Active Sparse-Aperture Millimeter-Wave Imaging Using Digital Correlators
- 123 Downloads
Millimeter-wave imaging systems have desirable characteristics, particularly in their ability to form images of objects obscured by various barrier materials. However, the relatively long wavelength of the millimeter-band implies a penalty in angular resolution, usually compensated using large-aperture systems. Synthesized apertures provide the desired collecting area with a reduced number of discrete detectors. In this research we designed, built, and characterized the performance of a prototype sparse-aperture imaging system, utilizing an active 94 GHz source. Discrete sensors were used to sample the radiation field backscattered from the object. The signals were down-converted using heterodyne receivers with digital in-phase and quadrature detection. Signal correlations were performed using the digitized data sets to reconstruct millimeter-wave images. Image-quality performance was experimentally evaluated using four different non-redundant aperture configurations, with good agreement to the theoretical expressions. The feasibility of digital electronic-focusing correction was also demonstrated over an object range from 400 to 700 mm.
KeywordsActive millimeter-wave imaging Aperture synthesis Digital correlation Digital phase detection
This work was supported by Northrop Grumman Corporation Aerospace Systems, Melbourne, Florida.
- 2.C. Hua-Mei, L. Seungsin, R.M. Rao, M.A. Slamani, and P.K. Varshney, "Imaging for concealed weapon detection: a tutorial overview of development in imaging sensors and processing," Signal Processing Magazine, IEEE. 22, 2, p. 52-61 (2005)Google Scholar
- 4.L. Yujiri, M. Shoucri, and P. Moffa, "Passive millimeter wave imaging," Microwave Magazine, IEEE. 4, 3, p. 39-50 (2003)Google Scholar
- 5.A. Thompson, J. Moran, and G. Swenson, Interferometry and Synthesis in Radio Astronomy, (John Wiley & Sons, 2001)Google Scholar
- 6.A.R. Harvey, and R. Appleby, "Passive mm-wave imaging from UAVs using aperture synthesis," The Aeronautical Journal. 107, 87, (2003)Google Scholar
- 7.Y. Xue, J. Miao, G. Wan, A. Hu, and F. Zhao. Development of the Disk Antenna Array Aperture Synthesis Millimeter Wave Radiometer. in Millimeter Waves, 2008. GSMM 2008. Global Symposium on. 2008. (2008)Google Scholar
- 8.L. Qingxia, C. Ke, G. Wei, L. Liang, H. Fangmin, and C. Liangbing. An aperture synthesis radiometer at millimeter wave band. in Microwave and Millimeter Wave Technology, 2008. ICMMT 2008. International Conference on. 2008. (2008)Google Scholar
- 9.L. Zhang, Y. Hao, C.G. Parini, and J. Dupuy. An experimental millimetre wave imaging system. in Antennas and Propagation Conference, 2008. LAPC 2008. Loughborough. 2008. (2008)Google Scholar
- 10.S.S. Ahmed, A. Schiess, and L.P. Schmidt. Near field mm-wave imaging with multistatic sparse 2D-arrays. in Radar Conference, 2009. EuRAD. European. 2009. (2009)Google Scholar
- 12.J.M. Blackledge, Quantitative Coherent Imaging, (Academic Press Inc, San Diego, 1989)Google Scholar
- 13.C.A. Balanis, Antenna theory : analysis and design. 2nd ed, (Wiley, New York, 1997)Google Scholar