The Experts below are selected from a list of 321 Experts worldwide ranked by ideXlab platform
Ferran Martín - One of the best experts on this subject based on the ideXlab platform.
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Microwave Sensors Based on Resonant Elements
Sensors, 2020Co-Authors: Ferran Martín, Paris VélezAbstract:This paper highlights interest in the implementation of Microwave Sensors based on resonant elements, the subject of a special issue in the journal. A classification of these Sensors on the basis of the operating principle is presented, and the advantages and limitations of the different sensor types are pointed out. Finally, the paper summarizes the different contributions to the special issue.
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On the Sensitivity of Microwave Sensors based on Slot Resonators and Frequency Variation
2019 International Conference on Electromagnetics in Advanced Applications (ICEAA), 2019Co-Authors: Jonathan Muñoz-enano, Paris Vélez, Cristian Herrojo, Ferran MartínAbstract:A study on the sensitivity of Microwave Sensors based on frequency variation and implemented by means of transmission lines loaded with slot resonators is reported in this paper. The result of this study reveals that for sensitivity optimization, the dielectric constant of the considered substrate should be small. Moreover, coupling capacitances between the line and the resonant element should be avoided, as far as such capacitances are not subjected to the influence of the material under test, and therefore tend to degrade the sensitivity. The study is validated by considering two different resonant elements, a complementary split ring resonator (CSRR) and a dumbbell defect ground structure (DB-DGS). The sensitivity is superior in the sensor based on the DB-DGS resonator, according to the reported theory.
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Microwave Sensors based on symmetry properties and metamaterial concepts: A review of some recent developments (Invited paper)
2017 IEEE 18th Wireless and Microwave Technology Conference (WAMICON), 2017Co-Authors: Javier Mata-contreras, Lijuan Su, Ferran MartínAbstract:This paper presents some sensing strategies for Microwave Sensors based on symmetry properties and metamaterial-inspired resonators. Symmetry disruption is the key aspect in all the cases. The Sensors consist of a transmission line loaded with one or two resonant elements in a symmetric configuration. Two types of Sensors are considered: (i) coupling modulation Sensors, and (ii) frequency splitting Sensors. The former are useful to monitor spatial variables and are of particular interest for angular displacement and velocity Sensors. Frequency splitting Sensors can be used as comparators or for differential measurements of permittivities in dielectric samples. Examples of applications are reported.
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A Review of Sensing Strategies for Microwave Sensors Based on Metamaterial-Inspired Resonators: Dielectric Characterization, Displacement, and Angular Velocity Measurements for Health Diagnosis, Telecommunication, and Space Applications
International Journal of Antennas and Propagation, 2017Co-Authors: Lijuan Su, Javier Mata-contreras, Paris Vélez, Ferran MartínAbstract:Four sensing approaches for the implementation of Microwave Sensors based on transmission lines loaded with metamaterial-inspired resonators are considered in this review paper, and examples of applications are pointed out. In all the cases, sensing is based on the effects that the magnitude under measurement causes in the transmission properties of the resonator-loaded line. Such four strategies are (i) resonance frequency variation, (ii) coupling modulation through symmetry disruption (causing variation of the notch depth), (iii) frequency splitting (also exploiting symmetry properties), and (iv) amplitude modulation of a harmonic signal. Such Sensors are useful in various scenarios, of interest in fields as diverse as characterization of dielectric materials for communication circuits, medical diagnosis and treatment with Microwave technologies, and Sensors for space applications, among others.
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Microwave Sensors Based on Symmetry Properties of Resonator-Loaded Transmission Lines
Journal of Sensors, 2015Co-Authors: Jordi Naqui, Ferran MartínAbstract:This review paper is focused on the design of Microwave Sensors using symmetry properties of transmission lines loaded with symmetric resonators. The operating principle of these Sensors is presented and then several prototype devices are reported, including linear and angular displacement Sensors and rotation speed Sensors. The main advantage of the proposed Sensors is the robustness against changing environmental conditions.
M.c. Dobson - One of the best experts on this subject based on the ideXlab platform.
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sensitivity to soil moisture by active and passive Microwave Sensors
IEEE Transactions on Geoscience and Remote Sensing, 2000Co-Authors: Yanlei Du, F.t. Ulaby, M.c. DobsonAbstract:The backscatter measured by radar and the emission measured by a radiometer are both very sensitive to the moisture content m/sub /spl upsi// of bare-soil surfaces. Vegetation cover complicates the scattering and emission processes, and it has been presumed that the addition of vegetation masks the soil surface, thereby reducing the radiometric and radar soil-moisture sensitivities. Even though researchers working in the field of Microwave remote sensing of soil moisture are all likely to agree with the preceding two statements, numerous claims and counterclaims have been voiced, primarily at symposia and workshops, espousing the superiority of the radiometric technique over the radar, or vice versa. The discussion is often reduced to disagreements over the answer to the following question "Which of the two sensing techniques is less impacted by vegetation cover?" This paper is an attempt to answer that question. Using realistic radiative-transfer models for the emission and backscatter, calculations were performed for three types of canopies, all at 1.5 GHz. The results lead to two major conclusions. First, the accepted presumption that vegetation cover reduces the soil-moisture sensitivity is not always true. Over certain ranges of the optical depth /spl tau/ of the vegetation canopy and the roughness of the soil surface, vegetation cover can enhance, not reduce, the radar sensitivity to soil moisture. The second conclusion is that under most vegetation and soil-surface conditions, the radiometric and radar soil-moisture sensitivities decrease with increasing /spl tau/, and the rates are approximately the same for both Sensors, suggesting that at least as far as vegetation effects are concerned, neither sensor can claim superiority over the other.
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Sensitivity to soil moisture by active and passive Microwave Sensors
IEEE 1999 International Geoscience and Remote Sensing Symposium. IGARSS'99 (Cat. No.99CH36293), 1999Co-Authors: Yang Du, F.t. Ulaby, M.c. DobsonAbstract:The backscatter measured by a radar and the emission measured by a radiometer are both very sensitive to the moisture content m, of bare-soil surfaces. Vegetation cover complicates the scattering and emission processes, presumably masking the soil surface and reducing soil-moisture sensitivity. Although researchers generally agree with the preceding statement, numerous claims and counterclaims have been voiced, espousing the superiority of the radiometric technique over the radar, or vice versa. The discussion often reduces to disagreements over the answer to the following question "Which of the two sensing techniques is less impacted by vegetation cover?" This paper is an attempt to answer that question. Using realistic radiative transfer models for the emission and backscatter, calculations were performed for three types of canopies, all at 1.5 GHz. The results lead to two major conclusions. First, the presumption that vegetation cover reduces the soil moisture sensitivity, is not always true. Over certain ranges of the optical depth /spl tau/ of the vegetation canopy and the roughness of the soil surface, vegetation cover can enhance, not reduce, the radar sensitivity to soil moisture. The second conclusion is that under most vegetation and soil-surface conditions, the radiometric and radar soil moisture sensitivities decrease with increasing /spl tau/ and the rates are approximately the same for both Sensors, suggesting that, at least as far as vegetation effects are concerned, neither sensor can claim superiority over the other.
Thomas Ohde - One of the best experts on this subject based on the ideXlab platform.
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Impact of Saharan Dust on Ocean Surface Wind Speed Derived by Microwave Satellite Sensors
Journal of Infrared Millimeter and Terahertz Waves, 2010Co-Authors: Thomas OhdeAbstract:In the present paper ground truth and remotely sensed datasets were used for the investigation and quantification of the impact of Saharan dust on Microwave propagation, the verification of theoretical results, and the validation of wind speeds determined by satellite Microwave Sensors. The influence of atmospheric dust was verified in two different study areas by investigations of single dust storms, wind statistics, wind speed scatter plots divided by the strength of Saharan dust storms, and wind speed differences in dependence of Microwave frequencies and dust component of aerosol optical depth. An increase of the deviations of satellite wind speeds to ground truth wind speeds with higher Microwave frequencies, with stronger dust storms, and with higher amount of coarse dust aerosols in coastal regions was obtained. Strong Saharan dust storms in coastal areas caused mean relative errors in the determination of wind speed by satellite Microwave Sensors of 16.3% at 10.7 GHz and of 20.3% at 37 GHz. The mean relative errors were smaller in the open sea area with 3.7% at 10.7 GHz and with 11.9% at 37 GHz.
E. Santi - One of the best experts on this subject based on the ideXlab platform.
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Global monitoring of hydrological parameters in Africa by using both active and passive Microwave Sensors
2009 IEEE International Geoscience and Remote Sensing Symposium, 2009Co-Authors: S. Paloscia, P. Pampaloni, S. Pettinato, E. Santi, F. Conti, S. De SantisAbstract:The possibility of a global monitoring of hydrological parameters in Africa was endeavored by using both active and passive Microwave Sensors. Two ALOS/PALSAR images of Ethiopia were compared with optical data and ground information collected on site by the Istituto Agronomico per l'Oltremare, in Florence. Moreover, AMSR-E data were used as a reference for investigating soil moisture and vegetation conditions. The brightness temperature and the backscattering coefficient values have been related to land features, obtained from ground data and cartographic and meteorological information.
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Monitoring Snow Cover Characteristics with Multifrequency Active and Passive Microwave Sensors
2006 IEEE International Symposium on Geoscience and Remote Sensing, 2006Co-Authors: M. Brogioni, G. Macelloni, S. Paloscia, P. Pampaloni, S. Pettinato, E. SantiAbstract:The importance of Microwave Sensors in monitoring snow parameters is well recognized. However, several problems are still open regarding the reliability of remote sensing for operational use. In 2002-2005 a series of ERS SAR and ENVISAT ASAR images were collected on the Italian Alps to monitor the temporal evolution of snow cover. In the same time a long sequence of multi-frequency radiometric data was collected with ground based Sensors. The measurements confirmed the potential of Microwave active and passive Sensors in monitoring the extent of wet snow cover and in estimating the liquid water content of wet snow and the snow water equivalent of refrozen snow.
Dennis L. Eggett - One of the best experts on this subject based on the ideXlab platform.
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Use of Hi-resolution data for evaluating accuracy of traffic volume counts collected by Microwave Sensors
Journal of Traffic and Transportation Engineering (English Edition), 2017Co-Authors: David K Chang, Grant G. Schultz, Mitsuru Saito, Dennis L. EggettAbstract:Over the past few years, the Utah Department of Transportation has developed the signal performance metrics (SPMs) system to evaluate the performance of signalized intersections dynamically. This system currently provides data summaries for several performance measures, one of them being turning movement counts collected by Microwave Sensors. As this system became public, there was a need to evaluate the accuracy of the data placed on the SPMs. A large-scale data collection was carried out to meet this need. Vehicles in the Hi-resolution data from Microwave Sensors were matched with the vehicles by ground-truth volume count data. Matching vehicles from the Microwave sensor data and the ground-truth data manually collected required significant effort. A spreadsheet-based data analysis procedure was developed to carry out the task. A mixed model analysis of variance was used to analyze the effects of the factors considered on turning volume count accuracy. The analysis found that approach volume level and number of approach lanes would have significant effect on the accuracy of turning volume counts but the location of the Sensors did not significantly affect the accuracy of turning volume counts. In addition, it was found that the location of lanes in relation to the sensor did not significantly affect the accuracy of lane-by-lane volume counts. This indicated that accuracy analysis could be performed by using total approach volumes without comparing specific turning counts, that is, left-turn, through and right-turn movements. In general, the accuracy of approach volume counts collected by Microwave Sensors were within the margin of error that traffic engineers could accept. The procedure taken to perform the analysis and a summary of accuracy of volume counts for the factor combinations considered are presented in this paper.
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How Accurate Are Turning Volume Counts Collected by Microwave Sensors
International Conference on Transportation and Development 2016, 2016Co-Authors: David K Chang, Grant G. Schultz, Mitsuru Saito, Dennis L. EggettAbstract:The Utah Department of Transportation (UDOT) has recently developed the Signal Performance Metrics System (SPMS) to evaluate the performance of signalized intersections dynamically. This system currently provides data summaries for several performance measures, one of them being turning movement volume counts. As this system became public, there was a need to evaluate the accuracy of the data collected by Microwave Sensors for the SPMS. UDOT considered first that sensor position, number of approach lanes, and volume level would affect the accuracy. Later, speed limit was added as another factor. Data were collected manually and compared with volume count data reported by the system. A mixed model analysis of variance was employed to analyze the effect of each factor on the accuracy of traffic volume counts. The volume level and number of approach lanes factors were found to have a statistically significant effect on the accuracy of traffic volume counts by Microwave Sensors.