Subj : Re: Homebrew antenna questions
To   : alt.ham-radio.vhf-uhf
From : nospam
Date : Thu Sep 29 2005 13:01:55

From Newsgroup: alt.ham-radio.vhf-uhf

On Wed, 28 Sep 2005 20:56:36 -0700, Carl / W6VDC <carl.hixon@cox.net>
wrote:

>Here is an example of my confusion.  Reading about j-poles, some folks 
>say that they MUST be grounded, the mast must be metal, etc.  Others 
>say don't use a metal mast and don't ground the j-pole.  Some say you 
>MUST use a 1:1 balun, others say a balun is not needed.  Geez, up is 
>down and down is up, it's all relative.
>
>I assume from the reading I have done, that if you ground the antenna 
>you should use a balun.  If you do not ground the antenna you don't 
>need a balun?  Is it a good idea to use a balun any way?
>
>Just 1 of 1000 questions.
>
>Carl

With regard to Jpoles.  In general they work ok without balun if
adjusted correctly.   Purists will insist it requires a balun but I'd 
proint out that practical application is often a compromize on
 theory and will work well.

There is no ground requirement for Jpoles to work correctly.
Lightining protection all antennas must provide some form of
protection by grounding or providing short arc path to ground. 
Jpoles of the traditional form maybe grounded and work well 
as the ground is really not part of  the antenna beyond it's support.
By that I mean, it impacts the operation of the antenna minimally or
not at all.   Lightining protection by grounding  for anything
sticking up in the air is a good thing.

The copper Jpole is popular as its easily built from easily obtained
material that is durable and has known perfomance.  The copper 
itself will patina and that is often good enough looking as is without
disturbing its performance.   The Jpole however is not a high
performance antenna anymore than a plain center fed dipole is.  
It's difference is the bottom section allows it to be fed from the 
end rather than  the middle.      Like all antennass high and in the
clear will insure best performance.

With all that I have Jpoles cut for 52/145/440 operation and they
work well in the copper pipe form.

Allison

.