On Jan 9, 5:35 pm, "J. Mc Laughlin" wrote:
Dear Jim Lux W6RMK:

I was not able to examine the probes that I saw in use at NBS in what was
probably the mid-70s.

The probes that I did see and use comprised three, orthogonal, very short
doublets with attached means for rectifying. The resulting DC was conveyed
away through a resistive, plastic transmission-line crafted to be almost
transparent to RF. These probes were used to estimate the size of strong EM
signals in the vicinity of equipment so as to be able to put better numbers
on EMC capabilities.

Yes.. The older works (50s and 60s) used carbon loaded string or
thread, but newer stuff uses conductive plastic. If the sheet
resistance of the material is 377 ohms/square then it's sort of like
lossy freespace.

Those three axis probes work fine for measuring the magnitude and
direction of the field, but they can't measure the phase, and to do
the nearfield to far field conversion you also need the phase.