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Antennas and Propagation Magazine, IEEE

Issue 2 • Date April 2009

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Displaying Results 1 - 25 of 61
  • IEEE Antennas & Propagation Magazine

    Page(s): 1
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    Freely Available from IEEE
  • Table of contents

    Page(s): 3
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    Freely Available from IEEE
  • Information for contributors

    Page(s): 4
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    Freely Available from IEEE
  • IEEE Antennas and Propagation Magazine Editors

    Page(s): 4
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    Freely Available from IEEE
  • Magazine Staff

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

    Page(s): 7
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    Freely Available from IEEE
  • Feature Articles and Contributions Solicited

    Page(s): 7
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (327 KB)  

    First Page of the Article
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  • Editor's comments

    Page(s): 8,237 - 240
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    Freely Available from IEEE
  • President's Message

    Page(s): 8
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    Freely Available from IEEE
  • New Antennas and Propagation Society Web Site: http://www.ieeeaps.org

    Page(s): 8 - 9
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    Freely Available from IEEE
  • Technical Co-Sponsorship of Meetings

    Page(s): 9
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    Freely Available from IEEE
  • Complete Link Budgets for Backscatter-Radio and RFID Systems

    Page(s): 11 - 25
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3890 KB) |  | HTML iconHTML  

    Backscatter radio - wireless communication by modulating signals scattered from a transponder (RF tag) - is fundamentally different from conventional radio because it involves two distinct links: the power-up link for powering passive RF tags, and the backscatter link for describing backscatter communication. Because of severe power constraints on the RF tag, a thorough knowledge of the backscatter channel is necessary to maximize backscatter-radio and radio-frequency identification (RFID) system performance. This article presents four link budgets that account for the major propagation mechanisms of the backscatter channel, along with a detailed discussion of each. Use of the link budgets is demonstrated by a practical UHF RFID portal example. The benefits of future 5.8 GHz multi-antenna backscatter-radio systems are shown. An intuitive analogy for understanding the antenna polarization of RF tag systems is presented. View full abstract»

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  • Characteristics of a Metal-Backed Loop Antenna and its Application to a High-Frequency RFID Smart Shelf

    Page(s): 26 - 38
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3489 KB) |  | HTML iconHTML  

    In this paper, a metal-backed loop antenna (MBLA) at high frequency (HF) is characterized and applied to a radio-frequency identification (RFID) smart-shelf system. The antenna is investigated in terms of impedance matching, resonant frequency, magnetic-field intensity/field distribution, quality factor, and detection range. The study shows that the magnetic-field distribution of the metal-backed loop antenna can be effectively controlled by changing the size as well as the separation of the backing metal plate. As a result, the detection range of an RFID system using such an antenna can be controlled. Such a feature offers great promise for the metal-backed loop antenna in applications for RFID smart-shelf systems. For such systems, controlling the coupling zone of the antennas is vital for constraining the interference between the antennas in adjacent tiers of the shelves, in order to achieve high system-detection accuracy. In addition, using a metal-backed loop antenna provides more flexibility for RFID smart-shelf-system design and implementation, so that the system is more cost effective. View full abstract»

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  • Methodology for Efficiency Measurements of Electrically Small Monopoles for Animal Tracking

    Page(s): 39 - 47
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2590 KB) |  | HTML iconHTML  

    For tracking purposes, small migratory birds are outfitted with antennas and transmitters so that their daily movements and migration patterns can be observed. In order to improve the practice of tracking wildlife and to extend the ranges over which animals can be tracked, it is necessary to characterize and fully exploit the parameters of the antennas being attached to animals. These birds provide a challenging opportunity to study the antennas used in wildlife tracking because of their small size (~15 cm in length) and light weight (averaging 26 g). For the first time, the present study provides a measurement methodology that can be used to estimate the efficiency of an electrically small antenna mounted to an approximate bird model, utilizing the Wheeler cap method. Because the antenna is less than one-eighth of a wavelength long and does not have a well-defined ground plane, measurement techniques are carefully considered and carried out. The results indicate that the bird model acts as a lossy ground plane for the transmitting monopole antenna. The radiating efficiency of the antenna-bird model system is conditioned by the size of the antenna as well as the effective resistance of the bird model. New recommendations for antenna and tracking-system design are provided, based on this investigation. View full abstract»

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  • The Design of Spherical Conformal Antennas Using Customized Techniques Based on NURBS

    Page(s): 48 - 60
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3910 KB) |  | HTML iconHTML  

    What do we do when there is a need to model antennas and ground planes that have a geometry that is not planar? The accurate representation of our geometry can make a significant difference in the results, especially at higher frequencies. This paper describes how some powerful computer-aided design (CAD) tools can be developed to represent difficult non-planar antenna geometries that cannot always be drawn using the commercial EM modeling packages. These CAD tools not only become very useful design tools, but are also essential when it comes to designing the complicated geometry associated with spherical conformal antennas. View full abstract»

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  • Change of address or delivery problems

    Page(s): 60
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  • CPW-Fed Quasi-Magnetic Printed Antenna for Ultra-Wideband Applications

    Page(s): 61 - 70
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2737 KB) |  | HTML iconHTML  

    An optimized coplanar waveguide fed quasimagnetic printed antenna for ultra wideband applications is described. A parameter study, motivated by a design procedure, allowed a substantial increase in the return-loss operational bandwidth. The numerically predicted performance was validated by means of physical measurements of fabricated samples. The measured radiation patterns of the antenna demonstrated its adequate radiation characteristics. The feed radiation was also investigated by means of physical measurements. View full abstract»

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  • Three-dimensional automatic mesh generation for hybrid electromagnetic simulations

    Page(s): 71 - 85
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (4060 KB) |  | HTML iconHTML  

    Hybrid mesh generation is required for finite-difference time-domain/finite-element time-domain (FDTD/FETD) hybrid simulations. A combined approach is presented to automatically generate Cartesian/tetrahedral hybrid meshes for open and closed structures. This approach first generates a buffer zone that surrounds a target with specified tightness. The advancing-front technique with ldquosweep-and-retryrdquo is subsequently applied to generate an initial tetrahedral mesh that fills the buffer zone. Finally, the tetrahedral mesh undergoes a combined quality improvement procedure. Due to the low profile of the resulting tetrahedral mesh, the sparse Cholesky decomposition can be applied effectively to solve the resulting FETD matrix. Several examples are provided to demonstrate the main features and the performance of the proposed automatic mesh-generation method. View full abstract»

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  • Errors in Projection of Plane Waves Using Various Basis Functions

    Page(s): 86 - 98
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2556 KB) |  | HTML iconHTML  

    Basis functions play important roles in computational electromagnetics (CEM). It is interesting to investigate the errors in the projection of the equivalent current of a plane wave using various basis functions. In this work, the projection error of various basis functions is studied. The basis functions involved are the pulse basis function, the triangular basis function, higher-order versions of these basis functions, and the divergence-conforming basis function on rectangular and triangular elements. The projection errors are derived in closed form. The asymptotic expression of the closed form is given. The analytical results are verified by numerical results. The projection error of the pth order one-dimensional (1D) basis is asymptotically inversely proportional to the (p+1)th power of the density of unknowns. Based on the closed-form projection errors in the one-dimensional case, it is found that when the expansion basis is fixed, the application of different testing functions only affects the coefficient of the projection error, rather than the order. Generally, the error of the divergence-conforming basis in the projection of curl-free vectors is less than that of divergence-free vectors. View full abstract»

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  • AP-S AdCom Minutes

    Page(s): 100 - 111
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  • National Radio Science Meeting

    Page(s): 112 - 113
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  • Chapter News

    Page(s): 114
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  • A Note from the Distinguished Lecturers' Chair

    Page(s): 115
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  • IEEE Transactions on Antennas and Propagation Announces a Special Issue on Antennas for Next-Generation Radio Telescopes

    Page(s): 116
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  • Design and Optimization of ESPAR Antennas via Impedance Measurements and a Genetic Algorithm [Antenna Designer's Notebook]

    Page(s): 118 - 123
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1447 KB) |  | HTML iconHTML  

    A method for the design of electronically steerable passive array radiator (ESPAR) antennas is proposed herein, based on impedance-matrix measurements and a genetic algorithm. The proposed technique is best suited for cases where commercial elements are used as building blocks for ESPAR development, since in such cases the conventional numerically based techniques used in the literature may not be applicable. An emulated ESPAR design and respective results are presented. They demonstrate the applicability and performance of the proposed technique, as well as its consistency with results derived from a commercially available electromagnetic simulator. View full abstract»

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Aims & Scope

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

Full Aims & Scope

Meet Our Editors

Editor-in-Chief
W. Ross Stone