The measurement of field strength in a screened enclosure

Describes how selectively placed radiation absorbing material (RAM) can be used to greatly reduce the Q value of the electromagnetic resonances which occur in unlined screened rooms. The results obtained for EMC conformance tests carried out in screened rooms often differ by 20 dB or more, when the tests are repeated in other rooms. Such results are dominated by the room resonances and the positions of the antennas and EUTs within the room. Detailed investigations of these resonances have been made and a damping procedure proposed which gives emission measurements in agreement with those made on an open-field site to within 5 dB from 30 MHz to 200 MHz