For many years emission testing in Anechoic chambers has been clearly defined between 30MHz-1GHz. The chamber calibration procedures are vital to be able to claim UKAS, FCC status or any other approval acceptance for EMC.

It has been acknowledged within the regulatory authorities and industry that with the rising frequency spectrum above 1GHz then more accurate and reliable methods of using the Anechoic chamber in this spectrum must be introduced.

CISPR 16-1-4 (edition 2) has now introduced a method of calibration of the chamber and EMC testing procedures for above 1GHz requirements.

Previously the industry had adopted Free Space Transmission loss techniques which used Horn antenna for both receive and transmit when calibrating above 1GHz. The newly introduced method is now based upon VSWR methods.

The result is that an Isotropic source antenna in conjunction with a broadband receive horn antenna is used and exposes more of the chamber to the source antenna beam energy emissions.

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Rainford EMC System is based St Helens, Merseyside, UK. www.rainfordemc.com