Two-dimensional near-field microwave holography

Abstract

A new two-dimensional (2D) holographic microwave imaging technique is proposed to reconstruct the 2D image of a target. It is based on the Fourier analysis of the data recorded by two antennas scanning together two separate rectangular parallel apertures on both sides of a target. The complex backscattered signals of the two antennas are first processed to localize the target in the range direction. Then, the 2D image of the target is reconstructed. No assumptions are made about the incident fields, which can be derived by either simulation or measurement. Both the back-scattered and forward-scattered signals can be used to reconstruct the image of the target. This makes the proposed technique applicable with near-field measurements. To evaluate the proposed technique, the range localization and the 2D image reconstruction of a predetermined simulated target are examined. Associated resolution limits, sampling constraints and the impact of noise are also discussed.

Three-Dimensional Microwave Imaging for Concealed Weapon Detection Using Range Stacking Technique

“…Recently, increasing terrors have been motivating the development of various concealed weapon detection techniques for better security monitoring at airports, courthouses, and other buildings [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15]. The ability to detect dangerous hidden items is seen as a significant tool in defeating terrorism in today's environment.…”

Experimental Synthetic Aperture Radar With Dynamic Metasurfaces

“…Historically, SAR has been employed from aircraft and satellite systems but the technique has increasingly been applied in cases where the standoff distance is significantly shorter. Holographic imaging systems [32], [56] for security screening [6], [8], [9], [30], [31] and feature-specific imaging [57], [58] are of increasing interest and the dynamic metasurface aperture is posed to make important contributions across the entire field of microwave sensing. …”

Three-Dimensional Far-Field Holographic Microwave Imaging: An Experimental Investigation of Dielectric Object

“…The far-field HMI technique is very different from various existing near-field microwave holography techniques [18][19][20][21]: (1) The far-field HMI technique uses physical displacement (scan of the distance) between the antenna array plane and the imaged object over a specified range (vertical) to obtain depth information from sequenced 2-D images, which is very different from holography system in [18,19] that is fixed along a range and uses ultra-wideband information to attain depth resolution. Furthermore, the scattered field formulation used in our paper is subject to a far-field approximation but not subject to a linear-Born approximation.…”

“…Tomography [13][14][15][16][17] reconstructs a map of the electrical properties in the breast using measurements of energy transmitted through the breast. Microwave holographic based techniques [18][19][20][21] do not require expensive ultra-high speed electronics as narrow-band signals can be converted to the baseband for digitization at a slower rate, thereby enabling imaging at significantly lower cost [22]. Microwave holographic methods use both magnitude and phase information in an inversion process, which reconstructs the target reflectivity as a function of position [23].…”