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