Thank you, Terry. And thanks to all who gave ideas. The double-L looks
interesting, but I'm not sure the vertical height I have will allow me to use
it. My tower is only 40 feet tall, and, to make things worse, the ground
slopes upward away from the tower in the direction I can use (back yard). I
want to keep everything up away from the ground, so that doesn't leave much
height to work with.
I appreciate some of the other ideas I got, as well, but I'm trying to avoid
putting in radials, at least for the moment.
I went ahead with my original thought yesterday - a horizontal dipole with one
shortened leg loaded with a coil 10 feet out from the feed point. I wound the
coil on 3 inch PVC. I ran out of daylight before getting the antenna
completely adjusted. It was a little long, and I had an SWR of 3 at the low
end of the band, going up as I tuned higher. My tuner matched it, and I worked
a station in Rhode island and one in West Virginia (I'm in Michigan). Not DX,
obviously, but at least I have something I can use for the band.
I went out this morning and took a few turns off the coil. SWR is now flat at
about 1820 kHz. Gets to 3 at about 1870 kHz. Looks good, as I'm probably
going to be using mostly CW. All I need to do now is solder up my connections
and secure the coil a little better. I'll try this out for a while and maybe
do something better for low-angle radiation later.
Thanks again to everyone. Time for me to go to work!
73 de Blair, NP2F
----- Original Message -----
From: Terry Conboy <n6ry@arrl.net>
Date: Sunday, December 6, 2009 7:23 pm
Subject: Re: [TowerTalk] dipole configuration
> Blair,
>
> You've gotten some good inputs on your question. Vertical
> polarization
> is definitely the way to go on 160m. Given your space
> constraints, the
> K2KQ "Double-L", would be a good antenna for you. See
> http://www.yccc.org/Articles/double_l.htm and
> http://www.yccc.org/Articles/Antennas/K2KQ/DBL-L.PPT K2KQ shows
> a dual
> band (80-160) version, but you can just leave off the 80m wires if
> that
> band isn't of interest. If you can't get the full height, you can
> lengthen the horizontal wires to keep the total length the same.
> The
> impedance will be a bit lower with less vertical height.
>
> N0HR has done some modeling of this antenna and includes radiation
> patterns: http://www.n0hr.com/160m%20and%2080m%20Double%20L.htm
>
> This antenna has a lot of low angle signal, but also fills in the
> null
> somewhat at high angles, making it good for short haul work, too.
> It
> will have a lot more bandwidth than an approach using loading
> coils and
> much more efficient than a low dipole.
>
> 73, Terry N6RY
>
> On 2009-12-04 5:10 AM, Blair S Balden NP2F wrote:
> > I'm getting set to put up a wire dipole for 160 meters. I'm
> considering 2 options, and I wanted to hear which one you guys
> think might be better. The feed point will be about 38 feet up on
> the side of a tower near the house. From there, I have just
> enough room to stretch out a full quarter wave to the back edge of
> my property, where I can get about 25 - 30 feet of height in a
> tree at the other end. So this leg of the dipole will be pretty
> much horizontal.
> >
> > For the other leg, I don't have that much room. I will need to
> put in a loading coil. I have about 60 feet to a tree in the
> front yard, where I can get about 25 feet of height. This is what
> I was planning, but I also thought about bringing that leg
> straight down from the feed point. In that case, the antenna
> would have one full-length horizontal leg and one short (about 30
> foot) vertical leg with a loading coil.
> >
> > Do you think anything would be gained by having part of the
> antenna vertical? Would I get some lower-angle radiation if I did
> it that way? Or would it work better more or less horizontal?
> >
> >
>
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