Microwave Imaging behind a Drywall using Synthetic Aperture Radar

Document Type : Research Paper

Authors

1 Electrical Engineering, University of Science and Technology, Narmak, Tehran, Iran

2 School of Electrical Engineering Iran Univ. of Science & Technology

Abstract

We study through a drywall imaging using synthetic aperture radar (SAR) method. Transmission and reflection characteristics of the wall are analyzed by a rigorous coupled-wave analysis (RCWA) method. The Bragg modes are investigated on analytic formulation and reconstructed image. The cutoff frequency for different Bragg modes is calculated and the relative power carried by each of these modes is shown. The Green function of such a periodic structure is derived by representing a line source radiation in the spectral domain. The analytical results are then validated by the numerical FEM results using the COMSOL software and the effect of the number of the Bragg modes is shown. Having numerically calculated backscattered fields of a target behind the wall and the free-space Green function, the SAR image of the target is computed and the image artifacts due to the presence of the wall are addressed. Firstly, we show that the target image is still distorted and not focused even with the background subtraction. Secondly, by properly employing the phase of the wall Green function instead of the free-space Green function, we indicate that the target image is successfully refocused.

Keywords


1- M. G. Amin, Through-the-Wall Radar Imaging FL, US, CRC Press, 2010.
2- M. Amin and K. Sarabandi, “Special issue on remote sensing of building interior,” IEEE Trans. Geosci. Remote Sens., vol. 47, no.5, pp. 1267-1368, May. 2009.
3- L. Li, W. Zhang, and F. Li, “A novel autofocusing approach for realtime through-wall imaging under unknown wall characteristics,” IEEE Trans. Geosci. Remote Sens., vol. 48, no.1, pp. 423-431, Jan. 2010.
4- M. Dehmollaian and K. Sarabandi, “Refocusing through building walls using synthetic aperture radar” IEEE Trans. Geosci. Remote Sens., vol. 46, no. 6, pp. 1589–1599, Jun. 2008.
5- R. Solimene and A. Cuccaro, “Front Wall Clutter Rejection Methods in TWI,” IEEE Geoscience and Remote Sensing Letters., vol. 11, no. 6, pp. 1158 - 1162, June 2014.
6- B. Yektakhah and M. Dehmollaian, “A Method for Cancellation of Clutter Due to an Object in Transceiver Side of a Wall for Through-Wall Sensing Application,” IEEE Geoscience and Remote Sensing Letters, vol. 9, no. 4, pp. 559- 563, July 2012.
7- Y.-S. Yoon and M. G. Amin, “Spatial filtering for wall-clutter mitigation in through-the-wall radar imaging,” IEEE Trans. Geosci. Remote Sens., vol. 47, no. 9, pp. 3192–3208, Sep. 2009.
8- V. Khorashadi-zadeh and M. Dehmollaian, “Through a Cinder Block Wall Refocusing Using SAR Back Projection Method,” IEEE Trans. Antennas Propag., vol.67, no. 1, pp. 1212–122, Feb.2019.
9- W. Honcharenko, H. L. Bertoni. “Transmission and reflection characteristics at concrete block walls in the UHF bands proposed for future PCS,” IEEE Trans. Antennas and Propag., vol. 42, no. 2, pp. 232-9, Feb. 1994.
10- M. G. Moharam, E. B. Grann, and D. A. Pommet, “Formulation for stable and efficient implementation of the rigorous coupled-wave analysis of binary gratings,” J. Opt. Soc. Amer. A, vol. 12, pp. 1068–1076, May. 1995.
11- D. G. Dudley, Mathematical foundations for electromagnetic theory. NY, United States, IEEE press, 1994.
12- Liu, E.g.C.L. Liu, J.W.S.: 'Linear Systems Analysis'. (McGraw-Hill, New York 1975)