Accession Number : AD0743994

Title :   An Automatic Antenna Impedance Compensator for Reentry Vehicles.

Descriptive Note : Technical rept. Jul 67-Jun 70,

Corporate Author : NEW MEXICO UNIV ALBUQUERQUE BUREAU OF ENGINEERING RESEARCH

Personal Author(s) : Potts,John S. ; Bocian,Edward S. , Jr

Report Date : MAR 1972

Pagination or Media Count : 226

Abstract : The plasma sheath that surrounds a vehicle on reentry into the earth's atmosphere at hypersonic speeds is a lossy, reflective, and time varying medium. Consequently, an on-board transmitting antenna that is tuned to an acceptable VSWR before launch becomes mismatched by the plasma and heating encountered during reentry. The report presents a device which will maximize automatically the power radiated from an X-band antenna immersed in a time varying reflective medium. This device, called an automatic antenna impedance compensator, consists of a reflectometer for sensing the complex reflection coefficient of the antenna, an electronic equivalent of a slide screw tuner that employs two variable ferrite phase-shifters for maintaining a matched condition, and a feedback control circuit that processes the signals from the reflectometer for use by the electronic tuner. (Author)

Descriptors :   (*ANTENNA COMPONENTS, *IMPEDANCE MATCHING), (*REENTRY VEHICLES, *BLACKOUT(PROPAGATION)), PLASMA SHEATHS, ATTENUATION, PHASE SHIFT CIRCUITS, REFLECTOMETERS, TUNING DEVICES, FEEDBACK, X BAND

Subject Categories : Unmanned Spacecraft
      Telemetry

Distribution Statement : APPROVED FOR PUBLIC RELEASE