• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.25 no.2
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• pp.255-258
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• 2014

Imaging in bistatic radar has been known a more difficult task than that in monostatic radar. It is because the behavior of the bistatic range and the bistatic Doppler due to the motion of a transmitter and a receiver is so random that the compensation procedure, which we call an imaging algorithm, is quite complicated. This paper presents a bistatic radar imaging algorithm that can be used in some specific bistatic radar geometry. We show this geometry can present rectangular-like resolution cell on isorange-isoDoppler contours map. We also present the associated resolution and simulation results.

• Proceedings of the IEEK Conference
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• 2000.11a
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• pp.505-508
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• 2000

The success of target reconstruction in SAR(Synthetic Aperture Radar) imaging system is greatly dependent on the coherent detection. Primary causes of incoherent detection are uncompensated target or sensor motion, random turbulence in propagation media, wrong path in radar platform, and etc. And these appear as multiplicative phase error to the echoed signal, which consequently, causes fatal degradations such as fading or dislocation of target image. In this paper, we present iterative phase error estimation scheme which uses echoed data in all temporal frequencies. We started with analyzing wave equation for one point target and extend to overall echoed data from the target scene - The two wave equations governing the SAR signal at two temporal frequencies of the radar signal are combined to derive a method to reconstruct the complex phase error function. Eventually, this operation attains phase error correction algorithm from the total received SAR signal. We verify the success of the proposed algorithm by applying it to the simulated spotlight-mode SAR data.

• Korean Journal of Remote Sensing
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• v.8 no.2
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• pp.79-91
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• 1992

With recent development in spaceborne imaging radar system, there are growing interests using satellite synthetic aperture radar(SAR) data in various applications. This study attempted to identify the relationships between several forest stand characteristics and radar backscatter, measured from space altitude altitude at three incidence angles. Shuttle Imaging Radar-B(SIR-B) data were collected over a forested area in northern Florida in October, 1984. By using various sources of reference data (forest type maps, inventory records, aerial photographs, and Landsat Thematic Mapper data), about 400 forest stands of known characteristics were carefully located in the radar data. Relative radar backscatter for the three incidence angles of SIR-B data were compared with known forest stand parameters such as mean tree height, diameter at breast height(DBH), stand density, biomass, and relative amount of understory vegetation. The results show that these stand parameters have statistically significant correlations with the radar backscatter. In addition, the SIR-B radar backscatter from a certain stand parameter turned out differently at the three different incidence angles. Finally, the types and characteristics of currently available satellite SAR data are discussed.

• Journal of IKEEE
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• v.25 no.1
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• pp.76-82
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• 2021

In this paper, the compressed sensing basic pursuit denoise algorithm adopted to synthetic aperture radar imaging is investigated to improve the object recognition. From the incomplete data sets for image processing, the compressed sensing algorithm had been integrated to recover the data before the conventional back- projection algorithm was involved to obtain the synthetic aperture radar images. This method can lead to the reduction of measurement events while scanning the objects. An ultra-wideband radar scheme using a stripmap synthetic aperture radar algorithm was utilized to detect objects hidden behind the box. The Ultra-Wideband radar system with 3.1~4.8 GHz broadband and UWB antenna were implemented to transmit and receive signal data of two conductive cylinders located inside the paper box. The results confirmed that the images can be reconstructed by using a 30% randomly selected dataset without noticeable distortion compared to the images generated by full data using the conventional back-projection algorithm.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.36D no.4
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• pp.34-41
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• 1999

Unlike the traditional radar system, Synthetic Aperture Radar(SAR) system is capable of imaging a target scene to ceertain degree of cross-range resolution. And this resolution is mainly depends on the size of aperture synthesized. Thus, a good system model and inversion scheme should be developed to actually give effect of synthesizing aperture size, which in turn gives better cross range resolution of reconstructed target scene. Among several inversion schemes for SAR imaging, we used an inversion scheme called wavefront reconstruction which has no approximation in wave propagation analysis, and tried to verify whether the collected data with synthesized aperture actually give the same support as that with physical aperture in the same size. To do this, we performed a signal subspace comparison of two imaging models with physical and synthesized arrays, respectively. Theoretical comparisons and numerical analysis using Gram-Schmidt procedures have been performed. The results showed that the synthesized array data fully span the physical array data with the same system geometry. This result strongly supports the previously proposed inversion scheme valuable in high resolution radar imaging.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.11
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• pp.1285-1294
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• 2010

This study describes the design and verification of short range UWB(Ultra Wideband) imaging radar that is able to display high resolution radar image for front area of a UGV(Unmanned Ground Vehicle). This radar can help a UGV to navigate autonomously as it detects and avoids obstacles through foliage. We describe the relationship between bandwidth of transmitting signal and range resolution. A vivaldi antenna is designed and it's radiation pattern and reflection are measured. It is easy to make array antenna because of small size and thin shape. Aperture size of receiving array antenna is determined by azimuth resolution of radar image. The relation of interval of receiving antenna array, image resolution and aliasing of target on a radar image is analyzed. A vector network analyzer is used to obtain the reflected signal and corner reflectors as targets are positioned at grass field. Applicability of the proposed radar to UGV is proved by analysis of image resolution and penetrating capability for grass in the experiment.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.40 no.1
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• pp.130-138
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• 2003

The classical image reconstruction for stripmap-mode Synthetic Aperture Radar is the Range-Doppler algorithm. When the spotlight-mode SAR system was envisioned, Range-Doppler algorithm turned out to fail rapidly in this SAR imaging modality. Thus, what is referred to as Polar format algorithm, which is based on the Plane wave approximation, was introduced for imaging from spotlight-mode SAR raw- data. In this paper, we have studied for the raw data processing schemes in the spotlight-mode Synthetic Aperture Radar. We apply the Wavefront Reconstruction scheme that does not utilize the approximation in spotlight-mode SAR imaging modelity, and compare the performance of target imaging with the Polar format inversion scheme.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.15 no.6
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• pp.471-476
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• 2022

In this paper, we propose an object detection using a 4D imaging radar, which developed to solve the problems of weak cameras and LiDAR in bad weather. When data are measured and collected through a 4D imaging radar, the density of point cloud data is low compared to LiDAR data. A technique for clustering objects and extracting the features of objects through voxels in the cluster is proposed using the characteristics of wide distances between objects due to low density. Furthermore, we propose an object detection using the extracted features.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.6
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• pp.654-660
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• 2013

This paper describes an imaging approach to detect targets behind a wall. To acquire the accurate information over the strong signals reflected by the wall and affected by multipath, a bi-static through-wall imaging radar using a noise waveform is proposed in this paper including the methodology of imaging the received signal. The complete derivation of the proposed approach is presented. And the result of tests is demonstrated to show the possibility of the proposed approach.

• Korean Journal of Remote Sensing
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• v.23 no.4
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• pp.237-245
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• 2007

GB-SAR (Ground-Based Synthetic Aperture Radar) system is an imaging radar that obtains high resolution 2-D image through a synthetic aperture effect from the accurate linear-motion control of antenna on the ground. The highly versatile system configurations and accurate repeatability of GB-SAR operation allow one to accurately monitor the stability of surface scatterers with millimeter accuracy by SAR interferometry. In this paper we introduce the development of a GB-SAR system and show the possibilities of SAR polarimetry and interferometry such as DInSAR, Cross-Track InSAR, Delta-f InSAR, and PSInSAR.