Civilian perspective [EMC testing]

In the 1970s there was an upsurge in the demand for electromagnetic compatibility (EMC) of civilian equipment. Besides the need for EMC in radio and TV reception other areas were growing, such as medical, industrial and scientific applications. Many of the methods for EMC testing were pioneered in the United States, whose government agent is the Federal Communications Commission. In order to make accurate absolute measurements of field strength the FCC decreed that half wave dipoles should be used. This led to the specification of a measurement distance of 30 m for accurate measurements at 30 MHz. Resonant dipoles at 30 MHz are 5 m long. At a distance of 30 m the uncertainties in field strength caused by field non-uniformity and mutual coupling between EUT and antenna should be insignificant. The standard method of emission testing at present makes use of an electrically conducting ground plane on an open area test site (OATS)