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Antennas and Propagation Magazine, IEEE

Issue 1 • Date Feb. 2011

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Displaying Results 1 - 25 of 64
  • [Front cover]

    Page(s): c1
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  • Table of contents

    Page(s): 3
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  • Information for Contributors

    Page(s): 4
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  • Magazine Staff

    Page(s): 5 - 6
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  • AP-S Officers and Administrative Committee

    Page(s): 7
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  • Feature Articles and Contributions Solicited

    Page(s): 7
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  • Editor's Comments

    Page(s): 8,237 - 240
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  • President's Message

    Page(s): 8 - 9
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  • Welcome

    Page(s): 10 - 11
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  • The Davenport Hotel and Tower

    Page(s): 12
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  • 2011 IEEE International Symposium on Antennas and Propagation and USNC/URSI National Radio Science Meeting Registration, Short Courses and Workshops

    Page(s): 13
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  • Social Events and Companion Tours

    Page(s): 14 - 17
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  • Rigorous Solutions of Electromagnetic Problems Involving Hundreds of Millions of Unknowns

    Page(s): 18 - 27
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2578 KB) |  | HTML iconHTML  

    Accurate simulations of real-life electromagnetic problems with integral equations require the solution of dense matrix equations involving millions of unknowns. Solutions of these extremely large problems cannot be easily achieved, even when using the most powerful computers with state-of-the-art technology. Hence, many electromagnetic problems in the literature have been solved by resorting to various approximation techniques, without controllable error. In this paper, we present full-wave solutions of scattering problems discretized with hundreds of millions of unknowns by employing a parallel implementation of the Multilevel Fast Multipole Algorithm. Various examples involving canonical and complicated objects, including scatterers larger than 1000λ, are presented, in order to demonstrate the feasibility of accurately solving large-scale problems on relatively inexpensive computing platforms. View full abstract»

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  • Changes of address or delivery problems

    Page(s): 27
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  • Getting the Magazine by Air Freight

    Page(s): 27
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  • Radiation Pattern Computation of Pyramidal Conformal Antenna Array with Active-Element Pattern Technique

    Page(s): 28 - 37
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    Pyramidal microstrip conformal antenna arrays are analyzed with the use of the Active-Element Pattern (AEP) technique. The active-element patterns of typical elements can be computed effectively by dividing a large antenna, array into small subarrays. This results in a simplified analysis process for a conformal antenna array, and a reduction of the computational resources. Radiation patterns of the pyramidal arrays are computed with the use of the Active-Element Pattern technique, as well as full-wave simulation of the whole array. A comparison of the radiation patterns and computation times with the two methods is given, which illustrates the effectiveness and advantage of the new method. View full abstract»

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  • Differential Evolution as Applied to Electromagnetics

    Page(s): 38 - 49
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    In electromagnetics, optimization problems generally require high computational resources and involve a large number of unknowns. They are usually characterized by non-convex functionals and continuous spaces suitable for strategies based on Differential Evolution (DE). In such a framework, this paper is aimed at presenting an overview of Differential Evolution-based approaches used in electromagnetics, pointing out novelties and customizations with respect to other fields of application. Starting from a general description of the evolutionary mechanism of Differential Evolution, Differential Evolution-based techniques for electromagnetic optimization are presented. Some hints on the convergence properties and the sensitivity to control parameters are also given. Finally, a comprehensive coverage of different Differential Evolution formulations in solving optimization problems in the area of computational electromagnetics is presented, focusing on antenna synthesis and inverse scattering. View full abstract»

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  • Low-Cost Digital Beacon Receiver Based on Software-Defined Radio

    Page(s): 50 - 55
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1311 KB) |  | HTML iconHTML  

    In this paper, we present a low-cost digital beacon receiver based on software-defined radio. A free software toolkit, GNU radio, was used to develop the beacon receiver's functionality. The hardware used was a parabolic antenna, a low-noise block converter, an Ettus universal software-radio peripheral, a Linux PC, and a Global Positioning System receiver. The total hardware cost of the developed beacon receiver was low compared to commercially available analog receivers. To validate the receiver, we compared the measured preliminary results of amplitude scintillation at 11.2 GHz with reported theoretical models. Comparisons between the measured values and the ITU-R model for the amplitude-scintillation distribution showed that the ITU-R model somewhat underestimated the statistic. The measured probability density function was also compared with the Moulsley-Vilar model. For small log-amplitude values, the Moulsley-Vilar model fit the measured statistic well, but slightly overestimated the statistic for large log-amplitude values. Good agreement was found between the measured and theoretical power spectral density of amplitude scintillation. The diurnal variation of the amplitude scintillation's standard deviation was calculated. It was largest at noontime, which was consistent with previously reported measurement results. To some extent, this may validate the performance of the developed receiver. The developed software is available from a software repository (http://www.sourceForge.net). enabling collaboration, development, and use of the software. View full abstract»

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  • Wire-Frame Monocone Antenna for Direction-Finding Applications on Unmanned Aerial Vehicle Platform

    Page(s): 56 - 65
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    A detailed design for a loaded wire-frame monocone antenna for direction-finding applications on an Army UAV platform is presented. This was used to compare simulation and measurement results of radiation-pattern and gain measurements for a scaled prototype mounted on a UAV wing, using the FEKO electromagnetic-simulation software. The results indicated that this antenna design offers bandwidth and gain performance that is far superior to many other passive antenna candidates. The results also confirm the accuracy and efficiency of using FEKO for modeling candidate antennas integrated onto large-scale Army platforms. View full abstract»

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  • Diagnostic Analysis of Radio Propagation in UMTS Networks Using High-Resolution Angle-of-Arrival Measurements

    Page(s): 66 - 75
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    This work describes high-resolution propagation measurements performed as a diagnostic survey in an operational UMTS network. The results were obtained using the measurement system previously presented in. Measurements were performed in a dense urban environment in Amsterdam, the Netherlands. Results showed that the measurement approach can be used to create a setup that is similar to the actual network scenario, and that is capable of accurately identifying the dominant propagation effects while moving through the environment. The results are especially important for mobile-system operators, because they revealed some of the causes of inadequate propagation prediction. This underlined the limitations of propagation-prediction models currently used by most mobile-system operators, and the importance of accurate propagation information to obtain the optimal network configuration. View full abstract»

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  • Chapter News

    Page(s): 76 - 78
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  • AP-S Distinguished Lecturer Program for 2009–2010

    Page(s): 79
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  • Broadband and Dual-Band Coplanar Folded-Slot Antennas (CFSAs) [Antenna Designer's Notebook]

    Page(s): 80 - 89
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    This paper presents a unified design methodology for dual-band and broadband coplanar folded-slot antennas (CFSAs). The design is achieved by using a coplanar waveguide-fed antenna element that is asymmetric with respect to the folded slot, and by adjusting the length of the stub inside the slot. A mathematical derivation, based on a transmission-line model for the asymmetrically-fed coplanar folded-slot antenna, is used on a single-frequency coplanar folded-slot antenna to determine the condition for a second resonance. In this way, when the second resonant frequency is close to the first, broadband uniplanar antennas with ~30%, bandwidth can be designed. In addition, at the dual-band mode, a frequency ratio (f2/f1) of the order of 2.5 or more can be obtained. The effect of the ratio of the feed-shift distance to the length of the stub on the bandwidth is an important parameter, and is shown for both the broadband and dual-band designs. The presented method and tables are simple to use, provide very accurate results, and correctly predict the resonant frequencies for the dual-band coplanar folded-slot antennas. The theoretical and simulated results were verified by measurements of fabricated prototypes. The design guidelines cover a broad range of applications in the 2.4 GHz to 5.25 GHz range, with various bands and bandwidths. View full abstract»

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  • Single-Feed Dual-Band Dual-Linearly-Polarized Proximity-Coupled Patch Antenna

    Page(s): 90 - 96
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    In this paper, two novel single-feed dual-band dual-polarized microstrip antennas, fed by proximity coupling, are presented. The first approach begins with a new patch antenna that provides dual-band dual-polarized operation by means of an open-circuit stub, added at the open end of the feed line. By adding a stub to the end of the feed line, one can make an antenna with two resonant frequencies. The first resonant frequency is approximately the same as that in the initial design, but the second frequency depends on the stub's length, the stub's location, and the location of the feed point across the patch's width. Moreover, the variation of the feed-line location with respect to the patch's length has no significant effect on the first resonance frequency, while the second frequency changes. The second approach that is studied to realize a dual-band dual-polarized design utilizes a microstrip-gap proximity-coupled feed mechanism. Further insight is sought through the investigation of the surface-current densities on the proposed patch antennas at their resonant frequencies. The radiation performance - including radiation pattern, cross polarization, and gain - is satisfactory within two bands. The CST simulation results and measurement results showed good agreement with each other. View full abstract»

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  • Introduction [Measurements Corner]

    Page(s): 98
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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