FlightAware Discussions

140’ tower application for adsb receiver

Hello, I have a 140’ tower and want to place my adsb antenna on it. What type of antenna and type of cabling should I use. Just want to be a feeder to flight aware.

I have not had my feeder up all that long, so please don’t take my words as gospel.

I have only used the FlightAware 1090 MHz antenna and have found it to work very well. I do have another antenna on order, but it has not arrived yet. So I have no comparison, but I have been happy with the FlightAware antenna in the short time I have had it.

As for the coax, I would recommend the best coax/heliax you can afford. As the frequency is just over 1 Ghz the attenuation of even reasonably good cable will negate the advantage of the height of your antenna. I will give you an example. I had a 30 foot length of LMR400 coax running to my FlightAware antenna. As the coax had a bad connector, I decided to replace it with a “high quality” coax I bought pre-made. When I replaced the LMR400 with the “high quality” coax my statistics took a very big nose dive. This continued until I was able to again replace the coax with the repaired LMR400. And that was only 30 feet.

Another possibility you may want to consider is installing a LNA (Low Noise Amplifier) right at the antenna.

As there is no one right answer for any particular installation, you may need to experiment to find what works best for you in your situation. There are many possible options.

I use Andrew Heliax FSJ4-50B half-inch SureFlex coaxial cable which has 3.604 dB attenuation per 100 feet at 1000 MHz. It does require a specific Type N connector which is attached with wrenches but does not require soldering. For a 140-foot tower, I would use no less than that. By comparison, LMR-400 has 4.1 dB loss per 100 feet at 1000 MHz and RG-6 has 9.4 dB. Sources: Commscope for Andrew and Times Microwave calculator for LMR-400 and RG-6.

I’d say it would be best to use an LNA for 1090 MHz close to the antenna.

That way you can use cheaper coax.
140 ft of LMR400 or something like that must be quite expensive and you still have quite some loss for such a long distance.
With an LNA you have 20 to 30 dB of amplification and 10 dB attenuation due to the coax run down the tower is not an issue. As such you can use RG6 with reasonable attenuation at 1000 MHz or one of the not quite as expensive cables like Belden H155.
No matter what cable you choose, be sure to check the attenuation in the datasheet for the particular product.

Or you could just put a box with the RPi on the tower and just run network cable with PoE up there.
It all depends on how you want to do it.

The gear also depends on your budget obviously.
This is probably the best but priciest antenna around: https://dpdproductions.com/collections/aviation-base-mobile-antennas/products/ads-b-vertical-outdoor-base-antenna
Otherwise i’d probably get an FA antenna, they are more reasonably priced.

Then there are 3 LNAs i’m aware of.
Professional grade? :

Hobby grade:

As for an USB receiver, i’m assuming you are already using an LNA:
Either one of the rtl-sdr compatible sticks:

I suppose with quite a bit of loss on the coax, the ProStickPlus would work as well.
Otherwise if you already have an LNA, the internal LNA of the ProStickPlus can be overloaded.

I’d personally probably go with an external bias-t.
Note that the Kuhne LNA has a different input voltage requirement compared to the other LNAs.
As for the other LNAs you can measure the current consumption when using 5V at the bias-t.
If due to the long coax run the current is too low, you can raise the supply voltage.
I think the uputronics typically uses 45 mA and the rtl-sdr LNA 120 to 150 mA.
But you can look that up.

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I am using the FA antenna followed by a LNA (amplifier/filter). Those are fed via the same coax cable.
My cable is a pre-connectorized RG6, from Amazon, 150 ft long. At the pole I have also a gas lightning arrester and a grounding wire leading straight down to a ground rod (no loops or turns).
Get a good quality LNA, because it will be essential for the RF chain signal/noise ratio.
Had to use some adapters from the SMA (LNA output, receiver dongle input) to the F connectors on the RG6 cable.

Inside the house (garage in my case) you will have the T-tap power injector and then the Pi plus the dongle, connected to your network (Wireless or Ethernet). I don’t use internal T-tap in the dongles because I choose to inject 7.5V and have a simple 5V stabilizer at the other end of the cable. Maybe a little overkill for some, it was super easy for me to do.

Adjust the gain, by trial and error, to match the level resulted from LNA gain minus the cable attenuation.
In this way those electronic devices are in a controlled climate.

To see how good it works my setup: https://flightaware.com/adsb/stats/user/SoNic67#stats-61996

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@SoNic67, is this the “deciduous tower” ? :smiley:

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Heck yes. Fall is coming, so I might attempt to target an even higher branch without those leafs in the way.

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Staring up at a few of mine scratching my head at which would be the best candidate as I will never get better reception at this house without some altitude.

How did you manage the antenna “tip-up” once you got the first line up ? I have visions of me somehow ending up with a snagged antenna facing horizontally :sweat_smile:

Pull point is above gravity center of the assembly. The bottom of the PVC pipe has attached a box with the LNC.
That oriented the pipe vertically under gravity.
Also I have a cord attached also on the bottom side of the pipe, and I have pulled that down and tied on the trunk. That keeps it from osscilating in wind.
I am pretty close to the trunk though, and that shields some of the signal. Not completely…

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Up a 140’ tower you want the best equipment you can afford, that’s a long way to climb if things go wrong!

The flightaware antenna is a good weatherproof design, I have one and it’s been up on my tower for more than a year of winter cold and summer heat and it’s doing fine.

I would use a preamp at the antenna (as close as possible) with a ceramic filter integrated. Install it in a waterproof enclosure. Use really good cable between the antenna and preamp, maybe LMR240 or LMR400 as these are double-shielded and UV resistant. Use professionally installed N connectors if you can.
From the pre-amp to the Pi, I think quad-shielded RG6 with solid Cu center and UV resistant jacket would be ok. If you want to spend some more LMR-400 would be fine, and connectors are easy to find/have installed. The pre-amp close to the antenna somewhat mitigates feedline loss between the pre-amp and receiver so it’s not as critical as an installation without a pre-amp.
Should have awesome range with a 140ft tower!

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Look forward to seeing what this will give to this height !
Do not hesitate to share your results and graphs with us :wink:

Pull point is above gravity center of the assembly. The bottom of the PVC pipe has attached a box with the LNC.
That oriented the pipe vertically under gravity.
Also I have a cord attached also on the bottom side of the pipe, and I have pulled that down and tied on the trunk. That keeps it from osscilating in wind.
I am pretty close to the trunk though, and that shields some of the signal. Not completely

I would love to see a picture of this. I have two tall leafy trees in my back yard… just saying :slight_smile:

This was last fall…

Maybe I’ll try to get higher this fall.

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Do you have any lightning arrestors on the antenna and mast? What’s the reception distance?

I have a coaxial Gas arrester and a wire going down to a ground rod. This is the station: