is also a section on the usage of ESD testing hardware). Test set ups include table-top apparatus, standing equipment, and in-situ. Electrical fast transients are generated when inductive, capacitive circuits are interrupted from inductive loads such as relays, coils, timers, motors, or contactors that generate arcs of different kinds. Test beds for electrical fast transient immunity and some physical examples of burst generators are discussed. The chapter ends with a discussion of high voltage surge testing per IEEE standards.
Chapter 9 addresses the subjects of grounding, shielding, and bonding that are usually the most popular subjects within EMC. As in other EMC books, the subjects are well covered with the help of the many good papers in this area that have been written over the last 20 years. Among the topics covered are: earthing of facilities and other systems (including the concept of earth impedance, single rod electrons, multiple rods, and measurement of ground noise resistance), single point/multi-point grounding, cable shield grounding, shielding and shielding effectiveness (theory of single and multiple shields), shielding materials, discontinuities and apertures in shields, cable shields, measurements of shielding effectiveness and an introduction to bonding issues.
Common mode filters are discussed in Chapter 10. Conventional filter analysis and design is a well-established science except that all this work assumes that the filter is ideal. This chapter covers mainly power line filters. Impedance mismatch effects are considered (i.e when load and source impedances are different). Lumped element low-pass filter types are considered such as capacitor filter, inductor filter, LC filter, the pi and T filter, lossy lines, and active filter. High pass/low pass filters and band reject filters are also considered briefly. The chapter ends with the subject of power line filter design for common mode and differential mode current suppression.
Chapter 11 addresses the importance of proper cable selection in achieving electromagnetic compatibility and minimizing interference. Among the topics discussed are absorptive cables (such as the single braid, double braid, foil, and their application depending upon the frequency and shielding effectiveness desired). Ribbon type cables are also discussed. The role of connectors in shielding effectiveness is discussed such as pig-tail effects, connector shielding and the “rusty bolt effect”. Together with connectors, EMC gaskets and the different kinds of gaskets most commonly used in the industry are reviewed. A couple of more items discussed in this chapter are the isolation transformer, which suppresses common mode and differential mode interference, and optical isolators to greatly reduce electromagnetic interference in signal transmission lines. The chapter ends with a brief discussion of transient suppression devices (gas discharged tubes) and semiconductor devices (varistors and zener diodes).
In Chapter 12, the concept of frequency assignment and spectrum conservation are discussed. Frequency allocation is important in order to make the several radio services function in a compatible manner without electromagnetic interference among each other. The increasing demands on the frequency spectrum necessitates the development of methods and frequency assignments for spectrum efficiency. The chapter outlines the principles of frequency assignment and proper spectrum usage. The final chapter, or Chapter 13, briefly covers EMC standards most familiar to the EMC community.
In summary, the book is well written and can be recommended as an introductory EMC book.
The natural growth of every organization requires new leadership from time to time in order to ensure that the leaders keep their ‘edge’. When I received the appointment as chair of the Education Committee in 1993 I had no idea how long that tenure should last. Within this last year I no longer had any doubt. It had become obvious, at least to me, that I no longer had the ‘edge’.
Fortunately, we have an excellent candidate for the chair of Education. Most of our members already know Dr. Maqsood (Mac) Mohd from attending the “Fundamentals Tutorials” that he masterminded and organized at the last four IEEE EMC-S symposia. Many may not have realized that Mac was also the Vice-Chair for Education. Based upon his experience within the Education Committee, and his record of contribution to the society, the Board of Directors followed the recommendation of the Committee Executive Board and appointed Mac as the Chair of the Education and Student Activities Committee.
I hope everyone in the EMC Society will join me in welcoming Mac as the new Chair of the Education Committee. I also hope many of you will also consider how you may be able to help the Education Committee. Many EMC-S members have talents, abilities, knowledge and skills that can significantly contribute to EMC-S Education activities. If you would like to help, please join us at the Symposium in Denver or contact Mac in Denver. The Education Committee meeting will take place on August 25th at 7:00 am (sorry about that) in the Plaza CT room in the Adam’s Mark Hotel. Please check the hotel directory when you arrive to catch any last minute changes.
With the Education Committee in good hands, I can just sit back and relax, right? Well, not exactly. The policy and procedures of the Education Committee prescribes that the recent past chairs remain in close communication with the current Chair in order to lend support when needed, guidance when asked and in general, kibitz from the sidelines on the activities of the new Chair and the Executive Committee.
At our meeting in Denver there will be opportunities for a major re-alignment of the personalities within the Education and Student Activities Committee. Most sub-committee positions usually remain under the direction of the persons who volunteered and were confirmed into that position from year to year. However, the Chair and the Executive Committee have the duty to review current activities of each position and make changes which they feel would be in the best interests of the Society as a whole. To quote the Policy and Procedure Manual, “Committee chairpersons, members at large, liaisons to other organizations, etc., shall be appointed at the discretion of the Chair with the consent of the executive board”.
I hope to see you in Denver.
Kimball Williams
Past Chair
Education and Student Activities Committee