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TRACKSAR Bounce Measurements

      TRACKSAR data is collected by mounting the radar antenna on a track that moves it horizontally to form a synthetic aperture; coherent SAR processing then converts the raw radar data into an image like the one shown below. METRATEK is able to provide 1-18 GHz measurement services at customer facilities using the highly portable Model 200 radar and 2.5 - 15 m tracks.

      When imaging a entire full-size aircraft on the ground, the radar antenna illuminates the ground and the target at the same time. We take advantage of this effect to increase sensitivity by 10-11 dB by positioning the target so the direct return and the ground-bounce return reinforce each other at the target.

Picture

      This 200 x 200- ft image of a NASA B-52 was taken with a Model 200 radar and a 45-ft SAR track  in 1989.  The SAR processing used proprietary METRATEK SAR STATION software that allows a short track to collect a much larger target image. 

This is an X-Band image taken at a range of 350 ft. The resolution is approximately 15 cm.  Much of the detail of this image is lost here - the full size image is 3 x 3 feet.

 The trails behind the engines are due to the radar signal's reverberating around inside the engines. In SAR images, the resulting time delays cause the reverberations to point back toward the center of the track          

      The color-coding on these images represents radar cross section from the lowest (bottom of colorbar) to the highest  values on a decibel (logarithmic) scale. The color scales are not the same in all the figures.

Picture

      This  X-Band image of a typical ground-bounce target zone was taken to verify the system sensitivity prior to measurement of a fighter aircraft. The Model 200 radar is looking at the target area from the bottom of the figure at a range of 180 feet. The target zone (between the  yellow dashed lines) is large enough for a fighter aircraft.. The lower green line is the return from the lip of the  the taxi way, and the upper green area is clutter behind the target zone.. The radar cross section of the target zone background (blue area) is on the order of -90 dB relative to 1 square meter , or one-billionth the return from a small aircraft such as a Cessna-172..

ares

     

      This image of Burt Rutan's ARES ground-attack aircraft was taken in the ground bounce mode with the Model 200 radar at Mojave, CA. The landing gear was down and covered with radar absorbing material. The radar signal penetrates the fiberglass skin and detects objects inside the aircraft. The line forward of the nose is due to the pitot  tube and the strong (red) returns in the forward part of the aircraft are the radio, instrument panel, and the pilot's seat, respectively.

 Copyright  METRATEK, Inc. 1998, all rights  reserved    

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