电磁兼容原理与工程应用(英文版)

Chapter 1 Introduction of Electromagnetic Compatibility 　　1.1 Electromagnetic Compatibility History and Basic Concepts 　　During the Second World War， the use of electronic equipment， especially radio transceivers， navigation equipment and radars， led to an increase in the number of interference between radio transceivers and navigation equipment on aircraft by redistributing the frequency of the transmission over a non-congested spectrum， or by keeping the cable away from the noise source to prevent cables from receiving interference. The interference problem can usually be resolved easily. At that time， the density of the electronics (mainly the electronic vacuum tube) was far less than today. Therefore， it was easy to implement the modification of the interference on a case-by-case basis to solve the electromagnetic interference (EMI) problem. 　　However， with the invention of high-density electronic components， such as field effect transistors invented in the 1950s， integrated circuits (IC) invented in the 1960s， and microprocessor chips invented in the 1970s， the interference problem became increasingly serious. As the demands for voice and data transmission increase， the spectrum becomes more and more crowded， which requires reasonable planning of the spectrum usage[1]. 　　Due to the increasing number of digital systems that interfere with wired and wireless communications， the US Federal Communications Commission (FCC) issued a regulation in 1979， requiring electromagnetic interference from all “digital devices” to be lower than a certain limit. The purpose of the regulation was to restrict “electromagnetic pollution”， to put an end to， or at least reduce the number of EMI cases. Because the digital devices sold in the United States had to meet the FCC mandatory restrictions， there was a strong interest in EMC disciplines among electronics manufacturers with products ranging from digital computers to electronic typewriters. 　　Many European countries had already enforced similar requirements for digital devices before the FCC promulgated the specifications. In 1933， the International Electrotechnical Commission (IEC) recommended the International Special Committee on Radio Interference (CISPR) to deal with emerging EMI issues at a meeting in Paris[1，2]. The committee published a document detailing the measurement equipment used to determine potential EMI problems. CISPR reconvened in London in 1946 after the Second World War. Subsequent meetings published various technical publications， discussed measurement techniques， and suggested the restrictions. Some European countries have adopted the restrictions of various versions recommended by CISPR. The FCC specification was the first one for digital systems in the United States. The restrictions were based on CISPR recommendations and were subject to the change in the U.S. environment. To prevent “field problems” associated with EMI， most electronics manufacturers had set internal limits and standards for their products in the United States. However， FCC specifications made such a voluntary act into a legal compliance program requirement. 　　These specifications have made EMC a key factor in market access for electronics. If a product does not meet the specifications in a certain country， it may not be sold in that country[2，3]. In other words， products that are fully functionally implemented cannot be purchased because they do not meet the specifications. 　　Work on electromagnetic compatibility started late in China and developed gradually from the 1970s. Some national standards and national military standards have been promulgated such as EMC design requirements and test methods， but the detailed design specifications are still lacking. The electromagnetic compatibility penetrates every electrical and electronic system and equipment. The electromagnetic compatibility problems can only be solved by management and coordination of overall design. 　　1.2 Electromagnetic Compatibility Standards and Measurement 　　Most electrical and electronic equipment， circuits and systems emit electromagnetic energy， either intentionally or unintentionally. This emission can generate electromagnetic interference. At the same time， many modern electronic devices， circuits， and equipment are capable of responding to or being affected by such electromagnetic interference. This problem has become more serious in modern semiconductor devices and VLSI circuits， which are prone to fail or even be completely damaged under electromagnetic interference because of their relatively low susceptibility thresholds for electromagnetic interference. Problems associated with electromagnetic emissions (generating electromagnetic interference) and equipment， subsystems， and devices against electromagnetic interference (electromagnetic compatibility) are common in the production and transmission of wireless broadcast， communications， control， information technology produ