Transceiver antennas for state identification transponder

This paper presents the results of developing antenna systems (AE) for a prospective aircraft onboard state identification transponder (SIT). The AE of an onboard SIT channel consists of a number of antennas. The whole of the AE patterns covers virtually all of the space around the aircraft. The need to improve individual antennas, as well as their onboard set as a whole is determined by the following. Large sizes of antennas and their protective enclosures prominent above the aircraft body do not improve aerodynamic and electromagnetic qualities of the aircraft. The available operating band provides only for the domestic SIT channels, while auxiliary antennas are required for the international SIT. The development of an AE that is free from the drawbacks listed above and which provides both domestic and foreign SIT operation is described in this paper.