Measurement Techniques - HP 11941A Operation Note

HP 11941 OPERATION NOTE
3-16. Measurement Techniques
3-17. The HP 11941A measures the magnetic field strength at the center of its sense loop, not at the probe
tip. Figure 6 details the relationship between the probe tip cover and the probe loop centerline. The probe is
designed to be held very close to potential radiating points. The plane of the probe tip loops must be
perpendicular to the radiating magnetic field as illustrated in figure 2. For example, if the seam of an
enclosure is being tested for EMI, hold the probe as illustrated in figure 7. When measuring the radiation
from a coaxial cable, position the probe as in figure 8, which shows the sense loops. The side of the probe
with the antenna factor calibration label should be facing away from the cable being measured. Do not use
the probe if the protective tip cover is missing or damaged.
3-18. The probe may be used as a source in susceptibility testing, as described in section 3-9 and also in
paragraph 3-15. In this application, hold the probe within 1 cm (0.394 in.) of the electronic circuit
component being tested.
Figure 6. Probe Tip Detail