Pub Date : 2012-12-06DOI: 10.1109/aps.2011.5997121
D. Chick, P. Collins, S. Goodman, R. K. Martin, A. Terzuoli
Electromagnetic direction finding using a set of three mutually orthogonal antennas is studied. The vector effective height concept from antenna theory is employed to develop three direction finding algorithms for use with the proposed antenna arrangement. The first algorithm estimates the direction-of-arrival by computing a vector that is perpendicular to the locus of the instantaneous electric field vector measured at the origin of the coordinate system. The second and third algorithms are based on the well-known maximum likelihood and MUSIC algorithms. For all algorithms we assume a narrowband signal model and that multiple incident waves can be separated in the frequency domain before processing each signal separately. In simulation, each algorithm successfully located the direction-of-arrival to within 2° for circularly polarized waves at SNR ≥ 35dB.
{"title":"Direction finding with mutually orthogonal antennas","authors":"D. Chick, P. Collins, S. Goodman, R. K. Martin, A. Terzuoli","doi":"10.1109/aps.2011.5997121","DOIUrl":"https://doi.org/10.1109/aps.2011.5997121","url":null,"abstract":"Electromagnetic direction finding using a set of three mutually orthogonal antennas is studied. The vector effective height concept from antenna theory is employed to develop three direction finding algorithms for use with the proposed antenna arrangement. The first algorithm estimates the direction-of-arrival by computing a vector that is perpendicular to the locus of the instantaneous electric field vector measured at the origin of the coordinate system. The second and third algorithms are based on the well-known maximum likelihood and MUSIC algorithms. For all algorithms we assume a narrowband signal model and that multiple incident waves can be separated in the frequency domain before processing each signal separately. In simulation, each algorithm successfully located the direction-of-arrival to within 2° for circularly polarized waves at SNR ≥ 35dB.","PeriodicalId":6449,"journal":{"name":"2011 IEEE International Symposium on Antennas and Propagation (APSURSI)","volume":"74 1","pages":"2853-2856"},"PeriodicalIF":0.0,"publicationDate":"2012-12-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87692894","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}
Pub Date : 2011-08-30DOI: 10.1109/APS.2011.5997003
C. Johnson, C. L. Wagner, Robert T. Rebich, Jeffery L. Young, D. Butherus
The excitation and propagation of extremely, super and ultra low frequency signals (ELF, SLF and ULF) in the range of 30 Hz to 3,000 Hz associated with ocean environments are of particular interest for applications dealing with deep-water communications or sub-surface emissions caused by power generation devices and lines. Due to the relatively long wave-lengths on the order of hundreds of meters or so in saltwater and the high-power nature of the sources, it is possible to detect these signals several kilometers from the source. In the current age in which sophisticated electromagnetic modeling tools have been developed for high frequency applications, the question has been asked whether these same tools can be applied to ELF, SLF and ULF applications (referred to as just ELF in subsequent discussions). In particular, we wish to ascertain the usefulness and robustness of the finite-difference, time-domain (FDTD) method, commercial codes (e.g. HFSS and Maxwell), and layered media modeling using Sommerfeld and quasi-electrostatic methods as applied to the ELF propagation problem. Each of these approaches has its strengths and weaknesses, as described in the ensuing sections.
{"title":"Propagation of low frequency signals in oceanic environments; theory, simulation and experimentation","authors":"C. Johnson, C. L. Wagner, Robert T. Rebich, Jeffery L. Young, D. Butherus","doi":"10.1109/APS.2011.5997003","DOIUrl":"https://doi.org/10.1109/APS.2011.5997003","url":null,"abstract":"The excitation and propagation of extremely, super and ultra low frequency signals (ELF, SLF and ULF) in the range of 30 Hz to 3,000 Hz associated with ocean environments are of particular interest for applications dealing with deep-water communications or sub-surface emissions caused by power generation devices and lines. Due to the relatively long wave-lengths on the order of hundreds of meters or so in saltwater and the high-power nature of the sources, it is possible to detect these signals several kilometers from the source. In the current age in which sophisticated electromagnetic modeling tools have been developed for high frequency applications, the question has been asked whether these same tools can be applied to ELF, SLF and ULF applications (referred to as just ELF in subsequent discussions). In particular, we wish to ascertain the usefulness and robustness of the finite-difference, time-domain (FDTD) method, commercial codes (e.g. HFSS and Maxwell), and layered media modeling using Sommerfeld and quasi-electrostatic methods as applied to the ELF propagation problem. Each of these approaches has its strengths and weaknesses, as described in the ensuing sections.","PeriodicalId":6449,"journal":{"name":"2011 IEEE International Symposium on Antennas and Propagation (APSURSI)","volume":"41 1","pages":"2395-2398"},"PeriodicalIF":0.0,"publicationDate":"2011-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78159171","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}
Pub Date : 2011-08-30DOI: 10.1109/APS.2011.5997231
Xin Xu, R. Adams
Overlapped, localizing local-global solution (OL-LOGOS) modes have been proposed to develop fast direct solvers for low frequency electromagnetic wave problems. The efficiencies of the resulting OL-LOGOS factorization algorithms have been demonstrated for the matrix equations associated with dense three-dimensional integral equations and sparse two-dimensional partial differential equations. In both cases, approximately O(N log N) time and O(N) memory complexities have been observed. In this work, the OL-LOGOS method is applied to three-dimensional scalar FEM systems. In order to improve the factorization speed and reduce memory costs for FEM applications, a pre-factorization permutation step is incorporated into the OL-LOGOS factorization algorithm. Numerical results demonstrate factorization and memory complexities of approximately O(N log N) and O(N) as the problem size grows.
{"title":"Fast direct solution of FEM systems using overlapped localizing modes on a shifted grid","authors":"Xin Xu, R. Adams","doi":"10.1109/APS.2011.5997231","DOIUrl":"https://doi.org/10.1109/APS.2011.5997231","url":null,"abstract":"Overlapped, localizing local-global solution (OL-LOGOS) modes have been proposed to develop fast direct solvers for low frequency electromagnetic wave problems. The efficiencies of the resulting OL-LOGOS factorization algorithms have been demonstrated for the matrix equations associated with dense three-dimensional integral equations and sparse two-dimensional partial differential equations. In both cases, approximately O(N log N) time and O(N) memory complexities have been observed. In this work, the OL-LOGOS method is applied to three-dimensional scalar FEM systems. In order to improve the factorization speed and reduce memory costs for FEM applications, a pre-factorization permutation step is incorporated into the OL-LOGOS factorization algorithm. Numerical results demonstrate factorization and memory complexities of approximately O(N log N) and O(N) as the problem size grows.","PeriodicalId":6449,"journal":{"name":"2011 IEEE International Symposium on Antennas and Propagation (APSURSI)","volume":"45 1","pages":"3265-3267"},"PeriodicalIF":0.0,"publicationDate":"2011-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80734780","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}
Pub Date : 2011-08-30DOI: 10.1109/APS.2011.5996652
C. Tienda, J. Encinar, M. Arrebola
In this paper, a dual-reflectarray antenna is proposed to generate a contoured beam for a DBS European coverage. The antenna optics is based on a compact range dual-reflector antenna, which produces low crosspolar radiation. The phase distribution of the subreflectarray is defined to simulate an equivalent hyperbolic subreflector with negative eccentricity. The phase distribution on the main reflectarray surface is synthesized to shape the beam providing the required coverage.
{"title":"Contoured-beam dual-reflectarray antenna for DBS application","authors":"C. Tienda, J. Encinar, M. Arrebola","doi":"10.1109/APS.2011.5996652","DOIUrl":"https://doi.org/10.1109/APS.2011.5996652","url":null,"abstract":"In this paper, a dual-reflectarray antenna is proposed to generate a contoured beam for a DBS European coverage. The antenna optics is based on a compact range dual-reflector antenna, which produces low crosspolar radiation. The phase distribution of the subreflectarray is defined to simulate an equivalent hyperbolic subreflector with negative eccentricity. The phase distribution on the main reflectarray surface is synthesized to shape the beam providing the required coverage.","PeriodicalId":6449,"journal":{"name":"2011 IEEE International Symposium on Antennas and Propagation (APSURSI)","volume":"64 1","pages":"109-112"},"PeriodicalIF":0.0,"publicationDate":"2011-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80829624","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}
Pub Date : 2011-07-07DOI: 10.1109/APS.2011.5997157
P. Focardi, P. Brown, Y. Rahmat-Samii
A complete and accurate RF model of the SMAP observatory has been presented in this paper. Extreme care has been used in modeling all the important parts of the spacecraft to provide reliable information about the performance of the instrument under various conditions. An ongoing work of RF model refinement based on the constant development of the spacecraft and instrument is also being carried on to keep the model up to date. Field of view studies have been performed and mechanical and thermal deformations are also being considered. Since radiation pattern measurements of the actual antenna are not planned, the development of this RF model represents a very important milestone for the mission.
{"title":"A 6-m mesh reflector antenna for SMAP: Modeling the RF performance of a challenging Earth-orbiting instrument","authors":"P. Focardi, P. Brown, Y. Rahmat-Samii","doi":"10.1109/APS.2011.5997157","DOIUrl":"https://doi.org/10.1109/APS.2011.5997157","url":null,"abstract":"A complete and accurate RF model of the SMAP observatory has been presented in this paper. Extreme care has been used in modeling all the important parts of the spacecraft to provide reliable information about the performance of the instrument under various conditions. An ongoing work of RF model refinement based on the constant development of the spacecraft and instrument is also being carried on to keep the model up to date. Field of view studies have been performed and mechanical and thermal deformations are also being considered. Since radiation pattern measurements of the actual antenna are not planned, the development of this RF model represents a very important milestone for the mission.","PeriodicalId":6449,"journal":{"name":"2011 IEEE International Symposium on Antennas and Propagation (APSURSI)","volume":"921 1","pages":"2987-2990"},"PeriodicalIF":0.0,"publicationDate":"2011-07-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77534129","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}
Pub Date : 2011-07-03DOI: 10.1109/APS.2011.5996812
A. Diaz-Bolado, P. Barrière, J. Laurin
The effect of the measurement setup configuration for Microwave Tomography (MT) is analyzed through several simple examples. Synthetic measurements are generated using a method of moments code and the well-known MR-CSI method is used for the solution of the inverse problem for the 2D TM scalar case. The quality of the reconstructed images is compared for the different configurations analyzed. Two configurations based on breast compression are compared to a classical circular measurement setup. An improvement in the quality of the reconstructed objects is observed when a compression of the object is applied due to the close proximity of the receivers. The Singular Value Decomposition (SVD) of the radiation operator is also obtained for the different configurations and the results obtained from this analysis further support the superior reconstruction capabilities of the presented configurations based on a compression of the object.
{"title":"On the effect of breast compression and measurement setup configuration in microwave tomography for breast cancer detection","authors":"A. Diaz-Bolado, P. Barrière, J. Laurin","doi":"10.1109/APS.2011.5996812","DOIUrl":"https://doi.org/10.1109/APS.2011.5996812","url":null,"abstract":"The effect of the measurement setup configuration for Microwave Tomography (MT) is analyzed through several simple examples. Synthetic measurements are generated using a method of moments code and the well-known MR-CSI method is used for the solution of the inverse problem for the 2D TM scalar case. The quality of the reconstructed images is compared for the different configurations analyzed. Two configurations based on breast compression are compared to a classical circular measurement setup. An improvement in the quality of the reconstructed objects is observed when a compression of the object is applied due to the close proximity of the receivers. The Singular Value Decomposition (SVD) of the radiation operator is also obtained for the different configurations and the results obtained from this analysis further support the superior reconstruction capabilities of the presented configurations based on a compression of the object.","PeriodicalId":6449,"journal":{"name":"2011 IEEE International Symposium on Antennas and Propagation (APSURSI)","volume":"74 1","pages":"714-717"},"PeriodicalIF":0.0,"publicationDate":"2011-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74316781","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}
Pub Date : 2011-07-03DOI: 10.1109/APS.2011.5996563
L. Gupta, D. Ruddock, M. T. Hall, F. Sadeghi, D. Peroulis
This paper presents a wirelessly powered strain telemeter for mechanical health monitoring applications. The telemter is integrated with a rectenna tuned at 2.4 GHz. The rectenna is comprised by a resonant printed dipole antenna, microstrip transmission line filters and commercially available high-frequency diodes. The experimental results demonstrate that the rectenna is able to deliver 8 mW of DC power to the wireless telemeter when illuminated by a 10-W Yagi transmitter with a gain of 15 dB placed at a distance of over 2.5 m.
{"title":"Remotely powered wireless strain telemeter","authors":"L. Gupta, D. Ruddock, M. T. Hall, F. Sadeghi, D. Peroulis","doi":"10.1109/APS.2011.5996563","DOIUrl":"https://doi.org/10.1109/APS.2011.5996563","url":null,"abstract":"This paper presents a wirelessly powered strain telemeter for mechanical health monitoring applications. The telemter is integrated with a rectenna tuned at 2.4 GHz. The rectenna is comprised by a resonant printed dipole antenna, microstrip transmission line filters and commercially available high-frequency diodes. The experimental results demonstrate that the rectenna is able to deliver 8 mW of DC power to the wireless telemeter when illuminated by a 10-W Yagi transmitter with a gain of 15 dB placed at a distance of over 2.5 m.","PeriodicalId":6449,"journal":{"name":"2011 IEEE International Symposium on Antennas and Propagation (APSURSI)","volume":"50 1","pages":"1437-1440"},"PeriodicalIF":0.0,"publicationDate":"2011-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75787274","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}
Pub Date : 2011-07-03DOI: 10.1109/APS.2011.5996861
K. Naishadham
Ferrite materials are widely used as chokes to minimize common-mode currents in antenna feeds, in the design of artificial magnetic conductors, and in the filtering of noise at radio frequencies (RF). Miniature inductors, consisting of a thinwire coil around a high-permeability soft ferrite core, find wide application in RF and microwave circuits. An understanding of the high-frequency parasitic and packaging effects, such as stray capacitance, magnetic losses, resonant characteristics, etc., useful in the design of these components, can be gained from an equivalent circuit characterization of the inductor. In this paper, we present a rigorous experimental method to fully characterize the frequency dependent RF behavior of ferrite inductors. The equivalent circuit parameters of the inductor, as well as the complex effective permeability of the core, are extracted in closed form from an accurate measurement of the RF impedance, without recourse to cumbersome optimization procedures.
{"title":"Extraction of rf permeability of ferrite materials using direct measurement of inductors on ferrite cores","authors":"K. Naishadham","doi":"10.1109/APS.2011.5996861","DOIUrl":"https://doi.org/10.1109/APS.2011.5996861","url":null,"abstract":"Ferrite materials are widely used as chokes to minimize common-mode currents in antenna feeds, in the design of artificial magnetic conductors, and in the filtering of noise at radio frequencies (RF). Miniature inductors, consisting of a thinwire coil around a high-permeability soft ferrite core, find wide application in RF and microwave circuits. An understanding of the high-frequency parasitic and packaging effects, such as stray capacitance, magnetic losses, resonant characteristics, etc., useful in the design of these components, can be gained from an equivalent circuit characterization of the inductor. In this paper, we present a rigorous experimental method to fully characterize the frequency dependent RF behavior of ferrite inductors. The equivalent circuit parameters of the inductor, as well as the complex effective permeability of the core, are extracted in closed form from an accurate measurement of the RF impedance, without recourse to cumbersome optimization procedures.","PeriodicalId":6449,"journal":{"name":"2011 IEEE International Symposium on Antennas and Propagation (APSURSI)","volume":"38 1","pages":"1863-1866"},"PeriodicalIF":0.0,"publicationDate":"2011-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74389624","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}
Pub Date : 2011-07-03DOI: 10.1109/APS.2011.5996487
Z. Jiang, C. Scarborough, D. Werner, P. Werner, C. Rivero‐Baleine, C. Drake
In this paper, we propose an isotropic metamaterial lens (meta-lens) with an operational frequency of 8.5 MHz for imaging applications. The cubic unit cells, composed of inductor-and and capacitor-loaded split rings, are aligned in a periodic three-dimensional dimensional lattice. The meta-lens provides an effective isotropic permeability μeff = −1 at 8.5 MHz. The lens enhances the evanescent fields, producing strong magnetic fields and sharp subwavelength resolution at the image plane. Measurements of a fabricated meta-lens were found to match full-wave simulations.
{"title":"An Isotropic 8.5 MHz magneti meta-lens","authors":"Z. Jiang, C. Scarborough, D. Werner, P. Werner, C. Rivero‐Baleine, C. Drake","doi":"10.1109/APS.2011.5996487","DOIUrl":"https://doi.org/10.1109/APS.2011.5996487","url":null,"abstract":"In this paper, we propose an isotropic metamaterial lens (meta-lens) with an operational frequency of 8.5 MHz for imaging applications. The cubic unit cells, composed of inductor-and and capacitor-loaded split rings, are aligned in a periodic three-dimensional dimensional lattice. The meta-lens provides an effective isotropic permeability μeff = −1 at 8.5 MHz. The lens enhances the evanescent fields, producing strong magnetic fields and sharp subwavelength resolution at the image plane. Measurements of a fabricated meta-lens were found to match full-wave simulations.","PeriodicalId":6449,"journal":{"name":"2011 IEEE International Symposium on Antennas and Propagation (APSURSI)","volume":"68 1","pages":"1151-1154"},"PeriodicalIF":0.0,"publicationDate":"2011-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74326907","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}
Pub Date : 2011-07-03DOI: 10.1109/APS.2011.5996409
Jeeheung Kim, S. Yoon, E. Jung, Jae W. Lee, Taek-Kyung Lee, W.K. Lee
In this paper, modified triangular-shaped waveguide-typed septum polarizer has been suggested and verified by using commercially available software and carrying out the comparison with the conventional rectangular waveguide-typed polarizer. It is expected that the proposed structure shows the better electrical performances than the conventional one in terms of the smooth energy-transfer of TE10 and TE01-modes. The simulated result shows that the proposed structure accomplished axial ratio of less than 0.32dB, return losses of lower than −32dB, and isolation characteristics between −24dB and −35dB at the target frequency ranging from 8 to 8.4GHz.
{"title":"Triangular-shaped stepped septum polarizer for satellite communication","authors":"Jeeheung Kim, S. Yoon, E. Jung, Jae W. Lee, Taek-Kyung Lee, W.K. Lee","doi":"10.1109/APS.2011.5996409","DOIUrl":"https://doi.org/10.1109/APS.2011.5996409","url":null,"abstract":"In this paper, modified triangular-shaped waveguide-typed septum polarizer has been suggested and verified by using commercially available software and carrying out the comparison with the conventional rectangular waveguide-typed polarizer. It is expected that the proposed structure shows the better electrical performances than the conventional one in terms of the smooth energy-transfer of TE10 and TE01-modes. The simulated result shows that the proposed structure accomplished axial ratio of less than 0.32dB, return losses of lower than −32dB, and isolation characteristics between −24dB and −35dB at the target frequency ranging from 8 to 8.4GHz.","PeriodicalId":6449,"journal":{"name":"2011 IEEE International Symposium on Antennas and Propagation (APSURSI)","volume":"23 1","pages":"854-857"},"PeriodicalIF":0.0,"publicationDate":"2011-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78509197","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}
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