Although the EMC community is familiar with the problem of EMI, EMI usually occurs inadvertently, and various country-specific and international rules and regulations establish requirements for negating EMI. What happens, however, when the EMI is not inadvertent; when it is, in fact, intentional? EMI could be used with criminal or terrorist intent to disrupt or damage electrical and electronic equipment and systems.

"Adverse effects of intentional EMI include the penetration of radiated or conducted high-power electromagnetic energy into an electronic system, resulting in upset or damage to the system," says Talgat Gazizov, associate professor at Tomsk State University of Control Systems and Radioelectronics (Tomsk, Russia).

Developed countries are heavily dependent on electronic systems and could be devastated if such systems came under attack. Manuel Wik, chief engineer and strategic specialist on future defense science and technology programs at the Defence Materiel Administration (Stockholm), says, "Our high-tech society depends heavily on systems that are vulnerable to electromagnetic high-power transient phenomena. Although the threat from criminal and terrorist activities is low to moderate today, it is thought that the threat will increase with time. Risk also increases with vulnerability. Therefore, we must closely follow developments in this field."

Criminal activities already reported include blackmailing of banks under the threat of disruption to their computers, jamming of radio and police transmitters, and overriding of security cameras and electronic locks with radio-frequency (RF) energy. Unfortunately, documentation on such activities has been scarce or nonexistent, making vulnerable facilities—including banks, hospitals, and Wall Street—less responsive to this threat.

In August 1999, the International Union of Radio Science agreed on a single term to describe all possibilities of criminal EMI and EM terrorism: intentional electromagnetic interference. The term is defined as "the intentional malicious generation of electromagnetic energy to induce noise or high-level disturbances into electrical or electronic systems with the intention to disrupt, confuse, or damage these systems for criminal or terrorist reasons." The method of interference, whether perpetrated by a criminal, terrorist, hacker, or prankster, is not essential to the definition. Rather, it is the presence of intent that distinguishes this form of electromagnetic threat.

Industry has been somewhat slow to react. According to William Radasky, president of Metatech Corp. and chair of IEC Technical Committee 77, Subcommittee 77C, awareness is very low. "We have in IEC a few people from industry—computer manufacturers and so forth—who are starting to become sensitive to this issue because they sell computers and they're worried about the security of those computers. There's a lot of technical interest from the research side, but in terms of organizations, IEC is really the only one that's working on this."

In June 1999, IEC expanded the scope of SC 77C to include intentional EMI. According to Radasky, "The committee previously dealt only with high-altitude electromagnetic pulse, but we have expanded the scope to deal with intentional EMI. We are now in the process of writing standards to tell people exactly what the threat is and how to protect against it." The standards are in the early stages, but the types of protection being considered are similar to those advanced during the Cold War to defend against the threat of electromagnetic pulse (EMP) from nuclear weapons. Radasky notes that the method used to generate the high-level transients is inconsequential, and that the same principles apply to all types. The subcommittee had published standards previously for protection against EMP.

The principles on immunity drawn from the European EMC Directive are a start, but according to Radasky, even they may not be enough. For instance, the immunity standards in the directive call for immunity to field strengths of 3 V/m for residential equipment and 10 V/m for industrial equipment. However, there have been reports of medical equipment inside ambulances shutting down at field strengths of 20 V/m, so even unintentional interference can cause problems. The threat is magnified when terrorists cause intentional interference and increase field strength to 100 or 200 V/m—which can be, according to Radasky, produced with equipment purchased at a local Radio Shack. A person can wreak havoc with electrical and electronic equipment, including computers, automobiles, airplanes, and telecommunication systems.

"The protection is not that hard," says Radasky. "It's a different problem than nuclear EMP where you've got an intense field that's covering a huge area all at one time. In this case, it's usually somebody nearby, so a combination of protection, monitoring, and physical security ought to solve the problem." Physical security should include barriers, such as fences and walls, to maintain a minimum distance between vulnerable systems and would-be criminals, terrorists, or hackers. "Physical security is one of the best forms of protection. The other one is monitoring. If somebody's computer is acting up, do you blame the software, do you blame the vendor, or do you blame outside interference?"

If a monitoring system can categorize the problem and identify it as outside interference, security can be sent to search around the building. "The effective distance of an interfering antenna is going to be relatively short, hundreds of meters or less," says Radasky. "So this means the equipment causing the interference must be nearby."

Current documents being worked on by 77C attempt to define the kinds of waveforms that can be easily generated and that threaten electronic systems. One concern, however, is revealing too much information. "We don't want to provide a toolkit for these activities," says Radasky. There is a fear that open discussion will encourage what it is trying to protect against, especially with the accessibility of ingredients necessary to build an EMI generator.

One potential ingredient, made available by the military, is old radars sold when facilities close down. "Anything that operates between 200 MHz and 4 or 5 GHz seems to be a real problem," says Radasky. "The reason they're for sale is that they're not very effective. Radar technology has improved drastically." But the radar doesn't need to be the newest technology to cause problems to electronic equipment and systems that aren't prepared for an intentional EM threat.

The possibility of intentional EMI has come under the scrutiny of the United States Congress. Representative Jim Saxton of New Jersey and Representative Roscoe Bartlett of Maryland have held several investigations concerning this threat and have lobbied Congress for funds for appropriate research. As early as February 1998, Saxton began holding hearings on the proliferation and threat of RF weapons.

The issue of intentional EMI has also begun to be addressed at international conferences. The 1999 International Zurich Symposium on EMC held the first workshop on intentional EMI, with nearly 200 people in attendance. And the 2001 Zurich Symposium was the culmination of several years of work in the field of intentional EMI. The symposium included the first refereed session on intentional EMI.

According to Radasky, "A lot of work has been done, but we're trying to emphasize the data side of things so we can show people that problems can occur at very high levels." Industry, however, has been resistant to stricter immunity standards—especially in the United States. "Manufacturers would rather let people take their chances with their products," says Radasky. "Europe has mandatory immunity standards, but these are fairly low-level, and there are still many reports of problems." A little extra immunity, however, in the form of shielding or filtering, can be very effective. "It doesn't have to be 100 dB," says Radasky. "Twenty dB may be enough. This factor of 10 makes it prohibitive for someone to cause a problem, because they have to be a factor of 10 times closer to cause the same field inside the shield."

The threat of intentional EMI is not limited to RF energy. "Most of the emphasis in this area has been on radio-frequency fields," says Radasky, "but the issue of injecting directly into the power and telecom systems has been overlooked." Yuri Parfenov and Vladimir Fortov, of the Russian Academy of Sciences Institute for High Energy Densities, recently experimented with injection of disturbances into power lines outside a building and found that the signals penetrate very easily and at a high enough voltage to cause damage to computers inside the building. Additionally, radiated fields often become a conducted threat due to coupling of RF energy to exposed wires.

Physical security, however, could also protect against this threat. Telecom centers for most buildings are contained in an easily accessible case with no more than a simple padlock. Such locks provide little security against direct injection into the telecom network. Additionally, there is usually minimal deterrent to hooking onto the power lines outside the building, which makes computers and electronic systems inside vulnerable.

"We did some testing in our laboratory on direct injection of Ethernet cables," says Radasky, "and we were surprised by the low level at which they were damaged—less than 500 V. And many companies are using Ethernet to connect buildings. At 500 V, we're talking about frying the chip completely. The board's just gone."

Intentional EMI includes both pulses and continuous-wave signals, in two basic forms. One is high-power microwave (HPM), a continuous-wave signal at a given frequency that continues for a microsecond or two at a gigahertz, like a radar. The other is ultra-wideband, which is essentially a fast pulse produced by a radar using pulse techniques rather than a continuous wave. These threats can be packaged in a mobile van or even a suitcase. However, the effective ranges decrease with size, but even a suitcase-sized threat is widely available. According to Peter Cotterill, managing director of MPE Ltd. (Liverpool, UK), an electromagnetic bomb in a suitcase can be purchased on the Internet at the cost of only $100,000, with a range possibly as high as 500 m. Mats Bäckström, of the FOA Defence Research Establishment (Linköping, Sweden), presented a study, "HPM Testing of a Car," at the 1999 Zurich Symposium and found that upset to unprotected car electronics by HPM can be caused at a range of 500 m from a van, 50 m from a suitcase.

For further information on the threat of—and protection against—intentional EMI, contact William Radasky by e-mail at wradasky@aol.com.

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Two Experts Join CE Editorial Advisory Board Homi Ahmadi David A. Case Compliance Engineering is delighted to announce that two experts in the field of product approval will share their years of experience by joining the editorial advisory board. Homi Ahmadi has been involved with product safety and approval since 1992, and David A. Case is an active member of numerous technical committees and has been testing products and obtaining approvals for the past two decades. Since 1996, Ahmadi has been an approvals manager at Cortech Systems (Simi Valley, CA), which designs and manufactures power supplies. He manages both the safety engineering and the EMC departments. His responsibilities include carrying out full type testing using the in-house laboratory, specifying alternative safety-critical components for new and existing products, setting up and running an EMC precompliance test facility, and generating and maintaining technical reports on EMC and safety. In recent months, he has also been working with the sales department as an applications engineer helping customers solve technical issues. Looking back over his long career, Ahmadi recalls that publishing his first article was one of the biggest challenges that he has ever tackled because "writing an article is very similar to giving a speech at a seminar. The material has to be 100% accurate and up-to-date, and the author needs to be prepared for any related questions from the audience." In the process of writing his first article, he quickly realized "how complex and deep some of the rules and regulations in various standards are and also that some of them even overlap." Since that time, he has written a number of articles and technical notes for engineering teams, and he has gained a tremendous amount of commercial and technical experience that will be used toward reviewing future articles for Compliance Engineering. Ahmadi believes there is a strong need for regulatory compliance. "It is exceptionally important to place safe and reliable products on the market," he says. In addition, as an increasing number of countries around the globe introduce new regulations or tighten their existing ones, he says, manufacturers must prepare themselves to face these challenges. "The introduction of new standards, the upgrading of existing standards, and the global adaptation of some standards only goes to prove this." Ahmadi notes that, in the past decade, the electronics industry in particular has gone through major regulatory changes, the most important one of which was the introduction of the CE mark in Europe. "This affects not only European Union (EU) manufacturers but also all other manufacturers whose products are sold in the EU. I believe that we will witness even tougher regulatory requirements in the future." Case's area of expertise is in wireless product certification. He has obtained approvals for various transmitters in more than 70 countries, including the first Federal Communications Commission (FCC) approval of the 11-Mb/sec transmitter. Besides FCC requirements, he is also familiar with transmitter requirements for the Department of Defense, Food and Drug Administration, and Federal Aviation Administration. Among his accomplishments was codeveloping a methodology to test a gasket material for a Personal Computer Memory Card International Association (PCMCIA) card. "The neat part was that six months later the engineer and I actually met for the first time. All other contact between us during the yearlong project to that time had been via faxes, voice, and e-mail." He says, "If the goals and parameters are set up front, you can complete any task, even if the support is only done remotely." Graduating from Purdue University in 1981, Case began his career at Heathkit Electronics (later acquired by Zenith Data Systems), where he was responsible for testing and obtaining approvals for Heathkit transmitters that have marked the birth of many budding radio electronics hobbyists. By 1995, Case was a senior compliance engineer with Aironet Wireless Communications, a developer of high-speed wireless local-area network products. However, late in 1999, Cisco Systems acquired Aironet to further their strategy to deliver open standards-based wireless solutions to mobile business environments. As a senior radio compliance engineer with Cisco, he furnishes high-end support to various wireless groups in the company. Mainly dealing with various radio standards, test methodology, and agency-related issues such as experimental licensing, certification, and radio test requirements, he also covers radio-frequency hazard issues for various transmitter groups and provides various levels of radio training for these groups. Case explains that his work philosophy is to gather information from many different sources before starting a new project. "I have been put into too many situations in which people base their opinions strictly on what is written in the rule book without looking at industry interpretations, applicable public notices, or other sources of information that might provide additional information or clarification. The rules are the starting place for the information and not the final place." Outside of Cisco, Case lectures for H&H Enterprises (Lincroft, NJ) on topics such as spread spectrum, global system for mobile communications, and personal communications service (PCS) testing. He serves on the editorial advisory staff of Wireless Design and Development and writes quarterly columns for IEEE EMC Society magazine and NARTE News. He has published more than 30 articles on subjects such as EMC, telecommunications, mean-time-between-failures analysis, and electrostatic discharge control. He was awarded the 1993 Marconi-Bell Award from the National Association of Radio and Telecommunications Engineers (NARTE) for his work with developing the NARTE program at Purdue University, Calumet campus (Hammond, IN). Case believes that with the proliferation of FCC Part 15 radio transmitters, PCS technology, and family radio services, the emphasis on wireless has grown. "It seems that every week I get an e-mail or a phone call from someone, including my competition, asking me a question about some wireless compliance issue or rule interpretation." Furthermore, the industry will need to address the home wireless interference issue in the near future. "We must develop guidelines to solve the problems that the FCC will not address, such as Part 15-to-Part 15 device interference issues."

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FYI Omitted Art The high-current I-V curve was omitted from Figure 1 of "Transmission-Line Pulse ESD Testing of ICs: A New Beginning," by Leo G. Henry, Jon Barth, Koen Verhaege, and John Richner (CE March/April 2001, page 48). The corrected Figure 1 is shown here. Omitted Text Some text was omitted from the end of Homi Ahmadi's article, "Calculating Creepage and Clearance Early Avoids Design Problems Later" (CE March/April 2001, page 61). The omitted text, including three references and the author's bio, follows: 2. BS EN 60950:2000, "Safety of Information Technology Equipment," British Standards Institute (BSI), United Kingdom. 3. IEC 60664:1980 "Insulation Coordination within Low-Voltage Systems Including Clearances and Creepage Distances for Equipment," International Electrotechnical Commission, Brussels. 4. BS EN 61010-1:1990, "Safety Requirements for Electrical Equipment for Measurement, Control, and Laboratory Use, Part 1: General Requirements," BSI, United Kingdom. Homi Ahmadi is approvals manager for Cortech Systems (Simi Valley, CA). He can be reached at Hahmadi@cortechsys.com.

 

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