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A method has been developed for the retrieval of the atmospheric boundary layer parameters in tropical cyclones, namely the dynamic speed, the wind speed at a 10 m height, and the roughness parameter. For the analysis, the wind speed profiles were obtained from NOAA GPS-dropsondes and collocated with the data from the Stepped-Frequency Microwave Radiometer (SFMR). The parameters of the atmospheric boundary layer from the GPS-dropsonde data were obtained by taking into account the self-similarity of the velocity defect profile. The emissivity, determined from the radiometric measurement data, was calibrated to the field data from the GPS-dropsondes. Empirical relations between the wind speed, dynamic wind speed, and aerodynamic drag coefficient with the surface emissivity have been proposed. Based on a comparison of the measured dynamic parameters and the surface emissivity, empirical formulas have also been proposed. From an analysis of cross-polarized Sentinel-1 SAR images and collocated SFMR measurements for hurricanes Irma (2017/09/07) and Maria (2017/09/21 and 2017/09/23), we have obtained the dependences of the NRCS on the ocean surface emissivity, surface wind speed, and friction velocity. These results could potentially be used to improve the algorithm for the retrieval of boundary layer parameters in tropical cyclones from remote sensing data. [ABSTRACT FROM AUTHOR]

Background:  To evaluate the radiant power of the light cure units (LCUs) in relation to their type, radiant exitance, number of years in clinical use, and condition of LCUs tips in governmental and public clinics in Dental Faculties in Sana'a City., Materials and Methods: LCUs were collected from different colleges at Sanaa City, Yemen, then LCU data as type, clinical age (<1 year, between 1-5 and ˃ 5-years), tip condition was visually inspected for damage and adhering debris, and the radiant exitance values of the tested LCUs. Radiant exitance values were subcategorized into three groups: <400, 400-850, and >850 mW/cm², labeled as inadequate, marginal, and adequate radiant exitances, respectively. A Woodpecker radiometer was used with a mode lasting of 20 seconds was used with each LCU. Descriptive statistics of the different parameters were evaluated with SPSS version 25. One-way ANOVA and Mann-Whitney tests were performed to determine the mean difference between the groups with a significance value of ˂ 0.05 was considered., Results: Two hundred twenty-three LCUs were surveyed, and the majority were Light-emitting diode (LED). Forty-nine (21.9%), 117 (52.4%), 57 (25.6%) recorded lesser than, 400-850, and more than 850 mW/cm², respectively. Radiant exitances of < year-old units were found to be higher than those of units used for ˃ 5 years with significant differences (p=0.001). The ANOVA test showed significant differences between the radiant exitance with clinical age and LCU tip conditions and a strong correlation p ˃ 0.050., Conclusion: LED curing lights were the most used in the tested Dental Faculties. More than half of the used LCU offered sufficient radiant exitance. Clinical age, the presence or absence of composite buildups, and damage to curing tips showed significantly affect radiant exitance values., Competing Interests: The authors declare no conflicts of interest related to the study, including financial, personal, or other relationships that may influence the study or its interpretation., (© 2024 Hasan et al.)

Spectrum sensing is needed in frequency agile cognitive radio systems, cognitive radar systems as well as in (cognitive) electronic warfare systems. This paper studies window based detectors where window shapes can be matched for the expected spectrum. The provided analytical results for the probabilities of false alarm and detection are valid for arbitrary windows. Based on the window shape mismatch analysis, it was concluded that the simple rectangular window is often sufficient if its bandwidth is properly set. Furthermore, based on the window bandwidth mismatch analysis, it was discussed how many different rectangular windows are needed to cover the instantaneous analysis bandwidth of the receiver without compromising too much on sensitivity. Finally, suitable constant false alarm rate threshold setting schemes were compared. It was observed that almost ideal setting schemes exist.

This study presents an original approach on how to generate a radiator with an emissivity less than one by using a conventional blackbody and a screen with a defined area density of holes. This is needed for the calibration of infrared (IR) radiometry, which is a very useful form of temperature measurement in industrial, scientific, and medical applications. One of the major sources of errors in IR radiometry is the emissivity of the surface being measured. Emissivity is a physically well-defined parameter, but in real experiments, it may be influenced by many factors: surface texture, spectral properties, oxidation, and aging of surfaces. While commercial blackbodies are prevalent, the much-needed grey bodies with a known emissivity are unavailable. This work describes a methodology for how to calibrate radiometers in the lab or in the factory or FAB using the “screen approach” and a novel thermal sensor dubbed Digital TMOS. The fundamental physics required to appreciate the reported methodology is reviewed. The linearity in emissivity of the Digital TMOS is demonstrated. The study describes in detail how to obtain the perforated screen as well as how to do the calibration.

• Normal concentrations of ionized calcium in children differ from adults. • Radiometer instruments record lab results for all analytes independent of the order(s) placed. • Radiometer data can be used to apply exclusion criteria and calculate reference intervals. Measurement of ionized calcium (iCa) reflects bioavailable calcium and has significant utility in children. However, robust pediatric iCa reference intervals (RI) have not been well-established. In this study, we retrospectively calculated RI for iCa in a pediatric population by accessing archived data acquired on Radiometer instruments and applying stringent exclusion criteria. Data saved on 4 Radiometer ABL800 FLEX blood gas analyzers were queried. Exclusion criteria were applied based on information available from these instruments. iCa results were plotted and inflection points were visually identified. Following outlier removal and partition verification, age-specific RI were calculated using a nonparametric rank order approach from > 5,000 individuals. Finally, the stringency of the exclusion criteria was assessed by calculating RI from additional results in the dataset and comparing to existing in-house ranges. Six age-specific iCa partitions were established from 0 to 19 years. Relative to adults, wider ranges for the central 95th percentile were observed early in life that progressively narrowed with increasing age and approached adult concentrations by 2.5 years. Analysis of concurrent data for sodium and creatinine in the dataset suggest the applied exclusion criteria reduced the likelihood of including results from acutely-ill children. Normal concentrations of iCa in children are more variable than adults. Observed differences may reflect the transition from maternally supplied calcium to nutritional sources, the maturation of calcium homeostatic mechanisms, and/or the need for calcium for growth/development. This study also demonstrates the feasibility and advantages of using data archived on Radiometer analyzers to establish pediatric RI. This approach enables rapid, cost-effective evaluation of large datasets and may be a feasible option when prospective or detailed retrospective analyses are not possible. [ABSTRACT FROM AUTHOR]

It is important to monitor the take-off and landing of civil aircraft using passive detection methods. Due to the strict aircraft safety requirements and the electromagnetic environment around an airport, using too many active detection methods should be avoided. Using an aircraft's microwave radiation signal detection is very advantageous because it does not actively emit signals and has a strong cloud penetration, suitable for all-weather observation. This paper introduces a synthetic aperture microwave radiation system for monitoring the take-off and landing of civil aircraft, which is characterized by real-time two-dimensional imaging, and the image refresh rate can reach 10 ms, which meets the high refresh rate requirements for aircraft imaging. Applicable system parameters and antenna array distribution scheme and imaging algorithm are given. Then the paper focuses on the error analysis and correction method of the system. The correction method is simple and fast, which avoids the disadvantage that the error needs to be corrected regularly in the laboratory environment, and is suitable for airport application. Finally, the simulation and experimental results show that this technology can be used for real-time monitoring of civil aircraft during take-off and landing, and it is a practical means to assisting landing. [ABSTRACT FROM AUTHOR]

The Soil Moisture Active Passive (SMAP) mission includes a unique combination of instruments intended to provide daily global soil moisture data with high accuracy and resolution. Due to radar instrument failure, the default resolution of the data product decreased from the intended 9 km to 36 km shortly after the mission started to return data. To improve this, we employed the Scatterometer Image Reconstruction algorithm in its radiometer form (rSIR) to enhance the resolution of the radiometer brightness temperature measurements from which the soil moisture was derived. This paper compares the soil moisture estimates created from the rSIR-enhanced brightness temperatures with SMAP project radiometer L2_SM_SP and SMAP-Sentinel L2_SM_P products reported on 9 km and 3 km grids, respectively. We find that the difference of the rSIR-enhanced passive soil moisture product is generally within 0.020 cm 3 cm − 3 RMS of the 9 km SMAP radiometer L2_SM_SP and 0.045 cm 3 cm − 3 RMS of the 3 km SMAP-Sentinel L2_SM_P soil moisture products. The accuracy of the rSIR soil moisture can be improved by including better antenna pattern correction methods applied to the input TB measurements. [ABSTRACT FROM AUTHOR]

The Earth's radiation budget (ERB), measured at the top of the atmosphere (TOP), quantifies the radiation imbalance between the Earth–atmosphere system and space. The ERB's measurement accuracy depends on the observation system's design and calibration technology. Fitting regional scanning data from polar satellite payloads is the most common way to obtain the global radiation budget. Additionally, the radiometers are calibrated by onboard stable radiation sources. We propose a new ERB radiometer operating at the Lagrange L1 point of the Earth–Moon system, which has the characteristic of observing the Earth and Moon on a hemispheric spatial scale. Hence, earth-integrated radiation can be measured directly. Furthermore, the Moon is used as a natural source for on-orbit calibration, and the attenuation of the instrument is monitored and corrected through periodic observations. This paper presents the concept of the radiometer and focuses on the design and analysis of the radiometer's observation systems based on optical design and stray radiation suppression. The results show that the system has good imaging quality. The external stray radiation suppression reached an order of 10−8, and the thermal stray radiation can be eliminated by temperature control and compensation. The radiometer will provide long-term integrated ERB data. [ABSTRACT FROM AUTHOR]

Medical microwave radiometry is a near-field passive thermometry technique that requires highly sensitive and stable receiver to gather and process the ultra-low power thermal radiation from biological tissues (−174 dBm/Hz). The noise measurements are susceptible to radio frequency interference (RFI) and influenced by variations in power reflection between the near-field antenna and radiometer input ($\rho $), instrument electronic noise ($\boldsymbol {T}_{ \boldsymbol {rec}}$), amplifier noise ($\boldsymbol {T}_{ \boldsymbol {A}}$), and system gain ($\boldsymbol {G}$). Design of a self-balanced dual frequency band Dicke radiometer is reported in this work with real time calibration to eliminate the influence of $\rho $ , ${ \boldsymbol {T}}_{ \boldsymbol {rec}}, \boldsymbol {T}_{ \boldsymbol {A}}$ and gain ($\boldsymbol {G}$) on the unknown source temperature ($\boldsymbol {T}_{ \boldsymbol {S}}$). The radiometer is designed for operation over 1.2-1.5 GHz (low frequency/LF) and 2.8-3.1 GHz (high frequency/HF) for deep and superficial tissue temperature measurements, respectively. The radiometer measurements are characterized using matched load and ultra-wideband spiral antenna using tissue mimicking phantoms. The linearity of source temperature measurements for the matched load is close to 1 with root mean square error of 0.22 and 0.37 °C in LF and HF bands, respectively. Radiometer noise measurements using UWB antenna in tissue mimicking phantom confirm stable measurements and immunity to ambient RFI. [ABSTRACT FROM AUTHOR]

Continuous remote monitoring of the atmospheric physical parameters is an urgent task for solving the issues related to meteorology, climatology, artificial influence on clouds, studying the physical parameters of cloud cover etc. In the developed countries such issues are solved using science-driven technologies of millimeter wave range radiometry. They allow, in particular, quick restoration of the values of total content and effective temperature of droplet and vaporous moisture in the atmospheric column, and distinguishing the areas with crystalline, droplet or vaporous water phases. This work aims at substantiating, by calculation and experiment, the possibility of large-scale solving the problems of continuous remote monitoring of the studied atmospheric moisture parameters using the method of centimetre wavelength range radiometry. To determine the best pair of frequencies for restoring the atmospheric moisture parameters based on radiometric data of remote sensing the linear absorption coefficients were calculated for clear atmosphere, for cloudy atmosphere depending on the temperature of drops and for rainfalls of various intensities for 4, 12, 20, 40 and 94 GHz frequencies. In order to calculate these data, we used a well-known MPM model (Atmospheric Millimeter-Wave Propagation Model). At the same time, calculation of the altitude profiles of the atmospheric meteorological parameters was carried out based on the ERA-15 model. Comparison of the data obtained by calculation, taking into account the progress of the technical parameters of the serial element base, indicated a possibility of solving the above problems in the centimetre wavelength as well. The research presents a description of the diagram and technical solutions, as well as the appearance of a two-frequency radiometric system with 1.5 cm and 2.5 cm ranges created at the National Aerospace University (KhAI) on the basis of an easily accessible modern element base and full-scale tests' results. The budget-friendly focus of the described product allows for radiophysical measurement with a sensitivity of radiometers exceeding 0.01 K while ensuring the cost of small-scale production of the radio technical part of the system, comparable to the cost of TV converters commonly used in everyday life.

As a result of the modernization of the DRG-05M dosimeter, a convenient device was obtained, which allows estimating the level of gamma- and X-ray radiation, beta-particles, and neutrons without changing the detector heads. Two devices were manufactured and a third one was prepared for metrological certification.

Sea surface salinity (SSS) in coastal zones with high temporal and spatial resolutions is also needed for scientific research and marine economy. However, one of the limitations of airborne L-band real-aperture microwave radiometers and synthesis aperture interferometric radiometers is high mass and volume or the high complexity of the system. To overcome the limitations, an L-band phased array radiometer is proposed as an alternative solution to monitor SSS in coastal zones from a small unmanned aerial vehicle (UAV). The L-band phased array radiometer is introduced, which only comprises a phased array and a single receiver. In addition, the calibration methods of the L-band phased array, radiometer that the external calibration method and the internal calibration method, are also introduced. A series of experiments was performed to assess the performance of the L-band phased array radiometer. The results indicate that the L-band phased array radiometer show a good performance in low pointing angles and low scanning angles. As a conclusion, the L-band phased array radiometer can be an alternative solution to monitor SSS in coastal zones with high temporal and spatial resolutions from a small UAV.

National Aeronautics and Space Administration's soil moisture active–passive (SMAP) mission potential to produce high-resolution soil moisture suffered adversely due to its L-band synthetic-aperture radar (SAR) failure. Other satellite-based L-/C-band SAR observations can be used within the SMAP active–passive algorithm. In this article, we evaluated the capability of ingesting ISRO's Radar Imaging Satellite-1 (RISAT-1) C-band SAR observations in the SMAP active–passive algorithm to obtain soil moisture at 1, 3, and 9 km over the agricultural region dominant by paddy that experiences seasonal flooding. We also improved the SMAP mission active–passive algorithm with a dynamic surface water bodies (ponding conditions) masking approach using the native RISAT-1 observations. The article shows that the use of surface water masks helps in mitigating the negative impact of surface water bodies in the active–passive disaggregation process. The SMAP–RISAT soil moisture retrievals at 1 and 3 km resolutions are found to have high unbiased root-mean-square error (ubRMSE) greater than 0.06 m3/m3 during very wet and high vegetative conditions. However, at low and moderate soil moisture states, the ubRMSE is below 0.06 m3/m3. Comparison of soil moisture retrievals at 9 km resolution with upscaled ground-based soil moisture measurements shows ubRMSE less than 0.04 m3/m3. This article is a precursor for estimating soil moisture for the upcoming RISAT-1A dataset over India. The findings will further help in the implementation of a microwave active–passive algorithm to retrieve soil moisture for future satellite missions involving radiometer-SAR instruments, and challenging geophysical conditions (i.e., dynamic surface water bodies).

Global warming causes the replacement of lichens by shrubs in alpine and Arctic ecosystems. Since shrubs have lower albedo than lichens, this shrub encroachment can lead to a positive climatic feedback, resulting in higher temperatures in the surroundings. Therefore, gaining knowledge on the surface albedo of shrubs and lichens is important. Environmental factors also influence the surface albedo, but have often been neglected, potentially leading to biased results. In an experimental setup, we analyzed albedos of the lichen species Cladonia stellaris, Flavocetraria nivalis and Cetraria islandica, and how albedo changes with a stepwise replacement by the dwarf shrub Empetrum nigrum. Albedo was measured with radiometers in a paired set up. By setting certain environmental variables and species composition (monocultures) to be constant, we quantified the impact of environmental factors such as cloud cover, aspect and zenith angle on the surface albedo of two lichen species. Surface albedo (mean values ± SD) differed between C. islandica (0.155 ± 0.015), C. stellaris (0.364 ± 0.019), F. nivalis (0.350 ± 0.022) and E. nigrum (0.154 ± 0.016), and an increase in shrub cover at the expense of lichen cover led to a corresponding decrease in albedo. A 0.6 reduction in clearness index (more clouds) produced a 0.054 albedo decline. On the north‐facing aspect, albedo was 0.023 lower than on the south‐facing aspect. Albedo increased by 0.032 with an increase in zenith angle of 15°. Albedo variations caused by these studied environmental factors significantly affect the radiation budget of alpine and Arctic vegetation. We therefore stress the importance of considering environmental factors when surface albedos are estimated. Likewise, our species‐specific measurements can be a basis for further studies of the impact of climate change on alpine and Arctic vegetation and species‐related feedback mechanisms. [ABSTRACT FROM AUTHOR]

On the basic theory of millimeter wave mixing technology, harmonic mixers in multiple different frequency bands are systematically studied. This paper innovatively establishes a 3D model of the diode, gives it material properties, and uses magnetic field circuit software for co‐simulation, and finally develops a beautifully structured W‐band 89 GHz sub‐harmonic mixer. Simulation and test results show that when the local oscillator (LO) is fixed at 45 GHz, the conversion loss of the LO at 84–89 GHz is better than 14 dB, and the minimum conversion loss is 9 dB. The actual test results are relatively consistent with the simulation trend. Plain Language Summary: In this paper, a design method of harmonic mixer is studied, and the correctness of the method and the accuracy of the model are verified by experimental results. Key Points: This paper systematically studies mixers in several different frequency bands. Starting from the study of the internal structure and material size package of Schottky planar diodes, some new modeling ideas were proposedA simulation method of field‐to‐path combination is proposed, and the transition circuit and the resonance matching circuit are analyzedThe designed harmonic mixer is tested and analyzed, which fully verifies the accuracy of the diode 3D electromagnetic model and the rationality of the simulation method [ABSTRACT FROM AUTHOR]

The Japanese MMX sample return mission to Phobos by JAXA will carry a rover developed by CNES and DLR that will be deployed on Phobos to perform in situ analysis of the Martian moon's surface properties. Past images of the surface of Phobos show that it is covered by a layer of regolith. However, the mechanical and compositional properties of this regolith are poorly constrained. In particular, from current remote images, very little is known regarding the particle sizes, their chemical composition, the packing density of the regolith as well as other parameters such as friction and cohesion that influence surface dynamics. Understanding the properties and dynamics of the regolith in the low-gravity environment of Phobos is important to trace back its history and surface evolution. Moreover, this information is also important to support the interpretation of data obtained by instruments onboard the main MMX spacecraft, and to minimize the risks involved in the spacecraft sampling operations. The instruments onboard the Rover are a Raman spectrometer (RAX), an infrared radiometer (miniRad), two forward-looking cameras for navigation and science purposes (NavCams), and two cameras observing the interactions of regolith and the rover wheels (WheelCams). The Rover will be deployed before the MMX spacecraft samples Phobos' surface and will be the first rover to drive on the surface of a Martian moon and in a very low gravity environment. [ABSTRACT FROM AUTHOR]

This paper presents measurements using a dual-polarised radiometer operating at 93 GHz to detect ice or water on asphalt in laboratory conditions. The brightness temperatures of both H and V polarizations were measured for a dry surface, liquid water, and ice on asphalt at observation angles of 50° and 56°. The results presented in this paper demonstrate that the studied road conditions can be identified by the radiometer. The measurements are compared with a model and surface parameters, such as dielectric constant and roughness are fitted and compared to reference values. The experiments and results, described in this article, are the first steps towards the future installation of a polarimetric sensor on a moving vehicle for traffic safety. [ABSTRACT FROM AUTHOR]

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The Temporal Experiment for Storms and Tropical Systems Technology Demonstration (TEMPEST-D) instrument is a five-frequency millimeter-wave radiometer operating from 87 to 181 GHz. The cross-track scanning radiometer has been operating on a 6U CubeSat in low Earth orbit since September 5, 2018. The direct-detection architecture of the radiometer reduces its mass and power consumption by eliminating the need for a local oscillator and mixer, also reducing system complexity. The instrument includes a scanning reflector and ambient calibration target. The reflector rotates continuously to scan the antenna beams in the cross-track direction, first across the blackbody calibration target, then toward the Earth over the full range of incidence angles, and finally to cosmic microwave background radiation at 2.73 K. This enables precision end-to-end calibration of the millimeter-wave receivers during every 2-s scan period. The TEMPEST-D millimeter-wave radiometers are based on 35-nm indium phosphide (InP) high-electron-mobility transistor (HEMT) low-noise amplifiers. This article describes the instrument and its characterization prior to launch. [ABSTRACT FROM AUTHOR]

An active–passive microwave retrieval algorithm for simultaneous determination of soil surface roughness parameters [vertical root-mean-square (RMS) height (${s}$) and horizontal correlation length (${l}$)] is presented for bare soils. The algorithm is based on active–passive microwave covariation, including the improved Integral Equation Method (I2EM), and is tested with global soil moisture active passive (SMAP) observations. The estimated retrieval results for ${s}$ and ${l}$ are overall consistent with values in the literature, indicating the validity of the proposed algorithm. Sensitivity analyses showed that the developed roughness retrieval algorithm is independent of permittivity for ${\varepsilon }_{s} > 10$ [-]. Furthermore, the physical model basis of this approach (I2EM) allows the application of different autocorrelation functions (ACF), such as Gaussian and exponential ACFs. Global roughness retrieval results confirm bare areas in deserts such as Sahara or Gobi. However, the type of ACF used within roughness parameter estimation is important. Retrieval results for the Gaussian ACF describe a rougher surface than retrieval results for the exponential ACF. No correlations were found between roughness results and the amount of precipitation or the soil texture, which could be due to the coarse spatial resolution of the SMAP data. The extension of this approach to vegetated soils is planned as an add-on study. [ABSTRACT FROM AUTHOR]

Subject and Purpose. One of the relevant areas of remote sensing of the environment is the development of microwave methods of passive sensing of the atmosphere. The biggest challenge occurring in radiometric measurements is measuring system calibration. The reason lies in the lack of external calibration elements whose brightness temperatures are known with a high accuracy. The paper deals with the method for determining the sky brightness temperature by relative measurements at different elevation angles. The brightness temperatures refined in the way fit for radiometric system calibration. Methods and Methodology. Basically, the approach is governed by the dependence of the atmospheric brightness temperature on the elevation angle in terms of the plane-layered isothermal atmospheric model. The measurements rely on a three-centimeter radiometric system having a horn-reflector antenna combined with the MPL-1 weather radar, the entire range of elevation angles being accessible. Besides, a combined setup of two, 10 GHz and 36 GHz, radiometers is involved for measurements from a building window. Results. The previously proposed methodology for radiometric system calibration against the sky temperature obtained by relative measurements at different elevation angles has been analyzed and tested. The calibration possibility has been examined in the case that zenith measurements are unavailable. Conclusion. The proposed method for getting sky temperatures upon relative measurements at different elevation angles significantly increases accuracy of radiometric system calibration and extends a range of weather conditions admitting calibration of the kind. It has been shown that the radiometric system calibration against the sky temperature is possible even with zenith measurements excluded.

Subject and Purpose. The paper is devoted to the noise immunity problem of the receiving channel of the radiometer as part of an integration passive-active radar system. The aim is to improve the detection of low-contrast radar targets against the background of radio wave reflections from the underlying land or sea. Methods and Methodology. The study was carried out by computer simulation using the equivalent circuit of the radiometer microwave filters. The suppression of target reflected signals interfering in the radiometer receiving channel was by means of the weighted summation of radiometric signals having passed through the filters of the main and mirror channels of the radiometer. In that case, the center frequencies of the filters were symmetric about the carrier frequency of the radar active part, and the complex transmittances of the filters were picked so (the weighting procedure) that they had equal moduli and opposite phases at that frequency. Results. The research was conducted at the 8 mm band frequencies for typical parameters of frequency-selective circuits. The focus was on the transmission characteristics of the useful radiometric signal and on the suppression of the probing signal of the radar active part, various values of the center frequency spacing of the main and mirror channels of the radiometer were considered. Effects exerted on the above-mentioned characteristics by deviations of actual parameters of the filters from their design values were estimated. Conclusion. It has been shown that a deep suppression of the probe signal at the radiometer input can be achieved along with a simultaneous high transmission level of the useful radiometric signal provided that the center frequency spacing regarding the main and mirror filters of the radiometer makes up 3...4 bandwidths of these filters. When the center frequency spacing measures 3...4 values of the filter bandwidth, the effect exerted by the deviation of actual filter parameters from their design values is found to be substantially less than for a smaller spacing.

A 3-D printed antenna subsystem, which proves its effectiveness in cost- & weight-reduction and reliability improvement over conventional CNC fabrication, is proposed in this paper. The proposed structure which integrates an orthogonal-mode transducer (OMT) and a corrugated horn is fully compatible to fabrication using high temperature resistant resin Acrylonitrile Butadiene Styrene (ABS) with 3-D printing technology, as well as coating using copper with electroless metallization method. Detailed design procedures are provided and a prototype operating at X-band is designed, fabricated and measured. Over the whole operating frequency range of 11.7 GHz~12.7 GHz, measured reflection coefficients are better than -22 dB and -12 dB for different polarization directions. A very good isolation better than 60 dB is achieved between two input ports. The cross polarization level is at least 30 dB lower than the co-polarization. Moreover, the effectiveness of the fabricated antenna is also verified in a polarimetric radiometer system.

Subject and purpose. The main factor which affects the development of modern marine radars and increase of their efficiency is the correct justification of the concept of construction and selection of technical requirements for the development of new devices. The purpose of this work is to analyze the existing methods of marine radar construction, generalize the results of long-term radio physical researches in different regions of the World Ocean and in the Black Sea water area as well, and on their basis to develop the concept for applied complex radar for surface situation control and navigation. Methods and methodology. During the development of construction concept and analysis of the offered radar features the method of mathematical modeling was used. Results. The concept for the complex radar system construction for surface situation control and navigation consisting of 3-cm radar and 8-mm radar with radiometer device is proposed. When choosing 3-cm wave range, the results of long-term radio physical researches conducted by Usikov IRE NASU in different regions of the World Ocean and the Black Sea water area were considered. The usage of 8-mm wave range allows one to carry out radar observation in the near-field zone where signals of 3-cm radar interfere and create strong reflections from the sea surface. The necessity to use 8-mm wave range radiometer is caused by the fact that reduction of the effective scattering cross section due to applied radio absorbing materials leads to increasing of object’s own radio brightness radiation. Therefore to detect barely visible (produced under Stealth technology) and low-sized targets the radiometer which allows to increase target contrast can be used. Conclusion. Conclusions on practical importance of the offered concept for construction of complex radar for surface situation control and navigation are made.

The characteristics of local thundersnow at fine spatiotemporal scale on 9 and 10 November 2009 in Beijing were analyzed, using wind profiler, microwave radiometer, automatic weather station, Doppler weather radar, and satellite data. Furthermore, the causes of winter convection are discussed. The results showed that it was reflux weather. The cause of the thunder and lightning was the elevated convection above the lower cold and dry air, and the trigger for convection was the short wave trough and convergencein the middle level. This thundersnow event developed from monsoon-like long-lasting water vapor transport at 850 hPa from the South China Sea along with strong instability of, and convergence in, the conveyor layer.

The Soil Moisture and Ocean Salinity (SMOS) satellite has been providing global data for more than 11 years. The algorithm to retrieve surface soil moisture (SM) and vegetation optical depth (VOD) from Brightness Temperatures (TB) has constantly evolved as our understanding of the instrument and of the responses to various ecosystems increased. The evolution of the radiative transfer modelling used in the inversion process is in part based upon ground measurements done on experimental sites. We present the particular case of an L-band radiometer placed on top of a 800- meter-high cliff. This design allows us to study large and various scenes when compared to classical experiments where a radiometer is placed 10–20 m above a surface. With our set up, the footprints cover areas larger than 300 m in diameter, covering thus several land use types and the footprint can be directed towards different dominant land classes (forest, crops, urban etc…). This paper presents the whole set up consisting of in situ measurements (soil moisture and surface temperatures) and L-band radiometry acquired by the LEWIS instrument at high incidence angles. We perform SM/VOD retrievals from brightness temperatures using various configurations which are compared to the in situ observations. We test in particular a 2-VOD retrieval approach that consists in deriving one SM for the entire scene but two VOD, one for agricultural/low vegetation and a VOD for the forest parts, which improves the performance of the SM/VOD retrievals.

A method has been developed for the retrieval of the atmospheric boundary layer parameters in tropical cyclones, namely the dynamic speed, the wind speed at a 10 m height, and the roughness parameter. For the analysis, the wind speed profiles were obtained from NOAA GPS-dropsondes and collocated with the data from the Stepped-Frequency Microwave Radiometer (SFMR). The parameters of the atmospheric boundary layer from the GPS-dropsonde data were obtained by taking into account the self-similarity of the velocity defect profile. The emissivity, determined from the radiometric measurement data, was calibrated to the field data from the GPS-dropsondes. Empirical relations between the wind speed, dynamic wind speed, and aerodynamic drag coefficient with the surface emissivity have been proposed. Based on a comparison of the measured dynamic parameters and the surface emissivity, empirical formulas have also been proposed. From an analysis of cross-polarized Sentinel-1 SAR images and collocated SFMR measurements for hurricanes Irma (2017/09/07) and Maria (2017/09/21 and 2017/09/23), we have obtained the dependences of the NRCS on the ocean surface emissivity, surface wind speed, and friction velocity. These results could potentially be used to improve the algorithm for the retrieval of boundary layer parameters in tropical cyclones from remote sensing data.

Accurate information on tropical cyclone position, intensity, and structure is critical for storm surge prediction. Atmospheric reanalysis datasets can provide gridded, full coverage, long-term and multi-parameter atmospheric fields for the research on the impact of tropical cyclones on the upper ocean, which effectively makes up for the uneven temporal and spatial distribution of satellite remote sensing and in situ data. However, the reanalysis data cannot accurately describe characteristic parameters of tropical cyclones, especially in high wind conditions. In this paper, the performance of the tropical cyclone representation in ERA5 (European Centre for Medium-Range Weather Forecasts Reanalysis 5th Generation) is investigated and analyzed with respect to IBTrACS (International Best Track Archive for Climate Stewardship) during the period 2018–2020. Comparisons demonstrate that ERA5 winds significantly underestimate the maximum wind speed during the tropical cyclones (>30 m/s) compared to those provided by IBTrACS. An effective wind reconstruction method is examined to enhance tropical cyclone intensity representation in reanalysis data in 94 cases of 31 tropical cyclones 2018–2020. The reconstructed wind speeds are in good agreement with the SFMR (Stepped Frequency Microwave Radiometer) measured data and SMAP (Soil Moisture Active Passive) L-band radiometer remotely sensed measurements. The proposed wind reconstruction method can effectively improve the accuracy of the tropical cyclone representation in ERA5, and will benefit from the establishment of remote sensing satellite retrieval model and the forcing fields of the ocean model.

Image reconstruction from discrete samples is fundamental in remote sensing. The reconstruction problem is more complicated when the sample locations are irregularly spaced and employ different aperture functions. Further, not all 2-D sampling configurations permit full image reconstruction of band-limited signals. In this article, 2-D signal reconstruction from irregular samples with variable apertures is considered using theory and examples. Exact reconstruction requires that the signal be band-limited and the sampling matrix be invertable. The results are sensitive to the sample locations and noise in the measurements. Illustrative examples are provided using simulation and actual data from the L-band Soil Moisture Active Passive (SMAP) radiometer. The general approach can be employed with other sensors. [ABSTRACT FROM AUTHOR]

The Tropical Rainfall Measuring Mission (TRMM) satellite was launched in 1997, and the observations continued for more than 17 years. The features of TRMM observation were as follows: (a) it followed a non-sun synchronized orbit that enabled the diurnal variation of precipitation to be investigated; (b) it carried a precipitation radar and microwave and infrared radiometers, along with two instruments of opportunity in the form of a lighting sensor and a radiation budget sensor; and (c) it worked as a standard reference for precipitation measurements for other spaceborne microwave radiometers, which enabled global rain maps to be developed. For science, TRMM provided precise and accurate rain distributions over tropical and subtropical regions. The rainfall results are primarily essential for the study of precipitation climatologies, whereas the three-dimensional images of precipitation systems enabled the study of the global characteristics of precipitation systems. Technologically, the spaceborne rain radar onboard TRMM demonstrated the effectiveness of radars in space, whereas the combination with other rain observation instruments showed its effectiveness as a calibration source. Multi-satellite rain maps in which TRMM was the reference standard have been developed, and they became prototypes of the multi-satellite Earth observation systems. On the basis of the great success of TRMM, the Global Precipitation Measurement (GPM) was designed to expand TRMM's coverage to higher latitudes. The core satellite of GPM is equipped with a dual-frequency precipitation radar (DPR) and a microwave radiometer. DPR comprises a Kuband radar (KuPR) and a Ka-band radar (KaPR) and can discriminate solid from liquid precipitation. The period of the precipitation measurement with spaceborne radars extended to more than 23 years, which may make it possible to detect the change of precipitation climatology related to change in the global environment. Although TRMM's and GPM's accomplishments are very broad, this paper attempts to highlight Japan's contributions to the science of these missions. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Remote Sensing is the property of Editorial Office of Journal of Remote Sensing & Science Publishing Co. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

We present a co-designed Dicke switch and low-noise amplifier (LNA) in which the switch incorporates a transformer-based topology and serves as the input matching network of the LNA. This topology is configured to minimize the amplifier gain mismatch between the two switching states caused by process variations while providing a low noise figure (NF). The circuit is implemented in a 0.13-μm SiGe BiCMOS technology, and it achieves more than 20-dB gain and minimum NF values of 4.5 and 0.58 dB at 300 and 20 K, respectively. It consumes a dc power of 15 mW. The front-end switch presents a peak isolation of 17 dB, and the input return loss is better than 15 dB across 45–70 GHz. A noise source is also coupled to the front-end circuitry to enable on-chip calibration. The noise performance and reliability of several on-chip p-n junctions were characterized, and the one with the highest excess noise ratio was coupled to the front-end circuitry. To the best of our knowledge, the lowest NF of an integrated switch and LNA at V-band frequencies is achieved in the present work, along with the first reliability study of on-chip noise sources in a SiGe BiCMOS technology. [ABSTRACT FROM AUTHOR]

When using traditional methods to measure the microwave/millimeter-wave emissivity of small targets, errors arise due to that the antenna's main lobe and side lobe cannot be completely covered by the target. To eliminate the errors exist in traditional measurement methods, this paper first analyzes the main sources of errors and gives the analytical expression of the errors. On this basis, an improved method named voltage method is proposed. To test the effectiveness of the improved method, the horizontal polarization emissivity and the vertical polarization emissivity of a metal plate coat with stealthy nano-materials were measured at different observation angles by voltage method and traditional method, respectively. A dick radiometer working in 35 GHz is used in the experiments. Simultaneously, the accurate emissivities of the target are obtained by standard arch method. The results show that the voltage method improves the measurement accuracy largely compared to the traditional method.

Aims and Objectives: Curing units in dental offices across Punjab are analyzed for a practical purpose. Materials and Methods: One thousand light-curing units regularly used by the dentists in dental offices across the state of Punjab were examined for their output intensity. Various factors include as follows: type, power of light-curing unit, material molecule formation on tip (YES/NO), diameter of guide tip, and frequency of bulb replacement. A radiometer, a magnifying glass, and a Vernier caliper were used. Data were collected and analyzed. Results: About 75.80% of dentists use light-emitting diode (LED) lights, while 24.20% utilize halogen lamps to cure dental composites. 36.60% of light-curing units of the state had light intensity below 300 mW/cm2, out of which 61.60% were quartz–tungsten–halogen (QTH) and 28.60% LED light-curing units. 17.40% of light-curing units recorded light intensity between 301 and 400 mW/cm2. 46% of light-curing units registered an output intensity of >400 mW/cm2. 79.60% of light units showed material particle buildup on light-curing tips. 62.40% of dentists never replaced the bulbs of their light-curing units. Two-third of dental the practitioners avoided infection control barriers on the tips of curing units. Conclusions: There is a deficit of knowledge among dental practitioners in Punjab regarding care of light-curing units. Dental light-curing units should be regularly checked and infection control remedies should be opted.

It is important to monitor the take-off and landing of civil aircraft using passive detection methods. Due to the strict aircraft safety requirements and the electromagnetic environment around an airport, using too many active detection methods should be avoided. Using an aircraft’s microwave radiation signal detection is very advantageous because it does not actively emit signals and has a strong cloud penetration, suitable for all-weather observation. This paper introduces a synthetic aperture microwave radiation system for monitoring the take-off and landing of civil aircraft, which is characterized by real-time two-dimensional imaging, and the image refresh rate can reach 10 ms, which meets the high refresh rate requirements for aircraft imaging. Applicable system parameters and antenna array distribution scheme and imaging algorithm are given. Then the paper focuses on the error analysis and correction method of the system. The correction method is simple and fast, which avoids the disadvantage that the error needs to be corrected regularly in the laboratory environment, and is suitable for airport application. Finally, the simulation and experimental results show that this technology can be used for real-time monitoring of civil aircraft during take-off and landing, and it is a practical means to assisting landing.

The Soil Moisture Active Passive (SMAP) mission includes a unique combination of instruments intended to provide daily global soil moisture data with high accuracy and resolution. Due to radar instrument failure, the default resolution of the data product decreased from the intended 9 km to 36 km shortly after the mission started to return data. To improve this, we employed the Scatterometer Image Reconstruction algorithm in its radiometer form (rSIR) to enhance the resolution of the radiometer brightness temperature measurements from which the soil moisture was derived. This paper compares the soil moisture estimates created from the rSIR-enhanced brightness temperatures with SMAP project radiometer L2_SM_SP and SMAP-Sentinel L2_SM_P products reported on 9 km and 3 km grids, respectively. We find that the difference of the rSIR-enhanced passive soil moisture product is generally within 0.020 cm3 cm−3 RMS of the 9 km SMAP radiometer L2_SM_SP and 0.045 cm3 cm−3 RMS of the 3 km SMAP-Sentinel L2_SM_P soil moisture products. The accuracy of the rSIR soil moisture can be improved by including better antenna pattern correction methods applied to the input TB measurements.

As a result of the modernization of the DRG-05M dosimeter, a convenient device was obtained, which allows estimating the level of gamma- and X-ray radiation, beta-particles, and neutrons without changing the detector heads. Two devices were manufactured and a third one was prepared for metrological certification. [ABSTRACT FROM AUTHOR]

• Ground based radiometer has been used to calculate cloud attenuation. • Significant cloud attenuation has been observed over Kolkata in monsoon at 30 GHz. • August shows the worst month scenario due to high value of LWP. • Cloud attenuation has been compared with rain attenuation. The objective of this study is to investigate cloud attenuation at 30 GHz frequency using ground-based microwave radiometric observations at a tropical location, Kolkata. At higher frequencies and lower elevation angles, cloud attenuation is of major concern at a tropical location. The location experiences high value of liquid water path (LWP), which is responsible for cloud attenuation, during the Indian summer monsoon (ISM) and pre-monsoon season. Significant amount of cloud attenuation has been observed during monsoon season at 30 GHz. Two years observations of exceedance probability of cloud attenuation and worst month statistics are presented. The variation of cloud attenuation with frequencies for different elevation angles has also been investigated. The seasonal and diurnal patterns of cloud attenuation are examined. Cloud attenuation, inferred from radiometric measurements before rain commencement, has been compared to rain attenuation at Ku-band. Exceedance probabilities of cloud and rain attenuation have been compared. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Remote Sensing is the property of Editorial Office of Journal of Remote Sensing & Science Publishing Co. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Online Turkish Journal of Health Sciences (OTJHS) / Online Türk Sağlık Bilimleri Dergisi is the property of Oguz KARABAY and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)