ETS-Lindgren 7405 E & H Near Field Probe Set - Manual (Page 16)

16 Operation www.ets-lindgren.com
Probe Selection
Choosing the correct probe is determined by the following:
 Whether the signal is E or H: If the signal is primarily is E-field, use
the ball probe or stub probe. If the signal is primarily H-field, use one of
the loop probes. If unknown, try one of each and select the one that
best picks up the signal.
 The strength of the signal: Select a probe that adequately receives
the desired signal of interest. Respectively, the ball probe and the
6-cm loop are the most sensitive of the E-field and H-field probes. The
stub probe and the 1-cm loop are the least sensitive.
 The frequency of the signal: If the signal is above 790 MHz, the
probe may go into resonance. See the upper resonant frequency listed
for each probe in Specifications on page 13.
In this illustration a
ball probe is used to
examine a flat cable.
The distributed
inductance over the
length of the cables
makes them
particularly susceptible
to common mode
problems. High
impedance sources
such as this are best
examined with an
E-field probe.
 The physical size of the space where the probe must fit:
Model 7405 includes a variety of sizes. See pages 8 –9 for a
description of each probe.