There was a need to use a drone while sitting in a car. But it’s not clear how to get the signal out. What kind of connector is used on the RM700B remote control, but it’s the same as on the GL800A. Who made the antenna extension or where can I buy an adapter or a ready-made antenna?

The same remote control is used with M30T and M300, M350.

No one has given me an answer. I found some adapters on my own:
1. option - ALIENTECH RC Plus adapter for DJI RC Plus (we get a QMA-K connector at the output)
2. option - You can also connect directly to the antenna outputs with the MCX J connector ( but the connections are not fixed in any way.)

I hope this helps someone.