----- Original Message -----
From: <n4kg@juno.com>
To: <TOWERTALK@contesting.com>
Sent: 27 April 2001 21:06
Subject: Re: [TowerTalk] Guy wires as inverted Vee?
> I believe an inverted vee will outperform a HORIZONTALLY POLARIZED
> DELTA LOOP (fed at the apex or in the center of the bottom wire) with
> the same Apex Height since the EFFECTIVE Height of the Delta Loop
> is much lower due to the bottom wire being so close to the ground.
>
> A VERTICALLY POLARIZED Delta Loop IS a very effective DX antenna.
> Feed 1/4 WL down from the Apex. Note that an equilateral loop for 80M
> is over 80 ft tall and thus must be "squished" to fit on a 70 ft tower,
> or, have the bottom corners pulled out from the tower. The pattern of a
> vertically polarized Delta Loop is more nearly omni-directional (3 db
> F/S) than an Inverted Vee.
Yep - my experience too. I feed mine at the bottom corner with 1:1 balun and
75ohm coax, though have also used Belden 9207 which is a screened 100ohm
twinaxial, 8.4mm o.d. meant for office data networks but great for this
application too, even at hi-pwr levels.
I have mine on a 60 foot support, and the two bottom corners are pulled away
from the base so that the bottom horizontal side is about 8 foot from the
ground. I don't know, but suspect that the fact that this is now a sloping
delta means I get better low angle than if it was purely a vertical delta,
in the same manner as a sloping dipole. Perhaps some modelling-expert could
take a look at this ??? Anyway, it gives great bangs-per-buck, and keeps me
happy !!
73s Tim EI8IC
www.qsl.net/ei8ic/ Irish contester Site, with section on budget contesting.
List Sponsor: ChampionRadio.com - Trylon self-supporting towers,
safety equipment, rigging gear, LOOS tension guages & more!
http://www.championradio.com
-----
FAQ on WWW: http://www.contesting.com/FAQ/towertalk
Submissions: towertalk@contesting.com
Administrative requests: towertalk-REQUEST@contesting.com
Problems: owner-towertalk@contesting.com
|