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

{"title":"Loop-type electrically small antenna loaded with non-foster circuit","authors":"A. Elfrgani, R. Rojas","doi":"10.1109/USNC-URSI-NRSM.2014.6927986","DOIUrl":"https://doi.org/10.1109/USNC-URSI-NRSM.2014.6927986","url":null,"abstract":"Although electrically small antennas (ESAs) have gotten an increase attention because of their wide applications in wireless communications, they are not efficient radiators because of their high quality factor (Q). Therefore, matching networks are required to improve their input impedance and radiation characteristics. However, due to gain-bandwidth restrictions, wideband matching cannot be achieved using passive networks. Non-Foster circuits (NFCs), such as negative capacitors, negative inductors, or some of their combinations, are attractive because they can be used in matching ESAs since they violate the gain-bandwidth limitation. Although NFCs are very attractive for microwave and antenna applications, they are active nonlinear circuits and therefore suffer from many issues including losses, difficulty in achieving good performance in the gigahertz frequency range, and most important, stability.","PeriodicalId":277196,"journal":{"name":"2014 United States National Committee of URSI National Radio Science Meeting (USNC-URSI NRSM)","volume":"3 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":"125406432","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":"The effect of feeding techniques on the bandwidth of millimeter-wave patch antenna arrays","authors":"F. Ayoub, C. Christodoulou, Y. Tawk, J. Costantine, S. Hemmady","doi":"10.1109/USNC-URSI-NRSM.2014.6927954","DOIUrl":"https://doi.org/10.1109/USNC-URSI-NRSM.2014.6927954","url":null,"abstract":"Antenna design at E-band frequencies is recently gaining more interest with the development of automotive radar applications and with research focusing on the possibility of using this frequency band for cell phone and data communication. At E-band frequencies, typical coaxial connectors cannot be used to feed printed antennas because their operation is limited to frequencies below 26.5 GHz. The use of other feeding techniques is needed. This paper discusses the effect of two different feeding techniques on the bandwidth of an array of rectangular patches used for automotive radar applications. The first feeding technique uses an RF-Probe which will be mounted on a transition from a grounded CPW (GCPW) to a microstrip line. The second feeding technique uses a rectangular waveguide to microstrip line transition. Both feeding techniques designs are easy to fabricate and do not incorporate any via holes connecting the upper ground plane to the lower ground plane. The array designed to test the differences caused by the feeding techniques consists of 64 elements of rectangular patches, with inset feeds, radiating at a center frequency of 73 GHz. A corporate feed is used to feed the elements of the array in phase. Both feeding techniques are used for comparison. It is shown that the bandwidth of the antenna array fed using GCPW is 3.75 GHz while it is 800 MHz for an antenna array fed using a rectangular waveguide (WR-12). Thus, feeding with an RF probe allows the array to exhibit a bandwidth that is 4.6875 times greater than the bandwidth of the antenna array fed using a rectangular waveguide (WR-12). The difference in the gain between the two arrays is negligible. The radiation pattern exhibits two main lobes in the 45o direction in the E-plane in both designs. The implementation and testing of the waveguide feeding technique is carried out at 34 GHz and show good agreement with simulated results.","PeriodicalId":277196,"journal":{"name":"2014 United States National Committee of URSI National Radio Science Meeting (USNC-URSI NRSM)","volume":"218 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":"122391779","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":"Measurement of sensitive current and charge motion using coherent averaging of remote low frequency magnetic field observations","authors":"J. Weinert, S. Cummer","doi":"10.1109/USNC-URSI-NRSM.2014.6928015","DOIUrl":"https://doi.org/10.1109/USNC-URSI-NRSM.2014.6928015","url":null,"abstract":"Summary form only given. Measuring lightning charge transfer, especially on time scales longer than several milliseconds, is a challenge. Instrumented towers can measure this quantity precisely but only for a tiny fraction of cloud-to-ground lightning. Electrostatic field measurements of lightning signals can provide robust estimates of this quantity, but the fast decay with distance of the electric field limits the measurement range to roughly 100 km at best. In contrast, low frequency and nearly-static magnetic fields from slowly varying lightning current decay much more slowly with distance and can therefore be measured at very long ranges. By measuring these low frequency magnetic fields, it is possible to broaden the geographic reach of lightning charge measurements. Sensitivity and noise, however, often limit these measurements to very large charge transfer lightning.Using data collected via search coil magnetic field sensors, we show how time-aligned coherent summation of many signals from lightning in a small geographic window can dramatically reduce the noise and thus enable the measurement of average (not individual) lightning currents and charge motion with very high precision and sensitivity. These average values (especially for long continuing currents) are often below the noise floor of remote measurement systems, especially for systems operating at long ranges (thousands of km) from the individual lightning events. Furthermore, by calculating averages over many thousands of lightning events, it is possible to achieve robust averages of different types of lightning under different storm conditions. Increasing the number of events analyzed further decreases the average noise received by the system, thus yielding improved results.","PeriodicalId":277196,"journal":{"name":"2014 United States National Committee of URSI National Radio Science Meeting (USNC-URSI NRSM)","volume":"201 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":"122458192","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":"Computer simulations driving improved implementation of Optical Projection Tomographic Microscopy","authors":"R. L. Coe, E. Seibel","doi":"10.1109/USNC-URSI-NRSM.2014.6927998","DOIUrl":"https://doi.org/10.1109/USNC-URSI-NRSM.2014.6927998","url":null,"abstract":"Summary form only given. Lung cancer is the leading cause of cancer related deaths worldwide with approximately 1.37 millions deaths per year. In July 2013, the U.S. Preventative Servies Task Force approved low-dose Computed Tomography (CT) for early detection of lung cancer in heavy smokers, however its potential implementation is hindered by safety concerns due to its use of radiation and its overall cost to the healthcare system. Low-dose CT is also only capable of detecting masses greater than 2mm in diameter, which could hinder physicians ability to detect and effectively treat the cancer. In an effort to perform early detection before masses are visible, VisionGate Inc. is developing a microscope based on Optical Projection Tomographic Microscopy (OPTM) to detect cancer at the cellular level. OPTM reconstructs threedimensional images of single cells from projection images acquired from different perspectives around the cell. This presentation will provide an overview of efforts performed in our lab to develop a computer simulation of OPTM. This simulation is designed to analyze all aspects of OPTM image formation, such as degree of specimen staining, refractive index matching, and objective scanning. The computer simulation is used in conjunction with experimental methods to refine conclusions and improve system design in a robust methodology. While this work is currently driving improved microscope design, in the long term it will provide a framework to develop quantitative microscopy where pixel values are directly related to cellular optical properties. These improvements will provide improved sensitivity and specificity for early detection and ultimately reduce lung cancer mortality. These benefits will be further bolstered by its ability to mitigate the impact of cost and radiation concerns inherent in low-dose CT screening.","PeriodicalId":277196,"journal":{"name":"2014 United States National Committee of URSI National Radio Science Meeting (USNC-URSI NRSM)","volume":"22 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":"132013505","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":"Three-dimensional ionosphere tomography with GPS-TEC from GEONET in Japan","authors":"M. Yamamoto, Gopi Seemala, Chia‐Hung Chen, A. Saito","doi":"10.1109/URSIGASS.2014.6929753","DOIUrl":"https://doi.org/10.1109/URSIGASS.2014.6929753","url":null,"abstract":"Measurement of ionospheric total electron content (TEC) by using the ground-based GPS receivers is now widely used. We can refer to it as GPS-TEC. As there are always several GPS satellites available for the measurement, it is a very good tool for constant monitoring of the ionosphere. One of the most dense and wide network of the GPS network is GEONET operated by Geospatial Information Authority of Japan (GSI). This is the network of more than 1000 points over the whole Japan with averaged spatial resolution of 25km. The GPS-TEC from the GEONET of every 30s is used for studies of ionospheric disturbances (e.g., [1] [2]). This paper reports three dimensional ionospheric tomography based on this database. We developed a way to solve the tomography equation by using the constrained least-squares fitting method. This technique is different from most other tomography solvers in the sense that it does not require the initial guess of plasma density at the beginning of calculations. Three dimensional plasma density distribution over Japan is determined to minimize the cost function that is defined as summation of “sum of squared error between model and observation” which is normal in the least-squares method, and the weight. The weight term is selected as summation of density differences with 6 neighboring cells around each grid point. We also need to modify “restrained parameter” to balance importance of these two terms. After development of several years we have reached a good level. In the presentation, we will show the tomography technique and results of calculation with the model and the real GPS-TEC data, and discuss possibility of 3D monitoring of the ionosphere by using this technique.","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":"133518386","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":"Transistor-embedded acousto-optic and nonlinear metamaterials","authors":"A. Katko, S. Cummer","doi":"10.1109/USNC-URSI-NRSM.2014.6927966","DOIUrl":"https://doi.org/10.1109/USNC-URSI-NRSM.2014.6927966","url":null,"abstract":"Summary form only given. We present experimental results showing the application of transistor-embedded metamaterials to realize nonlinear and acousto-optic metamaterials. Due to their nonlinear properties, transistors can be used to realize a large variety of useful radio frequency (RF) functions and applications. These include switches, oscillators, amplifiers, tunable resistors and capacitors, and other devices. Metamaterials provide a natural platform for embedding circuit elements at RF to implement useful functionality. The useful properties of transistors can be exploited by embedding transistors within metamaterial unit cells. We will demonstrate how transistors allow the realization of acousto-optic and nonlinear metamaterials. Transistors can be biased to operate in a number of regimes. For this work we focus on the linear regime of the transistor. In this bias range, we can consider the transistor to act as a controllable resistor in parallel with a capacitor, with tuning provided by a bias on the gate of the transistor. Embedding this within a metamaterial allows us to dynamically tune the resonant frequency and quality factor (Q) of the metamaterial by altering the gate bias of the transistor. By using an AC gate bias to tune the transistor, we can construct a nonlinear metamaterial. We demonstrate its nonlinearity by using the metamaterial as a mixer. An acoustic signal incident on a transducer such as a piezoelectric membrane or microphone produces an AC voltage. We apply this voltage to the transistor bias. An incident acoustic signal will modulate the resonant frequency or Q of the metamaterial. We construct a wireless acousto-optic modulator using the nonlinear acousto-optic metamaterial and experimentally demonstrate its efficacy.","PeriodicalId":277196,"journal":{"name":"2014 United States National Committee of URSI National Radio Science Meeting (USNC-URSI NRSM)","volume":"19 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":"116146745","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":"Spectrum congestion - Is it a technical problem?","authors":"Stephen Berger","doi":"10.1109/USNC-URSI-NRSM.2014.6928004","DOIUrl":"https://doi.org/10.1109/USNC-URSI-NRSM.2014.6928004","url":null,"abstract":"Summary form only given. Recent measurements find that 80% of WiFi devices crowd into the 2.4 GHz band, ignoring the greater bandwidth and reduced congestions available in the 5.8 GHz band. Even worse, within the 2.4 GHz band a few channels carry the majority of the traffic. This spectral crowding makes no technical sense when there are other channels and far less congested bandwidth available to these devices. The trend to congregate is observed with medical devices, which have expanded options and a clear mandate for reliability. Medical devices even have dedicated frequency bands, however, they concentrate on the most popular and crowded bands, along with a wide range of consumer devices. This paper will report the data that these statements are based on. It will then offer the hypothesis that the determinative factors in RF protocol and operating band are not technical but economic, psychological and sociological. The decisions on RF protocols and operating band are predetermined by hiring and management practices, performance metrics and rewards. This hypothesis leads to the conclusion that until these dynamics can be aligned with the need for improved spectral utilization. The first solution to improve spectral congestion is one which results in a correlation between product development and business practices with the requirements of improved spectral utilization efficiency. The paper will conclude by an analysis of the UPCS band, which has developed in a counter-trend fashion. By studying this exception to the dominant trend important insights may be gained on how device utilization of spectrum might be more effectively spread and spectral crowding reduced.","PeriodicalId":277196,"journal":{"name":"2014 United States National Committee of URSI National Radio Science Meeting (USNC-URSI NRSM)","volume":"95 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":"116258321","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":"Superquadric shaped nano-pillars for improved electromagnetic absorption in nano-structured solar cells","authors":"T. Brockett, Y. Rahmat-Samii","doi":"10.1109/USNC-URSI-NRSM.2014.6927967","DOIUrl":"https://doi.org/10.1109/USNC-URSI-NRSM.2014.6927967","url":null,"abstract":"Increasing the absorption efficiency is one of the key tasks towards maximizing the overall solar cell efficiency which is a product of absorption efficiency, carrier generation efficiency, and carrier extraction efficiency. It has been shown that nano-pillar array photovoltaic (PV) solar cells exhibit increased electromagnetic absorption in comparison to conventional flat solar cells. Furthermore, shaped nano-pillars, such as nano-conic and nano-pyramid arrays have better broadband properties than nano-pillar arrays. This can be potentially attributed to better matching between free-space region and the nano-structured array region, reducing inherent reflection from the surface. It was determined that a superquadric function could serve this purpose. This function, applied to the edge of the nano-pillars, allows the shape of the nanopillar to be modeled anywhere between a pure nano-pillar and a pure cone (or pyramid). This modeling allows for full-wave analysis of more realistic shapes that are more likely able to be fabricated. This presentation will investigate different superquadric nano-structured PV (photo voltaic) arrays for their reflection and absorption properties. Different shapes generated using the superquadric function will be evaluated for their optical properties ranging from hexagonal nano-pillar to hexagonal nano-pyramid. The elliptical superquadric nano-structures will be used for different parametric studies including height, radius, and incident angle variation. Novel representative results will be presented to highlight advantages and disadvantages of various configurations and potentially providing effective guidelines on the fabrication processes and their impact on the overall performance of nano-pillars.","PeriodicalId":277196,"journal":{"name":"2014 United States National Committee of URSI National Radio Science Meeting (USNC-URSI NRSM)","volume":"10 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":"124596579","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":"5.8-GHz noncontact vital sign detection radar with respiration harmonics cancellation","authors":"Jianxuan Tu, Jenshan Lin","doi":"10.1109/USNC-URSI-NRSM.2014.6928140","DOIUrl":"https://doi.org/10.1109/USNC-URSI-NRSM.2014.6928140","url":null,"abstract":"Summary form only given. Microwave Doppler radar is capable of detecting human heartbeat and respiration or mechanical vibrations from a distance away. This noncontact detection method has many potential applications in healthcare, veterinary medicine, biology, industrial manufacturing, etc. Through understanding of its detection mechanism and advances in hardware and software, the once bulky Doppler radar systems can be miniaturized while achieving the same or even better performance. In this paper, a 5.8-GHz noncontact Doppler radar vital sign detection system is presented. The radio frequency signal is sent and modulated by the respiratory and heartbeat displacement when it hits the subject. A 2×2 patch antenna is custom designed to meet the requirement of the system. The phase-modulated signal is captured by the Doppler radar and then amplified by the gain stages at the receiver. An I/Q mixer is employed to down-convert the signal and to avoid the null point issue of the demodulated signal. The baseband signal is then sent wirelessly through Zigbee interface to the computer for further processing. Both time-domain and frequency-domain analysis are employed to extract the heart rate (HR) and respiration rate (RR). The Complex Signal Demodulation (CSD) is performed before the frequency spectrum analysis. HR and RR are measured by searching the highest peak within the typical HR and RR range in the frequency spectrum. Because respiratory displacement is very obvious, counting the number of respiration peaks within a certain time is utilized as a reference to RR measurement. For HR measurements, since the higher order harmonics of RR, generated by the demodulation method and the displacements, might appear near HR peak in the spectrum and cause error in HR measurement, a respiration harmonics cancellation method is implemented to increase the accuracy of the HR measurement. A finger-tip piezoelectric heart rate monitor is used as the reference. After signal processing, HR measurements can get an accuracy of over 90%.","PeriodicalId":277196,"journal":{"name":"2014 United States National Committee of URSI National Radio Science Meeting (USNC-URSI NRSM)","volume":"60 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":"127134522","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 6U CubeSat constellation concept for atmospheric temperature and humidity sounding","authors":"S. Padmanabhan, Shannon T. Brown, P. Kangaslahti, D. Russell, R. Cofield, R. Stachnik, B. Lim","doi":"10.1109/USNC-URSI-NRSM.2014.6928053","DOIUrl":"https://doi.org/10.1109/USNC-URSI-NRSM.2014.6928053","url":null,"abstract":"To accurately predict how the distribution of extreme events may change in the future we need to understand the mechanisms that influence such events in our current climate. This includes understanding how modes of natural climate variability, such as the El Nino Southern Oscillation (ENSO), the North Atlantic Oscillation (NAO) and the Pacific Decadal Oscillation (PDO) impact the weather extremes. Our current observing system is not well-suited for observing extreme events globally due to the sparse sampling and in-homogeneity of ground-based in-situ observations and the infrequent revisit time of satellite observations. Observations of weather extremes, such as extreme precipitation events, temperature extremes, tropical and extra-tropical cyclones among others, with temporal resolution on the order of minutes and spatial resolution on the order of few kms (<;10 kms), are required for improved forecasting of extreme weather events.","PeriodicalId":277196,"journal":{"name":"2014 United States National Committee of URSI National Radio Science Meeting (USNC-URSI NRSM)","volume":"12 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":"127351751","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}