Re: OT - Interesting Accident with Homebrew Vertical

Posted by Steve Ellington on Feb 04, 2010; 5:09am
URL: http://elecraft.85.s1.nabble.com/OT-Interesting-Accident-with-Homebrew-Vertical-tp4511024p4511749.html

I think the original question was.....Can you feed the vertical section with
the braid and radials with center conductor?
I guess technically you could since neither one is grounded. It's weird to
think about.
Also I'm not too sure about all that "radial tuning" and canceling of
horizontal radiation if the radial system is only a few feet from the dirt.
It's interesting to think about how radiation is "canceled". Where's it go?
Think I'll go to bed and dream about this. 73
Steve
N4LQ
----- Original Message -----
From: "Don Wilhelm" <[hidden email]>
To: "Robert Fish" <[hidden email]>
Cc: <[hidden email]>
Sent: Wednesday, February 03, 2010 11:06 PM
Subject: Re: [Elecraft] OT - Interesting Accident with Homebrew Vertical

> Bob,
>
> Indeed elevated radials *are* a part of the antenna (actually radials in
> the ground are too).  Elevated radials must be tuned (while buried
> radials do not need to be).  To do that properly, connect each one - one
> at a time -  and resonate it with the vertical element.  When all have
> been tuned, then they can be connected together.
> To cancel the horizontal radiation component, the radials should be
> oriented in opposing directions - any pair should be in a straight
> line.  4 radials arranged 90 degrees apart is normally sufficient, and
> in a pinch, 2  placed 180 degrees apart are sufficient.
>
> It matters not whether the vertical part is fed from the center
> conductor or the shield.  The currents on the inside of the coax are
> balanced (equal and opposite currents).  The "magic" is to keep the
> current off the outside of the coax shield, and that is what common mode
> chokes (current baluns) should accomplish.
>
> 73,
> Don W3FPR
>
> Robert Fish wrote:
>>  I noticed
>> that I had hooked up the shield of the coax to the vertical element and
>> the center conductor to the radials. (I was experimenting with running
>> 180 deg out of phase for end fire and forgot to change it back). I am
>> not sure what that proves except that he radials really are half the
>> antenna. Working Africa from here on the west coast with only 100 watts
>> is pretty rare these days, so the backwards hookup is obviously working.
>>
>> I guess it makes sense that it shouldn't matter. What do you guys think?
>>
>>
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