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Re: [TowerTalk] low band antenna without good ground

To: towertalk@contesting.com
Subject: Re: [TowerTalk] low band antenna without good ground
From: Jim Brown <jim@audiosystemsgroup.com>
Reply-to: jim@audiosystemsgroup.com
Date: Thu, 22 Sep 2011 14:24:18 -0700
List-post: <towertalk@contesting.com">mailto:towertalk@contesting.com>
On 9/22/2011 1:31 PM, Alex Malyava wrote:
> I need an advice for low band antenna (80-40) which does not need good
> grounding system.

You are paying far too much attention to impedance measurements.  First, 
you should be using an antenna tuner to match the antenna to the rig. 
Second, you are expecting far too much from 100W on 80M.  559 is a great 
report for a path on the order of 3,000-4,000 miles on 80M, especially 
this time of year. I worked the NA Sprint last weekend, and was just 
barely making 75M contacts to GA and New England with 1kW on both ends 
and my dipole at 110 ft from my QTH in CA. That's a 2,500 mile path.  We 
made contacts ONLY because there were very good operators on both ends.

As to your antenna -- if you want to use it only on 80/75M, try for a 
length of about 65 ft, and try to make the radials about 25% shorter 
than that. If you also want to use it on 160M, try to make it about 
90-100 ft, and make the radials as long as you can.  You WILL need an 
antenna tuner, but if your rig has one built in, it will probably load 
it just fine.

73, Jim K9YC
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