Owen Duffy wrote:
Roy Lewallen wrote in
:

Maybe the lack of responses is because of the obscurity of the
"s-plane summation". I've never heard of it, and a web search brought
only one or two possible hits from publications I'd have to buy in
order to view. Any principle with that low a profile on the web is
pretty esoteric.

Roy Lewallen, W7EL


Roy, to kick it along a little...

The technique calls for making sets of measurements with the antenna in
three orthogonal orientations and summing the z, y and z plane values to
an "s plane" value to represent maximum field strength. I think the
summation that is typically used is the square root of the sum of the
squares.

The technique suits automated measurement where a series of perhaps
hundreds of measurements at different frequencies are made, the antenna
is manually changed, and the series repeated etc. Software is then used
to process the logged measurements.

Clearly there is an issue about the temporaral nature of separate
measurements in each plane at a given frequency.

Well, if the field is changing in an unknown way, measurements at x, y,
and z axes at different times would be meaningless of course.

I was interested in any standards or regulatory "procedures" that may
exist that describe / mandate such technique. Most procedures that I
have found just call for orienting the antenna for maximum response
rather than the x,z,z trick.

Calculation of the resultant for a static field is not really a trick.
In the absence of a triaxial instrument, that may be the only practical
technique available.

I would like to understand its application better to for a view about
the appropriateness to particular applications. I suspect its main value
is in automated EMC data capture.


You are talking about simply calculating the resultant of three
orthogonal vectors. Not an esoteric technique. Its main value is in
making a measurement without a triaxial instrument. Or, alternatively,
positioning a single-axis instrument for maximum reading and then
measuring the position coordinates of the instrument's axis.

Many triaxial instruments have three orthogonal probes and calculate and
display the resultant automatically. Three orthogonal measurements
separated in time and requiring separate calculation of the resultant is
a move away from automation and accuracy, I would think.

You might search instead for discussions on measuring static magnetic
fields with single-axis gaussmeters. Inexpensive gaussmeters are
commonly used in this manner. I get ~350K results in a google search on
"triaxial field measurement."



I am still on the BPL measurement tram!

Owen

Chuck

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