ヨサファット テトォコ スリ スマンティヨ

A dual-polarized antenna with multimode resonance and high selectivity is proposed in this article to cover the 5G sub-6 GHz bands. The proposed antenna achieves dual wide impedance bandwidth characteristics by incorporating a dual mode coupled patch and four planar coupled strips around the driven patch. Through the four resonant modes of these structures, the antenna effectively covers the two desired frequency bands. Moreover, the electric/magnetic coupling between the driven patch, dual mode coupled patch, and planar coupled strips enables the creation of three radiation nulls that suppress unwanted radiation. To further improve the out-of-band rejection level and half power beamwidth (HPBW), four shorted strips are introduced around the radiator. The introduction of these strips results in a fourth radiation null at higher out-of-band frequencies and expands the antenna's HPBW from 52° to 62°. To demonstrate the feasibility of the design, both the proposed antenna and its array were manufactured and tested. Measured results show that the filtering element was able to operate within frequency bands of 3.24-3.83 GHz (16.7%) and 4.74-5.30 GHz (11.2%) with a reference of $\vert \text{S}_{\text {dd11 } } \vert < -14$ dB. The input ports exhibited a high level of isolation, measuring 40 dB. Furthermore, the four radiation nulls proved effective in suppressing out-of-band radiation.

Ever since the last occurrence of a significant earthquake in the Mentawai megathrust zone in 2000, no significant earthquake events have been recorded, which, according to the earthquake repetition cycle, suggests that the zone is a potential epicenter of future earthquakes. The southern and northern parts of the zone have been struck by a significant earthquake with magnitude M > 8.0; however, in the potential location of the Mentawai Islands, earthquake energy has not been released. This research shows the tectonic activity, velocity, and shift that occurred owing to the thrust of the plate. The information is a vital reference for estimating the epicenter of the earthquake whose energy has not yet been released. We analyzed the tectonic characteristics according to the synthetic aperture radar data and geodetic global positioning system observations. The results show that the Pagai Islands are experiencing consistent tectonic deformations. The northern region of North Pagai and the Northern region of South Pagai are experiencing significant subsidence, while the southwest (SW) region of North Pagai and the south segment of South Pagai are experiencing significant uplift. The government and local authorities can use this information as a guide for developing strategies for disaster preparation.

Forest and land fires are disasters that greatly impact various sectors. Burned area identification is needed to control forest and land fires. Remote sensing is used as common technology for rapid burned area identification. However, there are not many studies related to the combination of optical and synthetic aperture radar (SAR) remote sensing data for burned area detection. In addition, SAR remote sensing data has the advantage of being a technology that can be used in various weather conditions. This research aims to evaluate the burned area model using a hybrid of convolutional neural network (CNN) as a feature extractor and random forest (CNN-RF) as classifiers on Sentinel-1 and Sentinel-2 data. The experiment uses five test schemes: (1) using optical remote sensing data; (2) using SAR remote sensing data; (3) a combination of optical and SAR data with VH polarization only; (4) a combination of optical and SAR data with VV polarization only; and (5) a combination of optical and SAR data with dual VH and VV polarization. The research was also carried out on the CNN, RF, and neural network (NN) classifiers. On the basis of the overall accuracy on the part of the region of Pulang Pisau Regency and Kapuas Regency, Central Kalimantan, Indonesia, the CNN-RF method provided the best results in the tested schemes, with the highest overall accuracy reaching 97% using Satellite pour l’Observation de la Terre (SPOT) images as reference data. This shows the potential of the CNN-RF method to identify burned areas, mainly in increasing precision value. The estimated result of the burned area at the research site using a hybrid CNN-RF method is 48,824.59 hectares, and the accuracy is 90% compared with MCD64A1 burned area product data.

Recently, unmanned aerial vehicles onboard synthetic aperture radar (UAV-SAR) have been developed by many institutions to provide high-resolution, real-time data acquisition and local emergency observation. The SAR system remains the issue to realize the system with the high resolution, lightweight, minimalized payload, power efficiency, high altitude operation, extreme environment, long-duration flight, and full polarimetric mode. For this purpose, our research group plans to develop the X-band circularly polarized UAV-SAR for disaster and environmental monitoring using the 25 kg payload of the UAV. The SAR system requires a broadband antenna and full circular polarization for precise observations. The antenna for the SAR systems requires a small size, lightweight, high gain, broadband for chirp pulse, and good antenna isolation and axial ratio (AR). For this purpose, we proposed the $4\times4$ ax-shaped radiator array antenna. The proposed antenna was simulated, fabricated, and measured in an anechoic chamber. Furthermore, the indoor polarimetric scattering SAR experiment was conducted using canonical targets to investigate the polarimetric SAR capability of the system with the proposed antenna. The result proves the performance of circularly polarized SAR.

This paper presents a novel regolith (in-situ) -based substrate for a circularly polarized antenna. Fabrication of regolith substrate using regolith soil, cement, and water in a specific combination. Regolith substrate has been measured which has a low dielectric constant of 2.08 and a dissipation factor of 0.00527. The antenna works at a center frequency of 6.175 GHz. It uses two-stacked regolith substrates with each substrate having a size of 30 x 50 x 2 mm3. It has an RHCP single radiating patch with a corner truncation. The results show that the measured impedance bandwidth and axial ratio bandwidth are 794 MHz (12.8%) and 386 MHz (6.25%), respectively. The antenna has a gain of 6.3 dBic and a VSWR of 1.4 at 6.175 GHz. Regolith has great potential for an antenna substrate to support future telecommunication infrastructure in the lunar environment.

Weather observations are usually derived from measurements and monitoring by sensors, radars, satellites, and human observation. Remote cameras are also used; however, meteorological experts typically report changes in the sky, clouds, and weather based on these images every hour or longer. Moreover, it is challenging to install additional cameras in more locations due to the lack of such experts. Because of the complexity of cloud textures, state-of-the-art (SOTA) Deep Learning (DL) models have been applied to limited cloud types, mainly in clear weather conditions. In addition, sky, cloud, and weather recognition from camera images typically implement multiple DL models. However, SOTA DL models have not considered the impact of weather changes, i.e., rain. This paper proposes PanopticBlue, an integrated transformer-based camera-sky-cloud-weather image recognition and classification model under adversarial weather conditions. Scene object recognition is also used to reduce cloud-type classification errors by DL. Experimental results show the superiority of the proposed DeepTex for many cloud types, i.e., unique cloud recognition, twilight cloud recognition, and Cb type cloud, and weather changes, i.e., rain, lightning, and fog, in enhanced accuracy and robustness over SOTA DL models. Moreover, vision language is used to enrich auto-briefing in weather conditions.

Application of fully polarimetric synthetic aperture radar (PolSAR) for detection of archaeological site in Muaro Jambi, Indonesia, is presented. Scale mode of manmade structure is constructed and is measured using setup reproducing ALOS PALSAR2 full polarization strip map mode. The backscattered signal is then decomposed and analyzed for each scattering mechanism. Both scale model and satellite measurement is analyzed. It is shown that the scattering mechanism of scale model confirms theoretical and real measurement of satellite data.

In the realm of regional emergency observation and real-time, high-resolution data acquisition, there is a burgeoning interest in the development of UAV equipped with Synthetic Aperture Radar systems (UAV-SAR). However, a critical challenge lies in achieving a UAV-SAR system that meets criteria such as high resolution, lightweight design, minimized payload, power efficiency, operational viability at high altitudes, robustness in extreme environments, extended flight durations, and full polarimetric functionality.To address this challenge, our research group envisages the creation of an X-band circularly polarized UAV-SAR system, designed specifically for disaster management and environmental monitoring, leveraging the 25 kg payload capacity of the UAV platform. The effective functioning of the SAR system necessitates a broadband antenna with complete circular polarization capabilities to ensure precise observations. The antenna must also be compact, lightweight, possess high gain, accommodate broadband chirp pulse signals, and exhibit excellent antenna isolation and axial ratio (AR).To this end, we put forth a novel design featuring a 4×4 array antenna outfitted with axe-shaped radiating elements. The proposed antenna underwent rigorous simulation, fabrication, and assessment within an anechoic chamber. Additionally, an indoor polarimetric scattering SAR experiment was conducted employing canonical targets to assess the polarimetric SAR proficiency of the system equipped with the proposed antenna.

The concern about the recurrence of land subsidence has arisen in Japan with urban development and new groundwater use. Land subsidence observation well has been utilized for monitoring the subsidence, but due to the recent aging of facilities and equipment, remote sensing technology is attracting attention. This paper seeks to assess the substitutability of Consecutive DInSAR with the land subsidence observation well. To investigate the subsidence in Kanagawa prefecture, Sentinel 1 images from August 2017 to March 2022 were analyzed by SARPROZ software based on Consecutive DInSAR, Global Navigation Satellite System (GNSS), and land subsidence observation well methods. Moreover, we assessed the new calculation model between land surface pressure and ground water called the law of material conservation to estimate land subsidence. The results revealed that the Consecutive DInSAR results agreed with the land subsidence observation well data, indicating the possibility of future substitution.

An interleaved shared-aperture dual-band dual-polarized base station array antenna is proposed in this article. The lower-band (LB) element is realized by using a multiple folded-dipole antenna (MFDA) and four parasitic loops. To interpret the working principle of the MFDA, a double folded-dipole antenna (DFDA) is firstly analyzed by using the transmission line (TL) model. Then, by combining two bended DFDAs and introducing four parasitic loops, a low cross-band scattering LB element with a high out-of-band rejection level of 16 dB is obtained to cover 2.3-2.7 GHz. The higher-band (HB) element with a wide impedance bandwidth of 42.5% (3.0-4.6 GHz), a high roll-off rate (RoR) of 249.2 dB/GHz, and a high out-of-band rejection level of 17 dB is obtained by introducing a meander line loop (MLL), a rectangular loop (RL), and V-shaped strips (VSS) near the dipole arms. By combining the proposed low-scattering low-pass LB element and the high- RoR high-pass HB element, a novel interleaved shared-aperture dual-band dual-polarized array antenna with a small frequency ratio of 1.46 and a high cross-band isolation level of 25 dB is realized. Due to the low-scattering characteristic and filtering response of the LB element, the radiation patterns of the wideband HB sub-arrays are almost unaffected.

Tropical peatland in Southeast Asia has undergone rapid degradation and shows large subsidence due to oxidation and peat shrinkage. The measurement of those deformations is thus valuable for evaluating the peat condition and assessing peat restoration. The time series interferometric synthetic aperture radar (TInSAR), especially with the small baseline subsets (SBAS) method, is capable of measuring long-term deformation. However, the dynamic surface scatterers often change in tropical peatland, which degrades the coherent scatterer (CS) distribution density. This article presents a simple and efficient TInSAR approach that enhances the CS density under such dynamic surface scatter variation based on the SBAS method. In the presented approach, a long-time series of single-look complex images is separated into subsets, and deformation estimation is performed for each subset. The effectiveness of this simple solution was investigated by InSAR simulation and validated using SAR observation data. We applied the subset SBAS approach to the three-year Sentinel-1A C-band SAR dataset acquired over tropical peatland in Indonesia. The analyses showed an improved number of CSs for the introduced subset approach. We further introduce the color representation of CS temporal behavior per subset for visual interpretation of scatterer change.

Earthquakes can inflict significant damage to structures and infrastructures. This paper presents a machine learning model to predict ground surface deformation (GDS) induced by earthquake events. The data on historical GSD is extracted from radar product of Synthetic Aperture Radar (SAR) data of one-year over five magnitude earthquakes that occurred within 200 kilometers of the Kota Padang Regency, West Sumatra. Building topology data of its footprint area, distance from shoreline, elevation, and coordinate were incorporated as the main features in the dataset. The earthquake parameters were taken from the USGS earthquake data catalog. Four machine learning algorithms of Neural Network (NN), Random Forest (RF), k-Nearest Neighbors (kNN), and Gradient Boosting (GB) are applied. The GSD from the trained models is predicted and compared with the measured GSD from the SAR’s product. The performances of proposed algorithms are evaluated in terms of the statistical index. A new dataset from the earthquake event in March 2022 is used to predict the GSD and further test the performance of the trained models. Overall, the four machine learning algorithms have outstanding performance, with a coefficient determinant of more than 0.9. The kNN algorithm outperforms compared to others in delineating the GSD. The trained models gave deficient prediction performance on the new dataset with a correlation coefficient of 0.228 predicted by the RF algorithm. Additional earthquake datasets and more unique features will improve the performance of the machine learning algorithms.

Eliminating ionospheric and/or atmospheric errors from SAR images is very important to improve the detection capability of interferometric SAR. In this study, we showed the improvement of the detection ability of the advanced Consecutive DInSAR method by applying the smoothing filter on continuous time domain, which is performed by the moving average method. The analytical accuracy of the Advanced Consecutive DInSAR was verified using Sentinel-1 and GNSS(Global Navigation Satellite System) data. The error reduction was occurred clearly from the 3 pairs images in the continuous time in the descending and ascending orbits. The RMSEs were decreased by 0.28 cm and 0.36 cm at the maximum for the descending and the ascending orbits, respectively, compared to no-using the filter. In the future, more highly accurate land deformation detection is expected by applying the smoothing filter on continuous time domain in the advanced Consecutive DInSAR.

This chapter discusses different techniques to realize low-cost beam-reconfigur-able and multi-beam directional antennas. Generally speaking, the cost of beam-reconfigurable high-directivity antennas can be reduced by addressing two of their main facets: decreasing the number of active antenna elements and avoiding the use of expensive RF components such as phase shifters. The design concepts of active frequency selective surfaces, antennas with parasitic elements, lens antennas, and antennas with metasurfaces are presented to decrease the number of active antenna elements. The design concepts of low-bit reflectarrays and transmitarrays, leaky-wave antennas, multi-beam antennas, tunable materials based array antennas, mechanical beam-steering antennas, and low-cost beamforming networks are presented to avoid the use of expensive phase shifters as essential components in array antennas. These different approaches and their specific techniques are discussed with examples and simulation or measurement results.

A dual-polarized filtering antenna with steep cut-off and compact size is developed for base-station applications. In this design, four controllable radiation nulls are obtained by utilizing split rings, slotted T-shaped branches, a single-stub tuner, and a parasitic loop. Split rings are first used as the dipole arms to obtain the first radiation null at upper out-of-band. Four T-shaped branches working as DGS are printed under the crossed dipoles to achieve the second radiation null. The connected outer conductors of the differential feed structure acting as a single-stub tuner can provide the third radiation null to further enhance the upper band rejection. Finally, a parasitic loop is incorporated around the split rings, and the out-of-band rejection of the lower band is further enhanced by the fourth radiation null. More importantly, the impedance bandwidth of the antenna can be expended with two newly introduced resonant modes. As a result, a compact filtering antenna with a wide operational bandwidth of 1.7–3.01 GHz (56%) is realized for |Sdd11|<−15 dB with the isolation higher than 38 dB. The out-of-band suppression is higher than 18.4 dB in 3.1–4.5 GHz and more than 47 dB in 0.8–1.1 GHz.

This work is purposed to provide microstrip antennas for a CP-SAR system with low sidelobe, tilted beam, and circular polarization. This antenna is configured for the L-band (1.27 GHz) mounting on an Unmanned Aerial Vehicle (UAV). The proposed microstrip antenna consists of three-square radiating elements, due to the ease in fabrication. Meanwhile, the proximity structure has been adopted in the feeding network. The tilted beam was obtained by arranging the different phases for each element. On the other hand, a low sidelobe was achieved by managing the power distribution of each patch using the Chebyshev polynomial. The proposed antenna was precisely printed and examined in an anechoic chamber to verify the characteristics of the antenna such as polarization, sidelobe level, and beam direction. Based on the measurement results, the proposed antenna has a tilted beam and a low side lobe that meets the specifications of the CP-SAR system.

This research developed a lightweight and robust radome for UAV and airborne circularly polarized synthetic aperture radar (SAR) using novel polymaterial. This paper discussed characteristics of polymaterial for radome designed for airborne SAR, ground test, and flight test at Yogyakarta, Indonesia in August 2017. The polymaterial radome acquired about 1 dB improved scattering gain compared to carbon fiber radome. In the future, the proposed radome using polymaterial is considered could be applied for radome of UAV and airborne, also mobile devices like vehicles, ships, and aircraft, and fixed ground devices of 5G and 6G.

Our laboratory developed airborne circularly polarized synthetic aperture radar (SAR) for disaster and environment observation. This paper explains the investigation of scattering characteristics of circular polarization in the ground test and flight test of circularly polarized SAR in the Hinotori-C2 mission onboard CN235MPA aircraft in March 2018 at Makassar, Indonesia. The ground test was held to investigate a multi-polarized single pulse scattering from various corner reflectors. The flight test was done with multipath to collect the full polarimetric circularly polarized images. The circularly polarized scattering clarification was done using trihedral, cylindrical, and omni corner reflectors. The result shows good agreement with the theory and our previous research. The proposed circularly polarized SAR will be employed in further study of scattering and calibration techniques.

In Indonesia, extensive tropical peatland has been facing land degradation due to deforestation and drainage canal construction. Such activities lead to the decrease of groundwater level (GWL), accelerating the peat decomposition, followed by peatland subsidence. This study addresses to estimate a three-year (from Jan. 2018 to Jan. 2020) tropical peatland subsidence over Kalimantan, Indonesia, using the time-series interferometric synthetic aperture radar (TlnSAR) technique by Sentinel-IA. TlnSAR analysis revealed the apparent large displacement found in 2019 due to a significant decline of GWL caused by positive Indian-Ocean dipole mode (IOD) event compared to other years. Furthermore, we employed GWL derived from satellite-based remote sensing data to investigate the relationship between subsidence and GWL and showed a mutual relationship.

This chapter introduces novel wideband C-band circularly polarized synthetic aperture radar (SAR) sensor as compact polarimetric (CP) SAR with a 3.6-m-diameter gold-coated molybdenum string mesh and a wrapped rib–centered feed parabolic antenna for low earth orbit operating in a 150-kg class microsatellite to observe global land deformations and environmental changes. This chapter explains the scattering characteristics of circular polarization as the concept of the sensor, the system configuration of microsatellite, and the radio-frequency system of the sensor. A ground test and flight test of the sensor to investigate system performance is introduced here. Image processing and applications are discussed at the end of this chapter.

Scientists have widely used remote sensing technology to observe surface phenomena, either happened by naturally or artificially. Land subsidence monitoring is one of the promising discoveries made by implementing remote sensing technology, particularly with radar images. The gap in radar image processing technology has been attempted to solve in this study with a real case study in Jakarta, Indonesia. The challenge of simplifying the complex processing step that involved different correction due to time acquisition in radar images have been explained in this study. Aside from that, many researchers believe excessive groundwater extraction and over-exploitation of groundwater can be caused land subsidence, though other factors like land deformation and geological change can accelerate the possibilities. Prior studies have illustrated the subsidence level and methodology to investigate how subsurface change can be indicated by radar image scattering. According to that, this study focused on subsidence escalation in Jakarta. Although other areas can have similar issues, further study will be required. In this study, the Persistent Scatterer Interferometric Synthetic Aperture Radar (PS-InSAR) method has been used in Terra SAR-X multitemporal data; the process strives to search for the indication of land subsidence in the study area. The benefit of this PS-InSAR is its capability to extract point clouds at a particular temporal coherence setting from the SAR image, representing a current surface level. The data has been collected and processed from 29 scenes from 2017 to 2021, thus showing the changes over the last four years. Analysis during that period found that land subsidence existed at a high rate, compared with 2017 data, perceived that in 2021 subsidence level was cumulatively around 9.85 cm in the Pantai Indah Kapuk, North Jakarta area, and 5.63 cm in the Kembangan area of West Jakarta. A ground check is needed to ensure this strongly connects with geological factors. Still, PS-InSAR can be a beneficial tool for the surface modelling in a broad area and rapid mapping for geoscience analysis.

Floods are the most common sort of natural disaster that occurs when a body of water overflows and submerges on dry terrain. Several regions in Sidoarjo District, East Java such as Kedungbanteng and Banjarasri Village, have experienced floods with varying heights since 2018 due to heavy rainfall in the areas. According to the Meteorological, Climatological, and Geophysical Agency (BMKG), rainfall intensity in these areas reach 100 mm/day. Furthermore, the physical environment in both areas shows land subsidence that causes a change in the flow pattern, which triggers its occurrence. This research incorporated different small baseline techniques of InSAR time series analysis and used GPS measurement to evaluate and monitor the land subsidence in both areas. The reseachers used Sentinel-1 SAR data both from ascending and descending for the period between 2017 and 2021. The results showed significant subsidence value by up to −200 mm/year both in Kedungbanteng and Banjarasri Village, and GPS observation also confirmed approximately −3.2 cm of subsidence value during 2 months of sampling observations. Using the neural network analysis, the reseachers predicted the time series displacement for one year and showed that a continuous trend of deformation still existed.

Several techniques have been proposed to observe long-term land surface deformation using phase information of synthetic aperture radar (SAR), for example, interferometric SAR (InSAR), differential interferometric SAR (DInSAR), permanent scatterer interferometric SAR (PS-InSAR), and small baseline subset (SBAS) using images of JERS-1, ALOS-1/2, ENVISAT, ERS-1/2, RADARSAT-1/2, TerraSAR-X, SENTINEL-1A/B, and so on. These methods have also been employed to investigate land deformation and the impact caused by the hot mudflow accident at the study area of regency of Sidoarjo, East Java province, Indonesia, where this disaster happened on May 29, 2006, and has been flowing until now. But these methods only derived the land surface deformation and did not figure geological situation in the Earth, especially the current of geological material outflow. Therefore, this research proposed the continuity equation of the law of conservation of material to estimate the current of material outflow to investigate the impact of the land surface disaster in the study area. The information of vertical deformation or subsidence is derived by the consecutive DInSAR using multispaceborne SAR and substituted into the proposed equation to estimate the volume and current of hot mud outflow. The differential global positioning system (GPS) data collected since 2006 were employed to validate the analysis result of land surface deformation, and the root means square (rms) error is 0.46 m. The result obtained the current at the center of the study area at the beginning of the mudflow period was 6800 m 3 /day and decreased from 2018 until now that matched well with the local reports. The proposed equation could also be applied for observation of land deformation, volcano, fault activity, underground water, and so on, using remote sensing technologies.

This paper presents an effort to evaluate the generated digital elevation model (DEM) from an active sensor onboard satellite of Sentinel-1A and from aerial photos taken using an unmanned aerial vehicle (UAV). The objective is to compare the quality of generated DEM and review the processes for disaster mitigation and prevention plans application. The radar data acquisition used in this study is pair of SLC-type radar data. The interferogram is processed from the coherence and the phase of complex data of the pair radar imageries. Meanwhile, aerial photography was taken within the smaller urban area in Padang City. The photogrammetry process to generate the DEM was conducted using the structure from motion (SfM) technique. The quality and procedures are reviewed by comparing the DEM products with other publicly available DEM data from DEMNAS, SRTM, and AW3D. This study found that generating the DEM from Sentinel-1 interferometry SAR is a challenging process. The product is unmatched and has lower quality compared to available DEM data due to several identified factors. In contrast, high computational cost photogrammetry produced good quality DEM if sufficient ground control points (GCP) were set.

This paper proposed a novel compact design of UWB antenna. Our design used an uni-planar EBG double-layer of FSSs to enhance performance characteristics of UWB antenna in operation frequency of 14 GHz/Ku Band. This UWB antenna occupies a compact size of 40.36 × 29.36 mm2 with space/gap between the radiator patch and double-layer of FSSs is 10 mm. We used a simple rectangular truncated-corner as a radiating patch. Double-layer of FSSs consist of a lower layer of FSS that used a unit cell of rectangular loop and an upper layer of FSS applied a wire grid. Optimized size of the truncated-corner is 2 × 0.5 mm2, optimal space/gap between radiator patch and double-layer of FSSs is 10 mm, and the width of a rectangular loop in the lower layer of FSS is 1.742 mm. Our proposed uni-planar EBG double-layer of FSSs based UWB antenna reaches S11 parameter of −42.381, a −10 dB impedance bandwidth of 1.941 GHz (12.964–14.905 GHz), and a VSWR of 1.0154 in operation frequency 14 GHz. In addition, our UWB antenna design has a high gain about 6.1 dB. Applying of uni-planar EBG double-layer of FSSs improve significantly the performance characteristic of UWB antenna.

Soil moisture is a critical component for Earth science studies, and Synthetic Aperture Radar (SAR) data have high potential for retrieving soil moisture using backscattering models. In this study, polarimetric SAR (PALSAR: Phased Array type L-band Synthetic Aperture Radar) data and polarimetric decompositions including span, entropy/H/alpha, and anisotropy, in combination with surface properties resulting from field and laboratory measurements, are used to categorize the natural surface condition and discriminate the backscatter parameter in the test site for applying the inversion soil moisture retrieval. The work aims to introduce the better of two examined models in the research for soil moisture retrieval over the bare land and sparse vegetation in arid regions. After soil moisture retrieval using the two different models, the results of comparison and validation by field measurement of soil moisture have shown that the Oh model has a more realiable accuracy for soil moisture mapping, although it was very difficult to find the best model due to different characteristics in land cover. It seems the inversion model, with the field observation and polarimetric SAR data, has a good potential for extracting surface natural conditions such as surface roughness and soil moisture; however, over- and under-estimation are observed due to land cover variability. The estimation of accurate roughness and moisture data for each type of land cover can increase the accuracy of the results.

Nautilus is the only surviving genus whose members were numerous and widely dispersed in the oceans throughout the Jurassic and Miocene times. It represents the only living member from the Family Nautilidae and is often considered as a living fossil. Nautilus is found with high biodiversity in Ambon, Indonesia, and were in special cases even found in Bangka Belitung, far from their original habitat. This study aimed to understand the historical component of the habitat and distribution of Nautilus in Bangka Belitung and to determine the depth, temperature, current, and environmental heterogeneity relate to Nautilus. Nautilus samples were found in Bangka Belitung Seas nearby a crack region at 50-75 m deep while the optimal depth of the Nautilus was 150-300 m, depending on the local area. The locations in the Bangka Belitung Seas where Nautilus found have sea surface temperatures between 30-31°C and 27-28°C during the East Monsoon and the West Monsoon respectivelly. The implications of temperature as a limiting factor are fairly significant, as it restricts the upper limit of the living habitat to predictable depths, which vary both geographically and seasonally during the West Monsoon when surface temperatures approach habitable levels. Sea currents at the Bangka Belitung Seas move at 0-0.6 m.s-1 during the East Monsoon and speed up near the North Natuna Sea. During the West Monsoon, currents predominantly flow from the Natuna Sea to the Java Sea at 0-0.5 m.s-1. Large-scale deep-water currents and the effects of smaller currents on scent dispersal influence the directional movements of Nautilus.

This article presents a novel broadband circularly polarized microstrip array antenna for synthetic aperture radar system onboard Cessna 172 Aircraft. The antenna employs an 8×8 matrix formation with uniform element separation of 0.5λ and single-proximity-coupled strip-line feeding. The circular polarization wave generation uses a curved-truncation patch and a circle-slotted parasitic patch above it to realize the broadband circularly polarized antenna. The broadening of the axial ratio bandwidth (ARBW) applies a fully serial sequential rotation on the array feeding network. Meanwhile, the gain is improved using a circle-slotted parasitic patch with a floating cover on the top layer. The prototype antenna has a physical aperture of 270 mm × 300 mm with 1.1-kg weight. The prototype produces an impedance bandwidth of 1.5 GHz (29.3%), ARBW of 1.62 GHz (30.6%), a gain of 18.17 dBic, and aperture efficiency of 26%. The azimuth and elevation beamwidth achieved 12.7° and 13.0° at the center frequency, respectively.

In a modern survey, information on the real condition of the study area is required to support the analysis and interpretation result of a study. However, obtaining information on the real condition in a wide covered area is difficult, particular in an area that hard to access and has varied topographic. The method that can imaging the real condition of a study area is observation using UAV/drone using structure from motion technique. Besides can be observed with a wide area, the detailed condition of the area also can be visualized. Structure from motion (sfm) is the technique that determines the spatial and geometric relationship of the target area through the movement of the camera. In this research, the sfm technique was applied to create the 3 dimension construction of the Kelok Sembilan flyover. The result show, 3D construction has a high spatial resolution in 2.99 cm/pixel measured in Ground Sampling Distance (GSD). Meanwhile, the horizontal relative resolution is 5.97 cm, and the vertical relative resolution is 8.95 cm.

Pekanbaru City, Riau Province, Indonesia is located at coordinates 0°25′29.20″-0°39′15.22″ N and 101°20′43.39″- 101°34′25.60″ E. This research aims to study the common causes of flooding in Pekanbaru city which has a good geological condition. This study uses two types of data as primary and secondary data in the form of geomorphological, geological, rainfall and land use data with a geographic information system (GIS) analysis that can help spatial analysis to determine the level of flood disaster vulnerability with visual mapping models. The geomorphological analysis shows 2 types of geomorphological units found: low-land denudational and low-land structural with river flow pattern consisting of dendritic, sub-dendritic and parallel. Rainfall is quite high in 2018 with 2621.5 mm and caused flood-prone areas which are divided into 3 categories: Non vulnerable area (64.575%), Medium Vulnerable area (23,386%) and Vulnerable area (12,039%) from the entire of the research area.