A nice simple near field probe can be made quite easily.
I took a piece of 141 semi rigid coax, and fit a SMA male
to one end, and trimmed the other end for an SMA male, but
did not install a connector. I then made a small coil by
winding 5T of enamel wire using the threads of a 6-32
screw as a form. I removed the screw, and soldered the
coil to the trimmed end of the 141 coax... with the coil
fit over the center insulation, and soldered one end to
the shield, and the other to the center pin.
A piece of heat shrink, and you are done.
You use an appropriate adapter or cable, and connect the
probe to a 50 ohm input... a scope, SA, whatever...
The flux sensitivity is along the length of the coil,
so you can tell easily how the measured signal is oriented
by the direction the probe is pointing.
-Chuck Harris
Carsten Bormann wrote:
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On 2020-10-14, at 16:04, wallydoc via groups.io <wallydoc@...> wrote:
Strongest birdie signals on SA were obtained with a sniffer, an O scope probe with the ground connected to the tip and put near the SMPS.
¡ which is pretty much a poor man¡¯s near-field probe.
(The reason why you might want a real one is to locate the source of the signal more precisely or to get a quantitative result.)
Gr¨¹?e, Carsten
