Field strength - S plane summation
 

I am looking for reference information for summation of field strength
measurements in x, z and z planes to the so called s-plane summation.

Does anyone have any pointers?

Thanks
Owen

Field strength - S plane summation
 

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

Owen Duffy wrote:
I am looking for reference information for summation of field strength
measurements in x, z and z planes to the so called s-plane summation.

Does anyone have any pointers?

Thanks
Owen

Field strength - S plane summation
 

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.

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.

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.

I am still on the BPL measurement tram!

Owen

Field strength - S plane summation
 

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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Field strength - S plane summation
 

"chuck" wrote in message
...
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."

Owen,

Where, I guess, "S" is the Poynting vector? I have made attempts at
estimating
the TRP from a NEC output file -- including the ground wave. The results
appear to be reasonably correct, but have no means of verifying the results.
If I am on the right track I can send you my Excel spread sheet clearly
showing
the method I used. I did the analysis for Reg in order to compute the true
radiation resistance of a ground mounted monopole. I have a MathCAD 7
document, which also shows the method I used, and is probably easier to
interpret.

73,

Frank

Field strength - S plane summation
 

"Owen Duffy" wrote in message
...

I am looking for reference information for summation of field strength
measurements in x, z and z planes to the so called s-plane summation.

Does anyone have any pointers?

Thanks
Owen

The only time I have ever heard reference to this it had to deal with
measureing the field strength of the far field beam of a radar antenna. Its
been a while but I am pretty sure it had something to do with checking out a
polarizer for proper operation when it was switched from linear to
circular..

Jimmie

Field strength - S plane summation
 

It's not clear what the objective is. NEC and EZNEC have the ability to
sum the power from the field at all calculated points. This is used in
its "average gain" calculation which reports the ratio of total power in
the field to power applied to the array. (NEC, but not EZNEC, also
applies another factor of two when evaluating a system over a ground
plane.) You can extract this total power value by multiplying the
reported average gain by the power from the sources (and the additional
factor of two if necessary).

I don't know if this is the end result you're after, but it sounds like
something in the right direction. You could of course analyze an antenna
with two orthogonal elevation plots and an azimuth plot to generate data
for three orthogonal planes, then sum them manually or with a simple
program. I have no idea what the meaning or use of the resulting number
might be, though.

Roy Lewallen, W7EL

Owen Duffy wrote:

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.

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.

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.

I am still on the BPL measurement tram!

Owen

Field strength - S plane summation
 

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.

Owen

Field strength - S plane summation
 

"Frank" wrote in
news:a5%Ch.98609$Fd.82750@edtnps90:


"chuck" wrote in message
...
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."

Owen,

Where, I guess, "S" is the Poynting vector? I have made attempts at
estimating
the TRP from a NEC output file -- including the ground wave. The
results appear to be reasonably correct, but have no means of
verifying the results. If I am on the right track I can send you my
Excel spread sheet clearly showing
the method I used. I did the analysis for Reg in order to compute the
true radiation resistance of a ground mounted monopole. I have a
MathCAD 7 document, which also shows the method I used, and is
probably easier to interpret.


Thanks Frank, it is more about summation of field strength measurements
in the real world to a single figure representing max field strength (in
whatever orientation) at that location and frequency.

I was hoping I might find procedures specified by regulatory authorities
for measurement of such... but searching hasn't turned up much.

Owen

Field strength - S plane summation
 

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?

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.

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

Roy Lewallen, W7EL

Field strength - S plane summation
 

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

Field strength - S plane summation
 

On Feb 21, 12:43 pm, "Jimmie D" wrote:
"Owen Duffy" wrote in message

...



I am looking for reference information for summation of field strength
measurements in x, z and z planes to the so called s-plane summation.

Does anyone have any pointers?

Thanks
Owen

The only time I have ever heard reference to this it had to deal with
measureing the field strength of the far field beam of a radar antenna. Its
been a while but I am pretty sure it had something to do with checking out a
polarizer for proper operation when it was switched from linear to
circular..

Jimmie

Also pretty sure the S was refered to as SIGMA, maybe this will help.

Jimmie

Field strength - S plane summation
 

Owen Duffy wrote:
Roy Lewallen wrote in
:

Owen Duffy wrote:
. . .
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.
. . .

And right you are -- I stand corrected.

Guess I was blinded by thinking of the statistician who drowned crossing
a creek which had an average depth of only three feet.

Roy Lewallen, W7EL

Field strength - S plane summation
 

Roy Lewallen wrote in news:12tqej81j7cb317
@corp.supernews.com:

Owen Duffy wrote:
Roy Lewallen wrote in
:

Guess I was blinded by thinking of the statistician who drowned crossing
a creek which had an average depth of only three feet.

Thanks Roy, I must remember that. It is a salutory reminder that the value
of an average (or a median for that matter) may be limited.

Owen

Field strength - S plane summation
 

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

No, no, no, never. Just ask the parents, the school boards, the principals,
and the kids. At least 95% are above average. Using a 4-point system (A=4
and so forth) they graduate with averages above 4.0 and with multiple
valedictorians (so no one will be hurt).

Bill - W2WO

Field strength - S plane summation
 

On Thu, 22 Feb 2007 02:53:12 GMT, Owen Duffy wrote:

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.

Hi Owen,

It sounds like you want a Black Body Absorber.

You might want to take your lead from that if you are building
instrumentation (the purpose of your data reduction).

Presumably you would also want it to be isotropic in sensitivity. If
my speculations are correct, the simplest method would be caloric
based, but the trick would be to get it to occupy a volume of space
AND present 377 Ohms; but then how would you shade if from the sun
(another notable field presence that would innundate your detector);
or if done at night, how would you cope with the infinite heat sink in
nearly half the field of view? Most caloric methods employ a bridge
configuration that balances out these disturbances.

So, the simplest method is not very simple at all. Compare it to the
more difficult methods and you may wish for it after-all.

73's
Richard Clark, KB7QHC