Isocouplers are series tuned, magnetically coupled isolation transformers that facilitate the co-location of an FM transmit antenna, an FM translator, a Studio-to-Transmitter microwave link dish, a cellphone transmit/receive site, or other services on a base insulated AM/MW broadcast tower. The FM isocouplers range in FM transmitter power rating from 1.5kW to 35 kW. Standard isocouplers are available for operating frequencies in the 30MHz to 1 GHz frequency range. Custom isocoupler designs may also be available.
You can use the Tower Impedance Calculator to get your tower’s impedance.