Jim Lux wrote:
John Smith wrote:
[A bunch of chit Jim, obviously, will/and does differ with]
Regards,
JS



I doubt that any antenna an amateur is likely to build has some physics
not adequately modeled by the math in NEC. Exactly what might be these
discrepancies in equations, formulae and assumptions? Considering that
NEC has had decades of validation against actual measurements and a lot
of really, really smart people looking at how it works, I'd be kind of
surprised.

I don't believe the above it correct. Indeed, if you will only review
my past objections and reflections on how "the NEC engine" demonstrates
"differences" you will be focused at the "focal point" of my "inquiries" ...


However, I can also easily believe that an amateur (or professional)
could build an antenna that has measured performance different than
expected from their NEC model of that antenna. The differences would
lie, most likely, in these areas:

Look, the dipole, standard monopole (1/4, 1/2, longwire, etc.) is NOT in
debate. Indeed, it is like NEC was designed to "explain/model" these, DUH!

1) Inaccuracies in the model itself. Things like earth properties (NEC
assumes uniform dielectric, it isn't) are an important source of error
for antennas close to the ground. Most amateur models do not include a
very good model of the surroundings (supports, trees, feedlines, etc.)

2) Inaccuracies in the measurements or not measuring the right things. A
good example is using NEC to get feedpoint characteristics, then
measuring at the rig, and not properly accounting for the transmission
line, particularly if the feedpoint Z is reactive.

In the professional antenna world, if someone models an antenna, then
builds it and tests it on the range, and the measurements differ from
what the model predicted, the usual assumption is that what was built
differed from what was modeled, or the measurements were off.

I could pick apart the above, attempt to poke fun, etc. -- however, I
would much rather join forces and attempt to focus on the points which
would lead us to real answers -- i.e., the arrl and illiterates have
already done enough damage, let us pursue a more productive path?

Leave us leave our minds open, OK?

Regards,
JS