A Low-Power Radar Imaging System

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, E. J. Rothwell, C. Coleman, and E. L. Mokole, ``A through-dielectric ultrawideband (UWB) switched-antenna-array radar imaging system" IEEE Transactions on Antennas and Propagation, Vol. 60, No. 11, November 2012, pp. 5495-5500.

G. L. Charvat, L. C. Kempel, E. J. Rothwell, C. Coleman, E. J. Mokole. "An ultrawideband (UWB) switched-antenna-array radar imaging system"  Waltham, MA:  IEEE International Symposium on Phased Array Systems & Technology, October  2010.

(slides from this conference)

G. L. Charvat, L. C. Kempel, E. J. Rothwell, C. Coleman, and E. L. Mokole, ``A through-dielectric radar imaging system," IEEE Transactions on Antennas and Propagation, vol. 58, Issue 8, pp. 2594-2603, August, 2010.

G. L Charvat, L. C. Kempel, E. J. Rothwell, C. Coleman, “A Low-Power, Real-Time, S-Band Radar Imaging System.” Boston Massachusetts: Antenna Measurement and Techniques Association Conference, November 2008.

(slides from this conference)

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

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

Blogs and Press

J.Baichtal, ‘Gregory Charvat’s dissertation now online,’ Make Magazine Blog, January 22, 2013.