[TowerTalk] 80/40 coax trap dipole design

TexasRF at aol.com TexasRF at aol.com
Thu Dec 16 06:36:29 PST 2010

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  
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.
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


-----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.  


TowerTalk  mailing  list
TowerTalk at contesting.com

More information about the TowerTalk mailing list