Low-Power X-Band Rail SAR

ABSTRACT

A near real-time radar-based imaging system is developed in this dissertation. This system uses the combination of a spatially diverse antenna array, a high sensitivity range-gated frequency-modulated continuous wave (FMCW) radar system, and an airborne synthetic aperture radar (SAR) imaging algorithm to produce near real-time high resolution imagery of what is behind a dielectric wall. This system is capable of detecting and providing accurate imagery of target scenes made up of objects as small as 6 inch tall metallic rods and cylinders behind a 4 inch thick dielectric slab. A study is conducted of through-dielectric slab imaging by the development of a 2D model of a dielectric slab and cylinder. The SAR imaging algorithm is developed and tested on this model for a variety of simulated imaging scenarios and the results are then used to develop an unusually high sensitivity range-gated FMCW radar architecture. An S-band rail SAR imaging system is developed using this architecture and used to image through two different dielectric slabs as well as free-space. All results are in agreement with the simulations. It is found that free-space target scenes could be imaged using low transmit power, as low as 5 picowatts. From this result it was decided to develop an X-band front end which mounts directly on to the S-band rail SAR so that objects as small as groups of pushpins and aircraft models in free-space could be imaged. These results are compared to previous X-band direct conversion FMCW rail SAR work. It was found that groups of pushpins and models could be imaged at transmit powers as low as 10 nanowatts. A spatially diverse S-band antenna array will be shown to be developed for use with the S-band radar; thereby providing the ability for near real-time SAR imaging of objects behind dielectric slabs with the same performance characteristics of the S-band rail SAR. The research presented in this dissertation will show that near real-time radar imaging through lossy-dielectric slabs is accomplished when using a highly sensitive radar system located at a stand-off range from the slab using a free-space SAR imaging algorithm.

Publications

G. L. Charvat, L. C. Kempel, C. Coleman, “A Low-Power High-Sensitivity X-Band Rail SAR Imaging System,” IEEE Antennas and Propagation Magazine, Vol. 50, No 3, June 2008, pp. 108-115.

G. L. Charvat, ``A Low-Power Radar Imaging System," Ph.D. dissertation, Dept. of Electrical and Computer Engineering, Michigan State University, East Lansing, MI, 2007.

Dissertation Defense Power Pointe Slides

Misc. PPT Slide Shows

G. L. Charvat, “A low-power radar imaging system,” The Boston Chapter of the IEEE APS Society, December 11, 2007.

An X-band front end was developed for this dissertation to test the ability of this radar system in an RCS measurement application.  This front end simply plugs into the S-band rail SAR IF/data acquisition racks and bolts on to the mechanized rail.  This X-band rail SAR was shown to be capable of imaging groups of pushpins using extremely low amounts of power, down to 10 nano-watts.  Other high sensitivity imagery was acquired showing positive results (see imagery page).

An X-band front end was developed for this dissertation to test the ability of this radar system in an RCS measurement application.  This front end simply plugs into the S-band rail SAR IF/data acquisition racks and bolts on to the mechanized rail.  This X-band rail SAR was shown to be capable of imaging groups of pushpins using extremely low amounts of power, down to 10 nano-watts.  Other high sensitivity imagery was acquired showing positive results.