Topband: contesting in a field

[James Rodenkirch]

With the caveat that I am not any kind of SME on 160 meter antennas, I would 
be surprised that you'd need much of a counterpoise for an End Fed Half 
Wave antenna.

My experiences with an End Fed Half Wave antenna show that a small (small as in length of a singular wire) counterpoise is all that's required.  Assuming the physics for an 80 meter or 40 meter EFHW antenna carries over to 160 meters I don't see the need for anything of length or numbers - for my 80 and 40 meter EFHW antennas I use about 3 feet of counterpoise....I've lengthened that wire up to a 1/4 wave and have noticed zero improvement in SWR or received signal strength at several RBNs.

72, Jim Rodenkirch, K9JWV

 


> From: k3ky at radioprism.com
> To: topband at contesting.com
> Date: Tue, 15 Nov 2011 22:15:04 -0700
> Subject: Re: Topband: contesting in a field
> 
> I like resonant, voltage-fed verticals for their simplicity. For field
> ops,
> they can be a very quick way to deploy a working antenna. On 40 meters,
> for example,  you're only dealing with 70ft- or 35ft if bent like an
> "L",
> Half Square, Bobtail, etc.
> 
> If you could catch Murphy on vacation, and if you can raise a large
> enough balloon to support ~268ft of smaller gage wire, you can go with
> a voltage fed half wave using an LC tank to tune it. Tap up the coil
> from the ground end with your coax for a 1:1 SWR (assuming your LC is
> properly resonated) Your farm isn't near any airports, is it? OTOH if
> it's windy, this could be a rather frustrating event. (technically,
> you're 'pushing it' a little with anything over ~200ft in height)
> 
> You don't need much of a counterpoise, feeding this way- roll out
> however much chicken wire or wire cloth as you care to- or think
> 'radials', if that is your preference. A denser, shorter radial field
> or counterpoise ought to work pretty well.
> 
> Having the current max up 134ft couldn't hurt. It ought to play
> reasonably well. As always, more ground is better ground. I like
> the roll(s) of chicken wire approach.
> 
> 73, David K3KY
> 
> 
> >The last thing I need is a reason to generate flammable gasses in bulk :)
> >
> >We homeschool, so maybe that would fit the stereotype everyone expects.
> >"And then they did a chemistry experiment and blew up their garage."
> >
> >I've thought about an inverted L at home, I have just short of an acre, I
> >think the above ground part wouldn't be a problem its the radials. I'm
> >assuming in the wide open spaces at the farm I can pursue the same elevated
> >radials I would for a kite/balloon vertical? The elevated vertical thing
> >seems to be the best bang for the effort, and in some ways less effort
> >especially for temporary ops like this.
> 
> Chris
> 
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