[TowerTalk] Concealed antenna issue

[Michael Tope]

Dave LaBat wrote:

>Current situation is about 45 feet of 12 gauge wire run up a pine tree with 
>around 24 radials of various lengths through the yard, certainly not in any 
>pattern. The wire runs almost alongside the tree trunk. I use a SGC auto 
>tuner at the base. This system kind of works. I can work the DX in the 
>Pacific but not toward Europe. I have always thought the antenna is probably 
>compromised by being right against the tree. I have no way to pull it away 
>from the tree, that would make it visible!
>
>I am  thinking of a 33 foot Zero five flagpole away from the trees. Radial 
>pattern won't be much better, still have to deal with a small backyard, pool 
>and lots of concrete.
>
>I am trying to improve the performance on the low bands, especially for DX. 
>I am going to try to use a high powered auto tuner and up my output to 
>around 500 watts. Will probably use a loop for receiving.
>
>I can probably sneak my MA80/40V onto the lot some night and see if that is 
>better than the tree.
>
>What does the group think with regard to:
>
>1) 80 meter perfromance of a 33 foot radiator. Any way to improve 80, other 
>than a 66 foot element (not happening, 33 feet is as tall as its going!)
>2) Will this be an improvment over the "tree vertical" ?
>
>Thanks all
>
>Dave NT6AA
>
>  
>

Dave,

I have a 60 ft top-loaded vertical here on a small lot (5000 sqft). Its 
40ft of base insulated/house bracketed Rohn 25 with a 20ft aluminum 
water pipe stinger above it. The antenna is pretty close to a 60ft pine 
tree (the base of the tree is about 15 feet from the tower). I often 
felt that the tree is zapping some "dBs" from the vertical, but there is 
no way to prove it. Having the house next to the Rohn 25 with the wire 
mesh behind the stucco probably doesn't help either. My radial system is 
far from optimal due to the constraints of the lot which may be a bigger 
factor in the antenna efficiency than the clutter field (nearby house 
and tree). Still the antenna is suprisingly effective for working DX on 
80 and 160. I am not "loud", but I've worked a number of Europeans on 
160 meters with it and I even managed to finally clear 100 countries 
after years of trying. One thing I noticed was that running a full 1500 
watts has been helpful. The difference between 500W and 1500W is 4.77dB. 
Imagine how much work you would have to do to your antenna to improve 
the gain by 4.77dB!!!

If you haven't do so already, you might try pulling the wire further 
away from the tree trunk if its possible. Or maybe the 33' flagpole with 
a toploading wire slanted up to the top of the 45' pine tree. Optimize 
every variable (radiation resistance, ground loss, output power) and you 
should do okay. When I am running 1500 watts, I am probably lucky to be 
louder than a guy running 100 watts into a full-sized vertical in the 
clear with a good radial system, but that's enough to have a little fun 
with. As I am sure you know, Europe is tough on 80 and 160 from here due 
to the auroral oval (especially on 160 meters). You just have to wait 
for the days when the polar cap absorption is low. When the "veil is 
lifted", however, the Europeans can be very loud here. I've heard a 
number of Europeans S9+ here on 160 meters when the band really opens.  
(those are the times when PW guys like me can work into Europe). More 
typically I hear nothing at all, so you have to be patient. Same thing 
on 80 meters, but to a much lesser extent.

Hope this helps.

73, Mike W4EF...........................