[TowerTalk] Two Vertical Antennas

[Paul Playford]

The first time I erected my 40m 4 square I installed 8 buried radials at
each element.  I was not happy with it's performance to the point I almost
did not put it back up when I moved.

But I bit the bullet after the move and I erected it with 4 elevated radials
(the feed point and radials are 2 1/2 meters above ground) and it works very
well,
thank you.

But I am a DXer.  I suspect that if I were interested in talking to someone
closer than say 3000 km, I would be happier with a dipole at 10 meters for
the high launch angle of the rf.

Just for yucks, you may want to try 4 elevated radials with your 40m
vertical and see what happens.  Erect them in a bat wing fashion - that is
come up from the feed point at roughly a 45 degree angle until you are a
couple of meters above ground and then out horizontally.  I determined the
length of my radials by installing 2 (no vertical element at this time) in a
dipole configuration, feed them at the center and cut them to resonance,
then
add 2 more for a total of 4.  Then erect the vertical and trim it to
resonance againsts the radials.  The vertical element will wind up being
slightly long which will tilt the radiation lobe down a couple of degrees
(but the lobe is so big you won't notice it) and the feed point z will be
lower but it will give you an idea of what it's performance will be.  For
this experiment you don't have to mess with your 60 radials as the antenna
will ignore them with the elevated radials.

And if you like the elevated radials you can raise the feed point of the
antenna and make it a permanent installation.  If the elevated radials don't
do anything for you then I just wasted a bunch of you time.

de Paul, W8AEF

----- Original Message ----- 
From: "Roger Parsons" <ve3zi at yahoo.com>
To: <towertalk at contesting.com>
Sent: Wednesday, August 04, 2004 2:19 PM
Subject: [TowerTalk] Two Vertical Antennas


> I have separate 7MHz and 10.1MHz quarter wave vertical
> antennas which are spaced about 60' Both have about 60
> radials and the radial fields do therefore cross each
> other to some extent. There is a very small amount of
> interaction between them, as one would expect, but not
> enough to significantly affect the matching. The feed
> impedances are much as expected, so they both seem to
> be working as they should be. They are both fed over
> the same hardline feeder with a switch box near the
> antennas. I am sure there are no feedline, switchbox
> or matching faults - I have physically exchanged the
> feedlines.
>
> The 10.1MHz antenna works beautifully - I snagged YV0D
> the first call after I found his listening frequency
> last night in a major pileup. The 7MHz antenna is a
> dog, which is very easily beaten in all directions and
> distances by a dipole at 40'. (The dipole is about
> 300' from the verticals and has a higher loss
> feedline.)
>
> Now why should that be?
>
> 73 Roger
> VE3ZI
>