2014 United States National Committee of URSI National Radio Science Meeting (USNC-URSI NRSM)最新文献

{"title":"2-D radio imaging of ionospheric electron density in the equatorial plane: Algorithms and results","authors":"Kirk Landin, F. Kamalabadi, P. Bernhardt","doi":"10.1109/USNC-URSI-NRSM.2014.6928064","DOIUrl":"https://doi.org/10.1109/USNC-URSI-NRSM.2014.6928064","url":null,"abstract":"Local depletions in the equatorial ionospheric electron density, known as Spread-F events, have been an active area of scientific research in the last decades. These are of special interest to the research community because of their potentially deleterious impact on trans-ionospheric communication links and navigation systems. The impetus for focused modeling and experimentation is the ultimate goal of predicting these events and subsequent mitigation of their negative impacts.","PeriodicalId":277196,"journal":{"name":"2014 United States National Committee of URSI National Radio Science Meeting (USNC-URSI NRSM)","volume":"25 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125075826","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Low profile wide band VHF/UHF antenna","authors":"Gregory A. Mitchell, W. Wasylkiwskyj","doi":"10.1109/USNC-URSI-NRSM.2014.6927979","DOIUrl":"https://doi.org/10.1109/USNC-URSI-NRSM.2014.6927979","url":null,"abstract":"Summary form only given. Many applications in communications and radar require antennas that conform to the surface of the supporting structure. Whenever applicable, the antenna aperture is approximated by a plane with the requirement that the dimension normal to the aperture (“profile”) be minimized. Low profile antennas are of special importance within the VHF/UHF bands where they are used as communications antennas on airborne platforms. In addition to low profiles, these antennas also require wide bandwidths. Meeting both requirements at the long wavelengths involved poses special difficulties. Although the subject of profile reduction for flush mounted antennas is not new, the number of papers dealing specifically with VHF/UHF band designs is surprisingly small. Two recently proposed designs employ variants of a discone antenna.","PeriodicalId":277196,"journal":{"name":"2014 United States National Committee of URSI National Radio Science Meeting (USNC-URSI NRSM)","volume":"26 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126158437","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"LEKID-based instruments for cosmic microwave background polarimetry","authors":"Glenn Jones","doi":"10.1109/USNC-URSI-NRSM.2014.6928109","DOIUrl":"https://doi.org/10.1109/USNC-URSI-NRSM.2014.6928109","url":null,"abstract":"After years of research and development, lumped-element kinetic inductance detectors (LEKIDs) are now competitive with other detector technologies for studying the polarization of the cosmic microwave background (CMB) radiation. One ultimate goal of this effort is the detection of the so-called inflationary B-mode polarization signature, which would yield the most convincing evidence for the theories of inflation and, if detected, would constrain the energy scale of these theories. The B-mode signal is predicted to be extremely small-in the nanokelvin range-requiring excellent sensitivity and exquisite control of systematics.","PeriodicalId":277196,"journal":{"name":"2014 United States National Committee of URSI National Radio Science Meeting (USNC-URSI NRSM)","volume":"433 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123416306","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Ocean salinity from space: Advances and challenges in L-band radiometry","authors":"T. Meissner, F. Wentz, K. Hilburn","doi":"10.1109/USNC-URSI-NRSM.2014.6928051","DOIUrl":"https://doi.org/10.1109/USNC-URSI-NRSM.2014.6928051","url":null,"abstract":"The Aquarius L-band radiometer/scatterometer system is designed to provide monthly salinity maps at 150 km spatial scale to an accuracy of 0.2 psu. The sensor was launched on June 10, 2011, aboard the Argentine CONAE SAC-D spacecraft. The L-band radiometers and the scatterometer have been taking science data observations since August 25, 2011.","PeriodicalId":277196,"journal":{"name":"2014 United States National Committee of URSI National Radio Science Meeting (USNC-URSI NRSM)","volume":"138 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115536571","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Characterization of side mounted vehicular antennas","authors":"Timothy W. Samson, M. Ignatenko, D. Filipović","doi":"10.1109/USNC-URSI-NRSM.2014.6928031","DOIUrl":"https://doi.org/10.1109/USNC-URSI-NRSM.2014.6928031","url":null,"abstract":"Summary form only given. Humvees are typically furnished with a wide range of antenna systems commonly mounted on the roof or bumper of the vehicle. While antennas mounted in these locations may have good performance, they both (roof and bumper) have limited room for additional antennas with new or expanded functionalities. Additionally, the roof- and bumper-based antenna systems may contribute to a large visual profile and may compromise both the mobility and safety of the vehicle. For this reason, it is fortuitous to mount antenna systems in alternative locations on a space constrained vehicle such as Humvee. This paper explores the vehicle and ground effects on the performance of antenna systems mounted on alternative vehicle locations. Moreover, we consider the antennas operating over very wide frequency range, classified under the frequency independent family such as spiral, log-periodic, and sinuous. These antennas are considered for a wide range of applications ranging from communications to jamming. Considering both, these antennas' utility, and ubiquitousness in the field, they make for a prime subject of study for side mounted antennas. This paper focuses primarily on the effects in the VHF/UHF/L-band regions for the mounted antennas over a variety of practical ground compositions. To properly characterize the performance in such a location and over diverse grounds, a variety of parameters are examined using commercially available software tools based on integral and partial differential equation methods. After the discussion of the low and high-complexity models, we evaluate first the vehicle/ground/antenna impact on the electric field at different distances from and around the vehicle in the close proximity to the vehicle itself. This study is especially important for jamming applications. The effect of ground losses on the propagation efficiency of the antenna systems is examined next. Impacts of antenna polarization, proximity to the ground, and pattern shaping are determined. Finally, the depolarization due to ground-based polarization variable losses, scattering from the vehicle body and the ground is explored. This paper shows that the vehicle sides may be considered for mounting various antenna systems operating over wide range of frequencies; however, the design needs to be carefully undertaken to insure that the diverse physics is properly and thoroughly accounted for.","PeriodicalId":277196,"journal":{"name":"2014 United States National Committee of URSI National Radio Science Meeting (USNC-URSI NRSM)","volume":"226 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122692198","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A propagation model for close-in distances and very low antenna heights based on both electromagnetic theory and measured data","authors":"N. DeMinco, P. McKenna, R. Johnk","doi":"10.1109/USNC-URSI-NRSM.2014.6928019","DOIUrl":"https://doi.org/10.1109/USNC-URSI-NRSM.2014.6928019","url":null,"abstract":"Summary form only given. This abstract describes a radio-wave propagation model that was developed at the Institute for Telecommunication Sciences (ITS) as the result of an investigation to create a short-range mobile-to-mobile propagation model. ITS reviewed and evaluated currently available radio-wave propagation models and came to the conclusion that none of these models were suitable for addressing the requirements of ultra-short distances (2 meters to 2 km) and very low antenna heights (1 to 3 meters). The model is valid for frequencies from 150 to 6000 MHz. The combined model that has been developed is based on both analytical calculations from the physics of electromagnetic field theory and actual measurements performed in three vastly different environments: rural, urban low-rise/suburban and dense urban high-rise. The results of the analytical work are available in an ITS report.1 The analytical method involves the calculation of the undisturbed electric field and calculation of the loss based on the amplitude of the electric field as a function of distance, frequency, and the ground constants. The undisturbed field is that electric field produced by a transmitter antenna at different distances and heights above ground without any field-disturbing factors in the proximity of the receiver antenna location. The ITS report shows via numerous examples that for most scenarios the difference between the propagation loss computed by undisturbed electric field method and a more exact theoretical methods is minimal.1 The undisturbed electric field method includes near-field effects, the complex two-ray model, antenna heights, ground constants, antenna near-field and far-field response and the surface wave. The Undisturbed-Field Model can be used for distances out to 2 km. It is particularly applicable for close-in distances less than 30 meters. The combined model is valid out to distances of 2 km. The measurements are pseudo-mobile, since the transmitter location is fixed and the receiver is moved through the environment following a predetermined driving pattern. Environmental clutter in the real environment can give rise to non-line-of-sight conditions in which scattering and diffraction dominate, even for very short path differences. There are two facets of the environmental clutter that contribute to the radio-wave propagation problem. First are the features of the static background, such as buildings, fences, trees and other vegetation, utility poles and wires, signage, etc. Second are the dynamic background features, such as vehicular and pedestrian traffic. This presentation will describe both the analytical model and how the measured data were used to create the combined model to represent a real radio-wave propagation environment. Some of the propagation prediction results for the three different environments will also be presented.","PeriodicalId":277196,"journal":{"name":"2014 United States National Committee of URSI National Radio Science Meeting (USNC-URSI NRSM)","volume":"13 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114154849","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Design and simulation of miniaturized PIFA antenna for biomedical sensors","authors":"Mohannad Alharbi, S. Noghanian","doi":"10.1109/USNC-URSI-NRSM.2014.6927969","DOIUrl":"https://doi.org/10.1109/USNC-URSI-NRSM.2014.6927969","url":null,"abstract":"Dielectric properties (permittivity and conductivity) of biological tissues are interest for biomedical microwave imaging. These properties should be measured in vivo to provide correct images of the tissue. Although there is a significant research done on ex-vivo and in-vitro tissue measurements, the in-vivo measurements have been limited due to the need for surgery or implanted sensors.","PeriodicalId":277196,"journal":{"name":"2014 United States National Committee of URSI National Radio Science Meeting (USNC-URSI NRSM)","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114426552","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Time-domain solution to Maxwell's equations for a lightning dart leader and subsequent return stroke","authors":"E. Thiemann, A. Gasiewski","doi":"10.1109/USNC-URSI-NRSM.2014.6928018","DOIUrl":"https://doi.org/10.1109/USNC-URSI-NRSM.2014.6928018","url":null,"abstract":"Summary form only given. Lightning detection and geolocation networks have found widespread use by the utility, air traffic control and forestry industries as a means of locating strikes and predicting imminent recurrence. Accurate lightning geolocation requires detecting VLF radio emissions at multiple sites using a distributed sensor network with typical baselines exceeding 150 km, along with precision time of arrival estimation to triangulate the origin of a strike. The trend has been towards increasing network accuracy without increasing sensor density by incorporating precision GPS synchronized clocks and faster front-end signal processing. Because lightning radio waveforms evolve as they propagate over a finitely conducting earth, and that measurements for a given strike may have disparate propagation path lengths, accurate models are required to determine waveform fiducials for precise strike location. The transition between the leader phase and return stroke phase may offer such a fiducial and warrants quantitative modeling to improve strike location accuracy. In this study we present an analytic solution to Maxwell's Equations for the lightning leader followed by a novel return stroke model. We model the leader as a downward propagating boxcar function of uniform charge density and constant velocity, and the subsequent return stroke is modeled as an upward propagating boxcar with a time dependent velocity. Charge conservation is applied to ensure self-consistency of the driving current and charge sources, and physical observations are used to support model development. The resulting transient electric and magnetic fields are presented at various distances and delay times and compared with measured waveforms and previously published models.","PeriodicalId":277196,"journal":{"name":"2014 United States National Committee of URSI National Radio Science Meeting (USNC-URSI NRSM)","volume":"41 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128295548","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Investigation of magnetized dusty plasmas in the laboratory and near-earth space environment","authors":"A. Mahmoudian, W. Scales, H. Fu","doi":"10.1109/USNC-URSI-NRSM.2014.6928105","DOIUrl":"https://doi.org/10.1109/USNC-URSI-NRSM.2014.6928105","url":null,"abstract":"The field of dusty plasmas has become a vigorous and established area of research for a number of decades now. In this work, two computational models are mainly developed to study possible plasma turbulence during the charged aerosol release experiments in space plasmas. Meanwhile, its applications for magnetized dusty plasmas for complex plasma research with upcoming experiment facilities at Auburn University is considered. Two new hybrid and full fluid two-dimensional computational models have been developed to investigate instabilities in nonuniform magnetized dusty plasmas. The magnetic fields have been applied to study the effect on plasma wave excitation.","PeriodicalId":277196,"journal":{"name":"2014 United States National Committee of URSI National Radio Science Meeting (USNC-URSI NRSM)","volume":"77 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114867742","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Super-enhanced optical energy concentration through a subwavelength aperture using a photonic nanojet","authors":"M. Hasan, J. Simpson","doi":"10.1109/USNC-URSI-NRSM.2014.6928009","DOIUrl":"https://doi.org/10.1109/USNC-URSI-NRSM.2014.6928009","url":null,"abstract":"Summary fom only given. Optical transmission through resonant subwavelength apertures in optically thick metal films have received an explosion of interest for their ability to overcome the diffraction limit of light and concentrate light efficiently into a subwavelength volume. This achievement has attracted the use of subwavelength apertures in numerous applications, i.e. in near-field optical microscopy, fluorescence correlation spectroscopy, nanoscale optical recording, optical lithography, ultra small photodetectors, novel nanoscale light source, and nonlinear optical processes, etc. In a separate line of research, photonic nanojets have been discovered and proposed for a number of applications ranging from optical data disk storage to high-speed photodetectors. A photonic nanojet is a sub-wavelength (as small as λ/3) narrow electromagnetic beam that can propagate multiple wavelengths from the shadow-side surface of a dielectric sphere. We present here a means to significantly compress the transverse width of a photonic nanojet by placing a plasmonic nano-aperture in its path. Three-dimensional (3-D) finite-difference time-domain (FDTD) modeling is used to demonstrate the superenhanced optical energy concentration capability of the photonic nanojet nano-aperture light-collection system. Specifically, 3-D FDTD results demonstrate that a gold nano-aperture illuminated by a nanojet compresses the nanojet from λ/3 to λ/6, which corresponds for an incident wavelength, λ = 633 nm to a reduction of the intensity full-width at half-maximum (FWHM) from ~ 220 nm to ~ 140 nm. Further, we achieve an absorption enhancement factor of nearly 350 in a subwavelength volume of 0.004 μm3 on the shadow-side of the gold nano-aperture for an incident wavelength, λ of 633 nm. The superenhanced, subwavelength concentration of light is achieved for both resonant and non-resonant plasmonic nano-apertures. This phenomenon may find utility in a wide range of applications, such as high-speed photodetectors, optical data storage, optical lithography, near-field optical microscopy, novel nanoscale light source, localized detection of embedded ultrasubwavelength inhomogeneity, fluorescence correlation spectroscopy, biosensors, etc.","PeriodicalId":277196,"journal":{"name":"2014 United States National Committee of URSI National Radio Science Meeting (USNC-URSI NRSM)","volume":"57 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124147007","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}