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

{"title":"Coherent scattering of electromagnetic waves from layered rough surfaces within the Kirchhoff regime","authors":"Alireza Tabatabaeenejad, M. Moghaddam","doi":"10.1109/USNC-URSI-NRSM.2013.6525123","DOIUrl":"https://doi.org/10.1109/USNC-URSI-NRSM.2013.6525123","url":null,"abstract":"Summary form only given. Scattering of electromagnetic waves from layered rough surfaces with an arbitrary number of layers finds applications in diverse environmental sensing scenarios, such as characterizing layering properties of terrestrial soil. While many of these applications rely on backscattering predictions using incoherent analyses, there is a need for prediction of the coherently scattered wave from layered rough surfaces. The primary application of the model presented in this work is remote sensing of subsurface soil moisture in forested regions. This model is intended for use in the NASA Airborne Microwave Observatory of Subcanopy and Subsurface (AirMOSS) mission, which uses a P-band synthetic aperture radar currently collecting data over key (vegetated) biomes of north America. Retrieval of soil moisture from radar measurements requires accurate and efficient forward scattering models. Several such radar scattering models exist for vegetated areas. These models identify scattering mechanisms including scattering from the crown layer, scattering from trunks, double-bounce scattering between the crown layer and ground, double-bounce scattering between trunks and ground, and backscattering from ground. It has been shown that at P- and L-bands, the trunk-ground mechanism becomes dominant, especially for tall stands. Moreover, as we will show, at P-band and in a layered structure, a subsurface layer can have a significant contribution to the total reflection of the incident wave. Therefore, it is important that a forest scattering model consider the coherent processes between soil layers in the modeling of the double-bounce mechanisms. To this end, not only a coherent scattering model is necessary but also subsurface layers should be taken into account. This work calculates the coherent component of the wave scattered by a layered rough surface structure within the Kirchhoff regime, where it is assumed that the scatterer surface at each point has a radius of curvature much larger than the wavelength. Application of the Kirchhoff approximation for electromagnetic scattering from single rough surfaces dates back to the 1970s. Several newer studies have applied this approximation to the problem of scattering from two-layer rough surfaces where calculation of the scattered wave involves numerical integration. While in this work we do not make any assumption about the layer thickness, except we implicitly assume it is large enough to avoid spatial overlaps between the boundaries, we make a few assumptions about the surfaces. We assume the surfaces not only have large radii of curvature to allow the use of the Kirchhoff approximation but also have small slopes so that the partial derivatives of surface profiles would be very small. Moreover, we assume roughness height is small so that the coherent component of the scattered wave would be dominant. We expect that at low frequencies such as P-band, many surfaces of interest satisfy these condit","PeriodicalId":123571,"journal":{"name":"2013 US National Committee of URSI National Radio Science Meeting (USNC-URSI NRSM)","volume":"69 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":"126096795","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":"An efficient spectral domain method of moments for Reflectarray antennas using a customized impedance matrix interpolation scheme","authors":"J. Budhu, Y. Rahmat-Samii","doi":"10.1109/USNC-URSI-NRSM.2013.6525070","DOIUrl":"https://doi.org/10.1109/USNC-URSI-NRSM.2013.6525070","url":null,"abstract":"The acceleration method to be presented is a novel interpolation of the impedance matrix elements over patch size thereby reducing the number of moment method runs needed in the parameter sweep used to generate the design curves. In the Reflectarray antenna design process, the spherical angles in the plane of incidence, formed by the unit normal vector of the ith patch and the incident ⃗k vector emanating from the feed phase center to the ith patch centroid, are unique to each and every element of the Reflectarray. Thus, each and every element demands a unique design curve. For electrically large Reflectarray antennas, say on the order of thousands of elements, this would be a tremendous undertaking using the popular commercially available tools such as HFSS or CST MWS. Even with an in-house developed code based upon the standard SDMoM algorithm, this would still require many hours and possibly days. Also, if one were given a set of requirements that must be met simultaneously, an often popular approach would be to choose global optimizers such as PSO or GA, and if the evaluation of the cost function took hours or days for each evaluation, then this strategy would be unfeasible. There exists, therefore, a strong desire to accelerate the standard SDMoM algorithm to an extremely rapid pace, on the order of seconds to minutes in lieu of hours to days. This is possible using the Z-matrix Interpolation scheme as presented in this talk.","PeriodicalId":123571,"journal":{"name":"2013 US National Committee of URSI National Radio Science Meeting (USNC-URSI NRSM)","volume":"585 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":"123415834","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 Novel MEMS reconfigurable wideband E-shaped patch element for advanced cognitive radio base stations","authors":"J. Kovitz, Y. Rahmat-Samii","doi":"10.1109/USNC-URSI-NRSM.2013.6525111","DOIUrl":"https://doi.org/10.1109/USNC-URSI-NRSM.2013.6525111","url":null,"abstract":"Cognitive radio offers new possible enhancements through its use of dynamic spectrum access, exploiting unused spectrum bands to expand bandwidth and overall system capacity. Development of cognitive radio systems has been underway, but there have only been a few antenna designs fitting the required functionality for these dynamic systems, which could benefit from dynamic antennas as well. The functionality required in a system also depends on the network architecture being utilized, and this research focuses on cognitive radio networks using a pre-existing infrastructure such as base stations and access points. For base station applications, directional patch antenna arrays can be implemented in order to provide sectoral access for nearby users.","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":"124961876","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":"Array configuration and total power calibration for the Large-Aperture Experiment to detect the Dark Ages","authors":"F. Schinzel, J. Craig","doi":"10.1109/USNC-URSI-NRSM.2013.6525024","DOIUrl":"https://doi.org/10.1109/USNC-URSI-NRSM.2013.6525024","url":null,"abstract":"The Large-Aperture Experiment to detect the Dark Ages (LEDA) pursues to answer questions related to the early universe about 100 million years after the Big Bang (http://www.ledatelescope.org). In order to achieve the required observational capabilities LEDA is currently developing signal processing instrumentation that comprises a large-N correlator expected to serve 512 dipole antennas with a 32 input prototype deployed at the first station of the Long Wavelength Array (LWA1) colocated with the Very Large Array in New Mexico. The correlator comprises a packetized CASPER architecture and combines FPGAs and GPUs for the F and X stages. The LEDA backend is going to provide a frequency coverage of 28-88 MHz.","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":"129295299","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":"Calibration of ground radars during the Mid latitude Continental Convective Cloud Experiment (MC3E)","authors":"J. Hardin, V. Chandrasekar","doi":"10.1109/USNC-URSI-NRSM.2013.6525118","DOIUrl":"https://doi.org/10.1109/USNC-URSI-NRSM.2013.6525118","url":null,"abstract":"This work provides a consistent table of the operational calibration biases of the primary ground radars in operation during the Mid Latitude Continental Convective Cloud Experiment (MC3E) in central Oklahoma. Inevitably, when operating radars small biases in the measurements get introduced from drifting performance of each of the many components that comprises the system, as well as from several different environmental variables. MC3E was a large joint campaign between the US Department of Energy and NASA consisting of many ground and airborne instruments working cooperatively to study mid latitude convective storms as part of the GPM Ground Validation field experiments. The primary ground radars have overlapping fields of view and are located nearby many other passive instruments such as disdrometers. Many of the ground radars have documented biases in their measurements that can have severe effects on derived products such as rainfall and attenuation corrected fields.","PeriodicalId":123571,"journal":{"name":"2013 US National Committee of URSI National Radio Science Meeting (USNC-URSI NRSM)","volume":"60 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":"126228133","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":"Tutorial: Phased array antennas for radio astronomy","authors":"K. Warnick, B. Jeffs","doi":"10.1109/USNC-URSI-NRSM.2013.6525069","DOIUrl":"https://doi.org/10.1109/USNC-URSI-NRSM.2013.6525069","url":null,"abstract":"This tutorial presentation will provide a basic introduction to recent applications of phased array antennas for radio frequency astronomical observations. Antenna arrays of four basic types are used for astronomical observations: (1) synthesis imaging arrays, (2) horn cluster feeds, (3) phased array feeds, and (4) aperture arrays. Synthesis imaging arrays are highly sparse arrays of dish antennas with extremely large separation between antennas relative to the electromagnetic wavelength. These kinds of arrays have been used for many decades and are routinely used at various RF and microwave bands at sites around the world. The focus of this presentation is on more recent research and development work on the third and fourth types of array antennas, which involve dense phased arrays combined with digital beamforming for astronomical observations.","PeriodicalId":123571,"journal":{"name":"2013 US National Committee of URSI National Radio Science Meeting (USNC-URSI NRSM)","volume":"18 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":"125785507","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":"Wave propagation in a random medium layer with rough boundaries","authors":"S. Mudaliar","doi":"10.1109/USNC-URSI-NRSM.2013.6525125","DOIUrl":"https://doi.org/10.1109/USNC-URSI-NRSM.2013.6525125","url":null,"abstract":"Wave propagation in random media, and scattering from rough surfaces have been studied extensively during the past few decades. However, the combined problem of propagation in random media with rough boundaries has not been well investigated. Yet there are many situations where there is a need for models involving random media and rough boundaries. To address this people have used hybrid approaches that directly add procedures from random media and rough surface scattering theories. Another popularly used approach for this problem is the radiative transfer theory. In contrast to these we present in this paper a unified approach which treats volumetric scattering and surface scattering on an equal footing. For illustration, we choose the following model. The permittivity of the random medium layer has a deterministic part and a randomly fluctuating part. The rough boundaries are parallel planes on the average. All random fluctuations of the problem are zero-mean stationary processes independent of each other. A point source excites waves in the random medium layer and we are interested in the propagation characteristics of waves in the layer.","PeriodicalId":123571,"journal":{"name":"2013 US National Committee of URSI National Radio Science Meeting (USNC-URSI NRSM)","volume":"67 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":"130249285","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":"Experimental evaluation of detection performance of a MIMO radar testbed","authors":"T. Otsuki, I. Pasya, T. Kobayashi","doi":"10.1109/USNC-URSI-NRSM.2013.6525117","DOIUrl":"https://doi.org/10.1109/USNC-URSI-NRSM.2013.6525117","url":null,"abstract":"Summary form only given. This paper reports on experimental evaluation of multiple input, multiple output (MIMO) radar detection performance using a developed MIMO radar testbed. The experimental setup represents a 2 × 2 MIMO (including a single input, single output (SISO)) configuration, using a M-sequence with an order of 6 as baseband signal, generated using an arbitrary waveform generator (AWG) with 2.5 GSample/s, and occupying 500 MHz of bandwidth. This signal is modulated using binary phase shift keying (BPSK) and up-converted to 3.5 GHz frequency band. The received signal is acquired using a downconverter and a digital storage oscilloscope (DSO) as time domain data, and processed offline. Threshold processing is carried out after matched filter processing. Furthermore, in order to change the signal to noise ratio (SNR), noise power is added with a noise source at the receiver input. Experiments were conducted in a radio anechoic chamber to exclude the effects of multipath. Upon estimating the detection performance of the system, we adopted three types of processing: MIMO, re-phased netted radar (RPNR), and distributed radar network (DRN) processing. The MIMO processing implements a non-coherent approach where the decision is made using the signal's power alone. In contrast, the RPNR performs a coherent approach, taking into account the signal's power and phase information. In addition, the received signals phase is re-aligned to maximize the SNR. The DRN implements a non-coherent threshold processing on each individual receiver and combines the results to obtain the detection decision. In each processing, the threshold was selected to fix the probability of false alarm at 10-6. The three schemes were experimentally examined and their detection performances were found better than the SISO. At 80% probability of detection, the RPNR, the MIMO and the DRN marked 9, 8, and 6 dB of improvement in SNR, respectively, compared to the SISO. Although the RPNR yielded the best performance, the MIMO performed nearly with lower complexity since it utilized a non-coherent approach. The experimental data were also reproduced closely by numerical simulation.","PeriodicalId":123571,"journal":{"name":"2013 US National Committee of URSI National Radio Science Meeting (USNC-URSI NRSM)","volume":"23 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":"132686568","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":"CubeSat based sensors for global weather forecasting","authors":"A. Gasiewski, B. Sanders, D. Gallaher","doi":"10.1109/USNC-URSI-NRSM.2013.6525008","DOIUrl":"https://doi.org/10.1109/USNC-URSI-NRSM.2013.6525008","url":null,"abstract":"Summary form only given. The positive impact of passive microwave observations of tropospheric temperature, water vapor, and surface variables on short term weather forecasts has been clearly demonstrated in recent error growth studies. However, current-era spaceborne passive microwave sensors remain singularly expensive and risky components of global weather forecast systems, while at the same time offer only limited temporal sampling capabilities. A fleet of small, low-cost satellite microwave sensors has the potential to provide reduced system cost and risk while simultaneously improving the time sampling of rapidly evolving weather. In an effort to study the potential of such a fleet the University of Colorado is developing the first low-cost CubeSat-based passive microwave sounder for demonstration as an element of a larger fleet of sounders for weather forecasting. The PolarCube satellite is an 8-channel 118-GHz temperature sounder providing ~15 km spatial resolution from an orbital altitude of ~350 km. It is based on a spin-scanned concept using the CU ALL STAR 3U CubeSat bus with a two point calibration method using a warm load and cold space. The development of the radiometer payload and bus are led by student teams at CU using low cost components. A launch into a sun-synchronous orbit for evaluation of polar sounding and imaging capabilities is tentatively scheduled for late 2013. The 3U to 6U CubeSat envelope is well suited to passive microwave imaging at frequencies at approximately V-band and higher due to the available aperture size and anticipated orbital altitudes for CubeSats. The use of redundant satellites within a fleet launched either in groups or as single payloads will moreover provide enhanced temporal resolution previously attainable using only geostationary concepts. While data communications to such fleets will likely require relay satellites at higher altitudes it is envisioned that the available orbital lifetimes without propellant boost will require fleet replenishment at rates modest enough for reduced operational system costs as well as facilitate regular technology infusion into sensing, navigation, data, and control electronics. In this presentation the design characteristics of the PolarCube satellite will be discussed, along with the ramifications of the CubeSat envelope restrictions on the cost, sampling characteristics, scanning capabilities, communications requirements, and expected measurement precision of a CubeSat passive microwave fleet.","PeriodicalId":123571,"journal":{"name":"2013 US National Committee of URSI National Radio Science Meeting (USNC-URSI NRSM)","volume":"54 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":"134494261","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":"Numerical simulation of the impact of the middle atmosphere parameters on the lower ionosphere and VLF/LF radiowaves propagation using MLS EOS AURA data","authors":"A. Lyakhov, A. Egoshin, J. Zetzer, K. N. Yakimenko","doi":"10.1109/USNC-URSI-NRSM.2013.6525134","DOIUrl":"https://doi.org/10.1109/USNC-URSI-NRSM.2013.6525134","url":null,"abstract":"EOS Aura Microwave Limb Sounder data on the middle atmosphere parameters have been used for the numerical simulation of the lower ionosphere. Real data on the temperature, geopotential height, water and ozone content were processed using the Fast Fourier Synoptic Mapping technique, providing the two-dimensional field along the radiopaths from European VLF/LF transmitters to the geophysical observatory “Mikhnevo” (55N, 37E). These parameters have been used in the numerical simulation of the electron density distribution. The control run was evaluated using MSIS and AFGL empirical models. The resulted ionospheres have been used in the simulation of VLF/LF radiowaves propagation using LWPC code. We present the comparison between the lower ionosphere parameters derived from satellite data, calculated on the empirical atmosphere models and two pure empirical models, namely, IRI and the built-in LWPC model. The comparison has been done for various seasons, sunlit and nocturnal conditions. The synoptic reconstruction has proven the existence of significant periodic perturbations in the mesosphere, which are important for the LF propagation and confirmed the results of SAVNET group on the C-layer complex dynamics. The results of the VLF/LF propagation simulation in the frequency range from 19 to 77 kHz under four ionospheres are presented.","PeriodicalId":123571,"journal":{"name":"2013 US National Committee of URSI National Radio Science Meeting (USNC-URSI NRSM)","volume":"51 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":"115619387","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}