2013 US National Committee of URSI National Radio Science Meeting (USNC-URSI NRSM)最新文献

{"title":"Beam-plasma interaction and langmuir turbulence","authors":"P. Yoon","doi":"10.1109/USNC-URSI-NRSM.2013.6525044","DOIUrl":"https://doi.org/10.1109/USNC-URSI-NRSM.2013.6525044","url":null,"abstract":"Summary form only given. The Langmuir wave turbulence generated by the electron beam-plasma interaction has been studied since the early days of plasma physics research. In the present talk a number of recent developments in this research topic shall be overviewed. The topics include [1] the problem of suprathermal electron generation by Langmuir turbulence, [2] the generation of electromagnetic radiation during the beam-plasma interaction process, and [3] the spatio-temporal beam and Langmuir turbulence propagation. First, the solar wind electron distribution function measured at 1 AU shows that the observed distribution possesses an energetic power-law tail component. The recent theory of Langmuir turbulence predicts that such an energetic tail distribution can be produced. Upon comparison with observed power-law index, it is found that the theory agrees remarkably well with observation. Second, the solar radio bursts known as type II and type III radio emissions are commonly interpreted in terms of nonlinear conversion of beam-generated Langmuir turbulence into EM radiation at the plasma frequency and its harmonic. However, the actual set of basic plasma turbulence equations that describe such a process has never been fully solved. We have recently begun to address this age-old problem, and we shall report the latest findings. Finally, the spatio-temporal evolution of the electron beam and Langmuir turbulence is of importance in both laboratory as well as space plasmas. This topic may have a direct relevance to ionospheric application, and recent developments in this are shall also be discussed.","PeriodicalId":123571,"journal":{"name":"2013 US National Committee of URSI National Radio Science Meeting (USNC-URSI NRSM)","volume":"29 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-06-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125632848","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":"Parametrization of an anisotropic ocean surface emissivity model based on WindSat polarimetric brightness observations","authors":"D. Smith, A. Gasiewski, S. Sandeep, B. Weber","doi":"10.1109/USNC-URSI-NRSM.2013.6525012","DOIUrl":"https://doi.org/10.1109/USNC-URSI-NRSM.2013.6525012","url":null,"abstract":"The goal of this research has been to develop a standardized fast full-Stokes ocean surface emissivity model with Jacobian for a wind-driven ocean surface applicable at arbitrary microwave frequencies, polarizations, and incidence angles. The model is based on the Ohio State University (OSU) two-scale code for surface emission developed by Johnson (2006, IEEE TGRS, 44, 560) as presented in our 2012 URSI talk. A total of five physical tuning parameters for the model were identified, including the spectral strength and the hydrodynamic modulation factor. The short wave part of the sea surface spectrum is also allowed to have an arbitrary ratio relative to the long wave part. The foam fraction is multiplied by a variable correction factor, and also modulated to allow an anisotropic foam fraction with more foam on the leeward side of a wave.","PeriodicalId":123571,"journal":{"name":"2013 US National Committee of URSI National Radio Science Meeting (USNC-URSI NRSM)","volume":"132 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-06-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131406512","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":"Radio science aspects of radar meteor observations: Where are we?","authors":"J. Mathews","doi":"10.1109/USNC-URSI-NRSM.2013.6525000","DOIUrl":"https://doi.org/10.1109/USNC-URSI-NRSM.2013.6525000","url":null,"abstract":"Detailed understanding of the radio science of (HPLA and “classical”) radar headand trail-echo radar scattering is required to correctly interpret observations. This understanding depends on mutually informed modeling and observation techniques. Observations yield intra-pulse and pulse-to-pulse details of each event that, via modeling, suggests how the plasma surrounding the meteoroid-and that then forms the meteor trail-is generated and evolves. This in turn reveals insight into underlying physical processes such as sputtering, fragmentation, flaring, and terminal processes relative to the more traditional (differential) ablation view of how the meteoroid interacts with the atmosphere. Details of these processes remain a source of controversy demanding further investigation.","PeriodicalId":123571,"journal":{"name":"2013 US National Committee of URSI National Radio Science Meeting (USNC-URSI NRSM)","volume":"31 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-06-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133218345","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":"Feedback calibration of the MOFF correlator","authors":"A. Beardsley","doi":"10.1109/USNC-URSI-NRSM.2013.6525142","DOIUrl":"https://doi.org/10.1109/USNC-URSI-NRSM.2013.6525142","url":null,"abstract":"Summary form only given. Proposed radio arrays to probe the Epoch of Reionization and dark energy through HI 21 cm measurements will require compact arrays with tens of thousands of antenna elements. The computation requirements of traditional XF or FX correlators for these arrays would easily reach the peta-flop regime, making the correlator a dominant cost. The MOFF (Modular Optimal Frequency Fourier) correlator has been developed as an alternative method for fully correlating these large numbers of elements. The MOFF shares the computational advantages of direct imaging or FFT correlators while making no constraints on the antenna arrangement or type. A major concern for this new correlator design is the calibration. In traditional data processing, self-cal or related algorithms use visibilities to determine the calibration during postprocessing. The MOFF correlator does not form visibilities, but rather forms the image directly. In addition the crucial software holography step of the MOFF requires the antenna power patterns to be known in real time to use as the gridding kernel. Fortunately it is possible to determine the calibration by correlating pixels of the electric field image with the antenna signal - feeding the correlator output back to the input. Through simulations we demonstrate this feedback calibration method for several realistic example arrays in the presence of noise and extraneous sources. We show that the calibration converges as expected for compact large-N arrays characteristic of future 21 cm cosmology experiments, allowing the correlator to form high quality dirty electric field images at a fraction of the computational cost for traditional correlator methods.","PeriodicalId":123571,"journal":{"name":"2013 US National Committee of URSI National Radio Science Meeting (USNC-URSI NRSM)","volume":"2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-06-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134156240","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":"DACOTA: The dense array for cosmological transitions","authors":"D. DeBoer, G. Bower, G. Keating, R. Plambeck, Tzu-Ching Chang, P. Ho, D. Marrone, A. Readhead","doi":"10.1109/USNC-URSI-NRSM.2013.6525026","DOIUrl":"https://doi.org/10.1109/USNC-URSI-NRSM.2013.6525026","url":null,"abstract":"The Epoch of Reionization (EoR) heralded the advent of the Universe we recognize today, containing stars, galaxies and super-massive black holes. A number of experiments to detect the red-shifted hydrogen signature of the atomic component of the intergalactic medium (IGM) are on-going (e.g. PAPER, MWA, LOFAR). Due to the faintness of the signal, the bright foregrounds, and the challenge of instrumental systematics, multiple techniques are essential to create a more robust detection and to provide the complete picture on the evolution of early galaxies.","PeriodicalId":123571,"journal":{"name":"2013 US National Committee of URSI National Radio Science Meeting (USNC-URSI NRSM)","volume":"12 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-06-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134477364","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":"Tuning the bandwidth and center frequency of micromechanical acoustic resonators","authors":"R. Olsson, Bongsang Kim, J. Nguyen, P. Clews, T. Pluym, K. Wojciechowski","doi":"10.1109/USNC-URSI-NRSM.2013.6525081","DOIUrl":"https://doi.org/10.1109/USNC-URSI-NRSM.2013.6525081","url":null,"abstract":"As the radio frequency (RF) spectrum has become more crowded, the need for adaptable RF components, especially filters, has grown. Recently, aluminum nitride (AlN) microresonator filters have been reported. These filters/resonators are small (<;1mm3), have the high quality factors (>1000) desired for steep filter roll-off, can achieve many filters covering a very wide frequency span (kHz to GHz) on a single chip and can be monolithically integrated with CMOS transistors for reconfiguring the filter array. Using AlN microresonator on CMOS technology, miniature, adaptable RF filters based on banks of switched filters have recently been reported.","PeriodicalId":123571,"journal":{"name":"2013 US National Committee of URSI National Radio Science Meeting (USNC-URSI NRSM)","volume":"74 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-06-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114543845","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":"Cognitive radio antennas that learn and adapt using Neural Networks","authors":"Y. Tawk, J. Costantine, E. Al-Zuraiqi, C. Christodoulou","doi":"10.1109/USNC-URSI-NRSM.2013.6525110","DOIUrl":"https://doi.org/10.1109/USNC-URSI-NRSM.2013.6525110","url":null,"abstract":"Cognition added to RF/antenna systems has extended software defined radio (SDR) communication systems into cognitive radio systems. Software defined radio has been established as a key enabling technology to realize cognitive radio. Thus a cognitive radio is an SDR that is aware of its environment, and autonomously adjusts its operations to achieve the designated objectives. A cognitive radio system is able to sense, reason, learn and be aware of its environment. A dynamic communication application such as cognitive radio requires antenna researchers to design software controlled reconfigurable antennas. The tuning ability of such antennas and the switching time are important to satisfy the requirements of continuously changing communication channels. Neural Networks (NNs) arose as a perfect candidate to control these antennas through Field Programmable Gate Arrays (FPGAs). NNs represent a perfect solution to add learning and reasoning to the cognitive radio antenna systems. In this work, a NN is applied on a reconfigurable antenna where switches are used to connect and disconnect the different parts of its structure. Reconfigurable antennas are potential candidate for cognitive radio since they are able to change their operating characteristics based on the channel activity. Applying NNs to such antennas result in the association of different antenna configurations with the various frequency responses. This association allows training the NN to be able to configure the antenna and regenerate switch combinations/frequency responses on demand. The NN is built and trained in Matlab Simulink and a Xilinx system generator creates the NN VHDL code to be transferred to the FPGA. The FPGA now controls the switches that are incorporated within the reconfigurable antenna structure. The application of NN on cognitive radio antenna systems allows such systems to react swiftly to any change in their environment. The cognitive radio antennas will regenerate the appropriate switch combinations using NN previous training. This will allow communicating over the unoccupied parts of the spectrum which are called white spaces. The dynamic changes that occur in the spectrum require a robust and fast antenna software control. Thus NN prove to be a valid and necessary technique to employ on CR antennas.","PeriodicalId":123571,"journal":{"name":"2013 US National Committee of URSI National Radio Science Meeting (USNC-URSI NRSM)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-06-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114210337","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":"Full wave EM calculation of polarimetric variables for the atmospheric scatterers with nonspheroidal shape","authors":"D. Mirković, D. Zrnic, A. Ryzhkov","doi":"10.1109/USNC-URSI-NRSM.2013.6525014","DOIUrl":"https://doi.org/10.1109/USNC-URSI-NRSM.2013.6525014","url":null,"abstract":"A model of spheroid is commonly utilized to simulate polarimetric characteristics of natural scatterers in atmosphere such as hydrometeors or biota (birds, insects, bats, etc.) The estimates of polarimetric radar variables are usually obtained using either closed form Rayleigh solutions, if size of particle is much smaller than radar wavelength or T-matrix codes otherwise.","PeriodicalId":123571,"journal":{"name":"2013 US National Committee of URSI National Radio Science Meeting (USNC-URSI NRSM)","volume":"65 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-06-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114580860","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":"Challenge on dielectric and metallic targets recognition for Radio Frequency Tomography","authors":"T. Negishi, V. Picco, D. Erricolo","doi":"10.1109/USNC-URSI-NRSM.2013.6525057","DOIUrl":"https://doi.org/10.1109/USNC-URSI-NRSM.2013.6525057","url":null,"abstract":"In this work, we discuss image reconstruction of metallic and dielectric targets for Radio Frequency (RF) Tomography. RF Tomography for detection of underground targets based on the first order Born approximation is described by L. Lo Monte (L. Lo Monte et al., “Radio Frequency Tomography for Tunnel Detection,” IEEE Trans. Geoscience and Remote Sensing, Vol. 48, No. 3, Mar. 2010, pp. 1128-1137) and it has been experimentally validated at the University of Illinois at Chicago (S. Nishikata et al., “Imaging of dielectric targets using RF Tomography” IEEE International Symposium on Antennas and Propagation and USNC-URSI National Radio Science Meeting, Chicago, IL, July 2012).","PeriodicalId":123571,"journal":{"name":"2013 US National Committee of URSI National Radio Science Meeting (USNC-URSI NRSM)","volume":"8 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-06-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116674729","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":"Precise measurement of the dielectric constant of seawater at 1.413 GHz: The capillary exit hole correction","authors":"R. Lang, Y. Zhou, C. Utku, D. L. Le Vine","doi":"10.1109/USNC-URSI-NRSM.2013.6525120","DOIUrl":"https://doi.org/10.1109/USNC-URSI-NRSM.2013.6525120","url":null,"abstract":"Summary form only given. The effect of the capillary-tube exit holes in the microwave resonant cavity used to measure the dielectric constant of seawater at L-band, is investigated. The cavity technique is a perturbation method that uses the change in the resonant frequency and Q of the cavity when seawater is added to determine the complex dielectric constant of seawater. The tube, through which the seawater is introduced into the cavity, enters through two small center holes in the cavity's endplates. It has been suggested in the literature that these small exit holes could affect the change in the resonant frequency measurement, thus introducing a frequency pulling error into the measurements. Numerical modeling of similar cavities indicates that a frequency pulling effect can occur due to the center holes in the endplates. These simulations indicate that a coaxial TEM-like mode is created in the connector that holds the capillary tube to the endplates. This TEM-like mode reflects from the end of the connector and acts as a resonant circuit. Since the seawater is acting as the center conductor of the TEM guide, the effect should be more noticeable as the conductivity of the seawater increases. The conductivity increases with increasingsalinity and temperature. To see whether the frequency-pulling effect is important, a lossy graphite cylinder with a hole in the center has been inserted into the connector, to attenuate the TEM wave. Measurements for high salinity and high temperatures have been made with and without the graphite cylinder. The results of the measurements will be discussed in this study.","PeriodicalId":123571,"journal":{"name":"2013 US National Committee of URSI National Radio Science Meeting (USNC-URSI NRSM)","volume":"5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-06-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125036197","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}