A Directional Transponder Antenna Subsystem
Final technical rept. 11 Oct 1971-29 Jun 1973
BENDIX CORP BALTIMORE MD COMMUNICATIONS DIV
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The significance of this R and D to the Air Force is the development of an aircraft transponder antenna subsystem which will receive interrogations from a maximum volume of space surrounding each antenna aperture, determine the angle of arrival of each valid interrogation and respond appropriately with a directive beam. The goals include improved receiver coverage to assure response to both air and ground based interrogators and formation of directive transmit beams to limit the volume over which transponder replies are detected. Use of directive beams would significantly reduce the system interference fruit levels of interrogation terminals. The first phase of effort was an antenna subsystem design trade-off study to select an approach to minimize system complexity and antenna installation problems and to maximize performance. A small ring array was selected which can determine angle of arrival and electronically steer a relatively narrow beam for the reply. The second and third phase of effort constructed and tested the design which evolved from the trade-off study. The transmit array diameter is 1.2 ft, contains 12 elements and produces a 28.5 deg beam width at the 1090 MHz operating frequency. The transmit beam is steered by use of phase shifters at the operating frequency.
- Electrical and Electronic Equipment
- Direction Finding
- Active and Passive Radar Detection and Equipment