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Antennas and Propagation Magazine, IEEE

Issue 2 • Date April 2002

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Displaying Results 1 - 23 of 23
  • Reginald Aubrey Fessenden and the birth of wireless telephony

    Page(s): 38 - 47
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    The year 2000 was the 100th anniversary of the transmission of the first voice over radio. On December 23, 1900, Prof. Reginald Aubrey Fessenden after a number of unsuccessful tries - transmitted "words without wires" over a distance of 1600 m, between twin aerial systems employing 15 m masts, located on Cobb Island, Maryland. The quality of the received wireless-telephony transmission was reported to be perfectly intelligible, but the speech was accompanied by an extremely loud, disagreeable noise, due to the irregularity of the spark. Spark? Yes. Fessenden had not yet developed a method to generate continuous waves. The sender was a spark transmitter, operating at 10,000 sparks/second, with an asbestos-covered carbon microphone inserted in the antenna lead. In spite of the primitive apparatus-used, the poor quality of the transmission, and the short distance, intelligible speech had been transmitted by electromagnetic waves for the first time in the history of wireless. Who was Fessenden? The purpose of this paper is to touch upon his life's history, and to give some detail of his accomplishments. However, the paper begins with an account of the birth of radio, so that the reader can appreciate Fessenden's place in history. View full abstract»

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  • Operator Theory for Electromagnetics, An Introduction [Book Review]

    Page(s): 72 - 73
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    Freely Available from IEEE
  • Propagation Corner

    Page(s): 108 - 110
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  • IEEE fiscal state of affairs: iv

    Page(s): 112 - 113
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    Freely Available from IEEE
  • Yahya Rahmat-Samii elected to royal flemish academy

    Page(s): 118 - 119
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    First Page of the Article
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  • Report of awards and fellow

    Page(s): 120
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    Freely Available from IEEE
  • How effective is your leadership style?

    Page(s): 124 - 125
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    First Page of the Article
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  • Report of the transactions editor

    Page(s): 126 - 128
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    Freely Available from IEEE
  • Report on asian presentations by AP-S distinguished lecturer

    Page(s): 128 - 130
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    Freely Available from IEEE
  • Report on AP-S distinguished lecturer presentation in Japan

    Page(s): 131
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    Freely Available from IEEE
  • Electromagnetic Modelling of Wire Antenna Structures [Book Review]

    Page(s): 73
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    Freely Available from IEEE
  • Electromagnetics and exotic media: a quest for the holy grail

    Page(s): 48 - 58
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (913 KB) |  | HTML iconHTML  

    During the past eight years, the authors have extensively studied the properties of linear homogeneous bianisotropic media. They have studied the Green's dyadics, the factorization of the Helmholtz determinant operator, the field and source decomposition, and plane-wave propagation in various classes of these media. We give an overview of our findings, and we place these findings in historical order. The results we found provide insight into the nature of Maxwell's equations, in general, and into the field propagation mechanisms in the different media, in particular. Finally, we mention that closed-form solutions are valuable as benchmarking results for numerical solutions View full abstract»

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  • A new view of millimeter-wave satellite communication

    Page(s): 59 - 61
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    Italian satellite results have broad implications for millimeter-wave satellite communication. We apply their results to high-elevation satellite systems, and find that attractive frequencies extend well beyond the Ka band, to emphasize 40-47 and 85-98 GHz View full abstract»

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  • Optimum directivity coverage of fan-beam antennas

    Page(s): 66 - 70
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    Cellular and point-to-multipoint wireless communication systems use fan-beam antennas for sector coverage from the central station. The ratio of the azimuth-to-elevation half-power beamwidth typically ranges from two for sites requiring low-gain antenna values to 25 or greater for sites covering large cells. This article presents an approximate formula for the antenna directivity of the fan-beam antenna using two parameters to describe the azimuth pattern shape, and two parameters for the elevation pattern. The directivity formula presented includes minor lobes. A variation of the fan-beam directivity formula is presented for the omnidirectional antenna. The directivity formula presented in this note is developed from separable-pattern functions, and uses a pattern-shape parameter in addition to the half-power-beamwidth value View full abstract»

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  • The building of the Telstar antennas and radomes

    Page(s): 80 - 90
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    July 11, 2002, marks the 40th anniversary of the first transatlantic transmission of a live TV signal via an active satellite (Telstar 1), between the United States and France (followed shortly by England). This event has been recognized by the IEEE as an electrical engineering milestone. The radome and antenna in Pleumeur-Bodou, France, which now form the basis for a telecommunications museum, have been designated as a national historical site by the French government. The author shares some impressions of this historical engineering milestone View full abstract»

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  • Why study electromagnetics: the first unit in an undergraduate electromagnetics course

    Page(s): 132 - 139
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    Maxwell's equations represent a fundamental unification of electric and magnetic fields, predicting electromagnetic wave phenomena. It may seem a little odd to devote so much effort to study solutions of the 19th century's best equations. Thus we ask the question: "Of what relevance is the study of electromagnetics to our modem society? "The goal of this unit is to help answer this question. Whereas the study of electromagnetics has been motivated in the past primarily by the requirements of military defense, the entire field is shifting rapidly toward important commercial applications in high-speed communications and computing that touch everyone in their daily lives. Ultimately, this will favorably impact the economic well-being of nations as well as their military security View full abstract»

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  • Scientific literature on biological effects of radio frequency radiation: criteria for evaluation

    Page(s): 140 - 142
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (397 KB) |  | HTML iconHTML  

    There are a number of general principles that should be applied to the evaluation of the scientific literature, to determine the probability of biological effects being caused by exposure to radio-frequency (RF) radiation. Specifically, before the claims of positive or negative effects in an individual report are accepted into the body of established scientific knowledge, that report should meet the criteria discussed. In analyzing the scientific literature to determine the probability of a biological response from exposure to RF energy, one must consider (1) the consistency of experimental results claimed, (2) the nature of the response and the biological system involved, (3) the ability to consistently replicate the results, and (4) whether results claimed and observations reported can be explained by previously accepted biological principles, or must be explained only on the basis of new, untested hypotheses View full abstract»

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  • Wireless telemedicine systems: an overview

    Page(s): 143 - 153
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    Rapid advances in information technology and telecommunications and, more specifically, wireless and mobile communications - and their convergence ("telematics") are leading to the emergence of a new type of information infrastructure that has the potential of supporting an array of advanced services for healthcare. The objective of this paper is to provide a snapshot of the applications of wireless telemedicine systems. A review of the spectrum of these applications and the potential benefits of these efforts is presented, followed by successful case studies in electronic patient record, emergency telemedicine, teleradiology, and home monitoring. It is anticipated that the progress carried out in these efforts and the potential benefits of emerging mobile technologies will trigger the development of more applications, thus enabling the offering of a better service to the citizen View full abstract»

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  • Phase and delay in corporate-fed arrays

    Page(s): 24 - 29
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    The distribution of phase and delay in corporate-fed phased arrays is examined. RMS phase errors versus scan angle are shown for digital phasers. The phaser bits should all be located at each element. The delayer bits can be also, but delayer loss, dispersion, temperature sensitivity, and size mitigate against using so many delayers. Alternative topologies, where delay bits are distributed in the corporate feed, are examined View full abstract»

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  • COMAR [IEEE Committee on Man Radiation]

    Page(s): 104 - 105
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    The author reports the activities of the IEEE Committee on Man and Radiation (COMAR). COMAR critically examines and interprets the literature on biological effects. Its findings are usually reported in the form of Technical Information Statements (TISs). While the Committee holds several regular meetings every year, most of the technical work is done offline, and discussed via e-mail. It should be pointed out that COMAR does not establish safety standards, but it has an interest in the standards activity within its scope View full abstract»

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  • On the use of scale brass models in HF shipboard communication antenna design

    Page(s): 12 - 23
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    A discussion on the use of scale brass models in the design and development of HF shipboard communication antenna systems is presented. This paper begins by providing a historical overview of how the US Navy and several private commercial enterprises began using scale models to develop these HF antenna systems. The discussion continues with a description of the HF scale-model range and measurement techniques used by Chu Associates in their HF scale model studies, performed for the US Navy and other foreign governments. Finally, a description of several of these HF antenna systems is presented View full abstract»

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  • Higher-order finite-difference schemes for electromagnetic radiation, scattering, and penetration .2. Applications

    Page(s): 92 - 101
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    For pt.1 see ibid., vol.44, no.1, p.134-42 (2002). Higher-order schemes for the finite-difference time-domain (FDTD) method - in particular, a second-order-in-time, fourth-order-in-space method, FDTD(2,4) - are applied to a number of problems. The problems include array analysis, cavity resonances, antenna coupling, and shielding effectiveness case studies. The latter includes a simplified model of a commercial airliner, with a personal electronic device operating in the vicinity of the aircraft. The FDTD computations are also compared to measured data for this case. Incorporating PEC and other types of material boundaries into higher-order FDTD is problematic; a hybrid approach using the standard FDTD method in the proximity of the boundary is proposed, and shown to perform well View full abstract»

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  • Command preprocessor for radio telescopes and microwave antennas

    Page(s): 30 - 37
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    The LQG (linear-quadratic-Gaussian) controllers, designed for the NASA Deep Space Network antennas, have small tracking errors and are resistant to wind disturbances. However, they induce limit cycling during antenna-slewing operations and target acquisition. The cycling is caused by the violation of the antenna's rate and acceleration limits. This problem can be avoided by introduction of a command that does not exceed the limits. The command preprocessor, presented, generates a command that is equal to the original command if the latter does not exceed the limits, and that varies with the maximum (or minimum) allowable rate and acceleration if the limits are met or exceeded. The preprocessor is comparatively simple, since it requires knowledge of the command at only the current and the previous instants of time, while the other known preprocessor requires knowledge of the terminal state and the acquisition time. Analysis and field tests of the preprocessor are presented. The dynamics of the preprocessor itself, and of the antenna with the preprocessor, are illustrated with the antenna's measured responses to typical commands 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
W. Ross Stone