Requirements of EN55022:2006+A1:2007
MET Laboratories performs Radiated Emissions Testing (above 1GHz) to the requirements of EN55022:2006+A1:2007 (Information Technology Equipment- Radio Disturbance Characteristics- Limits and Methods of Measurement). Previous versions of EN55022 did not require radiated emission testing above 1GHz. This version of EN55022 specifies REE testing up to 6 GHz. Test methodology is also significantly different from FCC/ANSI C63.4 requirements. This version requires testing to be done using a validated test site (chamber) according to CISPR 16-1-4.
The standard specifies that the testing is performed using a test site with reflection-free conditions (i.e. free space method). A regular semi-anechoic chamber does not provide a reflection free environment due to the metallic ground floor. In order to achieve free space conditions in a semi-anechoic chamber it becomes necessary to place absorbing material on the chamber floor between the EUT and the measuring antenna as shown in the set-up picture below.
The absorbing material eliminates the reflection from the floor and therefore simulates a free space environment. To ensure that the chamber meets the free space requirements, CISPR16-1-4 specifies a validation process as described in section 8, based on “Site VSWR” Measurements. This site validation method evaluates a given test volume for an applicable frequency range. The validation process requires a special dipole antenna, a network analyzer and absorbing material on the floor.
In addition to the differences in test and site validation methodology, the emissions limit is also different. The plot to the right demonstrates the comparison of EN55022:2006+A1:2007 REE limits (class B) with FCC requirements. For the average limit from 1G-3GHz, EN55022 is 4dB lower.
The chart on the left shows emissions comparison with CISPR B limit, with and without absorbers on the chamber floor.
As of October 1st, 2011 this standard became mandatory and the 2006 version was withdrawn. Manufacturers of ITE equipment intended for sale in the European Union will need to demonstrate compliance with the most current version of the standard. MET encourages ITE manufacturers to always consider having their products evaluated to the newest requirements before it becomes mandatory, as the limits are different than the FCC requirements.
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