[Elecraft] Attic Antenna

[Vic K2VCO]

N2EY at aol.com wrote:
> In a message dated 10/27/06 4:38:23 PM Eastern Daylight Time, 
> rohre at arlut.utexas.edu writes:
> 
> 
>> The Diamond bottom tube may, (and likely) contains a broad band ferrite 
>> cable choke.  
> 
> Probably - to keep RF off the outside of the coax. Such a choke would cost a 
> few dollars at most.

Actually, a choke on the coax would *prevent* the antenna from working 
unless it was mounted on a metal mast.  It needs a counterpoise and the 
coax shield provides it unless a mast or radials are present.

This is actually similar to the 'e-h' antenna, in which the alleged 
'antenna' at the end of the feedline serves to tune the shield of the 
feedline to resonance.  The shield actually does the radiating.  Adding 
a bead balun to an e-h antenna causes the antenna to stop working and 
the balun to get hot!  No, I don't want to start a thread on this 
antenna either!

In the Diamond antenna, the feedline is only half of the antenna, with 
the 22-foot radiator being the other half and the resistor smoothing out 
the SWR variations.
-- 
73,
Vic, K2VCO
Fresno CA
http://www.qsl.net/k2vco