PD 6591:1996

This standard PD 6591:1996 Guidelines on how to use anechoic enclosures that do not fulfil the requirements regarding normalized site attenuation for pre-compliance tests of products is classified in these ICS categories:

• 33.100.01 Electromagnetic compatibility in general

This guideline deals with the application of absorber-lined enclosures for radiated-emission tests according to CISPR 16 [1], CISPR 11 [2], CISPR 22 [3] and EN 50147-2 [4] in the frequency range of 30 - 1000 MHz.

Standard site acceptability criteria based on normalized site attenuation (NSA) measurements are given in [1, 4]. The chamber factor concept shall provide a method for more detailed evaluations of the performance characteristics of enclosures. Measured chamber factor data can, furthermore, be used to correlate test results from equipment under test (EUT) to open site results. Whereas NSA evaluates chamber performance with respect to theoretically calculated reference values, chamber factors are derived from comparative measurements between an enclosure and a good reference site.

If the measured site attenuation exceeds the “± 4 dB”-limit only in the frequency range of 30 - 200 MHz and by not more than ± 12 dB, then the methods described in this report may be applied. For equipment that is no larger than half a wavelength (including cables) the enclosure can then be used at the expense of higher test uncertainty in the lower frequency range.