I use this coupling method all the time.
Example, I have a 25 ft. vertical in the back yard connected with coax through an RF Systems 9:1 Magnetic balun at the base of the vertical. The coax runs into the house. Now how to couple that to the radio.
Find an old 4 inch ferrite bar. Strip the coax and using the two ends, wind about 15 turns of insulated wire (#24 telephone wire works well) around the ferrite bar. Connect the coil to the ends of the coax.
The number of turns is not totally important but you don't want or need too many and you want enough to make a difference. You're not tuning a circuit here, just providing inductive field to couple to the radio.