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

{"title":"Deployable antenna concepts for the Dark Ages Radio Explorer mission","authors":"D. Sigel, V. Bach, M. Thomson, R. Bradley, L. Amaro, J. Lazio, J. Burns","doi":"10.1109/USNC-URSI-NRSM.2013.6525025","DOIUrl":"https://doi.org/10.1109/USNC-URSI-NRSM.2013.6525025","url":null,"abstract":"The Dark Ages Radio Explorer (DARE) is a concept for a space-based cosmology mission designed to measure the sky-averaged spectrum from the highly-redshifted hyperfine 21 cm transition from neutral hydrogen (J.O. Burns, J. Lazio, et al., Adv. Space Res., 49, 433-450, 2012). From this sky-averaged spectrum, the formation of the first luminous objects at the end of the Dark Ages and during Cosmic Dawn (redshifts z = 11-35) can be tracked by their effect on the neutral intergalactic medium. The specific science objectives for the DARE mission are (1) When did the first stars form? (2) When did the first accreting black holes form? (3) When did Reionization begin? (4) What surprises does the end of the Dark Ages hold (e.g., dark matter decay)? The DARE spacecraft orbits the Moon for a mission lifetime of 3 years and takes data above the lunar farside, the only location in the inner solar system proven to be free of human-generated radio frequency interference and any significant ionosphere.","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":"130245774","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":"Tunable RF filters based on radially loaded evanescent-mode cavity resonators","authors":"A. Anand, J. Small, X. Liu, H. Sigmarsson","doi":"10.1109/USNC-URSI-NRSM.2013.6525080","DOIUrl":"https://doi.org/10.1109/USNC-URSI-NRSM.2013.6525080","url":null,"abstract":"The rapid development in wireless communication technologies has resulted in evermore complex RF and microwave communication systems. A promising solution to these challenges is reconfigurable wireless communication systems whose hardware parameters, such as frequency, bandwidth, power and efficiency, can be changed to make better use of the available spectrum. Tunable filters represent integral and critical components in such systems. In particular, tunable RF bandpass filters can be used for band selection, image rejection, and elimination of out-of-band emissions. Tunable bandstop filters enable dynamic rejection of interferers, thus improving the sensitivity and dynamic range of receiver systems.","PeriodicalId":123571,"journal":{"name":"2013 US National Committee of URSI National Radio Science Meeting (USNC-URSI NRSM)","volume":"33 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":"127084375","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":"Using transient properties of a tunable narrowband antenna to realize a dual-band antenna","authors":"M. Salehi, M. Manteghi","doi":"10.1109/USNC-URSI-NRSM.2013.6525031","DOIUrl":"https://doi.org/10.1109/USNC-URSI-NRSM.2013.6525031","url":null,"abstract":"Switched antennas have been used for wireless communication in order to achieve a direct modulation. A combination of semiconductor switch and a radiating element can be employed to decouple the information bandwidth from the antenna bandwidth. This method allows the system to operate in a wideband range using small and resonant antennas instead of wideband radiators. The first attempt to use a switched antenna to increase the impedance bandwidth was done by Merenda (USA Patent 5402133, March 28, 1995) and there have been several publications afterwards. However, most designs suffer from signal ringing, spurious radiation and high switching rate requirements.","PeriodicalId":123571,"journal":{"name":"2013 US National Committee of URSI National Radio Science Meeting (USNC-URSI NRSM)","volume":"55 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":"133830275","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":"First results from the NCAR 449 MHz, 126-element wind profiler radar","authors":"B. Lindseth, W. Brown, C. Martin, T. Hock, S. Cohn, Z. Popovic","doi":"10.1109/USNC-URSI-NRSM.2013.6524975","DOIUrl":"https://doi.org/10.1109/USNC-URSI-NRSM.2013.6524975","url":null,"abstract":"The National Center for Atmospheric Research (NCAR) Earth Observing Laboratory has recently developed a 449-MHz spaced antenna wind profiler radar. The system is divided into 18-element linearly polarized circular patch antenna subarrays that can be reconfigured. Three of the 18-element subarrays were combined and have been deployed to field projects such as the Persistent Cold-Air Pool Study (PCAPS).","PeriodicalId":123571,"journal":{"name":"2013 US National Committee of URSI National Radio Science Meeting (USNC-URSI NRSM)","volume":"105 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":"132745854","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":"Accurate electromagnetic modeling of melting hail","authors":"E. Chobanyan, J. Notaros, V. Chandrasekar, B. Notaroš","doi":"10.1109/USNC-URSI-NRSM.2013.6525013","DOIUrl":"https://doi.org/10.1109/USNC-URSI-NRSM.2013.6525013","url":null,"abstract":"Analysis of electromagnetic scattering from hailstones has conventionally been done using the T-matrix method. This method, which reduces exactly to the Lorenz-Mie scattering theory when the scattering particle is a homogeneous or layered piecewise homogeneous sphere, worked well so far when we tried to understand the measurements. However the measurements have become fairly sophisticated with many decades of multiple polarization measurements and the current models are not able to explain many of the nuances in the measurements, because the current model is not well suited for analysis of arbitrarily shaped and non-layered particles.","PeriodicalId":123571,"journal":{"name":"2013 US National Committee of URSI National Radio Science Meeting (USNC-URSI NRSM)","volume":"150 2","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-06-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132289173","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":"Phase and pattern calibration of the Jicamarca radar using satellites","authors":"B. Gao, J. Mathews, J. Chau","doi":"10.1109/USNC-URSI-NRSM.2013.6525060","DOIUrl":"https://doi.org/10.1109/USNC-URSI-NRSM.2013.6525060","url":null,"abstract":"Summary form only given. The Jicamarca Radio Observatory (JRO) main 50 MHz radar array antenna system with multiple receivers is being used to study the meteors using various interferometric configurations. In such systems, one of the major challenges is to know the phase offsets between the different receiver (interferometric) channels (legs). Such phase offsets are intrinsic to any such system and are due to different cable lengths, filters, attenuators, amplifiers, antenna impedance, etc. In response to investigating some ambiguous features in meteor head-echo results, we present a “new” calibration technique that employs satellites to produce accurate phase and pattern calibrations. Since the satellite is a point target and its orbit is gravitationally well defined, satellite returns can be used to test characteristics of the JRO interferometry process. In particular, the satellite yields a reliable source for phase and thus trajectory calibration. Using several satellites identified during standard meteor observations, we derive satellite orbital parameters by matching observed and modeled 3-D trajectory and Doppler results. This approach uncovered subtle phase distortions that lead to interferometry derived trajectory distortions that are important only to point targets. Additionally, the accuracy of this approach is such that we can suggest the origin of the phase errors and even adjust the vector orientation of the plane of the antenna array. The basis for this accuracy is the comparison of satellite range, Doppler, and trajectory properties relative to the corresponding gravitation orbit even thought the satellite is observed for only a few seconds. We present the array calibration and radar imaging of satellites results from our 15/16 April 2010 and summer 2012 meteor observations. Future observations of a priori known orbit satellites would likely yield significantly more accurate calibrations.","PeriodicalId":123571,"journal":{"name":"2013 US National Committee of URSI National Radio Science Meeting (USNC-URSI NRSM)","volume":"142 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":"132401099","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":"UTD analysis of foliage penetration for use in propagation modeling","authors":"D. E. Davis, G. Brown","doi":"10.1109/USNC-URSI-NRSM.2013.6525124","DOIUrl":"https://doi.org/10.1109/USNC-URSI-NRSM.2013.6525124","url":null,"abstract":"One of the key challenges in propagation modeling for point-to-point links is including the effects of foliage. Foliage is a volume scatterer and much of the work that has been done on modeling foliage is statistical in manner. However, such statistical models often do not fit easily into existing propagation models. Our past propagation modeling work has used MOMI to solve the scattering from a perfectly conducting or dielectric ground, and volume scattering media do not fit well into the two dimensional integral equation method. Similarly, such volumetric statistical models would not be a good fit for diffraction based propagation models. Thus, we sought a simple continuous medium which might adequately, though not perfectly, match the foliage layer attenuation and reflection.","PeriodicalId":123571,"journal":{"name":"2013 US National Committee of URSI National Radio Science Meeting (USNC-URSI NRSM)","volume":"50 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":"129240363","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":"Studying dipole moment modification in a single fluorescent dye beside metallic Nano-Particle based on the Green's function theory","authors":"F. T. Ladani, C. Guclu, S. Campione, F. Capolino","doi":"10.1109/USNC-URSI-NRSM.2013.6525098","DOIUrl":"https://doi.org/10.1109/USNC-URSI-NRSM.2013.6525098","url":null,"abstract":"Summary form only given. Enhancement of dipolar scattering can be achieved by locating the emitting dipole near a resonant nanosphere. In this study the dipole represents a fluorescent dye or an emitting quantum dot, and the nanosphere exhibits a plasmonic resonance at optical frequencies. It has been shown several times that a dipole excitation and emission can be greatly affected by the presence of a nanosphere at nanomener distance. This was considered for example in (J. Gersten, A. Nitzan, J. Chem. Phys. 73(7), 1980) in the case of Raman scattering, and in many other experimental works. In this paper, we investigate the emission of a fluorescent dye analytically, using the electric dyadic Green's function in a semiclassical electrodynamic model accounting for the nanosphere scattering, which is evaluated according to Mie theory. The dye is modeled as a dipole, illuminated by an incident wave and the one from the nearby nanosphere. We compare our results with previous ones, based on different approximations. More specifically, assuming the dipolar dye is located beside the NP, we analyze when the latter, in turn, modifies the dye dipole moment since the dye has a certain polarizability and hence responds to the local electric field. We report when this contribution is important for the determination of the dye emission rate and scattering. We use the Lorentzian oscillator model for calculating the polarizability of the dye and investigate excitation rate enhancements in various cases. As results show when the polarizability of the dye becomes comparable to that of the plasmonic nanosphere we have to consider the change in the dipole moment of the dye, as in our electrocynamic model.","PeriodicalId":123571,"journal":{"name":"2013 US National Committee of URSI National Radio Science Meeting (USNC-URSI NRSM)","volume":"91 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":"116450433","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":"Nonlinear multi-beam interactions in the D-region ionosphere","authors":"R. Moore, S. Fujimaru, D. Kotovsky","doi":"10.1109/USNC-URSI-NRSM.2013.6525106","DOIUrl":"https://doi.org/10.1109/USNC-URSI-NRSM.2013.6525106","url":null,"abstract":"Summary form only given. This paper presents experimental observations of ELF/VLF wave generation performed during multi-beam HF heating experiments at the High-frequency Active Auroral Research Program (HAARP) observatory. The primary objective of these experiments is to advance the scientific understanding of the nonlinear absorption processes occurring within the collisional D-region ionosphere. During the February, May, and August 2012 HAARP campaigns, a series of multi-beam HF transmissions were designed to produce inter-harmonic modulation products in the ELF/VLF range. Experiments were performed using a variety of simultaneous 2- to 6-frequency HF transmissions spaced at ELF/VLF frequencies. For instance, in order to generate the 3-frequency experiment using frequencies of 3,248,485 Hz, 3,251,515 Hz, and 3,250,200 Hz, one half of the array broadcast a synthesized-two-frequency (STF) modulation format centered on 3.25 MHz (X-mode) with a modulation frequency of 1515 Hz while the other half of the array broadcast CW at 3.250200 MHz (X-mode). In the presence of the auroral electrojet, this transmission format generated ELF/VLF tones at 1315 Hz, and 1715 Hz, and 3030 Hz, as expected. Additionally, in order to generate ELF waves by the cubic nonlinearity, one half of the array broadcast at 2,750,250 Hz while the other half broadcast at 5,499,500 Hz, generating ELF waves at 1000 Hz. These experiment were repeated using different HF frequencies, different modulation frequencies, and different HF power levels. During the May and August 2012 experiments, a frequency-time variation was imposed on the transmissions in order to enable time-of-arrival signal processing. Experimental observations are compared with the initial results of a multi-beam HF heating model that accounts for inter-harmonic mixing among the various field components. We demonstrate that not all observations (particularly those for the cubic nonlinearity generation method) can be explained without accounting for the electron temperature oscillations that occur at the second harmonic of the HF waves.","PeriodicalId":123571,"journal":{"name":"2013 US National Committee of URSI National Radio Science Meeting (USNC-URSI NRSM)","volume":"48 2-3 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":"123460777","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":"Ultrawideband microwave ablation therapy (UMAT)","authors":"E. Topsakal, E. Colebeck, M. Asili, R. Green","doi":"10.1109/USNC-URSI-NRSM.2013.6525130","DOIUrl":"https://doi.org/10.1109/USNC-URSI-NRSM.2013.6525130","url":null,"abstract":"Despite many advantages, there are major problems associated with the current microwave ablation systems. These problems are mainly due to the narrowband nature of the antennas used in these systems. Our data show that although at the start of the ablation procedure more than 90% of the power is transmitted into the tissue due to good antenna-to-tissue impedance matching, as the temperature increases in the tissue, power transmission efficiency drops down to as low as 20%. Such degradation in power delivery creates three major problems: (1) Most of the power is reflected back to the device causing extreme heating and creating unwanted ablation zones beyond the region of interest. Currently, this problem is addressed by cooling the antenna shaft which complicates the probe design and increases the cost. We discuss this issue in detail and provide references in the “background and significance” section. (2) More power from the generator is needed to create the desired ablation zone. Currently, the power levels are as high as 100Watts (W). Our preliminary data suggest that even 20W is enough to create the desired ablation zones with UMAT. (3) Unnecessary increase in ablation time. Total ablation time suffers because of the inefficient power delivery into the tissue.","PeriodicalId":123571,"journal":{"name":"2013 US National Committee of URSI National Radio Science Meeting (USNC-URSI NRSM)","volume":"11 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":"121532458","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}