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Author Topic: Load a tree...  (Read 1035 times)
N5LRZ
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« on: August 25, 2009, 06:56:39 AM »

Before Summer is over I plan to 'Load A Tree' as an antenna.  I have several very tall pine trees in the back yard and noted that they bleed gooey sap pretty darn good.

SOOOO I was thinking, a dangerous thing for me to do, why NOT run some coax to the tree and attach it to the tree using a small screw or something.  Sap has impure stuff in it.  That ol sap just might act as a good antenna, or at the very least a very bad antennna (but still an antenna).  A tuner will of coure be required along with a type of counterpoise still its a shot.

If anyone has any personal experience with such an attempt, how did your experiment turn out?
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WB5JEO
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« Reply #1 on: August 25, 2009, 08:33:44 AM »

The General would be proud. He was writing about it back in 1919. How-to diagrams and everything.

http://www.rexresearch.com/squier/squier.htm

And a 1975 IEEE article:

http://w5jgv.com/tree_antenna/1975%20January%20Ikrath%20IEEE%20tree%20antennas.pdf
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KE3WD
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« Reply #2 on: August 25, 2009, 09:38:20 AM »

I experimented with that some years ago when still living on my father's farmland.  

Would recommend that you use more than just a screw to attach center of coax to the tree, I used rather large threaded steel eye for the purpose, penetrating perhaps 2 - 3 inches into the bottom of the tree trunk.  

Also used radial wires underneath, hooked to the coax braid, in much the same fashion as with a vertical antenna.  

Coax was coiled at base into the typical ~10" diameter balun choke to preclude the coax shield as being the radiator.  

I found the trees to be a rather noisy antenna on the receive side.  

I did almost all of my experiments on CW, primarily 40 and 20 meters.  Power was always about 65W.  Was using a tube final rig back then, today's transistor output rigs, you would almost certainly need a very good fullrange antenna matching unit, I should think.  

Signal reports were only a couple or three dB down from what my old ground mounted Butternut vertical yielded -- in most cases.  

My best results were obtained with a huge old weeping willow tree, for what that's worth.  

This is NOT a good thing to do for the health of the tree involved.  

I think you would do a better job simply running a single wire up the tree to use as the radiator instead of the tree itself, with all of the above radials, etc. still being a part of the construction.
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AA4PB
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« Reply #3 on: August 25, 2009, 12:09:56 PM »

Now if the tree is conductive and its implented into the ground aren't you just putting a short across the coax unless you run a matching stub up the tree? Just like shunt feeding a tower. How do you adjust the tree for resonance? Can the roots act as radials?
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KE3WD
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« Reply #4 on: August 25, 2009, 04:58:21 PM »

I think those are non-problems, you just can't use the metal antenna model here.  

It is indeed a lossy situation, but it does indeed work.
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KB9CRY
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« Reply #5 on: August 26, 2009, 08:14:20 AM »

I only load up antennas.  A tree is not an antenna.
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KE3WD
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« Reply #6 on: August 26, 2009, 08:23:26 AM »

Many things that don't look like antennas can be pressed into service as an antenna.  

Learning experience.

Ham Radio is many things to many different people.  

Experimentation is enjoyed in a lot of different aspects and sometimes results in new inventions.  

Once those new inventions are discovered, published and marketed, there will be those who accept the new invention as a "norm".  The history of Ham Radio bears this out, some of us can remember when that new-fangled Single Sideband was "never going to catch on" and "wasn't worth the time of day" etc. etc. etc.

Or the Yagi-Uda antenna.

Or UHF.

Or Microwave communications.

Back in those younger days when I was experimenting with loading up all sorts of "nonantennas" I made successful QSOs on the CW bands using some weird stuff.  A 29-passenger schoolbus.  A large vertical mill.  Two metal lathes side-by-side turned out to work much like a dipole. I learned about mass and antennas from that.


--KE3WD
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KG6WLS
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« Reply #7 on: August 26, 2009, 09:36:40 AM »

I think it's a "sappy" idea.
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N7DM
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« Reply #8 on: August 26, 2009, 01:33:58 PM »

I really debated entering into this, but finally...

An antenna IS a conductor through which A.C. flows, and whose length is a significant portion of a wavelength.

Some years back, myself and another Seven took to entering Field Day using an unusual antenna. Specifically it was a 20 meter dipole made of 100% cotton 'rope'. For the week prior to F/D it was left soaking in a decidedly stinking container of somewhat salty liquid. Since *I* built it, *I* handled it as we went to pull it up. I alligator clipped on a chunk of 450 ohm twinlead, and we loaded it up, happily working for almost an hour. Then the thing dried out, conduction went West and we pulled it down, to replaced with a boring wire dipole.  The thing is though, IT WORKED. And 'PG' and myself will forever know that a 'Pee' antenna will work.

Load the snot out of that tree, OM! Other things radiate; I bet it will, too. Unless it is one of sea of trees, in which case some of the others will likely soak up all your outgoing signal....

DM
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WB5JEO
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« Reply #9 on: August 26, 2009, 06:54:00 PM »

"I think it's a "sappy" idea."

Leaf the puns out of it.
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AA4PB
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« Reply #10 on: August 27, 2009, 06:33:38 AM »

I note that the General's experiments indicated that it works best if the tree is tapped at 2/3 its height. It makes sense that you'd want to maximize the amount of wet wood between the ground and the feed point. It's more than just connecting the center conductor of coax to the tree near the ground. Note that a couterpoise of some type was used as well.

I also note that he used a single wire feed. This raises the question of how much the long feed wire (remember, it's at least 2/3 the height of the tree) is contributing to the signal reception. He noted that the signal improved when the actual connection was made to the tree but we don't know if that was because the tree was supplying signal or whether it was a matter of end loading the wire. We don't know if it resulted in a real signal increase or an improvement in signal to noise by lowering the noise.

I also expect there is a big difference between doing it at a few hundred Khz (or whatever frequency the General was using) and doing it at 20 meters.

Interesting stuff.
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N7DM
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« Reply #11 on: August 27, 2009, 06:41:05 AM »

Interesting indeed. I'd have thought a Gamma Match to the 'Nature Vertical' would be the way to go. Only one way to find out...........
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N3OX
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« Reply #12 on: August 28, 2009, 08:32:00 AM »

Look at how encouraging these comments are.  Sure, there are some detractors, but mostly people wanna say "TRY it and see what happens"

Funny that no one has come along and said something like :

"IF IF IF you need to use a tree as your antenna... IF IF IF you can't use PURE COPPER conductor in AT LEAST #00 SIZE, then you need to THROW AWAY your ham radio license and get off the air!!"

Funny that no one has come along and said something like

"You need AT AN ABSOLUTE MINIMUM 64 1/4 wave radials to feed a tree against!!  Nothing else is a RIGHT and PROPER tree antenna and ANYTHING ELSE will SUCK SCUM FROM THE BOTTOM OF THE WASTEWATER TREATMENT PLANT"

It's funny, because I swear there was a guy around these parts that would do that sort of thing... maybe he doesn't read the Misc forum?

It's funny, because once, that guy said, and I quote verbatim:

"IF the antenna you can put up is going to suck pond scum the DO NOT put up the antenna. Compromise antennas yield compromise results. NEVER compromise."

http://www.eham.net/forums/Elmers/229791

73
Dan
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73,
Dan
http://www.n3ox.net

Monkey/silicon cyborg, beeping at rocks since 1995.
N3OX
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« Reply #13 on: August 28, 2009, 10:56:54 AM »

In the Antenna Restrictions forum, N5LRZ writes:

"My reply is simple and strate forward...

Do NOT do anything unless you have the time, money and circumstances to do it right and proper.

I include Amateur Radio in that statement.

He should completely forget HF as long as his living situation is such that the cannot put up a proper antenna--NOT NOT NOT one of these shortened compromises POS antennas (I include that current ever so POS antenna that is being pushed so hard/that 43 ft job).

His sole and only use of amateur radio (unless he has access to a roof of the building and permission to put up a full size tribander) is solely and only that of VHF and UHF. AND AT THAT he is may be extremely limited by the electrical environment of his dwelling.


Should he just quit? If UHF and VHF are his only bands of daily guaranteed practicality then probably he should quit until and as to when he gets his damn ass out that appartment and into a half way decent home with a couple of acres in the country completely free of any anti antenna laws

UNTIL then yes he should retire, renew the licese to keep from loseing it, but until definately retire. "


From:

http://www.eham.net/forums/AntennaRestrictions/6074?page=3

And yet, N5LRZ wants to waste his precious, hard won ability to do things "right and proper" on loading up a tree.

Funny.
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73,
Dan
http://www.n3ox.net

Monkey/silicon cyborg, beeping at rocks since 1995.
N3OX
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« Reply #14 on: August 28, 2009, 11:07:37 AM »

By the way, if I look up the electrical conductivity of a tree, I find a paper

http://soil.scijournals.org/cgi/content/abstract/68/3/779

that has a peak value of about 10 deciSiemens per meter for the tree conductivity.

Taking the reciprocal of that gives a *resistivity* of 100 ohm * m.

So I go to EZNEC and see what happens with a 100 ohm*m wire 18 inches in diameter 40 feet tall when fed against ground on 40m.

It's got a current taper that looks exponential and a peak gain of about -27dBi.

73
Dan
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73,
Dan
http://www.n3ox.net

Monkey/silicon cyborg, beeping at rocks since 1995.
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