Готові списки джерел за темами / Antenna models

Добірка наукової літератури з теми "Antenna models"

Автор: Grafiati
Опубліковано: 10 грудня 2022
Оновлено: 28 січня 2023

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Статті в журналах з теми "Antenna models"

1

Warren, Craig, and Antonios Giannopoulos. "Creating finite-difference time-domain models of commercial ground-penetrating radar antennas using Taguchi’s optimization method." GEOPHYSICS 76, no. 2 (March 2011): G37—G47. http://dx.doi.org/10.1190/1.3548506.

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Анотація:
Very few researchers have developed numerical models of ground-penetrating radar (GPR) that include realistic descriptions of both the antennas and the subsurface. This is essential to be able to accurately predict responses from near-surface, near-field targets. We have developed a detailed 3D finite-difference time-domain models of two commercial GPR antennas — a Geophysical Survey Systems, Inc. (GSSI) 1.5-GHz antenna and a MALÅ Geoscience 1.2-GHz antenna — using simple analyses of the geometries and the main components of the antennas. Values for unknown parameters in the antenna models (due to commercial sensitivity) were estimated by using Taguchi’s optimization method, resulting in a good match between the real and modeled crosstalk responses in free space. Validation using a series of oil-in-water emulsions to simulate the electrical properties of real materials demonstrated that it was essential to accurately model the permittivity and dispersive conductivity. When accurate descriptions of the emulsions were combined with the antenna models, the simulated responses showed very good agreement with real data. This provides confidence for use of the antenna models in more advanced studies.
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2

Lampe, Bernhard, and Klaus Holliger. "Effects of fractal fluctuations in topographic relief, permittivity and conductivity on ground‐penetrating radar antenna radiation." GEOPHYSICS 68, no. 6 (November 2003): 1934–44. http://dx.doi.org/10.1190/1.1635047.

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Анотація:
Typical ground‐penetrating radar (GPR) transmitters and receivers are dipole antennas. These antennas have pronounced directivity properties and exhibit strong coupling to interfaces across which there are changes in electric material properties. Antenna coupling to the surface of idealized half‐space models has been the subject of intense research for several decades. In contrast, the behavior of antennas in the vicinity of interfaces with realistic topographic fluctuations and/or subsurface heterogeneities has been largely unexplored. To explore this issue, we simulate the responses of a typical surface GPR antenna system located on a suite of realistic fractal earth models using the finite‐difference time‐domain (FDTD) method. The models are characterized by topographic roughness of the air–soil interface and small‐scale heterogeneous distributions of permittivity and conductivity in the subsurface. Synthetic radiation patterns and input impedance values of the simulated GPR antenna system demonstrate that topographic roughness significantly affects the coupling of the antenna to the ground, whereas heterogeneities in the subsurface predominantly influence the antenna radiation through scattering and absorption along the propagation path.
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3

Koziel, Slawomir, and Anna Pietrenko-Dabrowska. "Fast Antenna Optimization Using Gradient Monitoring and Variable-Fidelity EM Models." Applied Computational Electromagnetics Society 35, no. 11 (February 5, 2021): 1348–49. http://dx.doi.org/10.47037/2020.aces.j.351143.

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Анотація:
Accelerated simulation-driven design optimization of antenna structures is proposed. Variable-fidelity electromagnetic (EM) analysis is used as well as the trust-region framework with limited sensitivity updates. The latter are controlled by monitoring the changes of the antenna response gradients. Our methodology is verified using three compact wideband antennas. Comprehensive benchmarking demonstrates its superiority over both conventional and surrogate-assisted algorithms.
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4

Mathur, Vinita, and Dr Manisha Gupta. "Morphology of Koch Fractal Antenna." INTERNATIONAL JOURNAL OF COMPUTERS & TECHNOLOGY 13, no. 2 (April 4, 2014): 4157–63. http://dx.doi.org/10.24297/ijct.v13i2.2902.

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Анотація:
Antenna is paramount element for the radio communication entity using radio frequency and microwaves. In twenty-first century wireless communication systems, there is a demand for wider bandwidth, multiband and low profile antennas for both commercial and military purposes. This has initiated antenna analysis in various directions; one of them is using fractal shaped antenna elements. Fractal concepts have emerged and advanced as a unique technique for designing compact UWB antennas, because of the self-similarityand space-filling attributes. In a fractal antenna, the multiple frequencies of operation depend on the total dimensions of the design and the scale factor. There are varied fractal geometries that have been found to be favorable in developing novel and new models for antennas. In this paper we will be discussing one such type of fractal antennas i.e. the Koch structure. Koch antenna can be designed with a triangle, rectangle and pentagon as its initiator. Their geometry and parameters have been analyzed in this paper.Â
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5

Koziel, Slawomir, and Anna Pietrenko-Dabrowska. "Variable-Fidelity Simulation Models and Sparse Gradient Updates for Cost-Efficient Optimization of Compact Antenna Input Characteristics." Sensors 19, no. 8 (April 15, 2019): 1806. http://dx.doi.org/10.3390/s19081806.

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Анотація:
Design of antennas for the Internet of Things (IoT) applications requires taking into account several performance figures, both electrical (e.g., impedance matching) and field (gain, radiation pattern), but also physical constraints, primarily concerning size limitation. Fulfillment of stringent specifications necessitates the development of topologically complex structures described by a large number of geometry parameters that need tuning. Conventional optimization procedures are typically too expensive when the antenna is evaluated using high-fidelity electromagnetic (EM) analysis, otherwise required to ensure accuracy. This paper proposes a novel surrogate-assisted optimization algorithm for computationally efficient design optimization of antenna structures. In the paper, the optimization of antenna input characteristic is presented, specifically, minimization of the antenna reflection coefficient in a given bandwidth. Our methodology involves variable-fidelity EM simulations as well as a dedicated procedure to reduce the cost of estimating the antenna response gradients. The latter is based on monitoring the variations of the antenna response sensitivities along the optimization path. The procedure suppresses the finite-differentiation-based sensitivity updates for variables that exhibit stable gradient behavior. The proposed algorithm is validated using three compact wideband antennas and demonstrated to outperform both the conventional trust region algorithm and the pattern search procedure, as well as surrogate-based procedures while retaining acceptable design quality.
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6

Rajni, Rajni, Gursharan Kaur, and Anupma Marwaha. "Metamaterial Inspired Patch Antenna for ISM Band by Adding Single-Layer Complementary Split Ring Resonators." International Journal of Electrical and Computer Engineering (IJECE) 5, no. 6 (December 1, 2015): 1328. http://dx.doi.org/10.11591/ijece.v5i6.pp1328-1335.

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Анотація:
In this work, we propose the design of metamaterial inspired compact circular patch antennas loaded with complementary split-ring resonators (CSRRs) for ISM band operation. CSRRs have been incorporated horizontally inside the dielectric. The various models of CSRR loaded antennas with different patch radius are produced and are evaluated numerically with Ansoft HFSS software. The results of the suggested antenna designs are presented that reveal a comparable impedance match and radiation characteristics with those of a normal patch antenna without CSRR. The proposed antennas yield high levels of miniaturization and similar performance to the conventional patch antenna at the 2.45GHz.
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7

Czawka, Giennadij, and Marek Garbaruk. "Matrix Analysis and Pulse Transmission of Antenna Array for MIMO UWB Systems." International Journal of Electronics and Telecommunications 57, no. 1 (March 1, 2011): 91–96. http://dx.doi.org/10.2478/v10177-011-0013-z.

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Анотація:
Matrix Analysis and Pulse Transmission of Antenna Array for MIMO UWB Systems This paper presents a theoretical matrix analysis of antenna structure consisting of two double-element planar antennas for ultra-wideband (UWB) application in 2*2 MIMO indoor communication systems. The structure and characteristics of pla-nar two-element UWB antenna are presented. Two matrix models of MIMO antenna system are represented in the paper. A stan-dard MIMO signal transmission matrix without taking into con-sideration the coupling between antennas is described. A new ap-proach to a full electromagnetic analysis based on the scattering matrix of the MIMO spatial antenna array is proposed. Func-tional power parameters for the whole MIMO UWB transmit-receive antenna structure are introduced. Results of computer si-mulations of different matrices describing a MIMO antenna sys-tem and the transmission propagation pulses are presented.
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8

Labun, Ján, Pavol Kurdel, Alexey Nekrasov, Mária Gamcová, Marek Češkovič, and Colin Fidge. "Specific Resonant Properties of Non-Symmetrical Microwave Antennas." Sensors 21, no. 3 (January 31, 2021): 939. http://dx.doi.org/10.3390/s21030939.

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Анотація:
The aircraft avionics modernization process often requires optimization of the aircraft itself. Scale models of aircraft and their antennas are frequently used to solve this problem. Here we present interesting properties of the resonant antennas, which were discovered serendipitously during the measurement process of some microwave antennas’ models as part of an aircraft modernization project. Aircraft microwave antennas are often designed as non-symmetric flat microwave antennas. Due to their thin, low and longitudinally elongated outer profile, they are also called tail antennas. An analysis of the resonant properties of non-symmetric antennas was performed in the band from 1 GHz to 4 GHz. The length of the antenna models ranged from 2 cm to 7 cm. The width of the antennas, together with the thickness of the strip, was always a constant parameter for one measured set of six antennas. In the measurement and subsequent analysis, attention was focused on the first-series resonant frequency (λ/4) of each antenna. During the evaluation of the resonance parameters, the flat microwave antenna models showed specific resonant properties different from those of conventional cylindrical microwave antennas. This article aims to inform professionals about these unknown specific properties of non-symmetrical antennas. The results of experimental measurements are analyzed theoretically and then visually compared using graphs so that the reader can more easily understand the properties observed. These surprising observations open up some new possibilities for the design, implementation, and use of flat microwave antennas, as found in modern aircraft, automobiles, etc.
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9

Kumari, Bibha, and Nisha Gupta. "Multifrequency Oscillator-Type Active Printed Antenna Using Chaotic Colpitts Oscillator." International Journal of Microwave Science and Technology 2014 (November 30, 2014): 1–10. http://dx.doi.org/10.1155/2014/675891.

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Анотація:
This paper presents a new concept to realize a multifrequency Oscillator-type active printed monopole antenna. The concept of period doubling route to chaos is exploited to generate the multiple frequencies. The chaotic Colpitts oscillator is integrated with the printed monopole antenna (PMA) on the same side of the substrate to realize an Oscillator-type active antenna where the PMA acts as a load and radiator to the chaotic oscillator. By changing the bias voltage of the oscillator, the antenna can be made to operate at single or multiple frequencies. To test the characteristics of the antenna at single and multiple frequencies of operation, two similar prototype models of printed monopole broadband antennas are developed. One of these antennas used at transmit side is fed by the chaotic Colpitts oscillator while the other is used as the receive antenna. It is observed that the antenna receives single or multiple frequencies simultaneously for particular values of the bias voltage of the oscillator at the transmit end.
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10

Koshkid’ko, V. G., and M. M. Migalin. "Design of a Slotted Waveguide Antenna by Means of VBScript Scripting Language Macros in CAD Ansys HFSS." Journal of the Russian Universities. Radioelectronics 23, no. 1 (February 28, 2020): 6–17. http://dx.doi.org/10.32603/1993-8985-2020-23-1-6-17.

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Анотація:
Introduction. Modern antenna devices contain a large number of repeating elements. The process of development of CAD models of such devices requires repeatedly performed operations that is a routine task for an engineer. Therefore, the problem of repeating operations automation arises when constructing antenna models with periodic structures.Aim. To demonstrate the automation of slotted waveguide antennas design process in CAD Ansys HFSS.Materials and methods. In order to determine the dimensions of the slotted waveguide antenna the energy method was used. Automation procedure of the design of the slotted waveguide antennas in CAD Ansys HFSS using the Visual Basic Scripting Edition macros was presented.Results. In order to design and edit slotted waveguide antennas in CAD Ansys HFSS four macros in the VBScript language were established: for slot subtraction from a broad wall of a rectangular waveguide at given coordinates; for removing the original slots created using the previous macro; for drawing a polyline passing through the centers of the slots, in order to verify the antenna’s near field realized distribution; for inclined slot subtraction from a narrow wall of a rectangular waveguide at given coordinates. Results of the macros usage were presented.Conclusion. The above mentioned macros allow one to automate the routine steps during the process of creating and deleting objects while designing an antenna model with periodic structures in CAD Ansys HFSS. Specified procedures for creating macros could be extended to a wide class of tasks related to the studies of characteristics of electromagnetic structures including repeating objects (phased antenna arrays, reflective arrays, slotted waveguide antennas, fractal antennas, log-periodic antennas, multi-layer lens antennas, ladder-type microwave filters).
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Більше джерел

Дисертації з теми "Antenna models"

1

Su, Tao. "Characterization of antenna radiation and receiving properties in complex environments based on physical models." Access restricted to users with UT Austin EID Full text (PDF) from UMI/Dissertation Abstracts International, 2001. http://wwwlib.umi.com/cr/utexas/fullcit?p3023561.

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2

Shekhar, Hemabh. "Multi-antenna physical layer models for wireless network design." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/22681.

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Анотація:
Thesis (Ph. D.)--Electrical and Computer Engineering, Georgia Institute of Technology, 2008.
Committee Chair: Ingram, Mary Ann; Committee Member: Andrew, Alfred; Committee Member: Copeland, John; Committee Member: Owen, Henry; Committee Member: Sivakumar, Raghupathy.
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3

Licul, Stanislav. "Ultra-Wideband Antenna Characterization and Modeling." Diss., Virginia Tech, 2004. http://hdl.handle.net/10919/29487.

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Анотація:
A new methodology is presented for characterizing an antenna system both in the time and frequency domain with one set of parameters using a singularity expansion method representation. A minimal set of parameter modeling antenna systems using the Matrix-Pencil method has been demonstrated. It has been shown that it is possible to obtain frequency-domain patterns from pole/residue models of antenna realized effective length. Thus, a pole/residue model of the antenna realized effective length presents a complete description in both the time and frequency domains. Once such a model is available, one can obtain the antenna pattern, directivity and gain in the frequency domain and the radiated transient waveform for an arbitrary excitation waveform and an arbitrary antenna orientation.
Ph. D.
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4

Cracraft, Michael Andrew. "Mobile array designs with ANSERLIN antennas and efficient, wide-band PEEC models for interconnect and power distribution network analysis." Diss., Rolla, Mo. : University of Missouri-Rolla, 2007. http://scholarsmine.umr.edu/thesis/pdf/mcthesis20070623_09007dcc80374999.pdf.

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Анотація:
Thesis (Ph. D.)--University of Missouri--Rolla, 2007.
Vita. The entire thesis text is included in file. Title from title screen of thesis/dissertation PDF file (viewed November 16, 2007) Includes bibliographical references (p. 134-136).
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5

Bengtsson, Mats. "Antenna array signal processing for high rank data models." Doctoral thesis, KTH, Signaler, sensorer och system, 2000. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-2903.

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6

Grimm, Markus [Verfasser]. "Analytic on-body antenna and propagation models / Markus Grimm." Hannover : Gottfried Wilhelm Leibniz Universität Hannover, 2019. http://d-nb.info/1176105191/34.

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7

Glenn, Dickins, and glenn dickins@dolby com. "Applications of Continuous Spatial Models in Multiple Antenna Signal Processing." The Australian National University. Research School of Information Sciences and Engineering, 2008. http://thesis.anu.edu.au./public/adt-ANU20080702.222814.

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Анотація:
This thesis covers the investigation and application of continuous spatial models for multiple antenna signal processing. The use of antenna arrays for advanced sensing and communications systems has been facilitated by the rapid increase in the capabilities of digital signal processing systems. The wireless communications channel will vary across space as different signal paths from the same source combine and interfere. This creates a level of spatial diversity that can be exploited to improve the robustness and overall capacity of the wireless channel. Conventional approaches to using spatial diversity have centered on smart, adaptive antennas and spatial beam forming. Recently, the more general theory of multiple input, multiple output (MIMO) systems has been developed to utilise the independent spatial communication modes offered in a scattering environment.¶ Underlying any multiple antenna system is the basic physics of electromagnetic wave propagation. Whilst a MIMO system may present a set of discrete inputs and outputs, each antenna element must interact with the underlying continuous spatial field. Since an electromagnetic disturbance will propagate through space, the field at different positions in the space will be interrelated. In this way, each position in the field cannot assume an arbitrary independent value and the nature of wave propagation places a constraint on the allowable complexity of a wave-field over space. To take advantage of this underlying physical constraint, it is necessary to have a model that incorporates the continuous nature of the spatial wave-field. ¶This thesis investigates continuous spatial models for the wave-field. The wave equation constraint is introduced by considering a natural basis expansion for the space of physically valid wave-fields. This approach demonstrates that a wave-field over a finite spatial region has an effective finite dimensionality. The optimal basis for representing such a field is dependent on the shape of the region of interest and the angular power distribution of the incident field. By applying the continuous spatial model to the problem of direction of arrival estimation, it is shown that the spatial region occupied by the receiver places a fundamental limit on the number and accuracy with which sources can be resolved. Continuous spatial models also provide a parsimonious representation for modelling the spatial communications channel independent of specific antenna array configurations. The continuous spatial model is also applied to consider limits to the problem of wireless source direction and range localisation.
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8

Herring, Keith 1981. "Propagation models for multiple-antenna systems : methodology, measurements and statistics." Thesis, Massachusetts Institute of Technology, 2008. http://hdl.handle.net/1721.1/43027.

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Анотація:
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2008.
Includes bibliographical references (leaves 219-223).
The trend in wireless communications is towards utilization of multiple antenna systems. While techniques such as beam-forming and spatial diversity have been implemented for some time, the emergence of Multiple-Input Multiple-Output (MIMO) communications has increased commercial interest and development in multiple-antenna technology. Given this trend it has become increasingly important that we understand the propagation characteristics of the environments where this new technology will be deployed. In particular the development of low-cost, high-performance system architectures and protocols is largely dependent on the accuracy of available channel models for approximating realized propagation behavior. The first contribution of this thesis is a methodology for the modeling of wireless propagation in multiple antenna systems. Specifically we consider the problem of propagation modeling from the perspective of the protocol designer and system engineer. By defining the wireless channel as the complex narrow-band channel response h e C between two devices, we characterize the important degrees of freedom associated with the channel by modeling it as a function of its path-loss, multipath/frequency, time stability, spatial, and polarization characteristics. We then motivate this model by presenting a general set of design decisions that depend on these parameters such as network density, channel allocation, and channel-state information (CSI) update rate. Lastly we provide a parametrization of the environment into measurable factors that can be used to predict channel behavior including link-length, Line-Of-Sight (LOS), link topology (e.g. air-to-ground), building density, and other physical parameters. The second contribution of this thesis is the experimental analysis and development of this modeling space.
(cont) Specifically we have gathered a large database of real wireless channel data from a diverse set of propagation environments. A mobile channel-data collection system was built for obtaining the required data which includes an eight-channel software receiver and a collection of WiFi channel sounders. The software receiver synchronously samples the 20-MHz band centered at 2.4 GHz from eight configurable antennas. Measurements have been carried out for both air-to-ground and ground-to-ground links for distances ranging from tens of meters to several kilometers throughout the city of Cambridge, MA. Here we have developed a collection of models for predicting channel behavior, including a model for estimating the path-loss coefficient a in street environments that utilizes two physical parameters: P1 = percentage of building gaps averaged over each side of the street, P2= percentage of the street length that has a building gap on at least one side of the street. Results show a linear increase in a of 0.53 and 0.32 per 10% increase in P1 and P2, respectively, with RMS errors of 0.47 and 0.27 a for a's between 2 and 5. Experiments indicate a 10dB performance advantage in estimating path-loss with this multi-factor model over the optimal linear estimator (upper-bound empirical model) for link lengths as short as 100 meters. In contrast, air-to-ground links have been shown to exhibit log-normal fading with an average attenuation of a ; 2 and standard deviation of 8dB. Additionally we provide exhaustive evidence that the small-scale fading behavior (frequency domain) of both Non-Line-Of-Sight (NLOS) air-to-ground and ground-to-ground links as short as tens of meters is Rayleigh distributed. More specifically, fading distributions across a diverse set of environments and link lengths have been shown to have Rician K-factors smaller than 1, suggesting robust performance of the Rayleigh model.
(cont) A model is also presented that defines a stochastic distribution for the delay-spread of the channel as a function of the link-length (do), multipath component (MPC) decay-rate ( ... attenuation per unit delay ... ), and MPC arrival-rate (q = MPCs per unit delay ... periments support the use of this model over a spectrum of link-lengths (50m-700m) and indicate a dense arrival-rate (q) (on the order of 1 MPC) in ground-to-ground links. In this range the frequency structure of the channel is insensitive to q, which reduces the modeling complexity to a single unknown parameter, P. We provide estimators for 3 over a variety of environment types that have been shown to closely replicate the fade width distribution in these environments. The observed time-coherence length (tc) of MPCs tend to be either less than 300ms (high-frequency) or 5 seconds and longer (low-frequency), resulting in a Rician-like distribution for fading in the time domain. We show that the time characteristics of the channel are accurately modeled as the superposition of two independent circularly symmetric complex gaussian random variables corresponding to the channel response due to a set of stable and unstable MPCs. We observe the S-factor, defined as the ratio of average power in stable to unstable MPCs (distinct from the Rician K-factor), which ranges between 0-30dB depending on environment and link length, and can be estimated with an rms error of 3dB in both ground-to-ground and air-to-ground link regimes. Experiments show improved performance of this model over the Rician fading model which has been shown to underestimate high fade events (tails) in the time domain, corresponding to cases where the stable MPCs destructively combine to form a null. Additionally, the Kronecker MIMO channel model is shown to predict channel capacity (of a 7x7 system) with an rms error of 1.7 ... (at 20dB SNR) over a diverse set of observed outdoor environments.
(cont) Experiments indicate a 3dB performance advantage in this prediction when applied to environments that are not dominated by single-bounce propagation paths (Single-bounce: 2.1 ... rms, Multi-bounce: 1 ... rms).
by Keith T. Herring.
Ph.D.
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9

Sherkat, Navid. "Approximation of Antenna Patterns With Gaussian Beams in Wave Propagation Models." Thesis, Linnéuniversitetet, Institutionen för datavetenskap, fysik och matematik, DFM, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-14437.

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The topic of antenna pattern synthesis, in the context of beam shaping, is considered. One approach to this problem is to use the method of point matching. This method can be used to approximate antenna patterns with a set of uniformly spaced sources with suitable directivities. One specifies a desired antenna pattern and approximates it with a combination of beams. This approach results in a linear system of equations that can be solved for a set of beam coefficients. With suitable shifts between the matching points and between the source points, a good agreement between the assumed and the reproduced antenna patterns can be obtained along an observation line. This antenna modelling could be used in the program NERO to compute the field at the receiver antenna for a realistic 2D communication link. It is verified that the final result is not affected by the details of the antenna modelling.
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10

Papou, Uladzislau. "Conformal and reconfigurable sparse metasurfaces : advanced analytical models and antenna applications." Thesis, université Paris-Saclay, 2020. http://www.theses.fr/2020UPASC027.

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Анотація:
Cette thèse de doctorat traite des métasurfaces constituées de diffuseurs sub-longueur d’onde conçus pour contrôler les fronts d’ondes électromagnétiques. Elle introduit des modèles analytiques et numériques inédits qui résolvent le problème de diffusion inverse en tenant compte des interactions entre éléments de la métasurface. Le manuscrit se concentre plus particulièrement sur des réseaux, périodiques ou non, de fils structurés, permettant la réalisation d’antennes reconfigurables électroniquement. Le manuscrit est divisé en deux grandes parties, l’une sur des arrangements périodiques de fils appelés métaréseaux et l’autre sur des métasurfaces éparses sans caractère périodique. Dans les deux cas, des réalisations expérimentales dans le domaine microondes viennent appuyer les développements théoriques. Dans la première partie, les conditions théoriques conduisant à un contrôle total des ordres de diffraction rayonnés par des métaréseaux, dont la période est composée de plusieurs fils structurés individuellement, sont établies et l’importance du contrôle du champ proche est alors soulignée. Par ailleurs, une expression analytique des paramètres effectifs des fils, s’appuyant sur une simulation numérique, a également été établie. Il devient ainsi possible d’exploiter des géométries quelconques pour des métaréseaux fonctionnant dans les domaines allant des microondes à l’optique. Dans la deuxième partie de la thèse, le modèle analytique des métaréseaux, réservé aux distributions périodiques planes, est généralisé aux distributions non périodiques de fils disposés sur des surfaces quelconques en s’appuyant sur le calcul de la fonction de Green. Ce concept est appliqué à des métasurfaces éparses intervenant dans une cavité Fabry-Perot ou dans une antenne semi-cylindrique. Enfin, la démarche est utilisée pour concevoir une métasurface éparse plane reconfigurable. Un prototype a été réalisé et utilisé pour démontrer expérimentalement le contrôle dynamique de l’onde, en champ lointain et en champ proche, via des applications telles que le dépointage de faisceau, la création de faisceaux multiples ou encore la focalisation au-delà de la limite de diffraction
This PhD thesis deals with electromagnetic metasurfaces for wavefront manipulation represented by arrays of scatterers engineered at subwavelength scale. The manuscript develops novel analytical and numerical models that allow one to solve the inverse scattering problem by taking into account all interactions between elements of a metasurface. Specifically, the manuscript focuses on sparse arrays, periodic or not, of structured wires for the application to electronically reconfigurable antennas. The manuscript is divided into two main parts, one on periodic arrangements of wires called metagratings and one on sparse metasurfaces when there is no periodicity imposed. Each part is endorsed by experiments performed at microwave frequencies. In the first part, theoretical conditions for arbitrary control of the diffraction patterns with metagratings, whose period is composed of multiple individually-engineered wires, are established and importance of the near-field regulation is highlighted. Moreover, an analytical retrieval technique is developed and allows one to consider, with the help of full-wave simulations, arbitrarily structured wires for metagratings operating from microwave to optical domains. In the second part of the thesis, the analytical model of metagratings is generalized, from planar periodic, to arbitrarily-shaped non-periodic distributions of wires by means of numerical calculation of a Green’s function. The concept is applied to design sparse metasurfaces in Fabry-Perot cavity and semi-cylindrical antenna configurations. Finally, the approach is applied to design a reconfigurable planar sparse metasurface. A fabricated sample is exploited to experimentally demonstrate dynamic control of the far-field radiation pattern and the near-field intensity distribution. As such beam-steering, multi-beam manipulation and subdiffraction focusing are shown
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Книги з теми "Antenna models"

1

Khashimov, Amur B., and Rinat R. Salikhov. Practical Models of Antenna Systems. Singapore: Springer Nature Singapore, 2022. http://dx.doi.org/10.1007/978-981-19-6219-6.

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Haupt, Randy L. Antenna arrays: A computational approach. Hoboken, N.J: Wiley-IEEE Press, 2010.

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Haupt, Randy L. Antenna arrays: A computational approach. Hoboken, N.J: Wiley-IEEE Press, 2010.

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Haupt, Randy L. Antenna arrays: A computational approach. Hoboken, N.J: Wiley-IEEE Press, 2010.

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Haupt, Randy L. Antenna arrays: A computational approach. Hoboken, N.J: Wiley-IEEE Press, 2010.

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6

Poljak, D. Electromagnetic modelling of wire antenna structures. Southampton, UK: WIT Press, 2002.

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7

Wu, Xuan Hui. Generalized transmission line method to study the far-zone radiation of antennas under a multilayer structure. San Rafael, Calif. (1537 Fourth Street, San Rafael, CA 94901 USA): Morgan & Claypool Publishers, 2008.

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8

Yngvesson, K. Sigfrid. Development of theoretical models of integrated millimeter wave antennas. Hampton, Va: Langley Research Center, 1991.

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Electronically steered arrays: MATLAB modeling and simulation. Boca Raton: CRC Press, 2013.

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10

Kontorovich, V. I︠A︡. (Valeriĭ I︠A︡kovlevich), ed. Wireless multi-antenna channels: Modeling and simulation. Hoboken, N.J: Wiley, 2011.

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Частини книг з теми "Antenna models"

1

Koziel, Slawomir, and Stanislav Ogurtsov. "Low-Fidelity Antenna Models." In SpringerBriefs in Optimization, 45–52. Cham: Springer International Publishing, 2014. http://dx.doi.org/10.1007/978-3-319-04367-8_5.

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Khashimov, Amur B., and Rinat R. Salikhov. "Mathematical Modeling VDB Antenna System." In Practical Models of Antenna Systems, 77–86. Singapore: Springer Nature Singapore, 2022. http://dx.doi.org/10.1007/978-981-19-6219-6_5.

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Khashimov, Amur B., and Rinat R. Salikhov. "On the Correspondence of Asymptotic Solutions to 2D and 3D Problems in Antenna Engineering." In Practical Models of Antenna Systems, 1–44. Singapore: Springer Nature Singapore, 2022. http://dx.doi.org/10.1007/978-981-19-6219-6_1.

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Khashimov, Amur B., and Rinat R. Salikhov. "Statistical Modeling of Characteristics of a Radio Beacon of an Instrumental Landing System." In Practical Models of Antenna Systems, 67–76. Singapore: Springer Nature Singapore, 2022. http://dx.doi.org/10.1007/978-981-19-6219-6_4.

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Khashimov, Amur B., and Rinat R. Salikhov. "Mathematical Models of DME Antenna Systems." In Practical Models of Antenna Systems, 87–108. Singapore: Springer Nature Singapore, 2022. http://dx.doi.org/10.1007/978-981-19-6219-6_6.

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Khashimov, Amur B., and Rinat R. Salikhov. "Methods for Correcting the Characteristics of Antenna Systems that Including the Influence of the Placement Object." In Practical Models of Antenna Systems, 59–66. Singapore: Springer Nature Singapore, 2022. http://dx.doi.org/10.1007/978-981-19-6219-6_3.

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Khashimov, Amur B., and Rinat R. Salikhov. "Mathematical Models of Antenna Systems Including Vertical Polarized Dipoles." In Practical Models of Antenna Systems, 45–57. Singapore: Springer Nature Singapore, 2022. http://dx.doi.org/10.1007/978-981-19-6219-6_2.

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Khashimov, Amur B., and Rinat R. Salikhov. "Development of Mathematical Models of High-Precision Antenna Measuring Systems." In Practical Models of Antenna Systems, 109–17. Singapore: Springer Nature Singapore, 2022. http://dx.doi.org/10.1007/978-981-19-6219-6_7.

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9

Costantine, Joseph, Youssef Tawk, and Christos G. Christodoulou. "Redundancy Reduction in Reconfigurable Antenna Structures." In Design of Reconfigurable Antennas Using Graph Models, 49–73. Cham: Springer International Publishing, 2013. http://dx.doi.org/10.1007/978-3-031-01540-3_4.

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Koziel, Slawomir, and Stanislav Ogurtsov. "Simulation-Based Multi-objective Antenna Optimization with Surrogate Models." In SpringerBriefs in Optimization, 105–17. Cham: Springer International Publishing, 2014. http://dx.doi.org/10.1007/978-3-319-04367-8_11.

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Тези доповідей конференцій з теми "Antenna models"

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Sulic, E., B. Pell, S. John, Rahul K. Gupta, W. Rowe, K. Ghorbani, and K. Zhang. "Performance of Embedded Multi-Frequency Communication Devices in Smart Composite Structures." In ASME 2008 Conference on Smart Materials, Adaptive Structures and Intelligent Systems. ASMEDC, 2008. http://dx.doi.org/10.1115/smasis2008-402.

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Lately, there has been an increased demand for vehicle manufacturers to incorporate a large number of communication, security, guidance and entertainment devices in their new vehicle models. In recent decades, the list has expanded from the AM and FM radio antennas to include GPS, mobile phone, collision avoidance radar, Digital Radio and Digital TV antennas. In addition, new technologies such as vehicle to vehicle and vehicle to road side communication are being implemented at 5.9 GHz in the next generation of vehicles. In the past the AM/FM antenna was typically a mast antenna protruding from the vehicle’s exterior, recently however, the trend has been to limit the visibility of vehicular antennas as much as possible to improve vehicle design and aerodynamics. This has lead to integration of antennae so that they become a seamless part of the vehicle structure. This paper reports on a parametric study of embedding an antenna in a polymeric composite substrate in relation to several material processing and coating parameters.
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2

Klyukin, Dmitriy, Aleksandr Demakov, Anton Ivanov, and Sergey Kuksenko. "MODELING THE ANTENNA INPUT IMPEDANCE BY THE METHOD OF MOMENTS." In CAD/EDA/SIMULATION IN MODERN ELECTRONICS 2021. Bryansk State Technical University, 2021. http://dx.doi.org/10.30987/conferencearticle_61c997eddbd2f6.91578385.

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The paper presents a comparison of excitation source models when modeling antennas by the method of moments. By using a set of adjacent edges when specifying the impact, it is possible to obtain correct results when the computational grid of the antenna model is more frequent. This is shown on the example of a symmetric electric vibrator.
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3

Wang, C. S., H. Bao, and W. Wang. "Coupled Structural-Electromagnetic Optimization and Analysis of Space Intelligent Antenna Structural Systems." In ASME 2008 9th Biennial Conference on Engineering Systems Design and Analysis. ASMEDC, 2008. http://dx.doi.org/10.1115/esda2008-59306.

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For high electromagnetic performances, large space truss antennas should have reflector surface with an extremely high precision. Due to the varied load and some random disturbances, active control strategy is always used in the kind of structure for the precise surface. For the improvement of the electromagnetic performances, an electromechanical synthesis optimization model of space antenna structure systems is developed based on the antenna’s characteristics, which adopts the axial gain of antenna and power consumption of actuators as the objective functions, and structural material strength and actuator’s capability as constraint conditions. The application of model to an 8-m antenna structure demonstrates the potential for significant improvement. The analysis results indicate the benefit of including electrical performance in model for necessary effort for shape control of large space antenna reflectors.
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4

Guo, Hongwei, Chuang Shi, Yuzhen Tang, Rongqiang Liu, and Zongquan Deng. "Design and Study for Dynamics Characteristics of Double-Layer Loop Deployable Antenna Mechanism." In ASME 2016 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/detc2016-59473.

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In order to design lightweight and high stiffness large-sized deployable antenna mechanism, a kind of slider crank basic deployable mechanism unit which is driven by elastic hinges and one sort of double-layer loop deployable antennas mechanism which is composed of the units are put forward. In this paper, the method of finite element dynamic models for double-layer loop deployable antenna mechanism and the control variable method are combined to conclude the interaction relationship between the fundamental frequency of double-layer loop deployable antenna with the mechanism geometric parameters of the antenna diameter, height, thickness and other geometrical parameters of the double layer loop antenna. On this basis, an empirical formula of fundamental frequency calculation of double-layer loop deployable antenna mechanism is achieved. According to the performance of the frequency of the antenna mechanism, the antenna diameter is divided into small diameter, large diameter and super large diameter three grades. The influences of the mass and the stiffness of antenna mechanism are taken into comprehensive consideration, then a comprehensive evaluation index of the single-layer and double-layer loop deployable antenna mechanism characteristics is set up to make comparative analysis of the dynamic characteristics of the unfolded single-layer and double-layer deployable antenna mechanism with different diameters. It is concluded that the applicable diameter range of the single-layer loop deployable mechanism is 1m to 20m, while the applicable diameter range of the double-layer loop is 20m to 100m.
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Dawidowicz, Karol, Grzegorz Krzan, Radosław Baryła, and Krzysztof Swiatek. "The Impact of GNSS Antenna Mounting during Absolute Field Calibration on Phase Center Correction – JAV_GRANT-G3T Antenna Case Study." In Environmental Engineering. VGTU Technika, 2017. http://dx.doi.org/10.3846/enviro.2017.183.

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The phase center corrections (PCC) of an GNSS antenna can be precisely determined using the absolute field calibration procedure with a precise robot. Using the Hannover’s automated absolute antenna field calibration technique developed by the Institute of Geodesy (University of Hannover) and Geo++ we demonstrate that the way of antenna mounting on the robot (distance from mechanical structures mounted underneath the antennas) can cause significant changes in the phase center offset and variations. For both the GPS and the GLONASS carrier signals L1 and L2 these changes are in the order of several millimeters. e also analyzed how these changes transfer to the coordinate domain. We investigated the differences between position estimates obtained using two different, individual and type-mean, elevation dependent PCC. There days of GNSS observations on very short baseline were used for these studies. The position time-series were derived using the RTKLib software package. We found that that the differences in the calibrations models propagate directly into the position domain, affecting sub-daily results and giving visible periodic variations in solutions. The best agreement with the “true position” we obtained using PCC from the individual calibrations.
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Yoon, Hwan-Sik, and Gregory Washington. "Analysis of Active Doubly Curved Antenna Structures." In ASME 1998 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 1998. http://dx.doi.org/10.1115/imece1998-0957.

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Abstract Recently, aperture antennas that have the ability to change their reflector shape through the usage of piezoelectric actuators have been studied. The results show that those antennas can exhibit beam steering and beam shaping in the far-field. However, the previous studies have been confined to cylindrical shape antennas. This study examines the use of “doubly curved” antenna structures to achieve better performance in controlling an antenna’s coverage area. The spherical antenna is modeled as a shallow spherical shell with a small hole at the apex for mounting. Following Reissener’s approach, a stress function is introduced and two governing equations are derived in terms of the stress function and the axial deflection. Next, the amount of deflections are evaluated from the calculated stress function and the axial deflection. As actuators, four PZT strip actuators are attached along the meridians separated by 90 degrees respectively. The force developed by the actuators are expanded in Fourier series and fed into the governing equations as boundary conditions at the outer edge. Finally, the Deflection vs. Applied Voltage is calculated analytically and its effect on the far-field radiation is given.
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Foged, L. J., L. Scialacqua, F. Saccardi, F. Mioc, J. L. Araque Quijano, and G. Vecchi. "Measured antenna models for numerical simulations of antenna placement scenarios." In 2016 IEEE International Symposium on Antennas and Propagation & USNC/URSI National Radio Science Meeting. IEEE, 2016. http://dx.doi.org/10.1109/aps.2016.7695819.

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Ghasemzadeh, Pejman, Subharthi Banerjee, Michael Hempel, Andrew Harms, and Hamid Sharif. "Detecting Dark Cars Using a Novel Multi-Antenna AEI Tag Reader Design for Increased Read Distance and Reliability." In 2020 Joint Rail Conference. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/jrc2020-8089.

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Abstract Automatic Equipment Identification (AEI) tags are installed on all rail cars in North America to tag rolling stock and facilitate fault detection using wayside detectors. And yet, railcars do get lost when parked on sidings, etc., resulting in so-called Dark Cars. No effective solution has been proposed for finding such lost rail cars due to the distance limitations in the current AEI tag readers. However, recent developments in the area of AEI tags in particular multi-antenna wireless communication systems and backscatter communications, now provide the opportunity to read AEI tags from much farther distances. The adavntage of using multiple antennas is to increase read distance and directionality through beamforming while adhering to FCC power limits. The key obstacle to long-distance AEI tag reading is the limited link budget, which is the combination of the FCC-mandated power limit coupled with the minimum required EM field strength needed to power the AEI tag during a read operation. Since it is not feasible to modify the AEI tags themselves because a large number of them installed on railcars, nor boost the transmit power, our design is focused on increasing directionality of the transmitted power. In this work, the authors thus propose a novel use of a Multi-Antenna Beamforming AEI tag reader mounted on — and powered by — a locomotive. This is to detect AEI tags on dark cars by a train passing the dark cars. The authors conducted an in-depth model-driven performance evaluation of this scheme. The analysis includes different channel models, signal reflection, and impact from velocity on read success rates. The channel models considered in this evaluation include multipath models such as Rayleigh, Rician, and Two-Ray Ground. The results presented by the authors show that our proposed novel approach is not only feasible to read AEI tags in this fashion over distances exceeding multiple track separation distances, but also practical, in most cases requiring 10 or less antennas with only simple beamforming methods employed.
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Santapuri, Sushma, and Stephen E. Bechtel. "Model-Based Optimization of Coupled Thermo-Electro-Magneto-Mechanical Behavior of Load-Bearing Antennas." In ASME 2010 International Mechanical Engineering Congress and Exposition. ASMEDC, 2010. http://dx.doi.org/10.1115/imece2010-38786.

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Load-bearing antennas are multi-functional sensing (actuating) and receiving (detecting) devices that are integrated with a load-bearing structure. These antennas are appealing for military applications, importantly Unmanned Aerial Vehicles (UAV). The antenna structure is subjected to mechanical forces, temperature gradients, and electromagnetic fields, giving rise to highly-coupled nonlinear thermo-electro-magneto-mechanical (TEMM) behavior. In the present work, we have developed analytical techniques and computational tools for multi-scale, multi-physics modeling of composite load-bearing antennas, specific to UAV applications. Our mathematical model, based predominantly on first principles, employs the thermomechanical governing equations (i.e., conservation of mass, momentum, angular momentum, energy and second law of thermodynamics) coupled with Maxwells equations. The macro-scale coupling terms that characterize the thermo-mechanical and electromagnetic interactions are deduced from micro-scale behavior. Our modeling has identified 92 nondimensional numbers which quantify the competition between physical effects in the operation of load-bearing antenna. Depending on the design of the structure and nature of the excitation, only a subset of physical effects are dominant, which dictates the appropriate computational model. A fixed relative ordering of all competing effects as quantified by nondimensional numbers, determines a regime of antenna/environment interaction. The mathematical structure of leading-order equations for various physical regimes is presented for use in the optimization and analysis of coupled TEMM behavior of load-bearing antennas.
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Tu, Sheng, Qingsha S. Cheng, John W. Bandler, and Natalia K. Nikolova. "Space mapping design exploiting library antenna models." In 2012 IEEE Antennas and Propagation Society International Symposium and USNC/URSI National Radio Science Meeting. IEEE, 2012. http://dx.doi.org/10.1109/aps.2012.6348752.

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Звіти організацій з теми "Antenna models"

1

Maragoudakis, Christos E., and Edward Rede. Validated Antenna Models for Standard Gain Horn Antennas. Fort Belvoir, VA: Defense Technical Information Center, August 2009. http://dx.doi.org/10.21236/ada629345.

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2

Batchelor, D. B., and M. D. Carter. An outgoing energy flux boundary condition for finite difference ICRP antenna models. Office of Scientific and Technical Information (OSTI), November 1992. http://dx.doi.org/10.2172/6719370.

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Batchelor, D. B., and M. D. Carter. An outgoing energy flux boundary condition for finite difference ICRP antenna models. Office of Scientific and Technical Information (OSTI), November 1992. http://dx.doi.org/10.2172/10129856.

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4

Kang, Intae, and Radha Poovendran. Design Issues on Broadcast Routing Algorithms using Realistic Cost-Effective Smart Antenna Models. Fort Belvoir, VA: Defense Technical Information Center, January 2004. http://dx.doi.org/10.21236/ada459825.

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5

Campbell, Seth, Zoe Courville, Samantha Sinclair, and Joel Wilner. Brine, englacial structure and basal properties near the terminus of McMurdo Ice Shelf, Antarctica. Engineer Research and Development Center (U.S.), September 2022. http://dx.doi.org/10.21079/11681/45303.

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We collected ∼1300 km of ground-penetrating radar profiles over McMurdo Ice Shelf, Antarctica, using frequencies between 40 and 400 MHz to determine extent, continuity and depth to the brine. We also used profiles to determine meteoric ice thickness and locate englacial features, which may suggest ice shelf instability. The brine extends 9–13 km inland from the ice shelf terminus and covers the entire region between Ross, White and Black Islands. Jump unconformities and basal fractures exist in the brine and ice shelf, respectively, suggesting prior fracturing and re-suturing. One 100 MHz profile, the most distal from the ice shelf edge while still being situated over the brine, simultaneously imaged the brine and bottom of meteoric ice. This suggests a negative brine salinity gradient moving away from the terminus. The meteoric ice bottom was also imaged in a few select locations through blue ice in the ablation zone near Black Island. We suggest that brine, sediment-rich ice and poor antenna coupling on rough ice attenuates the signal in this area. When combined with other recent mass-balance and structural glaciology studies of MIS, our results could contribute to one of the most high-resolution physical models of an ice shelf in Antarctica.
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Burke, G. J. Ground Model Options in the NEC-4.2 Antenna Code. Office of Scientific and Technical Information (OSTI), June 2011. http://dx.doi.org/10.2172/1117909.

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Johnson, William Arthur, Larry Kevin Warne, Roy Eberhardt Jorgenson, and Kelvin S. H. Lee. An improved statistical model for linear antenna input impedance in an electrically large cavity. Office of Scientific and Technical Information (OSTI), March 2005. http://dx.doi.org/10.2172/922749.

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Ling, Hao. Application of Model-Based Signal Processing and Genetic Algorithms for Shipboard Antenna Design, Placement Optimization. Fort Belvoir, VA: Defense Technical Information Center, January 2002. http://dx.doi.org/10.21236/ada399555.

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Adams, R. C., and P. M. Hansen. The Modal Decomposition of the Quality Factor of an Antenna in Prolate Spheroidal Coordinates. Fort Belvoir, VA: Defense Technical Information Center, September 2008. http://dx.doi.org/10.21236/ada487279.

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Nelson, Nathan, and Charles F. Yocum. Structure, Function and Utilization of Plant Photosynthetic Reaction Centers. United States Department of Agriculture, September 2012. http://dx.doi.org/10.32747/2012.7699846.bard.

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Light capturing and energy conversion by PSI is one of the most fundamental processes in nature. In the heart of these adaptations stand PSI, PSII and their light harvesting antenna complexes. The main goal of this grant proposal was to obtain by X-ray crystallography information on the structure of plant photosystem I (PSI) and photosystem II (PSII) supercomplexes. We achieved several milestones along this line but as yet, like several strong laboratories around the world, we have no crystal structure of plant PSII. We have redesigned the purification and crystallization procedures and recently solved the crystal structure of the PSI supercomplex at 3.3 Å resolution. Even though this advance in resolution appears to be relatively small, we obtained a significantly improved model of the supercomplex. The work was published in J. Biol. Chem. (Amunts et al., 2010). The improved electron density map yielded identification and tracing of the PsaK subunit. The location of an additional 10 ß-carotenes, as well as 5 chlorophylls and several loop regions that were previously uninterruptable have been modeled. This represents the most complete plant PSI structure obtained thus far, revealing the locations of and interactions among 17 protein subunits and 193 non-covalently bound photochemical cofactors. We have continued extensive experimental efforts to improve the structure of plant PSI and to obtain PSII preparation amenable to crystallization. Most of our efforts were devoted to obtain well-defined subcomplexes of plant PSII preparations that are amenable to crystallization. We studied the apparent paradox of the high sensitivity of oxygen evolution of isolated thylakoids while BBY particles exhibit remarkable resilience to the same treatment. The integrity of the photosystem II (PSII) extrinsic protein complement as well as calcium effects arise from the Ca2+ atom associated with the site of photosynthetic water oxidation were investigated. This work provides deeper insights into the interaction of PsbO with PSII. Sight-directed mutagenesis indicated the location of critical sites involved in the stability of the water oxidation reaction. When combined with previous results, the data lead to a more detailed model for PsbO binding in eukaryotic PSII.
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