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Re: [TowerTalk] Cage dipole revisited.

To: "Rick Stealey" <rstealey@hotmail.com>, <towertalk@contesting.com>
Subject: Re: [TowerTalk] Cage dipole revisited.
From: "Bill Aycock" <baycock@centurytel.net>
Reply-to: Bill Aycock <baycock@centurytel.net>
Date: Sat, 11 Apr 2009 21:54:31 -0500
List-post: <towertalk@contesting.com">mailto:towertalk@contesting.com>
Rick-
Why introduce this into this thread? The models you mention do not resemble 
the Cage dipole, so why?
There is enough distortion of the claims and references (eg, vertical 1/4 
wave) already. To really help, try modeling a real cage? The pertinent 
dimensions are easy to get, and a dipole for comparison should be easy. The 
claim that "Time Diversity" applies is ludicrous.
Bill--W4BSG

----- Original Message ----- 
From: "Rick Stealey" <rstealey@hotmail.com>
To: <towertalk@contesting.com>
Sent: Saturday, April 11, 2009 8:53 PM
Subject: Re: [TowerTalk] Cage dipole revisited.


>
> Today I did a little modeling with 4NEC2 on 80 meters.  First a regular 
> dipole showed a bandwidth of 200 KHz at the SWR=2:1 points.
> Then I decided to see how close to a real cage a pair of dipoles has to be 
> to get the same benefit.  So I added another dipole, fan style, to it and 
> got 320 KHz bandwidth.  I varied the length of the second dipole all over 
> the place.  I was modeling on 80 meters, and made the 2nd dipole small 
> (like the length of a 40 m dipole) and could see SWR dips in the 80m and 
> 40m bands when I did a frequency sweep.  Then I lengthend the small dipole 
> and watched the 2nd dip drop in frequency till it got close to the 80 m 
> band and the bandwidth began increasing.  But I was never able to get a 
> "double hump" inside the 80m band as I had hoped.
> But 320 KHz bandwidth was easily obtained.
> Now the question is, how different is a pair of dipoles (with 10-20 
> degrees angle between them)from a real cage dipole ?  So to do this I 
> modeled three dipoles, parallel to each other and separated a few feet 
> apart.  The bandwidth was the same as the fan, indicating to me that very 
> likely a simple two dipole fan antenna (both elements can be the same 
> length) will give good swr performance compared to a dipole and might be 
> worth the effort.  Sure would be simple to build compared to a cage
>
> Rick  K2XT
>
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