Topband: Re Small lot antenna idea (steve d)
M0VEY at aol.com
M0VEY at aol.com
Fri Feb 9 11:26:52 EST 2007
>Hello, I want to get some suggestions about this before I try it. I was
going to do something >similar to it earlier but I just havent got around to it
yet. Anyway, a buddy of mine was >telling me that I really need to get back
on Top Band as conditions are at their peak. So I >think I am going to take
his suggestion and throw something up - quite literally HI.
>My buddy, KA1VHF, said to get a piece of wire as long as I could get up and
then make a >loading coil to match it. The only problem with this approach
is it would be a VERY limited >bandwidth. So instead of making a loading coil
I started thinking of using my screwdriver >antenna as the loading coil
instead - after all, thats all it is, right? Only its motorized.
>The plan is to use insulated wire and drape it over the house (no trees to
speak of so >unless I erect a mast or tower, or go into the neihbors yard I
dont have any other support). >The screwdriver would be at one end of the wire
to load it.
>The question now becomes how to I ground it? I could tap into the plumbing
in the house, >but then the wire would be laying right on top of the
counterpoise. I dont know how that >would affect the signal.
> The other option would be to just string out a longwire from my room and
use my tuner to >load it. Then, use the plumbing as a counterpose. But again,
the wire would have to go over >the house.
>I could go AROUND the house, but the antenna would be at the most 6 feet
off the ground >(accept where it would slope up to my second story shack) and
10 feet from the house.
>Any ideas? Something that radiates is better than nothing, and something
that radiates >better is.. well, even better! But I have to make due with what
This worked for me & the top loading wire can be zig zagged.
After you have read this you can check out my yahoo group.
In early 2005 I spoke with Andy, G7LRR about homebrewing an antenna for
Topband that I could fit in my garden.Andy suggested using a design by Alan,
G4ERZ that I could fit in the 60' space I had. I had a head start, because Paul,
G6AXW had already made one which just needed altering so it could be coax
fed instead of being fed with a length of wire.
This antenna is space wound on a 6' length of 1 1/2" plastic pipe. It is
fixed to the pipe using a hot glue gun. Total length of wire is approx 130' with
half the wire helically wound on the pipe & the other half of the wire left
as a top loading wire. For this mk1 antenna a hole was drilled in the side of
the antenna, 2" from the bottom. I fed the coax in here & joined the centre
part of the coax to the Helical wire, using a choc-block. The braid side of
the coax was also connected to a choc-block so a wire could be attached &
returned to the ground system once the antenna was in the air. I will describe in
my next posting how to use an S0-239 connector as on the mk2.
I made a mounting loop at the top of the antenna so that I could pull the
antenna to the top of my 40' flagpole I use as a mast. I will describe how to
base mount this antenna in another posting. I use 2 counterpoises connected to
my ground system. One is 125' long & runs under the top loading wire. The
other is a very long wire running thru the bottom of a wooden fence alongside
I also buried a 3' copper hot water tank, 4' in the ground. This took 2 s
points off my background noise level & improved my TX signal. After trimming
the antenna wire the overall length of my Helical is approx 125'
My antenna is 40' in the air with the top loading wire sloping to 20' above
ground. I have had some good dx results & inter G contacts with the Helical.
Please post any messages to this group if you have any questions to be
Details of any of your homebrew Topband, base or mobile antennas would be
appreciated. Regards, Phil. m0vey
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