ABSTRACT
When referring to the regulatory testing of electronic components and consumer goods, the words electromagnetic interference (EMI) and electromagnetic compatibility (EMC) are sometimes used interchangeably. They are often confusing since they are connected in so many ways. In this chapter, we strive to demystify EMI and EMC by providing a basic, general overview of the testing equipment used and the criteria in each area. Every electrical equipment emits some level of electromagnetic (EM) radiation. Although we conceive of electronics as closed systems, the electricity that flows via circuits and cables is never completely contained. This energy can travel through the air as EM radiation and/or be transmitted along (or coupled onto) interconnecting I/O or power cables, a phenomenon known as disturbance voltages. EMI sources can occasionally be naturally occurring environmental occurrences, such as electrical storms and solar radiation; however, the EMI source is more frequently than not another electronic equipment or electrical system. While EMI may be produced by any electronic device, particular equipment and components such as telephones, welders, motors, and light emitting diode (LED) displays are more susceptible than others to cause interference. Because electronics seldom work in isolation, goods are often designed to function in the presence of some EMI. This is especially critical in military-grade and avionics equipment, as well as systems that must be dependable under all circumstances. EMC is a measure of a device’s ability to perform as intended in its shared operating environment while not interfering with the operation of other devices in the same environment. Immunity (or susceptibility) testing involves determining how a gadget will behave when exposed to EM radiation. Another step is to measure the quantity of EMI created by the device’s internal electrical systems, a technique known as emissions testing. The purpose of this chapter is to go through EMI and EMC.
