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

{"title":"Reduced turbulent mixing in a mesoscale NWP model for radar propagation forecasting","authors":"S. Fox","doi":"10.1109/USNC-URSI-NRSM.2013.6525088","DOIUrl":"https://doi.org/10.1109/USNC-URSI-NRSM.2013.6525088","url":null,"abstract":"The effect of the atmosphere on radar coverage in complex coastal environments is of great importance in many naval applications. Variations in atmospheric refractivity driven by vertical gradients of temperature and moisture can significantly enhance or reduce the range at which a particular target may be detected. Mesoscale Numerical Weather Prediction (NWP) models can be used to predict the spatial and temporal variation of atmospheric refractivity fields, which form the basis for forecasting radar coverage patterns.","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":"128755957","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":"Higher order volume and surface integral equation modeling of 3-D scattering and radiation problems","authors":"E. Chobanyan, M. Ilić, B. Notaroš","doi":"10.1109/USNC-URSI-NRSM.2013.6525072","DOIUrl":"https://doi.org/10.1109/USNC-URSI-NRSM.2013.6525072","url":null,"abstract":"The method of moments (MoM), as one of the most powerful and versatile general numerical tools for electromagnetic-field computations based on discretizing integral equations in electromagnetics, has been especially effectively used for full-wave three-dimensional (3-D) solutions to open-region (e.g., scattering and radiation) problems in the frequency domain. In the MoM analysis in conjunction with the volume integral equation (VIE) approach, the volume equivalence principle is invoked to represent a scattering or radiation structure containing linear dielectric materials of arbitrary inhomogeneity and complexity by a distribution of volume electric (polarization and conduction) currents (the real currents) radiating in free space, and the resulting VIE, with the total volume current density vector, or another vector proportional to it, as unknown quantity, is discretized by the MoM. The analysis of composite dielectric and metallic radiation/scattering structures can be performed combining the VIE for dielectric parts and the surface integral equation (SIE) based on the boundary condition for the electric field intensity vector for metallic parts, with surface electric currents (again, the actual currents) treated as an unknown quantity. This gives rise to a hybrid VIE-SIE or VSIE formulation, which solves simultaneously for the volume currents throughout the dielectric domains and the surface currents over the metallic surfaces.","PeriodicalId":123571,"journal":{"name":"2013 US National Committee of URSI National Radio Science Meeting (USNC-URSI NRSM)","volume":"43 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":"126044883","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 surface wind vector measurements from high-altitude aircraft using GPS delay-doppler maps","authors":"V. Zavorotny, E. Valencia, D. Akos, Adriano Camps","doi":"10.1109/USNC-URSI-NRSM.2013.6525021","DOIUrl":"https://doi.org/10.1109/USNC-URSI-NRSM.2013.6525021","url":null,"abstract":"Reflectometry of opportunity signals such as Global Positioning Satellites System, known as GNSS-R, has been developed in the last years as a technique with a great potential for ocean scatterometry, among other applications. Different approaches have been proposed to use GNSS-R for remote sensing of the ocean surface roughness. One of them is based on deriving some descriptor/metric from the measured delay-Doppler map (DDM) and directly relating it to a geophysical property of the scattering surface. For instance, different descriptors have been proposed in the literature to measure the DDM spreading caused by increase in ocean surface mean square slopes due to surface winds.","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":"131099952","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":"L band ionosphere scintillation impact on GNSS receivers","authors":"Y. Morton, S. Taylor, Jun Wang, Y. Jiao, W. Pelgrum","doi":"10.1109/USNC-URSI-NRSM.2013.6525119","DOIUrl":"https://doi.org/10.1109/USNC-URSI-NRSM.2013.6525119","url":null,"abstract":"Ionosphere scintillation is a natural interference encountered by RF signals propagating through the ionosphere. It can affect the performance of Global Navigation Satellite Systems (GNSS) signals and receivers. Since 2009, our research team has established several ionosphere scintillation monitoring and data collection system in Alaska, Singapore, and Hong Kong to collect both naturally occurring and artificially controlled L band scintillation data. As we enter the current solar maximum period, these data has provided us with a good opportunity to obtain statistical impact of high-latitude and equatorial scintillations on GNSS receivers.This paper presents the analysis results based on measurements obtained from a GNSS array in HAARP, AK and commercial receiver measurements from Singapore and Hong Kong. For the HAARP, AK setup, scintillation event triggers have been implemented to initialize RF front ends data recording systems during strong scintillations. A conservative event filter was created to allow us to extract all scintillation events with amplitude scintillation index S4 greater than 0.12 and phase standard deviation sigma phi greater than 6 degrees [3]. The low filter cutoff values are set to automatically flag both strong and weak scintillation events for further analysis. We are interested in both strong and weak scintillation because strong scintillation events have major impact on robustness of GNSS receiver operation, while the weak events are good indicators of ionosphere irregularities occurrence and plasma drift.","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":"130669008","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 lower bound of antenna efficiency based on the two-port model: How close is it?","authors":"J. Coder, M. Gołkowski, J. Ladbury","doi":"10.1109/USNC-URSI-NRSM.2013.6525048","DOIUrl":"https://doi.org/10.1109/USNC-URSI-NRSM.2013.6525048","url":null,"abstract":"The passive, unknown two-port antenna model that has been recently developed is used to investigate the loss and mismatch characteristics of an antenna. Previous work has shown that the two-port antenna model can be used to determine a lower bound of the antenna's transmitting efficiency with data taken from a single antenna in a reverberation chamber. The limit of this calculation is that it relies on assumptions made in the two-port antenna model and provides only a lower bound of the antenna's efficiency. One of the necessary assumptions is that the stirrer in the reverberation chamber is perfectly reflecting for at least a few positions.","PeriodicalId":123571,"journal":{"name":"2013 US National Committee of URSI National Radio Science Meeting (USNC-URSI NRSM)","volume":"22 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":"126720181","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":"Exploiting HF ambient noise to synchronize distributed receivers","authors":"D. Hong, J. Krolik","doi":"10.1109/USNC-URSI-NRSM.2013.6525144","DOIUrl":"https://doi.org/10.1109/USNC-URSI-NRSM.2013.6525144","url":null,"abstract":"Coherent processing of data from distributed HF receivers requires the receivers to be synchronized to an accuracy within fractions of a wavelength. The HF band extends from 3 MHz to 30 MHz and has wavelengths corresponding to time delays ranging from approximately 33 ns to 333 ns. Thus the receivers must be synchronized to within a few nanoseconds. This is typically beyond the capabilities of even GPS-disciplined oscillators. Traditional clock synchronization methods require distributing a common reference signal to all the receivers, either by cables or by using a local reference transmitter. Both these approaches introduce extra cost and complexity. In this paper, we present an approach for clock synchronization which uses the coherent component of wideband ambient HF background noise to estimate time delays between receivers. The approach exploits the flexibility of inexpensive broadband direct-conversion digital receivers in the 3 - 30 MHz band. Two techniques are presented for measuring time delays between receivers: 1) Time-domain Green's Function estimator based on an approach recently used in underwater acoustics, and 2) an optimal Maximum Likelihood (ML) estimator. Both estimators are shown to choose the maximum of particular generalized cross correlations. The Camer-Rao Lower Bound (CRLB) for time delay estimation from ambient noise is also derived and simulation results are presented that demonstrate the performance of the estimators. For low signal to noise ratio (SNR) or low time-bandwidth product (TBP), the estimators do not achieve the CRLB due to peak ambiguities in the generalized cross correlations. However, for sufficiently large SNR and TBP, we demonstrate that the ML estimator is able to overcome the peak ambiguities and achieve the CRLB. In this case, the ML estimator is able to achieve sub-nanosecond RMS delay errors using a 2.5 s observation of 2 MHz bandwidth isotropic HF ambient noise. Thus the ML estimator is the preferred method for synchronizing the distributed receivers.","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":"117235207","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":"Bandwidth enhancement of iron slot antenna with Reactive Impedance layer","authors":"Y. Koo, A. Fathy","doi":"10.1109/USNC-URSI-NRSM.2013.6525083","DOIUrl":"https://doi.org/10.1109/USNC-URSI-NRSM.2013.6525083","url":null,"abstract":"Summary form only given. Many planar antennas have been proposed for UWB system. The slot antenna is widely sought of for UWB applications. Various types of slot antennas have been recommended; such as circular, square, elliptical slot and different tuning stubs of rectangular, circular, and tapered shapes have been implemented for enhancing the bandwidth of antennas (Rezaul Azim, Mohammad Tariqul Islam, Norbahiah Misran, IEEE Antennas and Wireless Propagation Letters, Vol. 10, 2011). In addition, adding a surface with reactive impedance could help as well to widen the bandwidth. Compared to the bandwidth of a planar monopole antenna, typically, the bandwidth of a slot antenna is relatively narrower. However, the benefits of slot antenna include stable bi-directional radiation pattern and gain flatness over the band. Recently, we successfully developed an iron shaped slot antenna with a fork shaped tuning stub with a very wide bandwidth. The design has been developed and fabricated on FR4 substrate with a thickness of 1.57 mm and . The overall dimension of the antenna is 100 × 100 mm2. The experiment showed that the proposed antenna achieves a good impedance match, a constant gain and stable radiation pattern in the range of 0.85 to 3.0GHz (i.e. 3.5:1). Further bandwidth enhancement has been achieved using Reactive Impedance Layers (RILs) on top of slots antennas (Hossein Mosallaei, and Kamal Sarabandi, IEEE Transactions of Antennas and Propagation, Vol, 52, No. 9, Sept 2004). These layers are comprised of periodic either spirals, or split ring resonators (SRRs), or squares, etc. Generally, the period of the unit cell of the RILs is relatively small (<; 0.5λ) which would degrade the bandwidth, but in our implementation, we utilized a wider period of the RIL to keep the original bandwidth and to enhance the upper frequency range. The newly developed iron slot antenna with RIL with a periodic spiral layer of > 0.9λ spacing, demonstrated a slightly wider bandwidth from 0.81 to 3.29 GHz, which is 4:1 with almost the same gain of 6.5±0.5dB over the band.","PeriodicalId":123571,"journal":{"name":"2013 US National Committee of URSI National Radio Science Meeting (USNC-URSI NRSM)","volume":"22 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":"127955302","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":"Antenna design for microwave cancer ablation of osteosarcoma","authors":"E. Gamez, A. Rajagopalan, D. Furgeson, G. Lazzi","doi":"10.1109/USNC-URSI-NRSM.2013.6525128","DOIUrl":"https://doi.org/10.1109/USNC-URSI-NRSM.2013.6525128","url":null,"abstract":"Summery: Osteosarcoma is the most common primary malignant bone cancer in children. Because it usually develops from osteoblast (cells responsible for bone growth) it most commonly affects individuals between 10 and 25 years of age. This type of cancer often occurs in the long bones of the arms and legs at areas of rapid growth around the knees and shoulders. It is often very aggressive with risk of spread to the lungs. The five-year survival rate for osteosarcoma is approximately 65%. Among the different medical procedures being developed to treat tumors, microwave ablation stands out as one of the most promising. Some of the advantages offered by this technique over traditional treatments are: it requires minimal invasiveness; it localizes treatment to the affected area; it can be indicated for patients that cannot undergo surgery, drug treatments or chemotherapy; it provides fast treatments and healing times. The main types of microwave ablation applicators are: superficial and interstitial. Interstitial microwave ablation applicators are coaxial-based antennas like cap-choke, monopoles and dipoles. These applicators have the disadvantage of producing small ablation areas and requiring insertion into the tumor under treatment. Superficial applicators on the other hand do not require insertion but are large and produce unwanted heating on the healthy tissues surrounding the tumor. The disadvantages mentioned before demonstrate that traditional microwave ablation applicators are not suited to treat osteosarcoma. Typically osteosarcoma develops into large tumors that due to their size and shape cannot be treated effectively by traditional applicators. Additionally the theory behind microwave ablation applicators has being developed for soft tissues (skin, blood, muscle). These tissues have electrical properties that differ significantly from the properties of the hard tissues (bone cortical, bone marrow, bone cancellous) from which osteosarcoma develops. In this work we show the design of microwave applicators that can treat osteosarcoma effectively. The performance of these applicators is demonstrated through numerical simulations of the absorbed power and temperature increase, which were computed using FDTD and the Bio-Heat equation.","PeriodicalId":123571,"journal":{"name":"2013 US National Committee of URSI National Radio Science Meeting (USNC-URSI NRSM)","volume":"107 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":"131881665","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":"Resonant patch antennas on spherical ground planes and the need for fractional order associated legendre functions","authors":"S. Weiss","doi":"10.1109/USNC-URSI-NRSM.2013.6524980","DOIUrl":"https://doi.org/10.1109/USNC-URSI-NRSM.2013.6524980","url":null,"abstract":"Summary form only given. The traditional cavity model has been a valuable tool for the estimation of resonant modes of patch antennas since its inception nearly 30 years ago. This model is frequently used for planar antenna structures having canonical shapes in Cartesian, cylindrical, and elliptical coordinates. However, there is no limitation on the cavity model that requires the ground plane to be planar. As such, the cavity model can be useful for determining resonant modes of patch antennas having canonical shapes in spherical coordinates on a spherical ground plane. Indeed, the resonant modes readily follow by solving for the internal fields (underneath the patch) with the presumption of fictitious magnetic walls around the perimeter of the patch and electric walls on the top and bottom. Using a classical TE/TM decomposition of the fields, the resonant modes may be found.","PeriodicalId":123571,"journal":{"name":"2013 US National Committee of URSI National Radio Science Meeting (USNC-URSI NRSM)","volume":"17 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":"131170224","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 compact 118GHz radiometer for the Micro-sized Microwave Atmospheric Satellite (MicroMAS)1","authors":"I. Osaretin, W. Blackwell, G. Allen, S. Conrad, C. Galbraith, R. Leslie, W. Osborn, B. Reid, L. Retherford, M. Scarito, C. Semisch, M. Shields, E. Thompson, D. Toher, D. Townzen, R. Wezalis, K. Wight, N. Erickson","doi":"10.1109/USNC-URSI-NRSM.2013.6525009","DOIUrl":"https://doi.org/10.1109/USNC-URSI-NRSM.2013.6525009","url":null,"abstract":"Summary form only given. A novel compact radiometer observing nine channels near the 118.75GHz oxygen absorption line is introduced. The radiometer is designed as the payload for the Micro-sized Microwave Atmospheric Satellite (MicroMAS). MicroMAS is a dual-spinning 3U CubeSat that aims to address the need for low-cost, mission-flexible, and rapidly deployable spaceborne sensors. The focus of the current MicroMAS mission is to observe convective thunderstorms, tropical cyclones, and hurricanes from a near-equatorial orbit. As a low cost platform, MicroMAS offers the potential to deploy multiple satellites, in a constellation, that can provide near-continuous views of severe weather. The existing architecture of few, high-cost platforms, infrequently view the same earth area which can miss rapid changes in the strength and direction of evolving storms thus degrading forecast accuracy. MicroMAS is a scalable CubeSat-based system that will pave the path towards improved revisit rates over critical earth regions, and achieve state-of-the-art performance relative to current systems with respect to spatial, spectral, and radiometric resolution. The current MicroMAS mission will demonstrate the viability of CubeSats for high-fidelity environmental monitoring and space control that would provide profound advances by reducing costs, by at least an order of magnitude, while increasing robustness to launch and sensor failures. This discourse focuses on the compact radiometer designed for this CubeSat mission. The radiometer is housed in a 1U (10 × 10 × 10 cm) payload section of the 3U (10 × 10 × 30 cm) MicroMAS CubeSat. The payload is scanned about the spacecraft's velocity vector as the spacecraft orbits the earth, creating crosstrack scans across the earth's surface. The first portion of the radiometer comprises a horn-fed reflector antenna, with a full-width at half-maximum (FWHM) beamwidth of 2.4°. Hence, the scanned beam has an approximate footprint diameter of 20Km at nadir incidence from a nominal altitude of 500Km. The antenna system is designed for a minimum 95% beam efficiency. The next stage of the radiometer consists of superheterodyne front-end receiver electronics with single sideband (SSB) operation. The front-end electronics includes an RF preamplifier module, a mixer module, and a local oscillator (LO). The RF preamplifier module contains a low noise RF amplifier and a weakly coupled noise diode for radiometric calibration. The mixer module comprises a HEMT diode mixer and an IF preamplifier MMIC. The LO is obtained using a 30GHz dielectric resonant oscillator (DRO) and a resistive diode tripler to obtain a 90GHz LO frequency. A key technology development in the MicroMAS radiometer system is the ultra-compact intermediate frequency processor (IFP) module for channelization, detection, and analog-to-digital conversion. The antenna system, RF front-end electronics, and backend IF electronics are highly integrated, miniaturized, and optimized ","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":"132913131","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}