EMC Absorbers through the Years with Respect to the New Site VSWR Validation Procedure in the Frequency Range from 1 to 18 GHz - a Practical Approach

The article describes the development of EMC absorbers and EMC chambers until today. The first anechoic chamber in Europe was built mid of the sixties. Due to the fact that absorber chambers were not necessary in the early sixties - EMC measurements easily were possible on open area test sites (OATS) - this project was for long years the only EMC chamber in Europe. The market for EMC chambers increased with increasing radio services because of ambient. Mid of the eighties the market for EMC chambers again awoke. The technical requirement for EMC chambers was, to fulfil the VDE 0871. At the end of the eighties VDE founded a special committee discussing the requirements of alternate test sites. The volume method for validating test sites first was integrated in ANSI C 63.4 - 1988. In Cenelec - the European committee - also a working group was founded for establishing a EN standard for alternate test sites. The result was the EN 50147-1 (shielding) and -2 (NSA site validation). The volume method was integrated in CISPR 16 mid of the nineties. Meanwhile the volume method for NSA measurement of alternate test sites is well established. The technical development of EMC absorbers will be described discussing pyramidal foam absorbers, hollow pyramidal foam absorbers and hybrid absorbers - a combination of several absorbers (ferrite and foam absorber). New inventions like pyramidal foil absorbers also will be discussed. The new site validation (site VSWR) procedure from 1 to 18 GHz is shown.