C band

The National Aeronautics and Space Administration (NASA) Soil Moisture Active Passive (SMAP) mission was launched on 31st January 2015, with the aim of providing global soil moisture maps at 9 km spatial resolution by combining L-band radar and radiometer observations. However, after the SMAP radar became inoperable, NASA decided to utilize the Sentinel 1A/1B C-band SAR data in its place. The new version of baseline brightness temperature (Tb) downscaling algorithm for SMAP is tested using L-band airborne data to evaluate the capabilities of the C-band Sentinel-1A SAR relative to L-band radar data in downscaling the SMAP Tb for achieving high resolution brightness temperature. In this study, the downscaling algorithm used L-band airborne Synthetic Aperture Radar (SAR) backscatter (σ) collected from the fifth Soil Moisture Active Passive Experiment (SMAPEx-5) in south-eastern Australia to downscale 36 km L-band SMAP radiometer Tb pixels to 3 km and 9 km. The downscaling results were then compared with the published results using Sentinel-1A C-band backscatter, and evaluated against airborne 1 km resolution L-band passive microwave brightness temperature collected from SMAPEx-5. The results show that for vertical polarization the average Root Mean Square Error (RMSE) of downscaled Tb when compared with reference airborne Tb across 4 days at 9 km resolution were 4.9 K for Lband and 6.0 K for C-band, and increased to 9.3 K for L-band and 9.6 K for C-band at 3 km spatial resolution. Moreover, the correlation coefficient (R) of downscaled and reference Tb across the 4 days was 0.92 for L-band and 0.88 for C-band at 9 km, decreasing to 0.75 for L-band and 0.72 for C-band at 3 km spatial resolution. Accordingly, the RMSE increased and the correlation coefficient decreased when using C-band radar data in place of that at L-band. However, overall there is expected to be only a slight decrease in performance of the downscaling algorithm by using the Sentinel 1A data in place of the SMAP radar.

Wideband circularly polarized (CP) cross-dipole antennas with flat, cavity and artificial magnetic conductor (AMC) reflectors are proposed. Each proposed antenna consists of a pair of driven dipoles, a pair of vacant-quarter printed rings, and a 50Ω coaxial probe. The boomerang shape has been adopted in the crossed-dipole. This shape makes the design more compact, so it can be a good candidate in the antenna array because of reducing the mutual coupling. All numerical simulation works have been done using the ANSYS electromagnetic (EM) software based on the finite element method (FEM) algorithm. The presented crossed-dipole with a cavity has the best performance compared to ones with conventional flat and AMC grounds. However, the crossed-dipole with the AMC ground is a low-profile structure. Thus, the paper investigates and discusses the results of the proposed strctures thoroughly. The obtained impedance bandwidth (IBW) is 42% (5.1 7.85 GHz) and the axial-ratio bandwidth (ARBW) is 7.72% (5.86-6.32 GHz) for the crossed-dipole with the conventional flat ground (i.e., reflector). Furthermore, the IBW and ARBW for the antenna with the cavity reflector are 50.37% (5.08-8.5 GHz) and 26.4% (5.72-7.46 GHz), respectively. The antenna with the AMC ground has the characterstics of the IBW and ARBW as 38.16% (5.36-7.89 GHz) and 15.16% (5.79-6.74 GHz), respectively. All structures are designed to operate for the C-band and wireless local area networks (WLAN) applications.

The study outlined the soliton pulse order effects on the performance efficiency of the optical transceiver systems. The power after fiber is reported for various Soliton pulse order. Max optical signal power (SP) and min optical noise power (NP) are clarified versus time after optical fiber for various soliton pulse order. As well as the max electrical power amplitude against time period is demonstrated after electrical filter for various soliton pulse order. It is reported that the optical transceiver performance efficiency can be upgraded with the first soliton order pulse. The soliton technique is used for high speed communication transmission systems. Soliton technique is used to compensate the dispersion and balanced with nonlinear effects. The soliton order effects is then discussed to choose the suitable soliton order for high speed system performance efficiency. The soliton techniques can be used also for extended ultra high transmion distance with high data rates.

Abstract. Satellites carrying X-band Synthetic Aperture Radars (SAR) have recently been launched by several countries. These provide new opportunities to measure precipitation with higher spatial resolution than has heretofore been possible. Two algorithms to retrieve precipitation from such measurements over land have been developed, and the retrieved rainfall distributions were found to be consistent. A maritime rainfall distribution obtained from dual frequency (X and C-band) data was used to compute the Differential Polarized Phase Shift. The computed Differential Polarized Phase Shift compared well with the value measured from space. Finally, we show a comparison between a recent X-band SAR image of a precipitation distribution and an observation of the same rainfall from ground-based operational weather radar. Although no quantitative comparison of retrieved and conventional rainfall distributions could be made with the available data at this time, the results presented here p...

This paper presents a technique developed for the retrieval of the orientation of crop rows, over anthropic lands dedicated to agriculture in order to further improve estimate of crop production and soil erosion management. Five crop types are considered: wheat, barley, rapeseed, sunflower, corn and hemp. The study is part of the multi-sensor crop-monitoring experiment, conducted in 2010 throughout the agricultural season (MCM'10) over an area located in southwestern France, near Toulouse. The proposed methodology is based on the use of satellite images acquired by Formosat-2, at high spatial resolution in panchromatic and multispectral modes (with spatial resolution of 2 and 8 m, respectively). Orientations are derived and evaluated for each image and for each plot, using directional spatial filters (45°and 135°) and mathematical morphology algorithms. ''Single-date'' and ''multi-temporal'' approaches are considered. The single-date analyses confirm the good performances of the proposed method, but emphasize the limitation of the approach for estimating the crop row orientation over the whole landscape with only one date. The multi-date analyses allow (1) determining the most suitable agricultural period for the detection of the row orientations, and (2) extending the estimation to the entire footprint of the study area. For the winter crops (wheat, barley and rapeseed), best results are obtained with images acquired just after harvest, when surfaces are covered by stubbles or during the period of deep tillage (0.27 > R 2 > 0.99 and 7.15°> RMSE > 43.02°). For the summer crops (sunflower, corn and hemp), results are strongly crop and date dependents (0 > R 2 > 0.96, 10.22°> RMSE > 80°), with a well-marked impact of flowering, irrigation equipment and/or maximum crop development. Last, the extent of the method to the whole studied zone allows mapping 90% of the crop row orientations (more than 45,000 ha) with an error inferior to 40°, associated to a confidence index ranging from 1 to 5 for each agricultural plot.

The objective of this paper is to evaluate on bare soils the surface backscattering models IEM, Oh, and Dubois in X-band. This analysis uses a large database of TerraSAR-X images and in situ measurements (soil moisture and surface roughness). Oh's model correctly simulates the radar signal for HH and VV polarizations whereas the simulations performed with the Dubois model show a poor correlation between TerraSAR data and model. The backscattering Integral Equation Model (IEM) model simulates correctly the backscattering coefficient only for rms<1.5 cm in using an exponential correlation function, and for rms>1.5 cm in using Gaussian function. However, the results are not satisfactory for a use of IEM in the inversion of TerraSAR data. A semi-empirical calibration of IEM was done in X-band. Good agreement was found between the TerraSAR data and the simulations using the calibrated version of the IEM.

This The Aeronautical Mobile Airport Communications System (AeroMACS) is being developed to provide a new broadband wireless communications capability for safety critical communications in the airport surface domain, providing connectivity to aircraft and other ground vehicles as well as connections between other critical airport fixed assets. AeroMACS development has progressed from requirements definition through technology definition, prototype deployment and testing, and now into national and international standards development. The first prototype AeroMACS system has been deployed at the Cleveland Hopkins International Airport (CLE) and the adjacent NASA Glenn Research Center (GRC). During the past three years, extensive technical testing has taken place to characterize the performance of the AeroMACS prototype and provide technical support for the standards development process. The testing has characterized AeroMACS link and network performance over a variety of conditions for...

NeXtRAD is a fully polarimetric, X/L-band sensor network. It is a development of the older NetRAD system and builds on the experience gained with extensive deployments of NetRAD for sea clutter and target measurements. In this paper we will report on the first measurements with NeXtRAD, looking primarily at sea clutter and some targets, as well as early attempts at calibration using corner reflectors, and an assessment of the polarimetric response of the system. We also highlight innovations allowing for efficient data manipulation after measurement campaigns, as well as the plans for the future with this system.

The objective of this study is to improve the performance of semi-empirical radar backscatter models, which are mainly used in microwave remote sensing (Oh 1992, Oh 2004 and. The study is based on satellite and ground data collected on bare soil surfaces during the Multispectral Crop Monitoring experimental campaign of the CESBIO laboratory in 2010 over an agricultural region in southwestern France. The dataset covers a wide range of soil (viewing top soil moisture, surface roughness and texture) and satellite (at different frequencies: X-, C-and L-bands, and different incidence angles: 24.3˚ to 53.3˚) configurations. The proposed methodology consists in identifying and correcting the residues of the models, depending on the surface properties (roughness, moisture, texture) and/or sensor characteristics (frequency, incidence angle). Finally, one model has been retained for each frequency domain. Results show that the enhancements of the models significantly increase the simulation performances. The coefficient of correlation increases of 23% in mean and the simulation errors (RMSE) are reduced to below 2 dB (at the X and C-bands) and to 1 dB at the L-band, compared to the initial models. At the X-and C-bands, the best performances of the modified models are provided by Dubois, whereas Oh 2004 is more suitable for the L-band (r is equal to 0.69, 0.65 and 0.85). Moreover, the modified models of Oh 1992 and 2004 and Dubois, developed in this study, offer a wider domain of validity than the initial formalism and increase the capabilities of retrieving the backscattering signal in view of applications of such approaches to stronglycontrasted agricultural surface states.

as electromagnetic waves, and, vice versa, to gather electromagnetic waves in the space converting them as high-frequency energy into the electronic circuits. Thus a resonant antenna that resonates at a specific frequency is very efficient since it can induce large currents in the circuit. The wavelength at 2.45 GHz is calculated to be about 12 cm, so that a linear antenna that resonates at this frequency to induce a large current has to have an element 12 cm in length, or at least 3 cm for a quarter wavelength. When an antenna is to be used, however, in mobile equipment such as mobile phones, headsets, and PDAs, it should be as compact as possible in order to save space and improve design flexibility.

This paper is focused on deformation monitoring using a Persistent Scatterer Interferometry technique and the interferometric SAR data acquired by the Sentinel-1 satellite of the European Space Agency. The first part of the paper describes the procedure used to process and analyze Sentinel-1 interferometric SAR data. Two main approaches are described. The first one is a simplified Persistent Scatterer Interferometry approach that exploits two key properties of the Sentinel-1 data: the high coherence of the 12-day interferograms and the reduced orbital tube. The second approach is a full Persistent Scatterer Interferometry approach, where a more sophisticate data treatment is employed. The second part of the paper illustrates the results obtained with the two processing approaches. Two case studies are described. The first one concerns landslide detection and monitoring. In this case, the simplified Persistent Scatterer Interferometry approach was used. The second one regards the deformation monitoring of an urban area. In this case, a full Persistent Scatterer Interferometry approach was used.

Dual polarized weather radars, radars that can transmit both horizontal (H) and vertical (V) polarized waves, are becoming more common in the world. Dual polarization is accomplished via fast alternate transmission of H and V polarization or simultaneous H and V polarization transmission. The simultaneous H and V transmit mode is becoming quite popular since a high power, costly, polarization switch is not required. In either case, such radars can measure copolar differential reflectivity (Zdr) and copolar differential phase (φdp) which have been shown to significantly improve identification and quantification of precipitation, if measured accurately. In fact, The United States National Weather Service (NWS) network of NEXRAD radars is scheduled to be upgraded to the simultaneous H and V dual polarization mode with in the next few years. Critical to improved rainfall estimation with dual polarization radar is maintaining radar instrument calibration uncertainty of Zdr to about 0.1 d...

A case study of a miniature monopole planar fiddle or violin-shaped antenna that can be used in ultra-wideband (UWB) application is carried out. Such violin-shaped antenna is a circular patch accompanied with two circular cuts and overlapped with an elliptical patch on the top of it. It is small in size, simple in structure, feasible to construct and experimentally feasible to be manufactured and validated in lab. Furthermore, the handle of the fiddlelike structure serves as a microstrip 50𝛀 feeding line connected to the main patch structure body. However, the prototype of the designed antenna is manufactured on a substrate of a dielectric material of FR4 with a dielectric constant that equals 4.3 with dimensions of 28×18×1.6 mm3. The gain at the resonant frequencies reached different values throughout the covered frequency band; that is of (3.1 GHz up to 13.5 GHz) ranging between the values of (≈1.1 dBi up to ≈5.5 dBi) according to the return loss of the performance outcome. The empirically measured and simulated results have a suitable settlement and/or agreement and computations display that the antenna has a respectable frequency band, radiation, and characteristics of time domain in spite of the antenna's small size and simple design.

Hail is a major threat to agriculture, properties, and people, yet little is known about changes to hail with anthropogenic warming. Here, we use pan-European convection-permitting simulations, and a contemporary hail proxy benefiting from simulated thunderstorm features, and show that the potential for severe hail decreases under RCP8.5, except potentially for very large hail. This is despite an increase in the number of convective storms producing many small ice particles functioning as hail embryos. The decrease in severe hail potential is partly due to hail forming at higher altitudes as the atmosphere warms, which impacts both the updraft strength in the hail growth layer and the extent to which hail melts before reaching the surface. Our results contradict those from coarser resolution models which typically project future increases in hail frequency, estimated using environmental proxies. However, we find that future warm seasons feature a warmer thunderstorm type akin to hail-producing storms found in the tropics, where the largest hailstones can still reach the surface as evidenced from observations. In the future, these storms are most frequent over southern Europe, leading to regional increases in severe hail frequency. We conclude that society may need to be prepared for (infrequent but) more impactful hail in a future warmer world.

The reference distribution for the SwissFEL accelerator is based on ultra-stable Libera Sync 3 fiber-optic links operating at 3 GHz with &lt;2.4 fs added timing jitter. While s-band injector RF stations are directly supplied with these actively stabilized reference signals at 2.9988 GHz, the same 3 GHz optical links are used to transmit reference signals at 2.856 GHz (half c-band frequency) to the c-band LINACs, combined with a frequency doubleramplifier at the link end. A novel zero AM/PMconversion frequency doubler and an amplitude-/phasecontrolled power amplifier have been implemented in a compact 1HU 19inch unit. Key design concepts and measurement results will be presented. It will be shown that this inexpensive doubler-amplifier system adds only insignificant jitter and drift to the transmitted reference signals. As the same actively stabilized 3 GHz links can be used for sand cband RF stations, development of a more expensive 6 GHz fiber-optic link could be avoided. A higher ...

this study is to measure the impact of the insertion of demultiplexers based on Bragg grating filter on DWDM transmission system. An optical link has been developed using a simulator system.The impact of demultiplexers on 10 Gbit/s DWDM system is investigated for NRZ-OOK coding formats. Performances of demultiplexers with different crosstalk, filter bandwidth and insertion losses are analyzed to get the best system performance for 10 Gbit/s DWDM transmission system with high spectral efficiency. The simulations were conducted for different fiber’s lengths to assess the impact of demultiplexer on the link performance in terms of Bit Error Rate (BER). Key wordsoptical link, fiber optics, DWDM demultiplexer, simulator system, BER, filter Bragg grating.

This letter presents a triple band coplanar waveguide antenna with dual polarization characteristics. The proposed antenna exhibits both linear polarization and circular polarization characteristics. Triple band nature is achieved by using a flared ground plane. Circular polarization is achieved by terminating the feed line by a g/4 length stub, as this result in excitation of even-odd modes in phase quadrature. Resonating frequency of higher band is tuned by embedding a narrow slit (ws) in the ground plane. The antenna has compact 0.78 g × 0.78 g × 0.03 g geometry with circular polarization characteristics extending from 2.7 GHz 3.42 GHz and linear polarized characteristics from 4.4 GHz 5.16 GHz and 6.2 GHz 6.9 GHz. The lower band is circular polarized while the middle and upper bands are linear polarized and can be applied for WiMAX and C-band broadcasting applications.

This paper discusses the design of Low Cross Polarized feed for offset parabolic reflector antenna and its application. Conical corrugated horn antenna consists an input mode TE11 and the corrugation part requires a transition to HE11 mode for propagation. The paper presents the widely used design of mode converter-Variable depth slot mode used for TE11-HE11 conversion. Three different design of Corrugated horn antenna is presented for optimizing the value of Cross Polarization. The choice of the delta is the most important parameter for optimizing the value of cross polarization. The value of f/D is chosen 0.4 for offset parabolic reflector antenna. This design also provides high gain, good beam symmetry, and high bandwidth performance.

We present a numerical simulation study on the effect of the linewidth enhancement factor (α) of semiconductor laser and dispersion management methods of optical fibers on the performance of 40-Gb/s directly-modulated fiber links and their application in WDM systems. The dispersion management methods include the use of non-zero dispersion-shifted fiber (NZ-DSF), dispersion-compensating fiber (DCF), and fiber Bragg grating (FBG). The optimal values of the α-parameter and the best dispersion management method are applied to design and simulate a four-channel × 40-Gb/s WDM fiber system. The obtained results show that the increase in the α-parameter and/or fiber length reduces the performance of both the 40-Gb/s optical link and the WDM system. Regarding the 40-Gb/s optical link, when α = 1, using-NZ-DSF or + NZ-DSF, DCF with SSMF, and FBG with SSMF work to increase the transmission length from 1.6 km of a standard single-mode fiber (SSMF) to 7.2, 26.5, and 40 km, respectively. Whereas at α = 3.5, the maximum transmission length reaches 1.2 km when using SSMF,-NZ-DSF, or + NZ-DSF, while it increases to 13 and 35 km when using DCF with SSMF, and FBG with SSMF, respectively. In the designed WDM system, the use of FBG with SSMF is predicted as the most effective method for dispersion management. The maximum transmission length reaches 25 km when α = 1, but reduces to 12 km when α = 3.5.

A wideband S-shape microstrip patch antenna is proposed in this paper. The bandwidth is further increased by introducing PBG structure. Low volume and low profile configuration, easily mounted, low fabrication cost and light weight are the advantages of this antenna. With this design, a matching impedance bandwidth over 67.23% (from 4.0769 GHz to 8.2051 GHz) for VSWR< 2 was achieved. The proposed antenna operates in S-band and C-band with bandwidth over 1.72% and 67.23%. The proposed antenna is best suited for Cband communication. The maximum achieved gain of the designed antenna is 6 dBi with return loss of -33 dB.

This paper presents a new Double-E-Triple-H-Shaped NRI (negative refractive index) metamaterial (MM) for dual-band microwave sensing applications. Here, a horizontal H-shaped metal structure is enclosed by two face-to-face E-shaped metal structures. This double-E-H-shaped design is also encased by two vertical H-shaped structures along with some copper links. Thus, the Double-E-Triple-H-Shaped configuration is developed. Two popular substrate materials of Rogers RO 3010 and FR-4 were adopted for analyzing the characteristics of the unit cell. The proposed structure exhibits transmission resonance inside the S-band with NRI and ENG (Epsilon Negative) metamaterial properties, and inside the C-band with ENG and MNG (Mu Negative) metamaterial properties. A good effective medium ratio (EMR) of 8.06 indicates the compactness and effectiveness of the proposed design. Further analysis has been done by changing the thickness of the substrate material as well and a significant change in the effective medium ratio is found. The validity of the proposed structure is confirmed by an equivalent circuit model. The simulated result agrees well with the calculated result. For exploring microwave sensing applications of the proposed unit cell, permittivity and pressure sensitivity performance were investigated in different simulation arrangements. The compact size, effective parameters, high sensitivity and a good EMR represent the proposed metamaterial as a promising solution for S-band and C-band microwave sensing applications.

One of the key inputs to landslide susceptibility and hazard analyses is provided by a precise inventory map, including the information of landslide activity. In the last decade the satellite SAR Interferometry has been demonstrated to be a powerful tool for landslide mapping and monitoring. However, until now, the systematic use of the technique has been strongly limited by different aspects like the image availability, the revisit time and the loss of coherence. In this context, the Sentinel-1 constellation provides interesting characteristics for landslide mapping and monitoring: the wavelength (55.5 mm) and the short temporal baseline (6 days when Sentiel-1B data will be available). The latter one is expected to be a key feature for increasing coherence and for defining monitoring and updating plans. However, the exploitation of these high coherent data for landslide purposes is not straightforward and demands of new tools and methods to properly discriminate the real displacements. The aim of this work is to show which are, according to the authors experience, the main pros and cons of landslides mapping and monitoring with Sentinel-1 data. These conclusions are based on the analysis over three different test sites with different characteristics from the SAR view point: the Canarias Islands (Spain), the Molise region (Italy) and the Toscana region (Italy). The Canarias Islands test site shows a good example of how Sentinel-1 can systematically provide deformation maps over wide areas and with a very high sampling density. The Molise region application shows how the short temporal revisit time of Sentinel-1 allows the detection and monitoring of landslides also over agricultural areas. In particular, for this test site, are shown some examples of detection and update of active landslide phenomena. Finally, in the third example, the Toscana area, we show another example of difficult scenario, where the high temporal sampling has allowed the detection of some landslide phenomena. However, this test site is also a good example to show one of the main problems to be solved when applying short temporal baseline interferometry in rural environments: false deformation trends related to soil changes.