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Mast Vs Tree

Hello Chris, thanks for your video about your antenna. Very informative.

Cheers, Geoff vk3sq

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I threw things over a limb to obtain support exactly once. To answer your question, I have laid the wire on the ground and worked DX QRP. Almost no difference is with height IF one is on a peak. GL 73, Fred KT5X 900+ activations

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I can confirm that and it matches my experience.

Until recently, the weight was a metal nut that I could only throw a few feet. The antenna wire was mostly horizontal and yet DX connections on higher bands were regular. I couldn’t find any pronounced directivity either.

Like you, I suspect that the exposed location on a summit is the reason.

To find out more, I’m experimenting with a second vertical EFHW and switching back and forth between the two in the qso. So far there hasn’t been a clear winner.

73 Chris

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Use the pole and lean it against the tree for support. If needed, bungee pole to a limb. You don’t have to worry about snagging the wire in the tree. Additionally using a tree for support you can bungee to a sapling and have a clearer set up area for the wire. I use an EFHW in an inverted L configuration, fed at the bottom of the pole. Additionally, you can leave whatever weight you are using to throw the line at home.

Mike AD5A

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I am using always trees as support. Nearly all summits in the Bavarian Forest have some trees in the activation zone.
However my strategy always is to find a long and stable horizontal branch, where I throw the line across. This helps me to stay away from the tree trunk and ideally as well from other branches. Using a 7 m vertical I can erect the wire nearly vertical and stay away from branches at least some meters. Using the 14 m wire usually it ends in a 75 angle.
For the 20 m long EFHW I use the same tree position (horizontal branch as free as possible) , however attach the wire in the middle, at 10m to the throw line, then erect the line. As last step I fix the one wire end with some rope and a stone near to the earth, the other to the rig and get a quite suitable free hanging inverted V.

73 de Klaus , DL2KL

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When I first started activating, I used an arborist’s throw bag and line. I soon went to using a mast for several reasons:

  1. Repeatable process. I know I can set up my mast using much the same steps/options on any summit. This means I am on the air much sooner within a predictable time range. Throwing a line in a tree has many more variables from site to site. And I am pretty poor at it!
  2. If you activate in the winter, it doesn’t take many errant line tosses while wearing snowshoes to convince you to use a mast ;-).
  3. If you activate in the summer when the understory is bloomed out, it doesn’t take many times unsnarling your line from the bushes to convince you to use a mast ;-).

To adapt to most any setting, I carry a couple of bendable wires, 2 three foot velcro straps, and my version of the SOTABeams ground stake. One or more of those almost always is enough to secure my 15-17’ telescoping fishing pole mast.

As KT5X noted, operating from a summit forgives many sins that would be prohibitive elsewhere. I’ve laid my antenna atop bushes, or set it up as a loop only as far as I can reach when the forest is dense.

Speaking of reach – one compromise is to carry a mast to help lift your wire into the trees. Whatever you do, don’t let the perfect be the enemy of the good.

73 Paula k9ir

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Today on DM/NS-125
73 Chris

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That is the perfect picture illustrating what I tried to describe verbally above. :smile:
Thx for sharing

73 de Klaus

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Gerne Klaus. With pleasure! Good luck with the efhw. I use them exclusively for over 10000 sota qsos in 6 years.
73 Chris

Yesterday on Dm/Ns-127
73 Chris

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Tree.
Scott kw4jm

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To clarify, QSOs are possible in this manner from a prominent point of elevation. However, more QSOs of higher quality (RST) are likely if one elevates the antenna from the ground.

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I would do whatever VK2IO does, as I work him damn near every time I go out!

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In the motoring world there is a saying about internal combustion engines:

“There is no replacement for displacement”.

I cannot think of a succinct phrase for transmitters, but the greater the feeder current and the more free space, the better will be the report.

Some 4 years ago we had a conifer tree in our garden. it was over 35 ft high.

I had a cunning plan to build a quarter wave GP on 40m. I would run a wire up the tree some 3 ft from the trunk and install a set of 6 buried radials. I did my best to tune it up, but the tuning was very flat. In comparison tests with the dipole I usually use, (I realize the polarization and polar diagram are very different) I found it to be about 2 s points down.
The tree did not get a reprieve and was felled to become the town Christmas tree,

I realise that trees can be convenient and effective aerial supports, but there will be an element of compromise on the ERP and signal reports.

Regards
David
G0EVV

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You beat me to it. Well Done Sir!

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If you look at the impedance curves for antennas, showing how the impedance varies with height above ground, you don’t see anything on the graph about altitude above mean sea level.

In fact a low antenna, eg. A 40m dipole at a height of 3m, the impedance should be quite low, about 20 ohms. If the impedance of the antenna is not 20 ohms, but is say 40 ohms, there is 20 ohms of ground resistance soaking up your power. Efficiency is about 50%. However you may still make contacts, it’s not 1%. But that does not mean it is optimal.

My take on all that is that getting the antenna well above ground is always worth doing.

73 Andrew VK1DA/VK2DA

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Height is might!
The more height the mightier the signal.
Of course there is also a law of diminishing returns. :smiley:

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I’m sure you are correct. But using my 5w on an inverted V linked dipole I can normally work every station I can hear on summits and I’ve also worked as far as Indonesia. I always thought your signal would be reflected off rocky surfaces anyway as it is off water. My pole and 12- 14ft hight above ground may not be optimally efficient but it is effective.

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I can confirm that. Until half a year ago I could rarely throw my efhw more than 6m above the ground. With the new throwbag it is often more than 12m.
I can’t see any significant gain.
During my double activations with Uwe, DK8OA, I could switch back and forth between his 5m high and my 12m high efhw.
Surprisingly, there was no clear winner, surely on 30m and longer.
73 Chris
Edit
At 20m and shorter, the directivity of an EFHW changes with a more higher and pointed inverted vee and then makes the difference.

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