An Automatic Antenna Impedance Compensator for Reentry Vehicles.
Technical rept. Jul 67-Jun 70,
NEW MEXICO UNIV ALBUQUERQUE BUREAU OF ENGINEERING RESEARCH
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The plasma sheath that surrounds a vehicle on reentry into the earths 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
- Unmanned Spacecraft