TRANSPONDER ANTENNA/ADS-B Monopole, 978MHz, BNC Connector. The outer shell and element is nickel plated and the center conductor is gold over nickel plate. 104-17

The 104-17 transponder antenna is a mono-pole antenna that has a top loaded sphere which creates a factor of reliability and safety for a shorter antenna. This antenna offers a voltage standing wave ratio of 1.2:1 at 1,090 MHz and less than 2:1 at 1,030 MHz when connected with a 50Ω coaxial transmission line. The 104 series antennas feature an omni-directional, vertical-polarize radiation pattern when mounted to the underside of the aircraft.