Procedure for new draft of Defence Standard 59-41-calibrating screened room antenna combinations against OATS

Describes a procedure developed to calibrate screened room/antenna combinations for measurement of radiated emissions in the frequency range of 10 kHz to 30 MHz. The work was performed in order to derive a new draft version of the U.K. Defence Standard 59-41 for electromagnetic compatibility (EMC). Results of measurements using specially designed test equipment are presented as are results of measurements made using “real” equipment. The procedure, which is suitable for automatic analysis using spreadsheets, requires the measurement of both electric and magnetic fields and predicts the fields, which would be measured on an open field test site from the results obtained in a screened room. The aim of the procedure is to provide more repeatable measurement results that are comparable between test houses. It also avoids the reliance on antenna factors, which may have significant errors in the screened room due to the proximity of the conducting walls