Validation of Anechoic Chamber for Radiated Emission Test

Radiated emissions testing involve measuring the electromagnetic field strength of the emissions from the EUT and associated cables. To avoid interference from ambient signal of radio and other emitter in populated area, with the measurement, an anechoic chamber is essentially required. During testing, the ambient electromagnetic level in an anechoic chamber measured with the EUT de-energized and all auxiliary equipment turned on, shall be at least 6dB below the allowable specified limits when tests are performed in the chamber. Sometimes this ambient level is not achieved. This paper describes practical techniques applied for ensuring compliance with the ambient requirements for Radiated emission test as per MIL-STD 461. It also discussed the shielding effectiveness of the chamber.