Microwave Holography for Near-Field Imaging
M. Ravan, Reza K. Amineh, Natalia K. Nikolova
Department of Electrical and Computer Engineering, McMaster University, Canada
The relatively long wavelength (from 100 mm to 1 mm) of the microwaves and the millimeter waves allows for penetration in many optically opaque materials such as living tissues, wood, ceramics, plastics, clothing, concrete, soil, etc. Various methods have been proposed for microwave imaging. Among these methods, microwave holography [1] is a fast inversion technique that relies on the measurement of the magnitude and phase of the wave scattered from the imaged target. Knowledge of the magnitude and phase across an aperture allows Fourier-transform (FT) based reconstruction of the target's reflectivity. Microwave holography has been proposed for near-field analysis of antennas [2], biomedical imaging [3], and concealed weapon detection [4]. The technique proposed in [4] for concealed weapon detection can be used to form a high-resolution two-dimensional (2D) image of the target from a single-frequency measurement or a three-dimensional (3D) image from a wide-band measurement. A transmitter antenna and a receiver antenna move together on one side of the target to scan a rectangular planar aperture. The algorithm assumes that the wave emanating from the transmitter and the one reflected back from the target point are closely approximated by spherical waves. Here, we extend the single-frequency 2D holographic image reconstruction developed in [4] to include not only back scattered but also forward scattered signals. Also, our method does not make any assumption about the incident field such as the spherical or cylindrical wave representations. This is especially important in near-field imaging where the target is close to the antenna and the spherical assumption for the illuminating wave is not valid. This also makes the proposed technique applicable to heterogeneous background mediums.
IEEE Antennas and Propagation Society International Symposium (APSURSI)
2010
July
Due to copyright restrictions articles are not available for download. They are however indexed on this site and search results will therefore correctly indicate if such terms are present in the articles.
