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Antennas and Propagation Magazine, IEEE

Issue 3 • Date June 2010

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Displaying Results 1 - 25 of 69
  • [Front cover]

    Page(s): c1
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  • [Advertisement]

    Page(s): c2
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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): 8,214 - 217
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  • President's Message

    Page(s): 8 - 9
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  • 2011 IEEE International Symposium on Antennas and Propagation and USNC/URSI National Radio Science Meeting

    Page(s): 10 - 13
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  • Membership Application

    Page(s): 14
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  • Antenna Proximity Effects for Talk and Data Modes in Mobile Phones

    Page(s): 15 - 27
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3453 KB) |  | HTML iconHTML  

    Based on a recent study of the ways a phone is held (a grip study), CAD models of the human hand have been generated, and antenna proximity effects for both talk and data modes in mobile phones have been investigated using an FDTD code. The simulation results showed that the hand, and especially the index finger, exhibited a major contribution in determining the total loss when compared to the upper torso alone. The influence of the position of the fingers on the handset was found to be more important when close to the antenna. The palm-handset gap and the index-finger location were the main factors for both absorption and mismatch loss. Different data-mode hand phantoms and configurations were investigated, showing that both “overlapped” and “interlaced” grip styles similarly influenced the antenna's communication performance. View full abstract»

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  • Nature-Inspired Design Techniques for Ultra-Wideband Aperiodic Antenna Arrays

    Page(s): 28 - 45
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (6074 KB) |  | HTML iconHTML  

    Over the past few decades, much research has been invested in the exploration of wideband and ultra-wideband (UWB) antenna arrays. The goals of such array designs are to determine the best element arrangements, which yield radiation patterns possessing the highest degrees of side lobe suppression, and no grating lobes over the largest possible operating bandwidths. It has been recently shown that nature-inspired array-design methodologies can provide solutions that exhibit these ultra-wideband characteristics. This article provides an overview of two such designs: linear polyfractal arrays, and planar arrays of aperiodic tilings. Robust nature-inspired genetic-algorithm optimization techniques were utilized in the design of both types of arrays in order to obtain the best-possible UWB performance. This article also discusses the fabrication and experimental validation of two 32-element linear polyfractal array-design prototypes, which exhibited close agreement to the radiation performance predicted by simulation. These experimentally validated arrays possessed wide bandwidths with suppressed grating lobes and relatively low sidelobes for their size (-16.3 dB at f0 and -5.39 dB at f0)Additional simulations discussed in this paper showed that the benefits of these methodologies are amplified when applied to larger sized array designs (Le., arrays with larger element counts). One example exhibited a peak sidelobe level less than -19.34 dB over a 40:1 bandwidth. View full abstract»

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  • Change of address or delivery problems

    Page(s): 45
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  • Getting the magazine by air freight

    Page(s): 45
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  • On the Operating Principles of UWB, CPW-Fed Printed Antennas

    Page(s): 46 - 50
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (980 KB) |  | HTML iconHTML  

    The working principles of coplanar-waveguide (CPW) -fed, ultra-wideband (UWB) printed antennas are investigated. The behavior of the current distributions at different frequencies are examined. The modifications in the current distributions when the phase of the currents changes lead us to some conclusions on the behavior of UWB antennas. View full abstract»

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  • Form Invariance of Maxwell's Equations: The Pathway to Novel Metamaterial Specifications for Electromagnetic Reshaping

    Page(s): 51 - 65
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (4448 KB) |  | HTML iconHTML  

    We present spatial-coordinate transformation techniques to control the propagation of electromagnetic fields in several surprising and useful applications. The implementation of this approach is based on the fact that Maxwell's equations are form-invariant under coordinate transformations. Specifically, the effect of a general coordinate transformation can be realized by means of an equivalent anisotropic material, in which the original forms of Maxwell's equations are still preserved in the transformed space. Constitutive parameters of the anisotropic material are determined to appropriately reflect the consequences of the coordinate transformation on the electromagnetic fields. In this paper, we introduce novel implementations and interpretations of the coordinate-transformation approach for the purpose of “reshaping” objects in electromagnetic scattering, and for reshaping and miniaturizing waveguides. We demonstrate the applications of the proposed techniques via several finite-element simulations. View full abstract»

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  • The Split-Step-Fourier and Finite-Element-Based Parabolic-Equation Propagation-Prediction Tools: Canonical Tests, Systematic Comparisons, and Calibration

    Page(s): 66 - 79
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3288 KB) |  | HTML iconHTML  

    Powerful propagation-prediction tools, based on the split-step Fourier-transform and the Finite-Element-Method (FEM) solutions of the parabolic equation (PE) are discussed. The parabolic equation represents one-way propagation, and is widely used in two-dimensional (20) groundwave propagation modeling. It takes the Earth's curvature, the atmospheric refractivity variations, non-flat terrain scattering, and the boundary losses into account. MA TLAB-based numerical split-step parabolic-equation and Finite-Element-Method parabolic-equation routines were developed. These were used in canonical tests and comparisons to illustrate that the parabolic equation accounts for all of these effects. Both tools were calibrated against an analytical exact solution. View full abstract»

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  • Optimal Surface Adjustment by the Error-Transformation Matrix for a Segmented-Reflector Antenna

    Page(s): 80 - 87
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2360 KB) |  | HTML iconHTML  

    Panel-setting errors associated with a segmented primary reflector limit the electrical performance of the antenna. This paper addresses the influence of panel-setting errors on the electrical performance, in order to determine realistic error budgets, and to adjust the reflector-surface accuracy for such antennas. From the viewpoint of electromechanical coupling, an approximate expression for the error-transformation matrix (ETM) between the panel-setting errors and the aperture errors is derived. By comparing the numerical simulations with experimental results, it is found that the error in the error-transformation matrix is less than 11%. Based on the error-transformation matrix, the surface accuracy is adjusted by optimizing the panel-adjustment value. The numerical simulations showed that the results may be applied to antennas with realistic panel schemes, for prediction of their electrical performance and surface adjustment. View full abstract»

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  • National Radio Science Meeting

    Page(s): 88 - 89
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  • Chapter News

    Page(s): 90 - 91
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  • AP-S Distinguished Lecturer Program for 2009–2010

    Page(s): 91
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  • Estimation of Gain Enhancement Replacing PTFE by Air Substrate in a Microstrip Patch Antenna [Antenna Designer's Notebook]

    Page(s): 92 - 95
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    An easy estimation of the gain enhancement of a microstrip patch that occurs when a standard PTFE substrate is replaced by air is presented. The theory is verified for a wide range of antenna dimensions, using some measured and simulated data, indicating very close agreement amongst the data. This approach should be very handy and useful to a designer dealing with air-substrate microstrip antennas. View full abstract»

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  • In Memoriam: Allan Walter Love

    Page(s): 96 - 97
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  • [Advertisement]

    Page(s): 98 - 99
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Aims & Scope

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