Towertalk
[Top] [All Lists]

Re: [TowerTalk] 80 meter vertical question

To: towertalk@contesting.com
Subject: Re: [TowerTalk] 80 meter vertical question
From: David Gilbert <xdavid@cis-broadband.com>
Date: Fri, 21 Mar 2014 00:02:39 -0700
List-post: <towertalk@contesting.com">mailto:towertalk@contesting.com>
That statement is completely true as far as it goes, but I think it is 
possible to get a 1.1 SWR with a vertical portion that is electrically 
longer than 1/4 wavelength and radials that are somewhat shorter.  The 
combination can still be resonant but the feedpoint is essentially 
"off-center" to raise the impedance.  I've modeled that in EZNEC and 
verified it in practice with roof-mounted "ground plane" antennas I had 
at my previous QTH.
I'm not saying that's what John has ... just making a general comment 
for clarification.
73,
Dave   AB7E



On 3/20/2014 10:54 PM, Jim Brown wrote:
On 3/20/2014 4:40 PM, john nistico wrote:
I have put up a 80 wire vertical in some trees seeing I do not have a tower. I cut it 62ft6in so it should be on 3.750 however it seems long and the swr is 1:1 at 3550 or so. I have 10 radials and my longer version worked just fine. Any feedbck would be helpful.
Hi John,

If you have 1:1 SWR with a resonant quarter wave vertical, you have a poor radial system. The resistance at resonance of a quarter wave is about 35 ohms with an ideal radial system. That means you have 15 ohms of loss in the radials. 1:1 SWR is NOT a design objective for a quarter wave vertical! Instead, I would work on improving the radial system. Either a LOT more on-ground radials, or raise the radials as high as you can.
73, Jim K9YC
_______________________________________________



_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk

_______________________________________________



_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk

<Prev in Thread] Current Thread [Next in Thread>