ヨサファット テトォコ スリ スマンティヨ

Analyses of single-post-event polarimetric synthetic aperture radar (PolSAR) data permit fast and convenient post-disaster damage assessment work. By analyzing valid features, damaged and undamaged buildings can be quickly classified. However, the presence of oriented buildings in the disaster area makes the classification work more challenging. Many previous works extract the damage information of the disaster area by considering oriented buildings and undamaged parallel buildings as survived buildings. However, after-effect debris may create structures with random orientation angles. In our study on the Tohoku earthquake/tsunami disaster event, we found that some damaged buildings with large building orientation angles (with respect to the satellite flight path) are grouped as oriented buildings (undamaged buildings). In this paper, we propose a new earthquake/tsunami damage assessment method, particularly for urban areas, that takes this complex situation into consideration. The proposed method solves the problems of both urban-area extraction and damaged-building identification. For urban-area extraction, the proposed combined thresholding and majority voting method can accurately discriminate between urban and foreshortening mountain areas. Meanwhile, for damaged-building identification, the proposed new unsupervised damage assessment method classifies the buildings in a disaster area according to four conditions, and it outperforms the techniques used in existing works. The analysis results and the comparison with the supervised support vector machine (SVM) classification technique show that our proposed method can produce more accurate results for damage assessment using single-post-event PolSAR data. View Full-Text

Polarimetric synthetic aperture radar (PolSAR) data show good performance in near-real-time earthquake/tsunami damage assessment. In this paper, an improved damage level index for earthquake/tsunami damage level mapping of urban areas based on distance metric learning using full PolSAR data has been proposed. First, urban areas are extracted by our proposed classification method, which conjunctively uses multiresolution segmentation and support vector machine. Then, a double-bounce scattering power-based damage level index is adopted for damage level mapping. To solve the problem that the primary result does not match with the truth damage level in heavily damaged areas, distance metric learning method is introduced to calculate the Mahalanobis metric to compose an improved index. Extensive experimental comparison and analysis on L -band ALOS PALSAR data of Tohoku earthquake demonstrate the effectiveness of the proposed index. Both the analysis about damage level assessment map and sample areas' linear fitting with truth damage level indicate the improved damage level index achieves high accuracy. The same analysis was applied to evaluate the damage induced in Kumamoto earthquake event. The analysis result verified the robustness of the proposed damage level index.

This paper presents a polylactid-acid (PLA) based 3D printed circularly polarized 2 × 2 X-band horn array antenna for circularly polarized synthetic aperture radar (CP-SAR) sensor. The use of CP horn array antenna is to overcome some issues related with mismatch orientation and ionospheric effect of linear polarization sensor. The proposed array antenna which is intended to operate at X-band frequency is realized using PLA material through 3D printing technique and fed by series sequential feeding network implemented on a 1.6mm thick NPC-F220A dielectric substrate. From the result, it shows that the proposed CP horn array antenna has 3dB axial ratio bandwidth more than 400MHz in X-band frequency range.

The radiation pattern of the array antenna is an important characteristic in the synthetic aperture radar (SAR) sensor to maintain the quality of the images. In this work, an array antenna consists of five elements square microstrip antenna (SMA) having a low sidelobe level for SAR sensor is presented. The proposed antenna is designed to propagate in circular polarization with a corner-truncated technique. The low sidelobe level is obtained by implementing the Chebyshev polynomial to distribute the power to each element of the patch. For five elements square array antenna, the simulated axial ratio bandwidth (&lt 3 dB) of about 11.2 MHz (0.88 %), which is consistent with the measured fabricated model of 10.5 MHz (0.83 %). The maximum sidelobe levels of the proposed antenna for measurement and simulation are about 20.0 dB and 21.5 dB, respectively. The both measured and simulated results are in line with the theoretical design made by using Chebyshev polynomial of 20 dB. The low side lobe level and reasonable axial ratio bandwidth indicate the antenna is satisfying the specifications of SAR sensor.

In this paper, a low-profile wide bandwidth circularly polarized microstrip antenna is proposed as element for a C-band airborne circularly polarized synthetic aperture radar sensor. Several bandwidth improvement techniques were proposed and implemented. In order to increase impedance bandwidth, the antenna is constructed using double-stacked substrate with low dielectric constant, modified radiating shape for multi-resonant frequency, and a circle-slotted parasitic patch. Generation of the circularly polarized wave employs a simple square patch with curve corner-truncation as radiating element. The asymmetric position of the feeding is attempted to improve the axial-ratio bandwidth. To avoid a complicated feed network, the antenna is fed by single-feed proximity-coupled microstrip line. The effect of copper-covering on the upper layer for decrease undesired radiation wave emitted by the feeding is also studied and presented. Measurement results show that the impedance bandwidth and axial ratio bandwidth are 20.9% (1,100 MHz) and 4.7% (250 MHz), respectively. Meanwhile the measured gain is 7 dBic at the frequency of 5.3 GHz.

This paper presents a novel method of designing the compact dual-sense circularly polarized (CP) microstrip antenna/array with improved impedance bandwidth, axial ratio (AR) bandwidth, and interpolarization isolation. The lefthand and right-hand CP characteristics are achieved simultaneously by conceiving a vertically coupled resonant structure for the first time. Different from traditional methods, the antenna shows a compact size but exhibits the wide impedance and 3 dB AR bandwidths. For each input, two coupling paths are purposely designed to excite the TM10 and TM01-mode of the patch, respectively. By composing different coupling units in the two paths, an intrinsic ±90° phase difference over a broadband can be obtained, resulting in the broadband CP characteristics. In addition, a novel method of using the neutralization line between the two feeds is investigated to improve the isolation between the polarizations. Based on the dual-sense CP element, a 1 × 4 dual-sense CP array is composed to exemplify its potential applications in large arrays. Compared with traditional CP antennas, the proposed antennas have the advantages of compact size, simplified feed, broad impedance and 3 dB AR bandwidths, and improved isolation. Experimental results verify the predictions.

In this paper, a circularly polarized antenna for Synthetic Aperture Radar (SAR) application is presented. The antenna is proposed to be implemented for the airborne SAR and the spaceborne SAR. To enhance the bandwidth of the antenna, the Circular-Ring-Slot (CRS) technique is implemented on the ground plane and in a square slot in the centre of the patch. In this antennas design, the model of the slot on the radiator is also investigated. The antenna is printed on NPC-H220A substrates with the dielectric constant of 2.17 and thickness of 1.6 mm. The resonant frequency of the antenna design sets at 9.4 GHz with the minimum requirement of the bandwidth of 800 MHz. The antenna design is produced under the -10 dB bandwidth of reflection coefficient, S11 of approximately 27% (8.2 GHz-10.76 GHz) and left-handed circular polarization (LHCP). The gain of the antenna is 6.5 dBic and 12.7% (8.8 GHz-9.84 GHz) for the axial ratio bandwidth (ARBW). This paper includes the description and presentation of the completed discussion.

We developed L band (frequency 1.275 GHz) circularly polarized synthetic aperture radar (circularly polarized SAR) on-board unmanned aerial vehicle (UAV). This paper explains the configuration of system, antenna, and car-based experiment of circularly polarized SAR. The comparison of circularly polarized SAR and linearly polarized SAR by full polarimetric scattering experiment in anechoic chamber was done and discussed. The result shows circular polarization has less effect of orientation angle of target and could avoid the misalignment of transmitter and receiver antenna during UAV operation. Axial ratio and ellipticity images are also derived and introduced as novel classification technique in microwave remote sensing field using circularly polarized SAR or ellipticity characteristic of scattering wave.

Silica is one of the mineral needs of industry, especially in base materials for the primary or auxiliary raw materials. Silica sand on Rupat Island was identified on the northern coastline. Selected samples were measured to get the percentage of minerals/elements using X-ray fluorescence. Two adjacent scenes of ALOS PALSAR full-polarimetry data were used. The dielectric constant of samples was measured using a dielectric probe kit in the frequency range from 0.3 to 3.0 GHz and also used for calculating the backscattering coefficient. Freeman-Durdeen and Yamaguchi techniques were used to obtain the scattering decomposition of physical scattering from the incoherent object model base. Surface scattering is a very clear decomposition used to show the silica sand identification compared with other decompositions. From surface scattering, the backscattering coefficient value of silica sand resulted from −59 dB to −52 dB. Thickness estimation from satellite and field measurements show the minimum is 59 cm and the maximum is 74 cm, with the average differentiation between these measurements being 4.88 cm. The condition supported by the grain size of silica sand particles that have almost the same size and shape were conducted by using microscopic photograph testing. These values were caused by a slightly rough surface.

C-band, 4-8 GHz, inverse synthetic aperture radar (ISAR) experiments have been conducted to investigate the characteristics of a proposed synthetic aperture radar (SAR) system using circularly polarized antennas. The aluminum plate and dihedral reflectors were selected as targets to analyze the difference of scattering between odd-numbered and even-numbered bounce. SAR measurements with linearly polarized antennas were also performed for comparison. The SAR images show clear differences between co-polarization and cross-polarization setup of the antenna, and is consistent with theory.

In this paper, a tilted beam circularly polarized antenna is designed. This L-band antenna is designed to be mounted on the bottom of unmanned aerial vehicle (UAV) for circularly polarized synthetic aperture radar (CP-SAR) sensor. The antenna is composed of four elliptical elements and a proximity-feeding network. By arranging the phases different to each element, the main beam of radiation can be tilted to proposed angle for a side looking radar. The phase shifting is obtained by varying the length of the antenna feed line. A method of moment (MoM) is employed for optimizing the design and achieving a good circular polarization at the targeted frequency (1.27 GHz). The tilted beam and axial ratio indicate the antenna is promising for the CP-SAR.

災害や地球環境監視に効果を発揮する全天候型の地球センサである合成開口レーダを低コストで即応性のあるシステムにするために，無人小型航空機（UAV）や100kg級の小型衛星等の小型飛しょう体に搭載する研究開発が行われている．本論文では，その基本的な開発方針と開発実例を述べる．UAVにおける開発成果を小型衛星に転用していく際には，コンパクトな展開型アンテナとRF電力増幅器，観測時の尖頭的な電力と熱のマネージメント等がキーテクノロジーとなる．

In this paper, an elliptical microstrip array antenna with a low sidelobe level for circularly polarized synthetic aperture radar (CP-SAR) sensor is investigated. The low sidelobe level is obtained by implementing the Chebyshev synthesis method to distribute the power unevenly to each element of the patch. A Method of Moment is employed for optimizing the design and achieving a good circular polarization at the working frequency (L-Band). The simulated axial ratio (AR) bandwidth (<3 dB) for the five elements elliptical array antenna is around 11.2 MHz (0.88%), which is consistent with the measured value of 13.3 MHz (1.05%). The maximum sidelobe level of the proposed antenna is 23.3 and 21.4 dB for measured and simulated value, respectively. The simulated and measured results considerably agree with the theoretical design calculated using Chebyshev polynomial of 20 dB. The low sidelobe level and reasonable AR values indicate that the proposed antenna satisfies the specifications of the CP-SAR sensor.

A geospatial data sharing/overlay system, CEReS Gaia, has been developed to promote land surface environmental studies. The system is a strong tool to analyze land surface by overlaying satellite images, multiple thematic maps and research products. It is also useful for collecting land cover ground truth and comparing different maps. The system has the following features: a) international cluster system, b) open source, c) multi-language capability, d) free access with/without user registration, e) data upload by registered users, f) capability to overlay user data on other registered data and images from Web Map Service (WMS), and g) the option of free or selective data distribution. The system was published in August 2012 first and has been continuously improved since then. Any researcher can use CEReS Gaia by accessing the site 〈http://gaia.cr.chiba-u.jp/portal〉, and contribute as a system manager by contacting the author. The paper introduces characteristics of a newly developed system, CEReS Gaia.

Indonesia is undeniably true is one of the most disastrous country in the world when it comes to incidences of natural disaster. Besides its geologic setting of being squeezed by three major tectonic plates (Eurasian, Pacific and Indo-Pacific plates), its location in tropical region makes it also vulnerable in terms weather imposed disaster such as flood, landslides and typhoon. On the other hand, remote sensing technology has been developed intensively and extensively for the use of natural disaster mapping. On March 24, 2004, one of the major landslides occurred at the head of Jeneberang River in Bawakaraeng Mountain inactive volcano complex bringing huge amount of debris flowing to the lower stream of the river which endangered the Bili-Bili Dam in the district of Gowa, South Sulawesi. The Dam is very essential to the city of Makassar for the supply of drinking water and electrical power plant. This study aims to monitor the distribution and the surface displacement of the uncontrolled collapsed material of the previous landslide from the potential of material blockage to the Bili Bili Dam and possibility of future landslide by utilizing the Japanese Advanced Land Observation Satellite (ALOS) with Phased Array type L-band Synthetic Aperture Radar (PALSAR) images in the Differential Interferometric of Synthetic Aperture Radar (DInSAR) processing technique in three consecutive years of 2007, 2008 and 2009. With this technique the surface deformation of the landslide area can be measured and validated with ground measurement of Global Positioning System (GPS) and direct ground survey. Landsat images were also used to analyze the spatial extent of the area. The result shows the surface deformation occurred along the path of the collapse material where river discharge becomes an erosive agent that weakened the strength of the material cohesion which in turn creates further landslides. This phenomenon is dangerous to the people, crops and cattle surfacing this area. Therefore this area especially where cracks are found needed to be mapped and monitored and the result of the study must be distributed. In conclusion, this study is able to show that DInSAR technique with ALOS PALSAR image data can be used to monitor the post landslide area and to support the creation of landslide susceptibility map of the area. Small movement of cracks of 5-10 cms can be mapped in some parts of the surface displacement area. Using remote sensing technology this effort is effective and efficient to map such a large area.

Disasters, both natural and man-made, are increasing in their frequency and catastrophic impact in Indonesia. The Japanese L-Band SAR sensors satellite data (ALOS PALSAR) has ability to monitor disasters and measure any change occurred on earth surface. In this research, we proposed the usage of Differential Synthetic Aperture Radar Interferometry (DInSAR) to monitor landslide hazard in Kayangan catchment area, Yogyakarta, Indonesia. DInSAR is a remote sensing technique that can be used to accurately detect ground displacement or land deformation in the antenna line-of-sight (slant-range) direction using Synthetic Aperture Radar (SAR) data taken at two separate acquisition times. The DInSAR method is complementary to ground-based methods such as leveling and global positioning system (GPS) measurements, yielding information in a wide coverage area even when the area is inaccessible. The landslide map is generated over each area according to the DInSAR result. Our analysis reveals that Kayangan catchment area exhibits clear indications of slight movement in study area. The analysis result of land deformation was used to identify the acceleration caused by a destabilizing anthropogenic change and the relationship among seasonal precipitation and deformation variability. Copyright © (2013) by the Asian Association on Remote Sensing.

This paper present a circularly polarized microstrip antenna array for Unmanned Aerial Vehicle (UAV). The antenna element is designed using conventional rectangular microstrip antenna which is electromagnetically coupled fed by a microstrip line. The 1×4 element microstrip antenna array is then assembled on the surface of UAV cylindrical fuselage. The measurement result showed for 1x4 element antenna array that it operates at frequency 5.6 GHz with return loss characteristic of-22.24 dB. The impedance bandwidth at VSWR &lt 2 is 720 MHz. Moreover, the radiation pattern show omnidirectional. Both simulation and experimental results show the proposed antenna radiation characteristics can be achieved as specified. © 2013 Antenna Society of the Chinese Institute of Electronics.

Development of compact and low power consumption synthetic aperture radar (SAR) by Center for Environmental Remote Sensing (CEReS), Chiba University make it feasible to bring such payload in microsatellites. Under collaboration with Center of Satellite Technology, Indonesian Institute of Aeronautics and Space (LAPAN), the concept LAPAN-CHIBA microsatellite is being developed. The mission of the satellite is for land cover mapping, disaster monitoring, Cryosphere monitoring, and oceanographic monitoring. In land cover mapping, the mission is to classify the forest and non-forest area, estimation of tree trunk height, and mangrove area monitoring. The system design of the microsatellite is presented in this paper. The resulted system design shows that the satellite could perform the mission while meeting the dimensional and weight requirement of most auxilary payload launches. The design also show that the satellite will have sufficient power to operate the payload during its pass in Indonesia and Japan area, and ocasionally on other areas on non-direct downlink mode. © 2013 IEICE.