An imaging technique using confocal circular synthetic aperture radar

Ishimaru, Akira; Chan, Tsz-King; Kuga, Yasuo

doi:10.1109/36.718856

Cited by 141 publications

(67 citation statements)

References 7 publications

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“…As a result, the mutual coherence μ(H θ ) is the second largest value of μ c (H θ , l). (8), is a sinc function with respect to the interval l. Proof: Consider this problem in its continuous form, then (8) can be reformulated as…”

Section: The Pixel Interval and The Cross Coherencementioning

confidence: 99%

“…However, in RE, it is unable to reduce the mutual coherence for |ld θ | ≤ ρ θ , such that we can concentrate only on the cross coherence reduction for |ld θ | > ρ θ , which can eliminate the influence from pixels |ld θ | > ρ θ as much as possible. For this purpose, according to Equations (8) and (11), we propose to filter bases in H θ and column images by applying SVA (or adding windows).…”

Section: The Pixel Interval and The Cross Coherencementioning

confidence: 99%

“…Compared with InSAR, LASAR and CSAR are usually considered to obtain true 3D spatial resolutions of a scatter, while InSAR obtains only a height of the 2D resolution cell, such that it cannot distinguish two scatters in the same 2D resolution cell in elevation direction. Besides, LASAR has a better peak sidelobe ratio (PSLR) and easier flight path controlling than CSAR [8]. Thus, LASAR is more promising practical application, and we are concerned about LASAR in our paper.…”

Section: Introductionmentioning

confidence: 99%

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RESOLUTION ENHANCEMENT FOR LASAR 3D IMAGING VIA ℓ<sub>1</sub> REGULARIZATION AND SVA

Gao¹,

Shi²,

Wei³

2015

PIER M

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Abstract-Linear array SAR (LASAR) has been attracting more and more attention for its capability of obtaining three dimensional (3D) resolutions. However, the low resolution in cross track (CT) direction limited by the length of its linear antenna array has become the bottleneck of its practical applications. To overcome this problem, we present a novel algorithm based on sparse reconstruction (SR) to improve the resolution in CT direction. First, it establishes a 1D real-valued sparse model for LASAR, which deals with the 3D image column by column along CT direction in each equi-range slice. This enables it to handle large scenes. Second, it employs the spatially variant apodization (SVA) to filter bases of the measurement matrix. As a result, the cross coherence gets suppressed as well, and it is helpful to improve the performance of sparse reconstruction algorithms (SRAs). Third, we propose the resolution enhancement ability (REA), which provides a new idea to evaluate how many times the resolution could be improved. Experimental results validate that when the signal to noise ratio (SNR) is 30 dB, LASAR could usually obtain 2 times of resolution improvement in CT direction, while the proposed method further improves the REA by a factor about 2.5. Moreover, the 3D surface terrain simulation shows a great improvement for the digital elevation map (DEM) in resolution enhancement.

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Section: The Pixel Interval and The Cross Coherencementioning

confidence: 99%

Section: The Pixel Interval and The Cross Coherencementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

RESOLUTION ENHANCEMENT FOR LASAR 3D IMAGING VIA ℓ<sub>1</sub> REGULARIZATION AND SVA

Gao¹,

Shi²,

Wei³

2015

PIER M

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“…Generally, the resolution of an image is estimated by the mainlobe width of PSF [29]. Here, we consider the 3 dB mainlobe width of PSF as the corresponding range and cross-range resolutions: ∆x = ∆y ≈ 2.4 2k c sin θ i (16) where k c is the wavenumber at carrier frequency.…”

Section: Resolutionsmentioning

confidence: 99%

A Near-Field 3d Circular Sar Imaging Technique Based on Spherical Wave Decomposition

Zhang¹,

Pi²,

Min³

2013

PIER

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Abstract-A near-field three dimensional imaging algorithm for circular SAR is proposed in this paper. It adopts the theory of spherical wave decomposition to transform Green function to a superposition of plane wave components. Using this relation, the image-reconstruction can be implemented in frequency domain instead of in spatial domain, which simplifies the solving process of target reflectivity function, and allows for the target to be near to the radar. Through compensating phase factor and filtering at each elevation, we firstly get the ground CSAR signal of each elevation in frequency domain. Then, performing two dimensional inverse nonuniform fast Fourier transform and accumulating the results of all azimuth angles, the reconstructed two dimensional image corresponding to an elevation is achieved. Finally, using reconstructed image datum of all elevation, the three dimensional image of target is obtained. To demonstrate the imaging performance of our method, numerical simulations and experiments are conducted. By comparing the results with the focusing operator algorithm and the back-projection algorithm, it is found that the proposed algorithm is more efficient and can obtain a good imaging performance.

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“…Multi-circular synthetic aperture radar (MCSAR) is an extension of circular synthetic aperture radar (CSAR) [1][2][3]. MCSAR is an imaging mode where radar illuminates the target over multi-circular tracks [4][5][6].…”

Section: Introductionmentioning

confidence: 99%

Enhanced Three-Dimensional Imaging for Multi-Circular Synthetic Aperture Radar

Yu¹,

Lin²,

Bao³

et al. 2017

PIER M

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Abstract-In multi-circular synthetic aperture radar (MCSAR) mode, resolution and sidelobes are two important parameters to consider when representing imaging quality, as in other SAR imaging modes. In this paper, three-dimensional (3-D) resolution and cone-shaped sidelobes of MCSAR are analyzed for a point target in the scene center under the Nyquist sampling criterion. The results of the analysis show that resolution can be improved, and cone-shaped sidelobes can be suppressed by increasing the system bandwidth and the length of synthetic aperture in the elevation direction. But this will make the system of acquiring data more difficult. It turns out that some digital signal processing techniques can enhance 3-D imaging quality of MCSAR. In this paper, a simple method based on spectrum extrapolation and interferometric phase masking is proposed to improve 3-D resolution and suppress cone-shaped sidelobes of MCSAR. Experimental results regarding a tank model in a microwave anechoic chamber demonstrate that this method is effective.

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An imaging technique using confocal circular synthetic aperture radar

Cited by 141 publications

References 7 publications

RESOLUTION ENHANCEMENT FOR LASAR 3D IMAGING VIA ℓ<sub>1</sub> REGULARIZATION AND SVA

RESOLUTION ENHANCEMENT FOR LASAR 3D IMAGING VIA ℓ<sub>1</sub> REGULARIZATION AND SVA

A Near-Field 3d Circular Sar Imaging Technique Based on Spherical Wave Decomposition

Enhanced Three-Dimensional Imaging for Multi-Circular Synthetic Aperture Radar

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