3M ScanEM-C, Руководство пользователя

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the trace or spending hundreds or thousands of dollars on a special current
probe that only works at much lower frequencies.
The 3M
™
ScanEM-C Electromagnetic Near-Field Probes, as any field probe
would, show the signal slightly differently than the one actually residing on
the trace. This is due to an antenna factor of the trace. Experimenting with the
ScanEM-C Probe and the oscilloscope probe will show you the difference.
Also, the ScanEM-C Probes pick the sum of the emissions from the adjacent
traces and wires, so some discretion is needed when assessing the signal on
the screen.
Broadband Field Strength Probe
for a Multimeter
The ScanEM-C Probe provides DC
voltage that is a function of field
strength. Connect the ScanEM-C
Probe to the multimeter set to Volts
DC (typical scale of 2 V). You will
need a BNC to banana plug adapter.
Set the Level dial to zero (left-most
position). In the absence of the
electromagnetic field, the multimeter should show 0V. Should the multimeter
display any other voltage reading, use it as the correction factor to any further
field measurements. You can characterize the ScanEM-C Probe’s output using
a GTEM cell, and then convert the ScanEM-C Probe’s output into absolute
values of the field strength.
When using the ScanEM-C Probe with a multimeter, avoid touching the tip of
the ScanEM-C Probe with your hand—it may induce a feedback between the
typically non-shielded circuitry in a multimeter and the ScanEM-C antenna
that is amplified simply by your touching it.
A typical transfer function of the ScanEM-EC Probe is shown in Figure G to
10000
1000
100
10
1
Field Strength, mV/m
0 500 1000 1500 2000 2500 3000 3500
DC Output mV
Figure G: 3M™ ScanEM-DC Probe Response
(Typical)