# Tree Antenna?



## siafulinux

Anyone heard of this? I don't have a lot of knowledge about radio's but I read about this some time back and gave it a go with a radio that wasn't properly set up. I have got it correctly set now, think I need to give it a try again.

But anyway, if I'm not mistaken a radio is only as good as it's antenna and a good antenna can extend the range of communication (hope I'm not wrong on this). If so, and this tree antenna deal works, then I wonder if this would provide a quick, longer range or maybe just clearer communications?

Have an "antenna kit" with you, shove some spikes (nails) into a tree and start communicating.










George O. Squier ~ Trees as Antennas ( Scientific American, June 14, 1919 & British Patent Specification # 149,917)


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## Fn/Form

For receiving... anything that helps is welcome!

For transmitting... we know that impedance/antenna matching is one of the most important parts of efficient radiation. With trees I'm sure the impedance would vary wildly with the moisture content. It would be interesting to test.


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## UKarmr

Are you using Hf or VhF?
I'm an ex comms spec, we used to use HF a lot, common practise was to set the antenna length to the freq, insulate, the tie a spanner to the string and throw it over the highest branch we could- preferably facing the direction we wanted to talk to. 

Dipole antennas work well, if set low the ground very good for short range comms in mountainous areas (google NVIS- near vertical incident skywave)

All this was before digital comms of course!


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## alergyfree

I think it's fascinating.


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## Tirediron

This topic is covered in Paul Tawrell's Camping and wildeness survival Book, I think he mentions 1/4 wave antennas, 
Maybe UKarmr could explain this a little bit for the rest of us??? please


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## UKarmr

I can try!
basically (and its been a few years) every frequency has its perfect antenna length.
these are known as full wave antenna.
unfortunately these are unrealistic, for example a 5mhz frequency would require an antenna arm of nearly 200ft long (for a di-pole, that would be 200ft each arm)
a 1/4 wave antenna is commonly used where space is an issue.
so basically you would have antenna arms of just under 50ft each instead.

we always used to err on the longer side, then use a tuning unit to tune it out.

very basic idea really, hope it helps


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## DKRinAK

Tirediron said:


> This topic is covered in Paul Tawrell's Camping and wildeness survival Book, I think he mentions 1/4 wave antennas,
> Maybe UKarmr could explain this a little bit for the rest of us??? please


You can use some simple math for an antenna.

468/freq in Mhz = L(ength in feet)

SO - say you want an antenna for the 49 Meter band. (5950-6200 khz)

468/6 = 78 feet and so a half wave antenna, 39 feet and so on.

Or use this handy calculator on the web
Frequency Wavelength Calculator

Hope this helps


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## DKRinAK

siafulinux said:


> Anyone heard of this? I don't have a lot of knowledge about radio's but I read about this some time back and gave it a go with a radio that wasn't properly set up. I have got it correctly set now, think I need to give it a try again.
> 
> But anyway, if I'm not mistaken a radio is only as good as it's antenna and a good antenna can extend the range of communication (hope I'm not wrong on this). If so, and this tree antenna deal works, then I wonder if this would provide a quick, longer range or maybe just clearer communications?
> 
> Have an "antenna kit" with you, shove some spikes (nails) into a tree and start communicating.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> George O. Squier ~ Trees as Antennas ( Scientific American, June 14, 1919 & British Patent Specification # 149,917)


During the late unpleasantness in RVN, US SF used an adapter to utilize trees as an antenna. I had one as part of an AN/PRC-64 (Delco 1500) HF set.


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## DKRinAK

*MAth is fun!*



UKarmr said:


> I can try!
> basically (and its been a few years) every frequency has its perfect antenna length.
> these are known as full wave antenna.
> unfortunately these are unrealistic, for example a 5mhz frequency would require an antenna arm of nearly 200ft long (for a di-pole, that would be 200ft each arm)
> a 1/4 wave antenna is commonly used where space is an issue.
> so basically you would have antenna arms of just under 50ft each instead.
> 
> we always used to err on the longer side, then use a tuning unit to tune it out.
> 
> very basic idea really, hope it helps


468/Freq in MHz - Length in feet

or
check here
Amateur Vertical Antenna Calculator

And here is a link of links for all kinds of antennas.
Calculator - Antennas: Antenna Calculators


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## DKRinAK

*MAth is fun*



UKarmr said:


> I can try!
> basically (and its been a few years) every frequency has its perfect antenna length.
> these are known as full wave antenna.
> unfortunately these are unrealistic, for example a 5mhz frequency would require an antenna arm of nearly 200ft long (for a di-pole, that would be 200ft each arm)
> a 1/4 wave antenna is commonly used where space is an issue.
> so basically you would have antenna arms of just under 50ft each instead.
> 
> we always used to err on the longer side, then use a tuning unit to tune it out.
> 
> very basic idea really, hope it helps


468/freq in MHz = Length in feet.

There any number of site offering antenna calculators.


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## Davarm

DKRinAK said:


> 468/freq in MHz = Length in feet.
> 
> There any number of site offering antenna calculators.


Am trying to remember my theory, is that formula for a 50 or 72 ohm antana?

Long wire antenas have been used since Tesla invented radio(Tesla was recently recognized as the inventor, not Marconi). For reception, the longer the better. It is even possible to use live power lines for an antenna but unless you know what you are doing, DO NOT try this though.

When using a longwire antena for transmission, it is better to string the conductor perpendicular to the target due to the radiation pattern of that particular antena type, I think that is what UKarmr said.

For a dipole antena the impedence of the antenna is greatly effected by its height above ground, again am trying to remember my theory and pracice-its been a few years, I think 1/2 wave above ground in free space, is optimal.

Their has been talk that the communications industry is planning to use live commercial power lines to pass data traffic(internet and other types) and if that happens much of the radio spectrum will be totally unusable due EMI. This is alrady being done to a limited degree with Smart Power Meters.

HF antennas were always one of my strong points but that was 20-30+ years ago.


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## Davarm

Gave some thought to that longwire antenna for transmission, the radiation pattern would be a cone shape from the feed point with the conductor being the center of the cone, so in general pointing the antenna toward, not perpendicular to the target receiver would be good with about a 45 degree angel from the target being best.


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## DKRinAK

*50 Ohm it is*



Davarm said:


> Am trying to remember my theory, is that formula for a 50 or 72 ohm antana?
> 
> Long wire antenas have been used since Tesla invented radio(Tesla was recently recognized as the inventor, not Marconi). For reception, the longer the better. It is even possible to use live power lines for an antenna but unless you know what you are doing, DO NOT try this though.
> 
> When using a longwire antena for transmission, it is better to string the conductor perpendicular to the target due to the radiation pattern of that particular antena type, I think that is what UKarmr said.
> 
> For a dipole antena the impedence of the antenna is greatly effected by its height above ground, again am trying to remember my theory and pracice-its been a few years, I think 1/2 wave above ground in free space, is optimal.
> 
> Their has been talk that the communications industry is planning to use live commercial power lines to pass data traffic(internet and other types) and if that happens much of the radio spectrum will be totally unusable due EMI. This is alrady being done to a limited degree with Smart Power Meters.
> 
> HF antennas were always one of my strong points but that was 20-30+ years ago.


50 ohm. For a wide range of workable antennas, the ARRL has an Antenna book at a reasonable price point. I used it a lot while active duty, saved the day when working in restricted spaces around active airfields.

Otherwise, we would just put up a full wave dipole as an inverted V. Seemed to do fine when you had the space.


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## Davarm

When I was active duty, I also used the ARRL handbooks. I had about 10 years worth worth on my bookshelf, cant say how valuable they were. Ditched them when I got out and have kicked myself ever since.

The first antenna I ever made was an inverted V as a teenager when the CB craze was in full swing, bought a cheap radio but couldnt afford an antenna so made one.

Radio, for me HF, is a good skill/knowledge to have if TSHTF, 

Thanks for the formula will write it down for future reference.


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## k0xxx

Davarm said:


> [snip]
> 
> Their has been talk that the communications industry is planning to use live commercial power lines to pass data traffic(internet and other types) and if that happens much of the radio spectrum will be totally unusable due EMI. This is alrady being done to a limited degree with Smart Power Meters.
> 
> HF antennas were always one of my strong points but that was 20-30+ years ago.


Several electrical companies have been running Broadband over Power Lines (BPL) test systems for providing internet service for several years. In spite of being labeled as Part 15 compliant, and lawfully restricted from causing harm to licensed radio service like Amateur Radio, the results have not been good. Interference to Ham Radio in those areas was extensive, and in some cases, even to commercial broadcast stations.

You just can't transmit radio waves into an unencased long wire, essentially making the wire an antenna, and expect them not to radiate.


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## k0xxx

As far as using trees for antennas, while it can work and it certainly is stealthy, a dipole is a much more efficient and reliable option. A dipole can be strung up quickly, used as an inverted V, or as a NVIS (Near Vertical Incident Skywave) antenna to change the radiation pattern depending on needs.


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## Davarm

Yea, what k0xxx said.

You just can't transmit radio waves into an unencased long wire, essentially making the wire an antenna, and expect them not to radiate.


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## dataman19

This has been done on many occaisions... Trees make adequate antennas if you have the resources to match the impedance of the transmitter to the tree. they do not make good receiving antennas, way too much resistance in the sap, etc.....
..
Simple: You just drive a nail into the tree (a long nail is preferred) and a ground rod about three or four feet away (the longer the wavelength the farther away to place the ground rod - about 1/4 will work, 1/2 wavelength is better). Use an efficient antenna matching transformer to bring the VSWR down and go for it...
..
Many an AM radio station has used a tree as a temp transmitting antenna over the years.
..
I've done it. It definitely works. But the range is less than ideal, but in a pinch and inch or two is better than on inch....


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## ReconCraftTheta

Interesting thing to try... I might have to one of these weekends once I get my receiver back


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