RadioBanter - View Single Post

May 19th 06, 07:45 PM posted to rec.radio.amateur.antenna

wrote:
Richard,

Who, in your estimation, does qualify to discuss it?

I would like to hear from someone who has actually measured the
linearity of a simple antenna. I have not done this, so would only be
one guy with an opinion. Plenty of us around.

By 'simple antenna' I mean an antenna such as a wire dipole without
traps, baluns or other things that could degrade linearity. Since the
linearity of antenna systems in general is in question, the simplest
setup that answers the question would be best.

In the absence of measurement, can anyone comment on the modelling
software? Does it assume and model a linear system? If so, do we know
of any substantial nonlinear departures from the modelling software?

Anyone?

73,
Glenn AC7ZN

In order to measure something, you have to define what it is, first.
Cecil seems to think that in order for a simple dipole to be linear,
the current magnitude measured along its length has to be sinusoidal
in shape. Actually, though, I have it wrong. What he believes is that
since he can't detect any harmonics emanating from a sinusoidally
fed dipole, the current along its length must be a sinusoid. Actually,
it's supposed to be impossible to represent the current distribution
along a dipole using simple mathematical formulas because integral
equations have to be solved that are impervious to any solution
other than numerical approximation. That's why we need the various forms
of NEC. Cecil is wrong for the reason I've given in another post, and,
for reasons enumerated by Richard Clark. That won't stop the flow of
bellicose posts from him, though.
73,
Tom Donaly, KA6RUH