[TowerTalk] Ground radials/elevated radials

[Paul Playford]

> For example, did you know that if you use an elevated resonant
counterpoise the radials all radiate substantial
> signal in the nearfield area? Did you know the more radials you use the
less problem that is?  Or did you think 
> that with a "balanced layout" the radials don't radiate?

I want the radials to radiate.  I kinda liken each element as a half wave
dipole with one end of the dipole in the form of a big fan.  The worst I can
say about what I am doing is that I always have felt that I hear better than
I transmit - but then one morning when I had my 80m cq beacon running I was
spotted in Hungary with the comment 'no ears'.  Oops.

> Knowing the radials all act like antennas can help us plan a system
better. I'd never install other feedlines or 
> antennas parallel and close to a system using a few radials, knowing that.
I'd never  bring a radial near a 
> telephone line or TV antenna feedline. If I thought the radials was
"perfect", I might make a mistake and do that.

I am fortunate in that both of my 4 squares are in the clear.  The radials
and feed points are above surrounding objects.  No tall trees in the Arizona
desert to worry about.

> Did you know that you lose field strength with elevated systems if you
don't use a choke or current balun to 
> isolate the system from earth? I don't see many people isolate feedlines
from the feedpoint of small radial 
> systems, yet it can be as much as a dB or so change!

Somehow I confused the feed lines (plural) statement with the impedance
transformer/phasing lines that feed each element.  I do have current baluns
at the feed point to the Comtek phasing boxes, which does as you say.

> Like the comments before none of this says "don't use them".
> It just points out the quirks of using a sparse radial system of any type
and things you have to watch for.

> If you look at:
> http://www.w8ji.com/verticals_and_baluns.htm  and
http://www.w8ji.com/end-fed_vertical_j-pole_and_horizontal_zepp.htm
> you'll see how important it is to isolate feedlines even  on groundplanes
with four radials.

I use baluns on all of my antennas - just because.  I think the balun gives
me a more symetrical radiation pattern.

> I hear people constantly saying with four radials 1/4 wave or higher off
the ground the radials are "perfect", and 
> I've even heard people say "two radials are actually enough, they only
used four on a groundplane because it looks 
> better".
> Some antennas are even sold using end-fed radiators without any radials!

I like the comment "My antenna is flat across the band."  My four dummy
loads are also flat across the band.  And then there is the "I can work
everything I can hear".  But can you hear everything that can hear you?
Note my previous comment re the Hungarian station?

> At some point someone has to learn how the stuff really works in order to
make good decisions, even if they are 
> decisions on where and how to compromise.

There is something we learn with modelling software - all antennas are
compromises.  Makes me a strong advocate of rolling my own so I can control
where the compromises are made.  Many times I have had friends of mine look
at my antennas and make the comment "I would rather purchase a commercially
made antenna that works".  I love it.

> 73 Tom

de Paul, W8AEF

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