X-band Radar

Ratooning, the cropping practice of harvesting a second crop from the stubbles of the primary harvest, is gaining renewed popularity as a resource-efficient alternative to increase rice production. Although current remote sensing-based rice monitoring systems have considered rice ratooning systems, nothing is known about the temporal backscatter response of ratoon rice, which is necessary for accurate rice ratooning detection in cloud-pervasive regions. Using backscatter time series from Sentinel-1A/B data, for the first time, we characterized the temporal backscatter signatures of ratoon rice crops in four features (VV and VH polarizations, the ratio of VH/VV, and the radar vegetation index (RVI)) to determine the optimal period and SAR features for main and ratoon rice discrimination. We also investigated the influence of harvesting methods on the backscatter of stubbles and the difference in backscatter between ratoon crops in irrigated and rainfed rice. We obtained data covering three growing seasons (2018-19), rice field boundaries and farmer interview data on cropping practices in the Philippines. The backscatter differences were assessed using the Mann-Whitney U and the Kruskal-Wallis test, while the classification was performed using partial least squares discriminant analysis (PLS-DA). We found that the observation during the peak of the growing season could best distinguish main and ratoon rice, specifically in the reproductive (VH, p = .010) and ripening phase (VH/VV, p = .089 and RVI, p = .089). The PLS-DA model at the reproductive phase performed better, with an overall accuracy of 68% (AUC = 0.70) than the model from the ripening phase (OA = 60%, AUC = 0.64). The backscatter of stubbles from mechanically harvested fields is not significantly different from that of manually harvested fields. We also found no significant backscatter difference in ratoon crops across different water managements throughout all growth phases. This study demonstrates the potential of SAR Sentinel-1 time series data to determine periods and SAR features for optimal main and ratoon rice discrimination, which offers advantages for future remote sensing-based rice ratooning mapping and rice production estimation.

At airports, runway operation is the limiting factor for the overall throughput; specifically the fixed and overly conservative ICAO wake turbulence separation minima. The wake turbulence hazardous flows can dissipate quicker because of decay due to air turbulence or be transported out of the way on oncoming traffic by crosswind , yet wake turbulence separation minima do not take into account wind conditions. Indeed, for safety reasons, most airports assume a worst-case scenario and use conservative separations; the interval between aircraft taking off or landing therefore often amounts to several minutes. However, with the aid of accurate wind data and precise measurements of wake vortex by radar sensors, more efficient intervals can be set, particularly when weather conditions are stable. Depending on traffic volume, these adjustments can generate capacity gains, which have major commercial benefits. This paper presents Electronic scanning radar trials as Safety Net of a wake turbulence system supporting increased throughput as part of the European ATM research program SESAR, and complementary study UFO (Ultra-Fast wind sensOrs for wake-vortex hazards mitigation) funded by European FP7 program, on Radar EDR retrieval & Calibration.

In this paper a comb like microstrip patch antenna structure is proposed. This antenna has a total size of 100mm x 30mm x 1.6mm including ground plane which is fabricated using Fr-4 substrate with dielectric constant of 4.6. This is a hexa-band antenna structure as it has six operating frequency centred at 3 GHz, 4.3 GHz, 5.2 GHz, 8 GHz, 8.15 GHz, 8.5 GHz. Antenna parameters like return loss, directivity are shown in this paper. The designed antenna results are obtained using CST (Computer Simulation Technology) software. The aim of this antenna design is to achieve multiband applications and this antenna fulfil the requirement as it’s applications lies in three different frequency bands i.e. S band , C band and X band. This antenna is suitable for various wireless applications like radar, communication satellites. Index Terms – Multiband antenna, hexa-band antenna, CST, comb like structure.

Nearshore areas can be incredibly dynamic and therefore are difficult to monitor using traditional survey methods that typically provide only a snapshot of the physical conditions at the time of survey. These snapshot data are often re-used in the design of coastal defence interventions at a later date due to the high cost of data reacquisition over large areas. In this paper, a novel solution to large-area, continuous coastal monitoring is demonstrated. A shore-based radar station has been designed to collect image data within a 6 km range and derive a number of datasets including intertidal topography, subtidal bathymetry and surface currents. These data are then used in the development of beach management options to inform the Wyre Beach Management Outline Business Case which is currently being developed by Jacobs UK. At the time of writing, 10 weeks of data have been processed and have revealed the migration of sedimentary features along Rossall beach. Results derived using the radar system support anecdotal, previous scientific observations and modelled indications of sediment migration vectors, while revealing more detail on typical sediment fluxes along with system responses and recovery due to storm events. It is anticipated that this system will be the first of many permanent stations around the UK coastline, allowing a near-real time digital twin of the nearshore zone to be created and constantly updated. These datasets will form a crucial long-term evidence base for planning the most cost-effective coastal defence interventions and monitoring their effectiveness in response to variations in storminess, erosion and coastal squeeze being seen in the close vicinity of many vulnerable coastal areas.

Mapping the morphology of intertidal areas is a logistically challenging, time consuming and expensive task due to their large expanse and difficulties associated with access. A technique is presented here that uses standard marine navigational radar operating at X-band frequency. The method uses a series of time-exposure radar images over the course of a two-week tidal cycle to identify the elevation of the wetting and drying transitions at each pixel in the radar images, thereby building up a morphological map of the target intertidal area. This "Temporal Waterline" method is applied to a dataset acquired from Hilbre Island at the mouth of the Dee Estuary, UK, spanning March 2006 to January 2007. The radar gathered data with a radial range of 4 km and the resulting elevation maps describe the intertidal regions of that area. The results are compared with airborne LiDAR data surveyed over the same area and within the radar survey time period. The residual differences show good agreement across large areas of beach and sandbanks, with concentrations of poor estimations around points that are shadowed from the radar or likely to suffer from pooling water. This paper presents the theoretical framework of the method and demonstrates its stability and accuracy. The Temporal Waterline radar method is aimed at providing a useful tool for the monitoring and operational management of coastlines.

One goal of the Remote Sensing based Information and Insurance for Crops in emerging Economies (RIICE) project is to estimate, on an operational basis, rice production at national scale in primis targeted to food security and crop insurance purposes. There are two unique elements to this proposed service: 1. Multi-year, annual, and seasonal SAR data are acquired from all existing operational spaceborne systems are used and complemented by MODIS 250/500 m 16-/8-days composite data. This solution: − overcomes the spatial-temporal problem, hence assuring an appropriate temporal repetition at an adequate scale (i.e. spatial resolution) even over large areas; − provides sensor independent operational monitoring with sufficient data redundancy to ensure information delivery. 2. A crop growth simulation model estimates yield and hence production using dedicated remote sensing products in addition to the usual meteorological, soil, and plant parameters. This remote sensing-crop model approach to yield estimation: − uses relevant remote sensing derived information on rice phenology to initialize the model on the correct date; − uses remote sensing parameters as measurements of the crop's response to the environment and management thus reducing the reliance on other input data to the model that would impossible to obtain over wide geographic areas; − considers the spatial distribution of rice fields; − improves the yield estimation figures by forcing the model towards actual rather than attainable yields. Initial results and experiences gained in the past two years in seven Asian countries are presented and discussed. Index Terms-Synthetic Aperture Radar (SAR), Aqua and Terra MODIS, rice, cultivated area and extent, phenology, Leaf Area Index (LAI), yield.

Polycrystalline NiZn ferrites with the chemical formula (Ni 0.3 Zn 0.7) 1−x Me x Fe 2 O 4 where Me being Be or Cu and x=0.05, 0.1 and 0.25 have been prepared by a ceramic method. Certain magnetic properties such as the coercivity H c , initial permeability µ i , real part of the complex permeability µ' and saturation magnetization M s of the ferrites have been measured and discussed from the point of view of the substituting element type and contents as well as the average particle size.

Concerns about "emerging missile states" have spurred development of a system to defend the US from small-scale ballistic missile attacks. But the planned system could be compromised by simple countermeasures, and the security costs of deployment could be high.

− The X-band radar installed in Turin was used to analyze extreme events. About 3 years of radar maps have been analyzed in comparisons with about 30 years of measurements made by rain gauges located in the same area. The entire monitored area was divided into 4 subareas considering the complex orography near Turin, namely the flatlands, mountains, hills and urban areas. For each subarea, the Generalized Extreme Values (GEV) distributions are estimated considering rain gauges data and X-band radar maps. Radar maps are properly processed to be comparable with rain gauges measurements considering reference areas of different size centered over each available gauge. It is shown that a limited temporal availability of X-band radar maps can be sufficient to obtain a good GEV distribution estimation, and that X-band weather radars are a good instrument to analyze extreme rain events where a dense rain gauge network is not available.

Air flows in the troposphere have a major impact on air traffic safety and operations. By air flows, several phenomena can be distinguished with different spatial and temporal characteristic scales: the mean wind itself, its rapid fluctuations, called turbulence, and wake vortices which are structured motions generated by each aircraft. At low altitudes, during takeoff or landing phases, distance separations between aircrafts that limit today airport capacities were set up forty years ago to prevent the risk of wake vortices encounters in worst conditions. These out of date distance separations must be optimized since strength and lifetime of wake vortices vary a lot with weather conditions, like winds and turbulence. At high altitudes, during en-route flight phase, wake vortices as well as clear air turbulence can have a dramatic impact on aircraft safety. In this study, the way to measure wind, turbulence and wake vortices with new remote sensing techniques, 1.5 micron Coherent Doppler LIDAR, X-Band RADAR, and UV direct detection LIDAR, is detailed for ground-based or airborne applications. Sensor simulation tools and post-processing algorithms have been developed to retrieve wind, turbulence, especially EDR (eddy dissipation rate) and wake vortices parameters from sensors data and to assess their accuracy. Les mouvements d'air dans la troposphère ont un impact important sur la sécurité aérienne et le trafic aérien. Plusieurs mouvements d'air peuvent être distingués comme le vent moyen, les fluctuations rapides de vent, appelées turbulence ou encore les tourbillons de sillage générés par chaque avion en vol. A basses altitudes, durant les phases de décollage et d'atterrissage, les distances de séparation entre avions, qui limitent aujourd'hui les capacités des aéroports, ont été établies il y a quarante ans afin de réduire le risque de rencontres de tourbillons de sillage dans les conditions les plus défavorables. Ces régulations peuvent être optimisées puisque la dangerosité des tourbillons de sillage dépend des conditions météorologiques comme le vent et la turbulence. A hautes altitudes, les tourbillons de sillage, ainsi que les turbulences en air clair, peuvent avoir un impact dramatique sur la sécurité des vols. Dans cette étude, les méthodes de mesures du vent, de la turbulence et des tourbillons de sillage par de nouvelles technologies de télédétection active de type LIDAR Doppler cohérent 1.5micron, RADAR Doppler bande-X et LIDAR UV à détection directe seront détaillées. Pour chaque paramètre cible, les outils de simulation et les algorithmes de post-traitement développés seront présentés ainsi que les précisions obtenues.

This study presents a comprehensive simulation of a compact shared aperture antenna designed for dual S- and X-band operation. The antenna, measuring 82 by 82 mm and standing at a mere 4 mm in height, is specifically engineered to meet the stringent size constraints of nano-satellite units. Demonstrating right-hand circular polarization in both frequency bands, it covers a frequency range of 2.025 to 2.075 GHz for S-band and 7.75 to 8.75 GHz for X-band. Remarkably, the design achieves a realized right-hand circularly polarized gain of 6 dB in the S-band and an impressive 12 dB in the X-band. Notably, the antenna offers a wide impedance bandwidth, surpassing the chosen frequency ranges. Moreover, it exhibits minimal cross-coupling, with values below -25 dB in the S-band and below -30 dB in the selected X-band frequency range. This antenna design holds significant promise for space communication systems on nano-satellites. Index Terms—Antenna design, Dual-band, S-band, X-band,Circular Polarisation, Simulation.

The first weather radar campaign over Lima, the capital of Peru, a desertic area on the western side of the Peruvian Andes, was carried out to study the occurrence of rain events in summer 2018. The weather radar was installed strategically and was able to overlook three river basins: Rimac, Chillón, and Lurin. An X-band radar (PX-10 0 0) was used, which operates at 9.55 GHz. PX-10 0 0 was built by the Advanced Radar Research Center (ARRC) at the University of Oklahoma (U.S.A.). The radar operated from January 26th to April 1st, 2018, at Cerro Suche located 2910 m ASL and 55 km from the city of Lima. The PX-10 0 0 performed plan-positionindicators (PPI) for elevations starting at 0 °up to 20 °. The data presented here were obtained using a three-dimensional constant-altitude plan-position-indicator (3D CAPPI), which was generated by high resolution (250 m) nearest point algorithm.

Cork is a renewable and sustainable material, highly porous and lightweight. We valorised waste cork and recycled wine stoppers to make pyrolysed/carbonised solid cork, for use as economic and sustainable microwave (MW) absorbers at the microwave X-band (8-12 GHz), without binder or additives. Although cork is already a very lightweight material (0.16 g cm −3), the pyrolysed cork is five-times less dense at 0.031 g cm −3 , was amorphous graphitic carbon, and had an excellent shielding effectiveness (SE T) of −18 to −38 dB, depending on thickness, with attenuation of the electromagnetic energy through internal reflection within the cellular cork structure. Furthermore, this ultra-lightweight material has an extremely high MW specific shielding effectiveness or efficiency (SSE), between −640 to −1235 dB g −1 cm 3 over the entire X-band range, depending on thickness (3.0-8.6 mm), one of the highest reported for any pure carbon material, this upper value being more than twice that of any previously reported graphite-based foams.

Microstrip patch antenna is a low profile antenna that is capable of maintaining high performance over a wide spectrum of frequencies. In this paper the practical and experimental results obtained from the design, construction and test of an array circularmicrostrip patch antenna were discussed. The aim was to obtain a gain of 12dB, an acce pattern and a reasonable reflection coefficient cavity model was applied to analyze the patch and proper combination of the formulae; ADS2000 and MATLAB 2013 softwares were used. The array includes four circular elements made of aluminum with equal sizes, equal spacing and was grown on a resin substrate, with insect feed techniques. Comparison between practical results and the results obtained from the simulation shows that we reach our goals by a great degree of validity.

Recent studies have highlighted the need for high resolution rainfall measurements for better modelling of urban and peri-urban catchment responses. In this work, we used a fully-distributed model called “Multi-Hydro” to study small-scale rainfall variability and its hydrological impacts. The catchment modelled is a semi-urban area located in the southwest region of Paris, an area that has been previously partially validated. At this time, we make some changes to the model, henceforth using its drainage system globally, and we investigate the influence of small-scale rainfall variability by modelling three rainfall events with two different rainfall data inputs: the C-band radar data provided by Météo-France at a 1 km × 1 km × 5 min resolution, and the new X-band radar (recently installed at Ecole des Ponts, France) data at a resolution of 250 m × 250 m × 3.41 min, thereby presenting the gains of better resolution (with the help of Universal Multifractals). Finally, we compare the M...

A new algorithm is proposed, called the stream function method (SFM) for producing vector current maps from radial data measured by dual-site high frequency surface wave radar (HFSWR). In SFM, a scalar stream function is constructed under some oceanographic assumptions. The function describes the two-dimensional (2-D) ocean surface water motion and is used to obtain the distribution of vector currents. The performance of SFM is evaluated using simulated radial data, which demonstrates that SFM has advantages over typical vectorial combination methods (VCM) both in error acceptance and robustness, and excels another method based on least-squares fitting (LSF) in recovering the complicated current models. Furthermore, SFM is capable of providing the total currents based on radials from single-site radar. We also test the assumptions of horizontal non-divergence in the simulation. The new algorithm is applied to the field experiment data of Wuhan University's ocean state measuring and analyzing radar (OSMAR), collected in the coastal East China Sea during April 11-17, 2004. Quantitative comparisons are given between radar results by three current algorithms and in-situ current meter measurements. Preliminary analysis of the vertical current shear is given based on the current meter measurements.

Web cameras are transforming coastal environmental monitoring. Improvements in camera technology and image processing capabilities, paired with decreases in cost, enable widespread use of camera systems by researchers, managers and first responders for a growing range of environmental monitoring applications. Applications are related to transportation and commerce, preparedness, risk reduction and response, and stewardship of coastal resources. While web cameras are seemingly ubiquitous, operators often follow unique installation procedures and collect, store, and process imagery data in various ways. These inconsistencies significantly limit the ability for imagery data to be shared and utilized across research and operational disciplines. Similar to the early days of other remote sensing networks like High Frequency Radar, the benefits and downstream application of coastal imagery data can be greatly enhanced through centralized data access and standardization of data collection, analysis and dissemination. The NOAA National Ocean Service Web Camera Applications Testbed (WebCAT) was launched in 2017 in partnership with SECOORA, as a public-private partnership to address this coastal ocean observing standardization need. WebCAT is a pilot project relying on the private sector expertise of Surfline, Inc., to install and operate several web cameras capable of meeting the short-term needs of diverse users including NOAA, USGS, state health agencies, academia and others. The project aims to determine operational imagery collection, storage, processing, access, and archival requirements that will foster collaboration across research and operational user communities. Seven web cameras have been installed at six locations along the southeast United States coast (from Florida to North Carolina) for purposes including: counting animals on the beach and migrating right whales, identifying rip currents, validating wave runup models, and understanding human use of natural resources. Here we present a review of the state of coastal imagery data and an overview of the WebCAT project. Goals of an upcoming community workshop will also be presented along with our vision for how WebCAT can motivate a future sustained operational web camera network.

Air flows in the troposphere have a major impact on air traffic safety and operations. By air flows, several phenomena can be distinguished with different spatial and temporal characteristic scales: the mean wind itself, its rapid fluctuations, called turbulence, and wake vortices which are structured motions generated by each aircraft. At low altitudes, during takeoff or landing phases, distance separations between aircrafts that limit today airport capacities were set up forty years ago to prevent the risk of wake vortices encounters in worst conditions. These out of date distance separations must be optimized since strength and lifetime of wake vortices vary a lot with weather conditions, like winds and turbulence. At high altitudes, during en-route flight phase, wake vortices as well as clear air turbulence can have a dramatic impact on aircraft safety. In this study, the way to measure wind, turbulence and wake vortices with new remote sensing techniques, 1.5 micron Coherent Doppler LIDAR, X-Band RADAR, and UV direct detection LIDAR, is detailed for ground-based or airborne applications. Sensor simulation tools and post-processing algorithms have been developed to retrieve wind, turbulence, especially EDR (eddy dissipation rate) and wake vortices parameters from sensors data and to assess their accuracy. Les mouvements d'air dans la troposphère ont un impact important sur la sécurité aérienne et le trafic aérien. Plusieurs mouvements d'air peuvent être distingués comme le vent moyen, les fluctuations rapides de vent, appelées turbulence ou encore les tourbillons de sillage générés par chaque avion en vol. A basses altitudes, durant les phases de décollage et d'atterrissage, les distances de séparation entre avions, qui limitent aujourd'hui les capacités des aéroports, ont été établies il y a quarante ans afin de réduire le risque de rencontres de tourbillons de sillage dans les conditions les plus défavorables. Ces régulations peuvent être optimisées puisque la dangerosité des tourbillons de sillage dépend des conditions météorologiques comme le vent et la turbulence. A hautes altitudes, les tourbillons de sillage, ainsi que les turbulences en air clair, peuvent avoir un impact dramatique sur la sécurité des vols. Dans cette étude, les méthodes de mesures du vent, de la turbulence et des tourbillons de sillage par de nouvelles technologies de télédétection active de type LIDAR Doppler cohérent 1.5micron, RADAR Doppler bande-X et LIDAR UV à détection directe seront détaillées. Pour chaque paramètre cible, les outils de simulation et les algorithmes de post-traitement développés seront présentés ainsi que les précisions obtenues.

The objective of this study is to provide complete information on the dynamic relationship between X-band (3.11 cm) backscattering intensity (σ°) and rice crop’s leaf area index (LAI) at all growth phases. Though the relationship between X-band σ° and LAI has been previously explored, details on the relationship at the reproductive phase remain unstudied. LAI at the reproductive phase is important particularly at the heading stage where LAI reaches its maximum as it is closely related to grain yield, and at flowering stage where the total leaf area affects the amount of photosynthates. Therefore, this study examined the relationship of increasing LAI (vegetative to reproductive phase) and decreasing LAI (ripening phase) with TerraSAR-X (TSX) ScanSAR (3.11 cm) σ° at HH polarisation and 45° incidence angle. The results showed a statistically significant (R2 = 0.51, p value < 0.001) non-linear relationship of LAI with σ° at the vegetative to reproductive phase while no significant l...

The ephemeral nature of marine oil and gas seepages and their complex trajectories in the water column make seep sampling difficult and costly. Here we report on how active natural seepage can be detected and located in the water column and at the sea bed in real time through the integration of marine X-band radar, synthetic aperture radar, field observations, high resolution single beam acoustic methods, and meta-ocean data from the marine environment with a simple bubble rise model. The extent of predictions made using a bubble rise model narrow down the likely seafloor origin point of an observed surface feature to within a radius of 630 m within which clusters of acoustic contacts were detected. Use of averaged deep current velocities and directions narrows the radius to 130 m, and use of a smaller established range of bubble rise speeds from the Gulf of Mexico can narrow the predicted seafloor origin radius further to 16.5 m. These results are useful for focussing detailed sea bed search patterns for natural seepage and are also suggestive of a seep system with complex water column trajectories associated with Biloxi Dome in the Gulf of Mexico.

Dual-polarized probe systems can be used with some of the advantages: the two electric field components are simultaneously measured within a single scan, amplitude and phase drift affects the two polarization components in the same way, and there is no need for mechanical rotation of the probe. In this work we design and test a dual-polarized probe system at 60 GHz a conical horn, including the elements: SPDT (single pole double throw) switch, an OMT (orthomode transducer) both components with 40 dB isolation a square to circular transition (3.75 mm to 3.58 mm), cables and two coaxial to waveguide adapters up to 67 GHz for OMT-switch connection. A 27 dBi gain conical horn is designed by using WIPL-D software and in-house manufactured. The 60 GHz probe system is being assembled and tested in planar near-field (PNF) setup at DTU. The results are validated by comparison with WIPL-D simulations, showing a good agreement within the validity region, down to -30 dB pattern levels. Channel ...

When waves propagate in coastal areas at depths lower than one half the wavelength, they exhibit a different signature at the sea surface and the observed wavelength pattern enables inferring bathymetries. Commonly, a spectral analysis using the fast Fourier transform (FFT) is employed to derive wavelength and wave direction of swell waves, in nearshore regions. Nevertheless, it is recognized that this method presents limitations, particularly regarding depth inversion limits that do not allow obtaining bathymetric data close to the shoreline. This work explores a wavelet spectral analysis to obtain bathymetric data. This new imaging methodology is applied over different seafloors with 2D and 3D features such as longshore bars or headlands. The synthetic images of the water surface are generated from a numerical Boussinesq-type model that simulates the propagation of both regular and irregular waves. The spectral analysis is carried to estimate the water depths, which are validated ...

When waves propagate in coastal areas at depths lower than one half the wavelength, they exhibit a different signature at the sea surface and the observed wavelength pattern enables inferring bathymetries. Commonly, a spectral analysis using the fast Fourier transform (FFT) is employed to derive wavelength and wave direction of swell waves, in nearshore regions. Nevertheless, it is recognized that this method presents limitations, particularly regarding depth inversion limits that do not allow obtaining bathymetric data close to the shoreline. This work explores a wavelet spectral analysis to obtain bathymetric data. This new imaging methodology is applied over different seafloors with 2D and 3D features such as longshore bars or headlands. The synthetic images of the water surface are generated from a numerical Boussinesq-type model that simulates the propagation of both regular and irregular waves. The spectral analysis is carried to estimate the water depths, which are validated ...

Coasts are continually changing and remote sensing from satellite has the potential to both map and monitor coastal change at multiple scales. This study aims to assess the application of shorelines extracted from Multi-Spectral Imagery (MSI) and Synthetic Aperture Radar (SAR) from publicly available satellite imagery to map and capture sub-annual to inter-annual shoreline variability. This is assessed at three macro-tidal study sites along the coastline of England, United Kingdom (UK): estuarine, soft cliff environment, and gravel pocket-beach. We have assessed the accuracy of MSI-derived lines against ground truth datum tideline data and found that the satellite derived lines have the tendency to be lower (seaward) on the Digital Elevation Model than the datum-tideline. We have also compared the metric of change derived from SAR lines differentiating between ascending and descending orbits. The spatial and temporal characteristics extracted from SAR lines via Principal Component A...

The first weather radar campaign over Lima, the capital of Peru, a desertic area on the western side of the Peruvian Andes, was carried out to study the occurrence of rain events in summer 2018. The weather radar was installed strategically and was able to overlook three river basins: Rimac, Chillón, and Lurin. An X-band radar (PX-10 0 0) was used, which operates at 9.55 GHz. PX-10 0 0 was built by the Advanced Radar Research Center (ARRC) at the University of Oklahoma (U.S.A.). The radar operated from January 26th to April 1st, 2018, at Cerro Suche located 2910 m ASL and 55 km from the city of Lima. The PX-10 0 0 performed plan-positionindicators (PPI) for elevations starting at 0 °up to 20 °. The data presented here were obtained using a three-dimensional constant-altitude plan-position-indicator (3D CAPPI), which was generated by high resolution (250 m) nearest point algorithm.

The effects of different BiFeO 3 (BFO) additions (0, 20, 40, 60 and 80 wt%) on the SrFe 12 O 19 hexaferrite ceramic matrix (SFO) have been studied by Complex Impedance Spectroscopy (CIS), M€ ossbauer spectroscopy, magnetic hysteresis and X-Ray Diffraction (XRD) analysis. The solid state reaction method was used for the production of the SFO and BFO, the phase formation was confirmed by the XRD and Rietveld refinement, where the obtained fitting presented an effective refinement. The diffractogram for BFO-SFO composites presented all peaks in agreement with the BFO and SFO phases. The thermo-activated process was studied by the CIS and the Arrhenius equation in the composite series of BFO-SFO with SFO presenting higher values of activation energy between the analyzed samples and the frequency and temperature range studied was 1e10 MHz and 160 C to 300 C, respectively. The addition of BFO in the SFO ceramic matrix lead to an improvement of the thermal-stability of the composite, where a signal inversion of Temperature Coefficient of Capacitance (TCC), in the composites, was observed. The Nyquist plots showed the presence of a semicircle that was fitted by an equivalent circuit model using R-CPE association, showing the same profile in all samples. The M€ ossbauer spectrum of the composites demonstrate the typical five Fe 3þ site for M-type hexagonal ferrites even after the addition of BFO in a ceramic matrix. The addition of BFO in the formation of composites, with SFO, showed interesting results in the radio frequency range and presented magnetic properties that can be explored in applications in the area of telecommunications, medicine and military industry.

A new algorithm is proposed, called the stream function method (SFM) for producing vector current maps from radial data measured by dual-site high frequency surface wave radar (HFSWR). In SFM, a scalar stream function is constructed under some oceanographic assumptions. The function describes the two-dimensional (2-D) ocean surface water motion and is used to obtain the distribution of vector currents. The performance of SFM is evaluated using simulated radial data, which demonstrates that SFM has advantages over typical vectorial combination methods (VCM) both in error acceptance and robustness, and excels another method based on least-squares fitting (LSF) in recovering the complicated current models. Furthermore, SFM is capable of providing the total currents based on radials from single-site radar. We also test the assumptions of horizontal non-divergence in the simulation. The new algorithm is applied to the field experiment data of Wuhan University's ocean state measuring and analyzing radar (OSMAR), collected in the coastal East China Sea during April 11-17, 2004. Quantitative comparisons are given between radar results by three current algorithms and in-situ current meter measurements. Preliminary analysis of the vertical current shear is given based on the current meter measurements.

In this article we present the visualization of NEXRAD reflectivity data by means of first-order (bilinear) interpolation. We provide the comparison of the raw and interpolated data with the corresponding values obtained from TropiNet radar for weather events occurred in Puerto Rico. The analysis of the relative error of the interpolated data confirms that bilinear interpolation gives better reflectivity estimates than nearest-neighbor interpolation. The efficiency of the bilinear interpolation algorithm makes it suitable for real-time radar data visualization.

In this paper, a new flower-shaped microstrip line feed reconfigurable band-notched UWB monopole antenna using single varactor diode is introduced and fabricated. Different notch frequencies can be obtained using different capacitance values. The effect of changing the varactor position is also examined. The flower shape is first optimized to obtain UWB characteristics. Then, a slot is made in the microstrip line to be loaded later with a single varactor diode. A wide range of notch frequencies can be obtained using this simple configuration which covers most of the narrow band coexistence systems. The notch frequency can be lower by increasing the capacitance value. The notch frequency covers the WLAN band when C = 0.8 pF and covers the WiMAX band when the capacitance is changed to 0.7 pF for the same antenna configuration and varactor position. Two prototypes of the proposed antenna using two different single capacitor elements with capacitances 0.6 pF and 1.5 pF are fabricated, and their reflection characteristics are measured and compared with the simulated ones. Notch frequencies at 6.1 GHz and 4.3 GHz are obtained respectively in both simulated and measured antenna structures. The proposed antenna has a directive radiation pattern in E-plane and omnidirectional pattern in Hplane. Also, the gain is suppressed in the notched frequencies. The group delay is nearly stable in the UWB frequency range with very little variations, but it is distorted sharply at the notch frequencies. So, the proposed antenna is a good candidate for the modern UWB systems.

Comparative corrosion inhibition of mild steel in 0.5 H 2 SO 4 by the total alkaloids and tannins extracted from Parkia biglobosa seed bark and Jatropha curcas stem bark was investigated using gravimetric method at 30 0 C. Results showed that these phytocompounds inhibit the corrosion process of mild steel in the test solution and the inhibition efficiency depends on the concentration of the alkaloids and tannins as well as the exposure time. Their adsorption was found to obey the Temkin and Langmuir adsorption isotherms and this suggested that the inhibitor molecules have been spontaneously adsorbed onto the surface of mild steel through a physical adsorption mechanism. The inhibition efficiency is markedly higher in addition of alkaloid extracts when compared with that of tannins extracts. The inhibition efficiency increased with an increase of inhibitor concentration but decreased with exposure time.

TerraSAR-X is the first German Radar satellite for scientific and commercial applications. The project is a publicprivate partnership between DLR and EADS Astrium GmbH. TerraSAR-X consists of a high resolution Synthetic Aperture Radar at X-Band. The radar antenna is based on active phased array technology that allows the control of many different instrument parameters and operational modes (Stripmap, ScanSAR and Spotlight) with various polarizations. Following the TerraSAR-X launch, it is planned a six month Commissioning Phase covering the characterization and verification of the SAR mission. Within this phase, the Overall SAR System Performance takes care of the correct working and interaction of all SAR system elements essential for obtaining an optimum SAR Performance. The paper covers the first in-orbit characterization and verification results of the SAR system performance for TerraSAR-X operational and experimental modes. This characterization is divided into four phases: Initial Characterization, Scene Characterization-both mostly based on basic and experimental products-, and Verification of TerraSAR-X Instrument Command Generation. The different optimization strategies and performance trade-offs are investigated and discussed, including very first TerraSAR-X images. The result of the real SAR data analysis determines the final system baseline and thus the final image quality, e.g. Temperature compensation, Total Zero Doppler Steering, Up/down chirp toggling, transmitted bandwidth, timing interferences, etc.

The objective of the EuroROSE (European Radar Ocean Sensing) project was to combine area covering ground-based remote-sensed wave and current data with high-resolution numerical forecast models to provide nowcasts and forecasts for coastal marine operators. Two experiments to test and to demonstrate the system took place: one on the coast of Norway, north of Bergen in March 2000 and the second on the north coast of Spain at Gijon in October-November 2000. Qualitative and quantitative intercomparisons of the wave measurements and wave model products from these experiments are presented. These include measurements using the Wellen Radar (WERA) high-frequency (HF) radar, the WaMoS (Wave Monitoring System) Xband radar, a directional Waverider and output from the WAM wave model. Comparisons are made of the full directional spectra and of various derived parameters. This is the first-ever intercomparison between HF and X-band radar wave measurements and between either of these and WAM. It has provided a data set covering a much wider range of storm and swell conditions than had been available previously for radar wave-measurement validation purposes and has clarified a number of limitations of the radars as well as providing a lot of very useful radar wave data for future model-validation applications. The intercomparison has led to improvements in the data quality control procedures of both WaMoS and WERA. The two radar sytems measured significant wave height with mean biases of 3% and 6%, respectively, and mean direction differences of less than 2j in both cases. Limitations in the WAM model implementation are also discussed.

TerraSAR-X is the first German Radar satellite for scientific and commercial applications. The project is a publicprivate partnership between DLR and EADS Astrium GmbH. TerraSAR-X consists of a high resolution Synthetic Aperture Radar at X-Band. The radar antenna is based on active phased array technology that allows the control of many different instrument parameters and operational modes (Stripmap, ScanSAR and Spotlight) with various polarizations. Following the TerraSAR-X launch, it is planned a six month Commissioning Phase covering the characterization and verification of the SAR mission. Within this phase, the Overall SAR System Performance takes care of the correct working and interaction of all SAR system elements essential for obtaining an optimum SAR Performance. The paper covers the first in-orbit characterization and verification results of the SAR system performance for TerraSAR-X operational and experimental modes. This characterization is divided into four phases: Initial Characterization, Scene Characterization-both mostly based on basic and experimental products-, and Verification of TerraSAR-X Instrument Command Generation. The different optimization strategies and performance trade-offs are investigated and discussed, including very first TerraSAR-X images. The result of the real SAR data analysis determines the final system baseline and thus the final image quality, e.g. Temperature compensation, Total Zero Doppler Steering, Up/down chirp toggling, transmitted bandwidth, timing interferences, etc.

Although large amplitude ocean internal waves (IWs) may induce strong underwater currents and cause a severe threat to offshore drilling platforms, little research attention has been paid to the issue. This paper proposes a method for estimating the force and torque exerted by ocean IWs on a submerged vertical cylindrical pile using nautical X-band radar observations (collected by standard ship equipment) and in-situ buoyancy frequency data. Radar image signatures associated with IWs will be used to infer characteristics of the interior ocean dynamics. The nonlinear velocities of IWs are retrieved based on the use of the Radon Transform technique applied to the radar images. Given the vertical distributions of buoyancy frequency, the amplitudes of IWs are determined based on the Korteweg-de Vries (K-dV) equation for a continuous stratified finite-depth system. With the above parameters, the horizontal velocities induced by IWs and their acceleration can be calculated. Finally, the forces and torques exerted by IWs acting on a pile are estimated using Morison's empirical formula. As an example, the method is applied to data acquired on June 2009 in the northeastern South China Sea.

The ephemeral nature of marine oil and gas seepages and their complex trajectories in the water column make seep sampling difficult and costly. Here we report on how active natural seepage can be detected and located in the water column and at the sea bed in real time through the integration of marine X-band radar, synthetic aperture radar, field observations, high resolution single beam acoustic methods, and meta-ocean data from the marine environment with a simple bubble rise model. The extent of predictions made using a bubble rise model narrow down the likely seafloor origin point of an observed surface feature to within a radius of 630 m within which clusters of acoustic contacts were detected. Use of averaged deep current velocities and directions narrows the radius to 130 m, and use of a smaller established range of bubble rise speeds from the Gulf of Mexico can narrow the predicted seafloor origin radius further to 16.5 m. These results are useful for focussing detailed sea bed search patterns for natural seepage and are also suggestive of a seep system with complex water column trajectories associated with Biloxi Dome in the Gulf of Mexico.

Triple band-rejection MIMO/Diversity UWB antenna characteristics are described in this paper. Proposed antenna discards worldwide interoperability for microwave access WiMAX band from 3.3 to 3.6 GHz, wireless local area network WLAN band from 5 to 6 GHz and X-Band satellite downlink communication band from 7.1 to 7.9 GHz. Mushroom Electromagnetic Band Gap (EBG) structures helps to attain band notches in WiMAX and WLAN bands. Uniplanar plus shaped EBG structure is used for notch in X-band downlink satellite communication band. Decoupling strips and slotted ground plane are employed to develop the isolation amongst two closely spaced UWB monopoles. The individual monopoles are 90 angularly separated with stepped structure which helps to reduce mutual coupling and also contributes towards impedance matching by increasing current path length. Mutual coupling magnitude of more than 15 dB is found over whole UWB frequency range. The Envelope Correlation Coefficient is less than 0.02 over whole UWB frequency range.The variations in the notched frequency with the variations in mushroom EBG structure parameters are investigated.The antenna has been designed using FR-4 substrate and overall dimensions is (64 45 1.6 ) mm 3 .

A triple band notch MIMO/Diversity antenna using Inductance Boosted Compact Electromagnetic Band Gap (IB-CEBG) cells is presented in this paper. For obtaining compactness in the conventional EBG cell, spiral shaped defects are introduced. The proposed antenna obtains triple band notches in WiMAX (3.3–3.6 GHz), WLAN (5–6 GHz), and the X-band satellite communication (7.2–8.4 GHz) bands. IB-CEBG cells exhibits miniaturization of approximately 46% for WiMAX band, 50% for WLAN band and 48% for X-band Satellite communication band, compared to conventional EBG cells. To enhance the isolation among all four compact UWB monopoles, rectangular slots in the ground plane and parasitic decoupling arrangement are utilised. Further, a stepped structure with an angular separation of 90◦ is incorporated with individual monopoles to reduce mutual coupling effects. Stepped structure also helps in the better impedance matching by incrementing the path length. The results show that the magnitude of tran...

The objective of this study is to provide complete information on the dynamic relationship between X-band (3.11 cm) backscattering intensity (σ°) and rice crop’s leaf area index (LAI) at all growth phases. Though the relationship between X-band σ° and LAI has been previously explored, details on the relationship at the reproductive phase remain unstudied. LAI at the reproductive phase is important particularly at the heading stage where LAI reaches its maximum as it is closely related to grain yield, and at flowering stage where the total leaf area affects the amount of photosynthates. Therefore, this study examined the relationship of increasing LAI (vegetative to reproductive phase) and decreasing LAI (ripening phase) with TerraSAR-X (TSX) ScanSAR (3.11 cm) σ° at HH polarisation and 45° incidence angle. The results showed a statistically significant (R2 = 0.51, p value < 0.001) non-linear relationship of LAI with σ° at the vegetative to reproductive phase while no significant l...

In this paper, a loop antenna loaded with coplanar strip (CPS) line is proposed as a multiband antenna. The CPS line is added with two switches to vary the antenna perimeter to cover seven different bands. The CPS line introduced into the loop is not only useful in reconfiguring antenna dimensions but also provides stationary radiation patterns for the all the covered bands. The proposed antenna works in single and dual-band modes. When the proposed antenna works as a single band antenna, it produces a band from 4.2GHz to 5.7GHz. Under dual-band operation, it produces bands from 3.75GHz to 4.7GHz and from 6.4GHz to 7.8GHz. The other dual-band mode ranges from 3.5GHz to 3.8GHz and from 5.58GHz to 7.4 GHz. The simulated and measured results are in good agreement and the proposed antenna can be used satisfactorily for W-LAN and WiMax applications. The proposed technique can also be used for size reduction of loop antennas.

A new algorithm is proposed, called the stream function method (SFM) for producing vector current maps from radial data measured by dual-site high frequency surface wave radar (HFSWR). In SFM, a scalar stream function is constructed under some oceanographic assumptions. The function describes the two-dimensional (2-D) ocean surface water motion and is used to obtain the distribution of vector currents. The performance of SFM is evaluated using simulated radial data, which demonstrates that SFM has advantages over typical vectorial combination methods (VCM) both in error acceptance and robustness, and excels another method based on least-squares fitting (LSF) in recovering the complicated current models. Furthermore, SFM is capable of providing the total currents based on radials from single-site radar. We also test the assumptions of horizontal non-divergence in the simulation. The new algorithm is applied to the field experiment data of Wuhan University's ocean state measuring and analyzing radar (OSMAR), collected in the coastal East China Sea during April 11-17, 2004. Quantitative comparisons are given between radar results by three current algorithms and in-situ current meter measurements. Preliminary analysis of the vertical current shear is given based on the current meter measurements. Typically, one radar provides a radial current map and HF current measurement systems usually employ two or more sites situated tens of kilometers apart, allowing a vector current solution to be obtained by combining measurements from the respective sites . gave a vectorial combination method for dual-site radar, called VCM in this paper. The radials from two radars are linearly interpolated to a common grid and combined directly to get the vector current field. However, the calculation of one velocity component becomes unstable along the baseline or at large distances from the sites, where both sites measure the same radial component; the transverse component cannot be constrained. The analysis of also showed that the probability distribution of measurement error of the current vector depended on the azimuthal difference of the two radar beams. When the azimuthal difference is smaller than 45° or larger than 135°, the measurement errors of the current vector are much larger than when the azimuthal difference ranges from 45 to 135°. These instabilities are inherent shortcomings of radial measurement in that radial errors are amplified by VCM. The radio wave propagation laboratory (RPL) of Wuhan University, China has been developing the HF radar system OSMAR since 1997. reported the VCM measurements by * * * *

Este trabajo propone un sistema de detección basado en radar para calcular las orillas de un rio usando procesamiento de imágenes. El sistema estima orillas sin pérdida apreciable en resolución evitando costos asociados con batimetrías y/o imágenes satelitales. El sistema está compuesto por un radar comercial, un GPS, y un sensor de rumbo que se comunican a un nodo central que georrefencia las mediciones del radar y ejecuta los algoritmos de procesamiento de imágenes. El hardware se basa en un FPGA para interactuar con la señalización interna del radar y extraer la información requerida. El nodo central implementa un novedoso modelo para georreferenciar las mediciones en coordenadas WSG-84. Posteriormente, un algoritmo de tipo “seam-carving” se aplica sobre las coordenadas estimadas para crear las orillas basándose en la probabilidad de la medición. El sistema se valida usando información oficial, y los resultados muestran un ECP de hasta 6 m.

The objective of this study is to provide complete information on the dynamic relationship between X-band (3.11 cm) backscattering intensity (σ°) and rice crop’s leaf area index (LAI) at all growth phases. Though the relationship between X-band σ° and LAI has been previously explored, details on the relationship at the reproductive phase remain unstudied. LAI at the reproductive phase is important particularly at the heading stage where LAI reaches its maximum as it is closely related to grain yield, and at flowering stage where the total leaf area affects the amount of photosynthates. Therefore, this study examined the relationship of increasing LAI (vegetative to reproductive phase) and decreasing LAI (ripening phase) with TerraSAR-X (TSX) ScanSAR (3.11 cm) σ° at HH polarisation and 45° incidence angle. The results showed a statistically significant (R2 = 0.51, p value < 0.001) non-linear relationship of LAI with σ° at the vegetative to reproductive phase while no significant l...