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Antennas and Propagation Magazine, IEEE

Issue 4 • Date Aug. 2000

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Displaying Results 1 - 12 of 12
  • Reviews and Abstracts

    Page(s): 82 - 83
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (252 KB)  

    First Page of the Article
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  • Patent abstracts

    Page(s): 134 - 140
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    Freely Available from IEEE
  • C++, a better language for engineering applications

    Page(s): 95 - 101
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    In this review, we show the features of C++ that make it superior in comparison with other languages. Use of data hiding and objects are an important way to improve the quality of the software that is produced, because the final product is easier to develop, maintain, document, and upgrade. Because of the overloading mechanism, the elegance of some notations-such as in the example of the product among vectors and matrices-is now available, even when writing a computer program. In addition, the Standard Template Library provides a huge set of templates that save a great deal of time in the development of software. Here, only the features of C++ that are relevant to engineering applications have been briefly introduced with some examples View full abstract»

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  • A high-efficiency broadband HF wire-antenna system

    Page(s): 53 - 69
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    The purpose of this antenna design is to provide an efficient, broadband, wire-antenna system for RF communications. The benefits of the antenna include a single integrated antenna system for total band coverage, high system efficiency across the operating band, the capability to transmit and receive multiple signals instantaneously, and simple mechanical assemblies. The antenna design comprises various configurations of multiple transceivers, connected to a set of RF filters and associated impedance-matching networks, which are used to excite a plurality of trapped-antenna elements. The antenna system offers control over the antenna's directivity and the antenna's driving-point impedance by using sub-band systems, as defined by a series of RF filters and traps that divide the physical antenna element into varying radiating lengths. Continuous coverage over the entire frequency band of interest is achieved by using different physical antenna elements for adjacent sub-bands. The utilization of sub-bands reduces the impedance-matching network requirements, and helps to more efficiently radiate energy over the entire frequency band of interest. The resultant higher antenna system efficiencies allow for moderate and feasible performance specifications for transmitters, receivers, and matching-network components. The design can utilize various configurations and orientations of monopoles, dipoles, associated arrays, and RF traps View full abstract»

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  • Potentials of ultra-short-pulse time-domain scattering measurements

    Page(s): 35 - 45
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    This article illustrates the potentials of ultra-short-pulse time-domain scattering measurements, and describes a facility to perform such measurements. The main advantages of measuring in the time domain are the high range resolution and the relatively simple measurement setup. A time-domain radar cross section measurement of a flat plate is performed, to illustrate the advantages of such methods over a conventional frequency-domain setup. The measurement was performed with a sampling oscilloscope, a pulse generator, and two 2-12 GHz ridged-horn antennas. Because the horns were not designed for transmitting transient signals, an additional system-response measurement, in combination with a software deconvolution algorithm, restored the impulse response of the object under test. Further processing separated the response of the object from clutter. A comparison of the time-domain data with calculated and measured frequency-domain radar cross sections shows good agreement. The high range resolution (100 ps) enabled the separation of scattering mechanisms (i.e., reflection, single and multiple diffraction). It is concluded that ultra-short-pulse time-domain measurements could be very beneficial View full abstract»

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  • The field equivalence principle: illustration of the establishment of the non-intuitive null fields

    Page(s): 122 - 128
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    The field equivalence principle, one of the fundamental concepts in electromagnetics, has numerous applications. However, for a beginning student, it is not easy to understand this concept thoroughly and to appreciate it. The dilemma faced by beginning students is illustrated. We have sources in a finite Region I, and an arbitrary mathematical surface separating Regions I and II. The equivalent problems for the exterior and interior regions are specified with the use of electric and magnetic equivalent currents impressed on the boundary surface. The acceptance of the establishment by the equivalent sources of the non-intuitive null field for the exterior problem (by the equivalent sources and the original source for the interior problem) is commonly bothersome and not comfortably realized. In order to clarify this, we revisit Love's and Schelkunoff s forms of the equivalence principle. Subsequently, we discuss two simple, analytically tractable illustrative examples, consisting of plane-wave fields in two half-space regions, separated by an infinite planar surface. In particular, the emphasis is on the establishment of the non-intuitive null fields developed by these equivalent sources. Various forms of equivalence are illustrated by simple analytical field expressions View full abstract»

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  • A very large antenna for the 1.8 MHz band

    Page(s): 75 - 79
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    This article describes a large 1.8 MHz antenna system that generates significantly more forward gain than that produced by commonly-used phased-vertical arrays. It provides coverage of all four azimuthal quadrants, along with a choice of four elevation angles, which may be selected at the turn of a switch View full abstract»

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  • Distributed power control in CDMA cellular systems

    Page(s): 152 - 159
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    In wireless cellular communication, it is essential to find effective means for power control of signals received from randomly dispersed users within one cell. Effective power control will heavily impact the system capacity. Distributed power control (DPC) is a natural choice for such purposes, because, unlike centralized power control, DPC does not require extensive computational power. Distributed power control should be able to adjust the power levels of each transmitted signal using only local measurements, so that, in a reasonable time, all users will maintain the desired signal-to-interference ratio. In this paper, we review different approaches for power control, focusing on CDMA systems. We also introduce state-space methods and linear quadratic power control (LQPC) to solve the power-control problem. A simulation environment was developed to compare LQPC with earlier approaches. The results show that LQPC is more effective, and is capable of computing the desired transmission power of each mobile station in fewer iterations, as well as being able to accommodate more users in the system View full abstract»

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  • The first phased-array antennas in Russia: 1955-1960

    Page(s): 46 - 52
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    The first phased-array antenna in the Soviet Union was developed under the supervision of Professor Yuri Yurov, at Leningrad Electrical Engineering Institute (Technical University), in 1955. It was a four-element array of dielectric-rod radiators, fed through reciprocal ferrite phase shifters. The array was intended for use in radar, for automatic aiming at the target. In Yurov's group, the theory of phased-array antennas was developed. In 1960, a 61-element array, in the form of a lens filled with ferrite phase shifters, was designed, manufactured, and investigated. Later, the investigations were moved from the university to industrial research centers View full abstract»

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  • Propagation prediction techniques and antenna modeling (150 to 1705 kHz) for intelligent transportation systems (ITS) broadcast applications

    Page(s): 9 - 34
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    This paper discusses the basic aspects of radio-wave propagation and antenna modeling at 150 to 1705 kHz. The paper contains descriptions of both sky-wave and ground-wave propagation-prediction models, in addition to the methodology used to analyze antennas that operate in this band. A method of calculating and normalizing antenna gain for system computations is also discussed. The sky-wave models described in this paper are valid from 150 to 1705 kHz. The ground-wave models described in this paper are valid from 10 kHz to 30 MHz. The propagation of radio waves from 150 to 1705 kHz includes both a ground wave and a sky wave, and is quite different from propagation at any other frequency. The methods used for antenna modeling and analysis in this band are also quite unlike those in other bands. The AM broadcast band of 535 to 1605 kHz is planned to be used in the advanced traveler information systems (ATIS) of intelligent transportation systems (ITS), to provide information such as road conditions, road hazards, weather, and incident reporting for rural travelers. The band of frequencies from 285 to 325 kHz is presently being used in another application of ITS, called the Differential Global Positioning System (DGPS), which will be used for precision location of vehicles. The propagation-prediction models and antenna-analysis methods described here can be used for designing systems and making performance predictions for both of these ITS applications, or for any other systems that operate in this band of frequencies from 150 to 1705 kHz. Some examples of comparisons of measured and predicted data are also presented. A computer program that includes all of these propagation-prediction models and antenna-modeling techniques was used View full abstract»

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  • The use of current sources in wire moment-method analysis and the feed-network interaction with an array

    Page(s): 79 - 80
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    Discusses the 1.8 MHz transmitting phased array antenna of Christman (2000). The present author presents an NEC-4 analysis of the BOP (both arrays fed out of phase) and BIP (both arrays fed in phase) cases. Antenna radiation patterns are shown 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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W. Ross Stone