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Old March 19th 09, 06:37 PM posted to rec.radio.amateur.antenna
Cecil Moore[_2_] Cecil Moore[_2_] is offline
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First recorded activity by RadioBanter: Mar 2007
Posts: 3,521
Default colinear representation in NEC

Jim Kelley wrote:
I agree that electromagnetic traveling waves are the kinds of waves

that propagate on and cause radiation to emanate from an antenna. But
your claims about 'standing waves not changing phase along the antenna' ...

Jim, I thought you have EZNEC. Here are the currents at all of
the segments along a 20m dipole with 21 segments from end to end.
Please note that in a dipole that is 180 degrees long, the phase
of the (mostly standing-wave) current varies by less than 3 degrees.
How can the current in a 180 degree antenna vary by less than 3 degrees?

Quoting my web page: "Standing wave current cannot be used to directly
measure either a valid amplitude change or a valid phase shift through
a loading coil. All of the reported conclusions based on loading coil
measurements using standing-wave current on standing-wave antennas are
conceptually flawed." Owen had an epiphany of a sort when he realized
that fact of physics.

20m dipole 3/18/2009 5:28:50 PM

--------------- CURRENT DATA ---------------

Frequency = 14.2 MHz

Wire No. 1:
Segment Conn Magnitude (A.) Phase (Deg.)
1 Open .0836 -2.75
2 .23595 -2.57
3 .37707 -2.38
4 .50791 -2.17
5 .62692 -1.95
6 .73226 -1.71
7 .82218 -1.44
8 .89511 -1.13
9 .94979 -0.78
10 .98539 -0.37
11 1 0.00
12 .98539 -0.37
13 .94979 -0.78
14 .89511 -1.13
15 .82218 -1.44
16 .73226 -1.71
17 .62691 -1.95
18 .50791 -2.17
19 .37707 -2.38
20 .23595 -2.57
21 Open .0836 -2.75
--
73, Cecil http://www.w5dxp.com
"Government 'help' to business is just as disastrous as
government persecution..." Ayn Rand

P.S. I posted this reply but it didn't show up on my server.
I apologize if it is a duplicate.