Roy Lewallen wrote in
:

Owen Duffy wrote:
Roy Lewallen wrote in news:12tpng510pvr140
@corp.supernews.com:

It's not clear what the objective is. NEC and EZNEC have the ability
to

This is about measurement in the field of emission field strengths,
and techniques for coming up with a single number representing the
emission field strength on a particular frequency at a particular
location.

I understand that, but "representing" in what way -- an average,
weighted average, RMS, probability density, something else? And what
would it mean? Is it supposed to tell how much interference will be
created for the overall community? Will an antenna with a narrow beam
pointing straight up give the same number as one with a narrow beam
pointing horizontally, or are the data for the axes weighted
differently?

Typically, it would the a set of measurements reduced to a descriptor of
centrality and variability, eg median and percentile or inter quartile
range or whatever.

I think it is intended to equate to the field strength that would be
measured using a linearly polarised antenna oriented for maximum pickup.


This is a means of data reduction, in which the result has less
information than the original data. 3D field strength data *does*
represent the emission field strength, but any summation and
consequent reduction represents less information than this.

I'm not saying that industries or the regulatory agencies won't use
something like this to "prove" whatever they need to prove -- but it
should undergo some critical scrutiny to see just what its meaning
really is.

The question comes up in a context of we amateurs measuring and
documenting background noise levels, and whether the z, y, z - S is
better than just swinging a loop for maximum response and recording the
measurement.

I am of the view that the three dimensional measurement is really a
technique suited to automated measurement of a large set of frequencies
with and instrument that has a single plane antenna that it cannot re-
orient, and whilst it addresses that issue, it is unnecessary
complication for a hand held loop that can be maximised.

But, my opinons are not very important, I am interested in any formal
testing procedures, and the opions of other knowledgeable and experience
practitioners like yourself Roy.


After all, half the children in the schools are below average!

Not necessarily, it depends on the population distribution, doesn't it?
Exactly half would be less than the median, provided there were an odd
number of children.

Pickiness over averages aside, your comments are appreciated Roy.

Owen