PRESENTED at EMC 2000 WROCLAW Poland 26-30 June 2000

Intentional Electromagnetic Interference (EMI) is a new threat to electronic systems. Society's dependence on computer systems has increased rapidly over the past decade, and the susceptibility of these electronic systems to EM interference is increasing every year. At the same time hackers, criminals and terrorists are able to build EMI sources that can readily produce high level transient radiated and conducted disturbances. This paper reviews the overall threat and recommends actions to deal with the problem. 1. INTRODUCTION There is likely to be an increase in the number of incidents involving intentional EMI in the future. It is important that engineers be aware of the threat that it poses and that those who design critical applications where malicious damage would have serious consequences should start to consider this in their designs and the layout of their systems. Engineers need to be aware of the problem, assess the risks posed to their equipment and applications and then take appropriate counter measures. Intentional EMI can be attractive, because it can be undertaken covertly, anonymously and at some distance away from physical barriers, such as fences and walls. It can cover a great number of targets and leave minor traces or none at all. Those involved can range from careless people to pranksters, vandals, criminals and terrorists, whether state-sponsored or otherwise. Electronic components and circuits, such as microprocessors, are working at increasingly higher frequencies and lower voltages and thus are increasingly more susceptible to electromagnetic interference (EMI). At the same time, there have been rapid advances in radio frequency (RF) sources and antennae, and there is an increasing variety of equipment capable of generating very short RF pulses that can disrupt sophisticated electronics. Pulse radiation devices may consist of two main types. They may be high power microwave (HPM) devices producing high power in a narrow frequency band, which could cause ‘front door’ damage, or ultra-wide-band (UWB) devices, which produce a narrow time-domain pulse, and are more likely to cause ”back door” disruption or damage. As the power density of the EM field decreases with the square of the distance from the source, the proximity of an EM generator to the targeted equipment is clearly a major factor in the damage likely to be caused. Other types of EM sources are radiating continuous narrowband or wideband jammers, and EM injectors that are coupled (galvanic or inductive) directly to cables entering a facility. 2. RECOGNITION OF THE PROBLEM Intentional EMI has been recognized as an area that needs to be considered by representatives of the International Union on Radio Science (URSI) and the International Electro technical Commission (IEC). The URSI General Assembly in August 1999 in Toronto issued a resolution recommending the scientific community in general and the EMC community in particular to take into account the threats of intentional EMI and to undertake a number of actions. Earlier in the same year the IEC Technical Committee on EMC recommended that its subcommittee SC 77C deal with high power transient phenomena under a wider scope of work. The new scope is: ”Standardisation in the field of electromagnetic compatibility to protect civilian equipment, systems and installations from threats by man-made high power phenomena including the electromagnetic fields produced by nuclear detonations at high altitude.” Hearings in the US Congress on 17 June 1997 and 25 February and 20 May 1998 on Radio Frequency Weapons and their proliferation indicate the seriousness of EMI as a present and future threat. Commercial aircraft regulations which require that all radios, mobile phones, computers, CD players, etc. be turned off before take-off and landing, are well known to the public and indicate the seriousness of EMI in general. Similarly, hospitals restrict the use of mobile phones, which can affect patient monitoring and other medical equipment. The possibility of EMI involvement in the crash of TWA Flight 800 has been discussed in published articles. (The Boeing 747 exploded at a height of about 13.000 feet near Long Island, New York in July 1996. There has been much speculation about the cause of the explosion, which has still not been definitely established.) A Swedish study has revealed that high-power microwave (HPM) sources can stop cars at a distance of 900 meters and cause serious damage at a distance of 30 meters. Although dangerous in the wrong hands, this type of application could be of interest to law-enforcement agencies if it would allow stolen or fugitive vehicles to be brought safely to a halt from high speeds. High-power EM emitters could be installed in vans along highways in order to stop car traffic and to cause malfunctioning of traffic signals. Similarly, if the vans were parked outside the perimeter of a large airport, they could disrupt the proper functioning of systems for take-off and landing. If such vans were left outside computer centers, they could cause malfunctioning of computer systems and would result in very high costs in lost business, mistrust and a bad reputation among customers. Of course, if the computer center controlled critical industrial systems, the results could be even more serious in terms of injury and loss of life. 3. WHAT CAN BE DONE ABOUT IT? The electromagnetic compatibility (EMC) community must be prepared to deal with new threats as they emerge. This article is intended to make people aware of the following: · the existence of intentional EMI and associated phenomena; · the fact that Intentional EMI can be undertaken covertly and anonymously and that physical boundaries such as fences and walls can be penetrated by electromagnetic fields; · the potentially serious nature of the effects of intentional EMI on the infrastructure and important functions in society, such as transportation, communication, security and medicine; · the major potential impact of such major disruptions of these important functions, in terms of loss of life, health, money, information, trust, time, and possibly other areas; · the need for additional research into intentional EMI in order to understand the large variation of susceptibility levels and system weaknesses and to establish appropriate levels for dealing with such treats; · the need for the development and recognition of techniques for appropriate protection against intentional EMI and of methods that can be used to protect the public from the damage to the infrastructure that could occur as a result of such intentional EMI; · the need to develop special EM monitors to determine when an attack is underway; · the necessity for high-quality testing and assessment of system performance when exposed to these special electromagnetic environments; · the need for the EMC community to provide usable data to support the formulation of standards of protection. 4. CONCLUSIONS Intentional EMI is a new threat to electronic systems. Fortunately this threat has been recognized by several international organizations, the IEC and URSI, and new work is underway to deal with the threat.