HC-12 external antenna for underwater use

Hello. I would just like to ask about the HC-12 module. I just bought x2 hc-12 module that comes with the spring antenna. In my project one hc-12 module (connected with the arduino nano) will be a transmitter node and will submerged in the water to send ADXL335 data while the other one will be at the receiving end. I know rf won't work underwater so what I did was I connected a 3 ft. stranded wire in the antenna port in the hc-12 module while the other end of it was connected to the spring antenna floating and sealed in a waterproof buoy. I thought in this way the radio waves will travel in the 3 ft. wire and will propagate in air with the antenna at the buoy. However, as I submerged the hc-12 module there was no data being received. What do you think seem to be the problem? btw the antenna at the receiving end ,I just soldered the spring antenna directly at the antenna port. Thanks!

If you add 1 metre of wire to a 20cm antenna it becomes a 1.2m antenna which is for an entirely different frequency.

You need to have the HC12 (with its standard antenna) above the water.


Your idea simply wont work. You need the HC12 and the spring antenna in the floating buoy, and then a connection to the ADXL335 which can be under the water.

Thank you for your response. I'll just put the hc-12 module in the buoy. can you recommend what type of wire to use if I have to put out 4 wires from the buoy to the adlx335?