Far-Field Radar Cross-Section Determination from Near-Field 3-D Synthetic Aperture Imaging with Arbitrary Antenna Scanning Surfaces

*This work has been submitted to the IEEE for possible publication. Copyright may be transferred without notice, after which this version may no longer be accessible.<div><br></div><div>In this study, we propose a generalized algorithm for far-field radar cross-section determination by using 3-D synthetic aperture imaging with arbitrary antenna scanning surfaces. This method belongs to a class of techniques called image-based near-field-to-far-field transformation. The previous image-based approaches have been formulated based on a specific antenna-scanning trajectory or surface, such as a line, plane, circle, cylinder, and sphere; majority of these approaches consider 2-D radar images to determine the azimuth radar cross-section. We generalize the conventional image-based technique to accommodate an arbitrary antenna-scanning surface and consider a 3-D radar image for radar cross-section prediction in both the azimuth and zenith directions. We validate the proposed algorithm by performing numerical simulations and anechoic chamber measurements.<br></div>

Spherical Scanning 3-D Microwave Imaging of Near-field Scatterers Mutually Coupled With an Antenna Array

<div>*This work has been submitted to the IEEE for possible publication. Copyright may be transferred without notice, after which this version may no longer be accessible.<br></div><div><br></div>In this article, we propose a 3-D synthetic aperture imaging method with spherical antenna scanning to identify scatterers located close to an antenna array, such as fixtures or support of the antenna. Previous studies have shown that 2-D and 3-D synthetic aperture imaging techniques with planar, circular, and cylindrical scanning can successfully reconstruct spatial images of near-field scatterers. The spherical scanning approach considered in this article is expected to improve the 3-D image resolution because more angular diversity can be achieved in the elevation direction. However, as we show in this study, simple extension of the previous techniques to the spherical case results in undesired blur artifacts in the reconstructed image. To overcome this problem, we introduce a correction factor in the image reconstruction. The proposed imaging algorithm is validated by numerical electromagnetic simulation based on the method of moments.

Spherical Scanning 3-D Microwave Imaging of Near-field Scatterers Mutually Coupled With an Antenna Array

<div>*This work has been submitted to the IEEE for possible publication. Copyright may be transferred without notice, after which this version may no longer be accessible.<br></div><div><br></div>In this article, we propose a 3-D synthetic aperture imaging method with spherical antenna scanning to identify scatterers located close to an antenna array, such as fixtures or support of the antenna. Previous studies have shown that 2-D and 3-D synthetic aperture imaging techniques with planar, circular, and cylindrical scanning can successfully reconstruct spatial images of near-field scatterers. The spherical scanning approach considered in this article is expected to improve the 3-D image resolution because more angular diversity can be achieved in the elevation direction. However, as we show in this study, simple extension of the previous techniques to the spherical case results in undesired blur artifacts in the reconstructed image. To overcome this problem, we introduce a correction factor in the image reconstruction. The proposed imaging algorithm is validated by numerical electromagnetic simulation based on the method of moments.

Far-Field Radar Cross-Section Determination From Near-Field 3-D Synthetic Aperture Imaging With Arbitrary Antenna Scanning Surfaces

In this study, we propose a generalized algorithm for far-field radar cross-section determination from 3-D synthetic aperture imaging with arbitrary antenna scanning surfaces. This method belongs to the class of techniques called image-based near-field to far-field transformation. The previous image-based approaches were formulated based on a specific antenna scanning surface or trajectory such as a line, a plane, a circle, a cylinder, and a sphere--and the majority of them considered 2-D radar images to determine the azimuth radar cross-section. We generalize the conventional image-based technique to accommodate an arbitrary antenna scanning surface, and consider a 3-D radar image for radar cross-section prediction in both the azimuth and zenith directions. We demonstrate the proposed algorithm via numerical simulations and anechoic chamber measurements.

Far-Field Radar Cross-Section Determination From Near-Field 3-D Synthetic Aperture Imaging With Arbitrary Antenna Scanning Surfaces

In this study, we propose a generalized algorithm for far-field radar cross-section determination from 3-D synthetic aperture imaging with arbitrary antenna scanning surfaces. This method belongs to the class of techniques called image-based near-field to far-field transformation. The previous image-based approaches were formulated based on a specific antenna scanning surface or trajectory such as a line, a plane, a circle, a cylinder, and a sphere--and the majority of them considered 2-D radar images to determine the azimuth radar cross-section. We generalize the conventional image-based technique to accommodate an arbitrary antenna scanning surface, and consider a 3-D radar image for radar cross-section prediction in both the azimuth and zenith directions. We demonstrate the proposed algorithm via numerical simulations and anechoic chamber measurements.