FlightAware Discussions

Antenna in the trees

Just wondering how much signal is blocked by trees/foliage. I’m thinking of hoisting the receiver up a tree since I can get it at least twice as high than anything else I can do at the moment. Do you guys think putting the antenna that close to trees/branches/foliage would attenuate the signal too much?

Thanks!

For better or worse, it will certainly attenuate it to some degree. My 1090 tracker is gable mounted and there is a large maple that blocks it most of the year. My tracking results are better in the winter when there are no leaves on the tree, but still usually in the top 100 feeders even when blocked. I had another feeder on the other side of town on my Dad’s Ham tower which was unobstructed. It actually got lower results. Maybe too many signals walking on each other is a bad thing… The results certainly surprised me.


https://www.itu.int/dms_pubrec/itu-r/rec/p/R-REC-P.833-9-201609-I!!PDF-E.pdf

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It all depends what other obstacles you can avoid by getting the antenna higher.

If there are many slightly smaller trees putting the antenna on the biggest one will be an improvement.
If you get above other structures it’ll be an improvement as well.

If you just get it higher and previously the only obstruction was the tree you put it up into, it’s not worth it in my opinion.

There aren’t so many nearby obstacles I would avoid by putting it up a tree, I would just like to get some height for better range. I will try to work on this and let you guys know my results!

Height doesn’t necessarily get you better range.

Check this thread:
What is the Maximum Range I can Get?

Do two panoramas with different height above the ground and compare them.

Is this your receiver: https://flightaware.com/adsb/stats/user/harlow2209#stats-98679

What is your antenna/cable/receiver setup?
My gut says there is room for improvement in that area.

This is what I did:

Yes. I actually have set up 3 sites, but my primary site is the only one that’s online at the moment.
My setup: FA Antenna >> 3ft RG58 >> FA Filter >> FA ProStick Plus >> RPi. Lowered the gain to what I believe is preforming the best. No adapters on the antenna or coax. The elevation at my location isn’t the greatest, that’s why I want to go as high as possible.

Have you checked the panorama? It will show you exactly what your theoretical range is and what raising the antenna will by let’s say 40 ft will improve.

I can check it for you if you don’t minde providing exact coordinates.

Is that just cable or is that the pigtail that converts N to SMA?

Do you have attenuation figures for that cable? RG58 is generally not a good cable.

Also 3ft of cable, is the antenna even outside?
Having it outside and above the roof line is very important, probably more important than height in your case.

I’ve run through a few scenarios on the panorama and I’m still not getting near the range the website states.
The cable has an N connector on one end and SMA on the other. I’ll try to get an N-SMA adapter and connect the dongle directly to the antenna to see if the cable is hurting it.
Yes, it is outside. I have the RPi/Dongle mounted in an enclosure below the antenna on a mast. Fed with PoE LAN.

3 ft shouldn’t be a big problem, but testing with another adapter can’t hurt.

Have you seen this:
Thoughts on optimizing gain

There is no one best gain setting but the above is a good guideline.
What is your gain set to?

You might have electrical noise in the area, sometimes the FA filter with the ProStick Plus just doesn’t cut it in regards to noise.
Personally i would recommend the rtl-sdr v3 dongle plus their LNA.

You could try shielding the dongle from the power supply you use. Maybe it’s generating noise.
As a test you could wrap the dongle it aluminium foil. Probably not good for the summer though in regards to heat, so not a permanent solution.
But for testing it should be fine.

Thanks for all the help!
I’m going to try some more troubleshooting with the physical equipment setup. It’s just difficult since the data in the area changes constantly!
I believe the gain is currently set to 40. Seems to have the best message rate/range ratio. There’s a local airport too so I don’t know how overpowering those signals are either.

Install some graphs:
https://github.com/wiedehopf/graphs1090#graphs1090

Then you get a percentage of “strong messages” and also a signal level graph.

Oh very cool. I’ll be doing that now!

What kind of data ranges should I be aiming for on these graphs?

That depends on what you want.

My opinion on it is in the 2nd post of this thread:
Thoughts on optimizing gain

Having the mean signal level somewhere around -10 or maybe -8 is a good starting point.

If the antenna is below the height of surrounding trees, houses etc, then raising it improves the range considerably, but in the directions of obstructions only. In other clear-of-obstruction directions, there is no appreciable advantage.

Once the antenna is above obstructions, raising it any further does not give any appreciable advantage.

This table applies to the directions where there is no obstruction, and antenna can see the horizon

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Thanks for the chart. Unfortunately my home isn’t in a great spot to begin with. If I were to mount the antenna on top of the house, I still have 80 foot trees on one side and a hill on the other side. I’m thinking any elevation in my case will help. Just worried that putting the antenna too close to the forest would hurt more than help.

If the hill is as high as the trees and closer than a mile then putting it up there will most likely help.

If it is more than one row of trees the signals already need to go through the forest in one direction at least.

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