For 160 meters, 1/4 wl is 128 feet, six inches, give or take.
At 60 feet high, that 128.5 foot hypoteneuse will create a triangle 114
feet-ish along the ground, which will make it virtually indistinguishable
from one-half of a horizontal dipole that starts at a clearly insufficient
height off ground for DX and tapers to near-zero elevation.
Couple that with the fact that even under the best circumstances (a tower
height allowing for at the very least a 45-degree slope), the half-sloper is
a highly unpredictable antenna design, and I don't like the sloper's
chances. Like VA5DX says, the sloper may work or it may not, but I think
your chances are better on 80 given the 60-foot tower height.
Since you are contemplating an inverted-L, you obviously have no aversion to
radials. That may be the way to go, but the inverted-L appears to work best
when cut for at least 5/8-wl total length. Some say 3/4-wl.
A few options that might work even better: Shunt-feed the tower. This will
take experimentation to get the drop wire height and spacing to tower
correct as well as the capacitive network needed at the bottom. If you can
add a loading coil and a whip at the top (Minooka), even better. Radials,
radials, radials.
Build an 80-meter inverted vee with twinlead or open wire for a feedline to
the ground. Short the feedline at the ground and feed it just like a
vertical. Over radials. This has the advantage of being able to be
constructed to serve as both an 80-meter vee AND a 160-meter top-load
vertical if you wish and gets the outside ends of the antenna off the
ground. You can also use coax.
Build a 160-meter inverted vee but with no feedline and the two legs of the
antenna shorted to each other where the feedline normally would go. Feed it
at one end (at the ground) with radials under the tower, under the feedpoint
and under the far end, with one wire running as a radial between the coax
sheild and the far end of the antenna. This is DeMaw's half loop (also
modelled successfully by Belrose in a half-delta configuration.)
I don't mean to demean the sloper. W8JI says it's an unpredictable design
and I have no reason not to believe him, but it also has been shown to work.
But I just think it won't be high enough in this application.
73, kelly
ve4xt
----- Original Message -----
From: <RLVZ@aol.com>
To: <towertalk@contesting.com>
Sent: Sunday, November 13, 2005 7:04 PM
Subject: [TowerTalk] 160-m Inverted L or Sloper?
> Hi guys,
>
> For 160-meter DX work, and a tower height of only 60', would you
recommend
> an Inverted L or a 1/4 wave Sloper?
>
> Thanks!
> K9OM
> _______________________________________________
>
> See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless
Weather Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any
questions and ask for Sherman, W2FLA.
>
> _______________________________________________
> TowerTalk mailing list
> TowerTalk@contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk
_______________________________________________
See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless Weather
Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any questions
and ask for Sherman, W2FLA.
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