Wavefront Correction for Large, Flexible Antenna Reflector

A wavefront-correction system has been proposed as part of an outer-space radio communication system that would include a large, somewhat flexible main reflector antenna, a smaller subreflector antenna, and a small array feed at the focal plane of these two reflector antennas. Part of the wave-front-correction system would reside in the subreflector, which would be a planar patch-element reflectarray antenna in which the phase shifts of the patch antenna elements would be controlled via microelectromechanical systems (MEMS) radio-frequency (RF) switches. The system would include the following sensing-and-computing subsystems:

• An optical photogrammetric subsystem built around two cameras would estimate geometric distortions of the main reflector;
  
• A second subsystem would estimate wavefront distortions from amplitudes and phases of signals received by the array feed elements; and
  
• A third subsystem, built around small probes on the subreflector plane, would estimate wavefront distortions from differences among phases of signals received by the probes.

The distortion estimates from the three subsystems would be processed to generate control signals to be fed to the MEMS RF switches to correct for the distortions, thereby enabling collimation and aiming of the received or transmitted radio beam to the required precision.

This work was done by William A. Imbriale and Vahraz Jamnejad of Caltech and Yahya Rahmat-Samii, Harish Rajagopalan, and Shenheng Xu of the University of California, Los Angeles, for NASA’s Jet Propulsion Laboratory. For more information, download the Technical Support Package (free white paper) at www.techbriefs.com/tsp under the Electronics/Computers category. NPO-46053

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