The roof antenna is a 38db Gain, 50 ohm antenna. The re-radiating amplifier has a 110V/220V/240V Plug-in transformer which powers the amplifier and the roof antenna. The signal from the roof antenna is amplified and radiated out the re-radiating antenna. If the GPS receiver has line of sight with the re-radiating antenna, it will receive the signal up to 100 feet away. The antenna voltage is standard set at 5VDC otherwise the customer must designate the source voltage and power supply preferred. For Example: HNRRKIT-N/5/110 is a Hangar Network Re-Rad Kit with a 110V power supply sending 5vdc to the antenna.