You can from what I understand transmit RF from balloons - https://ukhas.org.uk/doku.php?id=start https://ukhas.org.uk/doku.php?id=start has lots of info. Ther

You can from what I understand transmit RF from balloons - https://ukhas.org.uk/doku.php?id=start https://ukhas.org.uk/doku.php?id=start has lots of info. There are limitations on what frequencies and power you can transmit at, iirc the power is around 10mW.