Another option to consider is to reduce the amount of antenna that is
supported by the balloon by using a lower section of rigid mast and then
completing the antenna with the balloon supported wire. In other words for
every foot of antenna that is a rigid mast you need that much less wire that
is balloon supported.
I use this technique to fly a balloon from my sailboat here in Seattle and
over the saltwater of Puget Sound. In my case I rig a 28 foot long
fiberglass mast to the mainsail track of the boats main mast and host it to
the top. This provides me an non-conductive anchor point that is approx. 75
feet above the deck of the boat. I run a 12 gauge wire from the deck to that
point and then reduce the wire size to 18 gauge. In the past I have used as
small as 26 gauge when that's all I had available. The 26 gauge is
theoretically a bit small from an efficiency stand point on 160 but I worked
48 states in one ARRL 160 weekend with it so it can't be all that bad. This
configuration means I only have to support approximately 60 feet of wire
with the balloon and a 30 inch party balloon has more than enough lift and a
smaller size would work. I rig a piece of monofilament fishing line
(controlled by a fishing reel) to the base of the balloon to allow me to
launch and retrieve the balloon. Besides reducing the weight the balloon
needs to support this approach also addresses the blow down issue. If the
wind blows hard then it is an inverted L - the less wind there is the more
it is a vertical. I've used this successfully when the wind was in the mid
20's with no problem. The SWR bounces around a bit but that's all.
Last season I had a problem because they moved a big boat with a 80 foot
mast up alongside me in the marina and his mast with its expensive wind
instruments on the top was within reach of the balloon so I had to use an
inverted L with the far end supported by a friends mast. Didn't matter much
performance-wise because both antennas are completely over saltwater in
every direction so work very well.
Just another option to consider if you have a way of providing a rigid
support for the lower section of the antenna and that you can fly the
balloon from. The March/April 2005 issue of NCJ has an article describing
this approach.
73/Patrick
W7TMT
> -----Original Message-----
> From: towertalk-bounces@contesting.com
> [mailto:towertalk-bounces@contesting.com] On Behalf Of Rick Craig
> Sent: Tuesday, December 16, 2008 6:15 PM
> To: towertalk@contesting.com
> Subject: Re: [TowerTalk] balloon supported antenna
>
> The problem with having a round balloon supporting a wire is
> that it will lay over, almost horizontal in just a slight
> breeze. At 5 mph, most of the wire will be on the ground.
> What is needed is a "barrage
> (sp?) balloon" with fins on the back end. This provides lift
> and makes it want to sail into the wind rather than laying
> over. Look at an advertising balloon and you will see that
> they are all of this design.
>
> Good luck, Rick, N6ND
>
>
> n6nd at arrl dot net
>
> _______________________________________________
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