Radiated emission emc testing using full anechoic chambers

Nowadays, many types of electronic equipments are operating together in the same electromagnetic (EM) environment. EMC means that a device is compatible with its EM environment, which means that no interference is caused by and it does not emit levels of EM energy that cause EMI in other devices in the vicinity. The most important section of EMC is ?emission?. All manufactured electronic devices that would be sold in USA and EU are restricted by government regulations to a very limited ?radiated? field strength leaking out of the case. To market a device, it must be proved by measurement that the device emits fields that are smaller than the permitted values. Hence, radiated emission test is required by operating the equipment in a controlled environment. The test must be done in a ?quiet? electromagnetic environment such as a shielded anechoic chamber or in a facility located well away from urban areas, where the ambient field strength is small. Worldwide regulatory requirements specify the use of Open Area Test Sites (OATSs) or Semi Anechoic Chambers (SACs) for the measurement of radiated emissions from unintentional radiators. SACs have very big sizes and their initial cost is very high. And OATSs are not effective choice if they used alone, because the ambient noise is very high. Full Anechoic Chambers ? which have low initial cost and small size ? can not be used instead of SACs, but they can be used as precompliance test site while compliance test is performed in Open Area Test Site.