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Re: [TowerTalk] Multi-band dipoles

Subject: Re: [TowerTalk] Multi-band dipoles
From: Jim Brown <>
Date: Thu, 21 Apr 2011 09:11:31 -0700
List-post: <">>
On 4/20/2011 7:03 PM, K8RI on TT wrote:
> It's been mentioned that with fan dipoles the lowest frequency band has
> it's band width increased

Correction -- In a fan dipole made from parallel wires, the lowest 
frequency band has the full SWR bandwidth as if no other antenna were in 
the fan. The higher frequency band(s)  have their SWR bandwidth reduced 
by roughly one half. This works out just fine when the lowest frequency 
is 75/80M, because the higher bands are a relatively low percentage 

Another VERY important point -- coax, especially BIG coax, has VERY 
little loss on 160M, and only a bit more on 75/80M, so moderately high 
SWR (up to 5:1, for example) that might be present far off frequency 
still doesn't add much loss.  You WILL need a decent antenna tuner to 
work at the band limits. I use Ten Tec 229 and 238 tuners, which have 
better than average efficiency and, because of their design, once they 
are tuned, they tend to maintain a match over a much wider bandwidth 
than T-section tuners.

73, Jim Brown K9YC

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