Generalities on Radiated Interference

Abstract

During the first part of the twentieth century, electromagnetic interference (EMI) was primarily a concern for telecommunications via wire and radio. In these specific engineering communities, highly qualified engineers developed quite sophisticated analytical approaches to predict interference levels, taking into consideration the sources’ parameters, the propagation media and the sensitivity of the pertinent telephone or radio receivers. The typical sources of EMI until the 1960s were natural atmospheric noise, motor commutators, fluorescent lights, automobile ignition systems and 50/60 Hz overhead lines (unintentional sources), plus jamming by other authorised (and sometimes unauthorised) radio transmitters.