[TowerTalk] 80/40 coax trap dipole design

[TexasRF at aol.com]

Peter, you might want to look at the pdf copy of the original article.  
There is no "trap" per se in the design.
 
Instead, there is a clever arrangement using a parallel LC circuit that  
provides inductive loading on the lower frequency and capacitive loading on 
the  higher frequency. It just so happens that this LC circuit does resonate 
at a  frequency that is about halfway between the low and high bands of the  
antenna.
 
The cool thing about this design is that the entire length of the antenna  
is used on both bands; providing a bit of gain on the higher band in a 
manner  similar to a collinear dipole or distributed C design.
 
73,
Gerald K5GW
 
 
 
 
 
In a message dated 12/16/2010 8:08:25 A.M. Central Standard Time,  
dj7ww at t-online.de writes:

It will  not work on two bands without a trap

73
Peter

-----Original  Message-----
From:  towertalk-bounces at contesting.com
[mailto:towertalk-bounces at contesting.com]  On Behalf Of Jim Thomson

Barry's designs use a loading coil in each leg  rather than a trap, and 
the coils are roughly at the point where the  insulator would be for a 
half wave on the higher band. Then the coils, and  a bit more wire.  The 
160/80 version is roughly 160 ft long, the  80/40 version is a bit under 
100 ft.  


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