[TowerTalk] Balun on a vertical

Jim Lux jimlux at earthlink.net
Mon Oct 9 11:40:36 EDT 2006


At 08:02 AM 10/9/2006, Dan Hearn wrote:
>"Since a vertical always has this basic lack of symmetry, there is no way
>to connect a feedline directly to the antenna without setting up
>common-mode currents that will make the feedline radiate. A coax-fed
>vertical always needs some kind of device to prevent the outer surface
>of the coax behaving as an unwanted part of the antenna."
>
>We know that buried radials are affected by the soil around them to the
>extent that they are not capable of being resonated. It seems to me that a
>buried feedline would not need a choke to stop current on the shield outer.
>Anyone agree or disagree?

One could conceivably resonate a buried wire, but, generally, it 
would be pretty lossy.  It would just be another radial.

I think you'd just want a choke where the feedline comes into the 
shack, just to make sure that RF stays on the "inside" of the coax.


>Dan, N5AR
>
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