Hi Doug
In doing some research on various antennas, the half-sloper was
described in various texts as a "bastard antenna". As you indicated,
works well for some, not well for others. One person spent quite a
bit of time with EZNEC trying to figure out what was going on with
this thing. What he finally surmised was that the tower is the active
radiating element, and the sloping wire tunes it. The direction the
wire slopes is of minor importance - you get a slight bulge in the
pattern, but no null off the back.
One he figured the tower is the radiating element, the next step was
to add radials. I added quite a few, and found this antenna to be a
good performer. Its an easy antenna to install, and may well be worth
trying.
The biggest thing is to get a decent SWR, and this will vary based on
tower height, top loading, attachment point and angle of the sloping
wire. I got lucky - I have 5 element 10 and 15 monobanders on top of
a 64 foot Trylon, and the sloping wire is about 45 degrees, attached
about four feet from the top. It is definatly vertically polarized.
I put up an inverted vee off a 48 foot tower about 200 feet away from
this, and was listening to a local who was using a horizontal long
wire about 15 feet off the ground, 30 miles away. S9 on the inverted
vee, and barely readable on the half sloper. Have noted similar
differences between DX (vertically polarized) vs horizontal (close in
stuff).
Tom - VE3CX
On Mon, Nov 10, 2008 at 10:43 AM, Doug Renwick <ve5ra@sasktel.net> wrote:
> Tom,
>
> Interesting comment on adding radials. I use half-slopers from my 110'
> guyed self-supporting tower on 160m. They work really well but I don't
> use any radials. I am also aware that half-slopers work well at some
> qths and not well at all at other. Maybe the answer is to add radials.
> How did you discover this radial thing?
>
> Doug
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