Frequency and azimuthal variations of radar cross section and their influence upon low-frequency SAR imaging

<div><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.</div></div><div><br></div>In this study, we present an improved and unified approach for image-based radar cross-section (RCS) measurement by 2-D synthetic aperture radar (SAR) imaging with an arbitrary curved antenna scanning trajectory. Because RCS is a quantity defined in the far-field distance of an object under test, direct RCS measurement of an electrically large target is often infeasible owing to the spatial limitation of the measurement facility. The method proposed in this study belongs to the class of techniques referred to as the image-based near-field to far-field transformation (NFFFT) to convert the near-field data of scattering experiment into the far-field RCS. In a previous study, we have developed an NFFFT based on 3-D SAR imaging with an arbitrary antenna scanning surface. However, the previous approach is only applicable to the surface scanning which is impossible for a certain case such as measurement using airborne SAR or vehicle-borne SAR. Therefore, one requires an alternative method that can accommodate an arbitrary scanning curve, which is the subject of this study. We derive a generalized correction factor for image-based NFFFT which is designed to ensure the integral transformation in the image reconstruction process be self-consistent for electrically small scatterers. We provide a series of numerical simulations, an indoor experiment, and an airborne SAR experiment to validate that the proposed scheme can be utilized for various situations ranging from near-field to far-field distance.

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Partially Transparent Jaumann-Like Absorber Applied to a Curved Structure

International Journal of Antennas and Propagation ◽

10.1155/2011/708987 ◽

2011 ◽

Vol 2011 ◽

pp. 1-7 ◽

Cited By ~ 8

Author(s):

Alireza Motevasselian ◽

B. L. G. Jonsson

Keyword(s):

Sensitivity Analysis ◽

Cross Section ◽

Low Frequency ◽

Radar Cross Section ◽

Frequency Interval ◽

Two Dimensional ◽

Resistive Layer ◽

Front End ◽

Low Pass ◽

Metal Backing

A Jaumann absorber with its metal backing replaced with a combined low-pass and polarizer FSS is investigated with respect to its absorption and its polarization-dependent low-frequency transparency properties. This structure is applied to an idealized curved wing-front end, and its monostatic radar cross-section is determined. The FSS-Jaumann structure preserves an absorption similar to the planar Jaumann absorber in the higher frequency interval and enables a partial transparency in the TEzpolarization at 1 GHz. In addition, once the structure is applied to the wing-front end, a significant reduction in two-dimensional radar cross-section for both the TMzand TEzpolarization over 2–16 GHz is observed. A sensitivity analysis shows that the resistivity of the inner resistive layer has a large impact on the 1 GHz transmission.

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Low-frequency radar cross-section computations

Proceedings of the IEEE ◽

10.1109/proc.1963.1705 ◽

1963 ◽

Vol 51 (1) ◽

pp. 232-233 ◽

Cited By ~ 10

Author(s):

K.M. Siegel

Keyword(s):

Cross Section ◽

Low Frequency ◽

Radar Cross Section

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Unified Approach For Multiscale Radar Cross-Section Measurement by Synthetic Aperture Imaging

10.36227/techrxiv.17693723 ◽

2021 ◽

Author(s):

Takuma Watanabe ◽

Hiroyoshi Yamada

Keyword(s):

Cross Section ◽

Integral Transformation ◽

Near Field ◽

Radar Cross Section ◽

Synthetic Aperture ◽

Far Field ◽

Unified Approach ◽

Reconstruction Process ◽

Sar Imaging ◽

Airborne Sar

<div><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.</div></div><div><br></div>In this study, we present an improved and unified approach for image-based radar cross-section (RCS) measurement by 2-D synthetic aperture radar (SAR) imaging with an arbitrary curved antenna scanning trajectory. Because RCS is a quantity defined in the far-field distance of an object under test, direct RCS measurement of an electrically large target is often infeasible owing to the spatial limitation of the measurement facility. The method proposed in this study belongs to the class of techniques referred to as the image-based near-field to far-field transformation (NFFFT) to convert the near-field data of scattering experiment into the far-field RCS. In a previous study, we have developed an NFFFT based on 3-D SAR imaging with an arbitrary antenna scanning surface. However, the previous approach is only applicable to the surface scanning which is impossible for a certain case such as measurement using airborne SAR or vehicle-borne SAR. Therefore, one requires an alternative method that can accommodate an arbitrary scanning curve, which is the subject of this study. We derive a generalized correction factor for image-based NFFFT which is designed to ensure the integral transformation in the image reconstruction process be self-consistent for electrically small scatterers. We provide a series of numerical simulations, an indoor experiment, and an airborne SAR experiment to validate that the proposed scheme can be utilized for various situations ranging from near-field to far-field distance.

Download Full-text