High Altitude Balloon Communication

I'm trying to create a High Altitude Balloon (HAB), and the main problem I have is communication with it. I have a couple of LoRa RFM9X Radios which can apparently do 20Km Range. Many sites suggest using LoRa radios to communicate with the balloon, but my issue is, I thought the maximum range for LoRa Radios was around 20Km. Is this different in the air as oppose to on the ground?
Can I increase this range in any way to maximise my range?

Does anyone have any other simple but cheap methods of communication with the balloon?


My own attempts with LoRa were pretty disappointing, so I went back to RFM69. I'm no expert, but this site might have some useful information for you.

The difference is entirely in your antennas. Every antenna has a radiation pattern. They need to have maximum gain in the desired direction, not spread around the entire universe.
Do you have options available for different antennas?

I currently have screw on antennas, which I'm sure I could replace with alternatives.

I think I also have a TV satellite dish, which I could use at the ground station to amplify the signal?

Does it have an LNA and down-conversion to match your unknown transmitter/receiver?

I thought the maximum range for LoRa Radios was around 20Km

The current record for LoRa transmissions from a balloon is somewhere around 800 km. You do need an antenna on both TX and RX, and unobstructed line of sight.

I currently have screw on antennas

Are they specified for the frequency in use? Post links to everything, so we don't have to guess. A satellite dish will not be useful.

I have 2 of these rfm9x radios.
The antennae I have for them are not optimised for 433MHz, they are taken off a WiFi Router.
Will the RFM9X's be suitable for further than 20km radio transmission to each other, not to a LoRaWAN tower, if I were to use these antennas?
Ideally I'd be able to communicate between my station and the balloon over more like 50km.

Hi, @benbenson2004
Welcome to the forum.

This link should help you, it even includes a High Altitude tracking software.
This is a well documented site by one of forum members' , I believe.

Tom... :smiley: :+1: :coffee: :australia:

That's probably an optimistic ground path distance (obstacles completely dominate the actual range possible).

However paths from ground to a balloon are guaranteed line-of-sight, so you should easily get much more range than a ground path(*). However sometimes the protocol in use enforces range limits by timeouts - 20km round-trip takes 133µs for instance.

(*) https://en.wikipedia.org/wiki/Free-space_path_loss#Free-space_path_loss_formula

Impossible to say. Using the wrong antenna will REDUCE the range and can even damage the transmitter.

I suggest to follow the suggestions on the Adafruit page, but a 1/4 wave (17 cm) piece of wire is always pretty good for 433 MHz.

Go and ask for support from your local radio amateur section for the design of a 70cm full size arial.

20km, you must be kidding.

Way back in early 2015 a record was set for two way control of a high altitude balloon, a humble foil party balloon in this case, 269km @ 434Mhz @ 10mW;

That was using fairly modest 1042bps LoRa and at a low altitude of 8km, at lower data rates you would get 3 times the distance.

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832km, 868Mhz, 25mW;

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