Tom, W8JI writes:
"Beware that the TOA of a vertical almost certainly is not correct.
Remember the programs Earl (and many of us including myself) use
calculate
pattern at a very long distance over flat earth. Using that method, any
amount of loss in the media supporting ground wave signals produces
nearly
zero field strength along the ground. We know that pattern isn't true at
distances that compare to the height of the ionosphere on 160!"
======
I agree with Tom to some extent, however the TOAs I posted should be
close enough for purposes of this discussion. Yes, NEC-2 and
MiniNec-based software modeling results in zero radiation from any
vertical at zero degrees elevation, but we all know that isn't true, or
we would hear any ground wave signals.
--
(snip)
--
"The vertical performance differences could very well be tied into
antenna efficiencies or less than ideal patterns rather than other
differences."
======
I forgot to mention that the antenna gain/TOA tables I prepared were
modeled with zero ground resistance connection for the verticals,
therefore they were 100% efficienct. Also, the types of soils modeled
extended from beneath the antennas to the horizon in all directions. If
you're an east coast W1 with your antenna on the ocean beach, you can't
expect those kinds of gains and TOAs to the west for verticals, hi -- but
to the east, yes -- the models are for "ideal" situations.
73, de Earl, K6SE
_____________________________________________________________________
You don't need to buy Internet access to use free Internet e-mail.
Get completely free e-mail from Juno at http://www.juno.com
Or call Juno at (800) 654-JUNO [654-5866]
--
FAQ on WWW: http://www.contesting.com/topband.html
Submissions: topband@contesting.com
Administrative requests: topband-REQUEST@contesting.com
Problems: owner-topband@contesting.com
|