Amplified Near-Field Probes For A Spectrum Analyzer - 3M ScanEM-QC CTK019 User Manual

3M ScanEM-QC Electromagnetic Near-Field Probe farther away from the
™
emission source until distortions go away.
CAUTION!
UNLIKE SOME PASSIVE PROBES, THE SCANEM-QC PROBE IS NOT A REVERSIBLE
DEVICE—DO NOT SUPPLY A SIGNAL INTO ITS OUTPUT! IT CAN PERMANENTLY DAMAGE
YOUR PROBE.

Amplified Near-Field Probes for a Spectrum Analyzer

Connect the ScanEM-QC Probe to the INPUT of the spectrum analyzer
with the supplied cable. Some spectrum analyzers require the use of a
BNC-to-N adapter.
The performance of the ScanEM-QC Probes is superior to those of passive
probes. The ScanEM-QC Probes have broad and flat frequency responses
within a specified range (see page 13 for details). The ScanEM-QC Probe's
built-in amplifiers provide ~20dB of gain, eliminating the need for an
external pre-amplifier.
Figure C shows a typical frequency response
of the 3M ScanEM-EQC Probe vs. an
™
equivalent passive probe. As seen, passive
probes typically fail at lower frequencies
(below 200MHz) where most of the
fundamental frequencies and many of the
strongest harmonics of the tested equipment
are located.
Avoid overloading the probes with a very
strong field—it may induce distortions in the
ScanEM-QC Probe amplifiers. The ScanEM-EQC Probe, for example,
begins to overload at field strengths of approximately 4V/m.
12
Figure C: Typical Frequency
Response of 3M ScanEM EQC
™
Probe vs. Passive Probe