RAK4630 detect when antenna disconnects

I wonder if there is a way to detect antenna disconnect? I trust the U.FL connector, but if it comes undone, since it could damage the RF chip, I want to design a way to power off the board when it senses an antenna disconnection. I want to use the RAK4630 in a moving vehicle, which might experience shocks, vibration, and sudden accelerations that could mechanically detach one of these small antennas from its connector.

The only two way I can think of is

  1. to have downlinks from the LoRaWAN server to the device from time to time and test the RSSI levels. If they are very bad over several downlinks, it could indicate a loose antenna connection.
  2. to analyze the RSSI level of received packets on the LoRaWAN server. If they are very bad over several uplinks, it could indicate a loose antenna connection as well.

I think that idea works great for non-moving end nodes, however, my end node will be moving, so the LoRa connection will be variable, meaning RSSI might be too all over the place to conditionally use to shut board power off.

Would there be a way to measure the impedance or noise floor through the antenna port? I imagine when an antenna disconnects, the load “seen” by the RF radio is probably a lot different.

I do not know a way to measure impedance or noise floor.

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I think a cool feature for the future would be an automatic built-in system to detect antenna disconnect and turn off the board to save it from being damaged. Then a special uplink could be sent to whatever connection we have and notify the server that the internal antenna disconnected.

I will forward this to our R&D teams, but no promises.

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