--------- Forwarded message ----------
From: "George Shaw" <george.shaw@ukf.net>
To: <towertalk@contesting.com>
To: <towertalk@contesting.com>
Date: Mon, 10 Dec 2001 09:45:33 -0000
Subject: RE: [TowerTalk] Tall
Message-ID: <MABBIGLJMINHBOPDDLFBCEHICPAA.george.shaw@ukf.net>
Ok this may seems a silly question but with all this talk of 2000' +
towers
it got me thinking. WHY does the height of the tower matter so much? Is
it
to elevate the antenna above the surrounding ground level due to some
sort
of RF coupling or is it to gain max distance?
To maximize distance. It extends the horizon. 99.9% of the commercial
towers around are for VHF/UHF, where line of sight is important. Launch
angles for skywave propagation is not a consideration.
Is it not easier to mount a shorter tower on higher ground atop a hill?
It the hill top ground is suitable for tower construction and the hill is
properly located, it can be a desirable alternative.
I have a 300' tower beside me but if it was moved 1/3rd mile east it
would
place the top of the antenna at 1500 ' as it's up a hill? So is it that
the
antenna needs to be a certain wavelength from g/l ?
License restrictions may limit ultimate height. Also, many tower sites
are critically located. I have a broadcast tower that cannot be moved
even 1/4 mile due to possible interference to a co-channel station.
Amateur installations, in general, are simply optimized for greatest
coverage within the limitations of the individual's wallet. Also,
limited by covenants, spouses, etc.
Commercial installations, on the other hand, are usually limited by
interference contours. Using fixed frequency, channelized operation,
they invariably share channels, and consequently, transmitter/antenna
location can become very "tricky."
73...Don, K9NR
--
George Shaw
eMail: george.shaw@btinternet.com
eMail: george.shaw@ukf.net
Fax/Voice Mail: +44 (0) 87 0133 6126
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Problems: owner-towertalk@contesting.com
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