Comparison between high level radiated susceptibility tests and coupling measurements

It is well known that High Power Microwaves (HPM) can disturb, and even destroy modern electronics. In the recent years, FOI and others have shown that the sensitivity of electronic equipments shows a substantial dependence on the irradiation direction of the object. These results stem from low level coupling measurements. The reason for doing a coupling measurement rather than a high level Radiated Susceptibility test (RS-test) is that much lower field intensities can be used and is therefore much easier to perform. However, the goal is to do a RS-test, and we have therefore performed a high level RS-test and compared the results to the results of coupling measurements. As test object we have used a generic missile (GENEC), which has been irradiated from many directions in one plane. The RS-test was performed by monitoring at which field strength a digital electronic inside GENEC failed to work properly. This report shows that the apparent directivity differs in details between the RS-tests and the coupling measurements, but typical lobe widths and the maximum apparent directivity are almost identical.