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Antennas and Propagation Magazine, IEEE

Issue 6 • Date Dec. 2002

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Displaying Results 1 - 20 of 20
  • Raj Mittra: 2002 AP-S Distinguished Achievement Award

    Publication Year: 2002 , Page(s): 87
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    Freely Available from IEEE
  • Reviewers list

    Publication Year: 2002 , Page(s): 103
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    Freely Available from IEEE
  • Dealers of lightning: xerox PARC and the dawn of the computer age [Book Review]

    Publication Year: 2002 , Page(s): 108
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    Freely Available from IEEE
  • Acoustics of layered media I and II [Book Review]

    Publication Year: 2002 , Page(s): 108 - 110
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    Freely Available from IEEE
  • 2003 IEEE fellows announced

    Publication Year: 2002 , Page(s): 136
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    Freely Available from IEEE
  • Correction - "Comment: on the equivalent circuit of a receiving antenna"

    Publication Year: 2002 , Page(s): 146
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  • US patent and trademark office proposals to speed up the patent process

    Publication Year: 2002 , Page(s): 152 - 162
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  • Implementing distributed FDTD codes with Java mobile agents

    Publication Year: 2002 , Page(s): 115 - 119
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (453 KB)  

    The main objective of this work is to highlight the advantages of coupling Java FDTD implementation with the mobile-agent computing paradigm, and to promote this approach as a flexible and valuable tool for the distributed solution of complex and large-scale problems. Therefore, we present key issues related to the distributed implementation of a finite-difference time-domain (FDTD) code using Java mobile agents. The Java object-oriented FDTD code is described, and special agent communication and synchronization aspects related to FDTD are presented in detail. View full abstract»

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  • A critical study of the circuit relations of two distant antennas

    Publication Year: 2002 , Page(s): 32 - 37
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (381 KB) |  | HTML iconHTML  

    In this work, we present a critical study of the circuit relations for two distant coupled antennas: either both are transmitting, or one is transmitting and one is receiving. We found that Carter's two mutual impedances, Z12 and Z21, are not applicable to these two cases. Two sets of circuit relations have been formulated, with two sets of wave impedances, to characterize these new circuit relations. It is shown that the coupled wave impedances are not equal to each other, and they satisfy a conjugate relation with a negative sign. Such a relation also applies to Carter's Z12 and Z21. View full abstract»

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  • Analysis of the S-band communication link between the automated transfer vehicle and the data relay satellites in the presence of the space station

    Publication Year: 2002 , Page(s): 12 - 23
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1000 KB) |  | HTML iconHTML  

    This paper addresses the electromagnetic modeling of the communication link between the automated transfer vehicle (ATV) and the Tracking & Data Relay Satellite System (TDRSS). The link is analyzed during the ISS attached phase, i.e. when the ATV is docked on the International Space Station (ISS). The main objective of the study is to verify, by adopting a deterministic approach, if in every ISS orbit there are at least 15 minutes available to safely establish the ATV-TDRSS link. View full abstract»

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  • Simulation of mobile fading channels

    Publication Year: 2002 , Page(s): 172 - 183
    Cited by:  Papers (2)
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    Many aspects of a mobile radio system are basically determined by the propagation characteristics of the channel. Therefore, an understanding and good knowledge of mobile radio channels is essential for the analysis, design, and operation of wireless systems. It allows the successful development, evaluation, and testing of any current or future communication system, whether it is for cellular mobile telephony, for radio paging, or for mobile satellite systems. This article tries to present a simple and efficient way to simulate mobile channels for development and testing of mobile wireless systems, using some of the commercial circuit-analysis and simulation programs. So, in parallel with an overview of fading-channel propagation mechanisms and aspects, compact simulation models are given that can effectively be used for further analysis and understanding of the operation of mobile fading channels. View full abstract»

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  • Antenna scanning techniques for estimation of spacecraft position

    Publication Year: 2002 , Page(s): 38 - 45
    Cited by:  Papers (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (522 KB) |  | HTML iconHTML  

    Scanning movements are added to a tracking antenna's trajectory to estimate the true spacecraft position. The scanning movements are composed of the harmonic axial movements of an antenna. This motion produces power variations of the received signal, which are used to estimate the spacecraft's position. Three different scanning patterns (conical scan, Lissajous scan, and rosette scan) are presented and analyzed in this paper. The analysis includes the evaluation of the estimation errors due to random or harmonic variation of the antenna's position, and due to random and harmonic variations of the power level. Typically, the estimation of the spacecraft's position is carried out after completing a full scanning cycle. Sliding-window scanning is introduced in this paper, wherein the spacecraft-position estimation is carried out in an almost-continuous manner, and it reduces the estimation time by half. View full abstract»

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  • Ionospheric effects on satellite land mobile systems

    Publication Year: 2002 , Page(s): 24 - 31
    Cited by:  Papers (12)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (613 KB) |  | HTML iconHTML  

    Satellite-ground radio systems are now so sensitive that ionospheric changes can disrupt their performance. This paper discusses some satellite-to-ground propagation problems in the UHF and L bands caused by the Earth's ionosphere. Such problems include signal time delay, signal dispersion, Faraday rotation, and scintillation. View full abstract»

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  • On the radiation from a large, open-ended waveguide

    Publication Year: 2002 , Page(s): 98 - 100
    Cited by:  Papers (3)
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    The expressions for the electric field radiated from a large, open-ended rectangular-waveguide aperture have been derived for the propagating H and E modes, since the available expressions are erroneous. View full abstract»

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  • The Numeric Python EM project

    Publication Year: 2002
    Cited by:  Papers (1)
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    The Numeric Python EM project started out as a conversion of ToyFDTD to Numeric Python (a fast vector oriented module for the Python programming language). Surprisingly, the simulation ran almost as fast as the original C-language version. Since Python is an interpreted language, the simulation conditions can easily be altered and run immediately. This makes Numeric Python an ideal prototyping language for EM simulators. View full abstract»

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  • Expanding our students' brainpower: idea generation and critical thinking skills

    Publication Year: 2002 , Page(s): 140 - 144
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (431 KB) |  | HTML iconHTML  

    How do we teach our students to think? This is not a skill that they can pick up by doing "X" number of homework problems; it is the product of good habits that must be practiced and honed on a daily basis. It is a state of mind that continually questions "Who? What? Where? When? How? Why?" In light of this reality, we developed this segment for the "Introduction to Literature Review and Proposal Writing" graduate course this past summer. Our goals during this three-day class period were: · To define the creative process · To identify techniques that enhance creativity · To practice idea generation and critical thinking skills in controlled settings This segment helps smooth the transition between the undergraduate mentality of "teach me" to the desired graduate-student mentality of "enable me." It attempts to demystify the creative process, which most people associate with inspired moments and geniuses, so that students can deliberately foster an atmosphere that will help them generate new research ideas. View full abstract»

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  • Cellular-phone radiation effects on cancer in genetically modified mice

    Publication Year: 2002 , Page(s): 165 - 168
    Cited by:  Papers (2)
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    A television interview, given by the authors of a paper reporting the results of an Australian study on the occasion of its publication (Utteridge et al. 2002) in the September, 2002, issue of the joumal Radiation Research, proclaimed that long-term exposure to microwave radiation (900 MHz) from Global System for Mobile Communication (GSM) phones is safe. Moreover, the paper's authors asserted their findings as countering a previous Australian study (Repacholi et al. 1997), which reported an increased incidence of lymphomas in mice of the same transgenic strain and from the same supplier as those used in their experiment. The study has been widely reported by the popular media. A closer reading of the scientific paper reveals that it is fraught with inconsistencies, which make it very difficult to accept its results and conclusions as published with confidence, without further clarification and/or candid answers to some compelling questions. It appears that the study was conducted with care, but there was a lapse somewhere in the execution of the experiment, or in the sourcing of animals, or in the analysis of data, or in the environmental conditions under which the investigation was conducted. Thus, instead of shedding light on whether cell-phone radiation is safe, the latest report has abetted the controversy. View full abstract»

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  • Gravity deformation measurements of 70 m reflector surfaces

    Publication Year: 2002 , Page(s): 187 - 192
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (511 KB) |  | HTML iconHTML  

    Two of NASA's Deep Space Network (DSN) 70-meter reflectors were measured using a Leica TDM-5000 theodolite. The main reflector surface was measured at five elevation angles, so that a gravity-deformation model could be derived that described the main-reflector distortions over the entire range of elevation angles. The report describes the measurement equipment and accuracy, and the results derived from the data. View full abstract»

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  • Power flow between adjacent electric dipoles

    Publication Year: 2002 , Page(s): 68 - 76
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (554 KB) |  | HTML iconHTML  

    The Poynting vector field is shown for two adjacent electric dipoles, when there is a phase difference between them. There is a boundary around the two dipoles, inside which the time-averaged Poynting-vector field flows from one dipole to the other, and outside which it flows outwards. It is shown that in spite of the behavior of the Poynting-vector field, in which the time-averaged power leaves one dipole and enters the other, it complies with Poynting's theorem for harmonic fields, and maintains the constancy of the net radiated power. It is also shown that the total time-averaged power radiated from the two-dipole system comes from the small area between the axis along which the two dipoles are aligned and the boundary or separatrix at one of the dipoles. This two-dipole model also helps us understand the behavior of the Poynting-vector field near the edge of a semi-infinite current sheet. View full abstract»

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  • Modeling EM structures in the neural network toolbox of MATLAB

    Publication Year: 2002 , Page(s): 46 - 67
    Cited by:  Papers (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1483 KB) |  | HTML iconHTML  

    Neural networks are systems that can be trained to remember the behavior of a modeled structure at given operational points, and that can be used to approximate the behavior of the structure outside of the training points. These neural-net approximation abilities are demonstrated in the modeling a frequency-selective surface, a microstrip transmission line, and a microstrip dipole. Attention is given to the accuracy and to the efficiency of neural models. The association between neural models and genetic algorithms, which can provide a global design tool, is discussed. Portions of the MATLAB code illustrate the descriptions. View full abstract»

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The IEEE Antennas and Propagation Magazine covers all areas relating to antenna theory, design, and practice.

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Editor-in-Chief
Mahta Moghaddam