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Antennas and Propagation Magazine, IEEE

Issue 4 • Date Aug. 2010

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Displaying Results 1 - 25 of 67
  • [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): 8,224 - 225
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  • President's Message

    Page(s): 8 - 9
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  • 2010 IEEE International Symposium on Antennas and Propagation and CNC-USNC/URSI Radio Science Meeting

    Page(s): 10
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  • Instructions for AP-S & and URSI Authors

    Page(s): 11 - 12
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  • Steering Committee Contacts

    Page(s): 13
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  • An RFID Tag Antenna Tolerant to Mounting on Materials

    Page(s): 14 - 19
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2126 KB) |  | HTML iconHTML  

    This paper presents a novel UHF RFID tag antenna for mass-retailed products. The tag is realized on low-cost material. The antenna is composed of two elements: a planar dipole-based antenna, matched with a small inductive coil. In particular, it is able to work when directly mounted on different materials. When the permittivity or the thickness of the material on which it is mounted changes, the antenna's impedance varies around a fixed impedance on the Smith chart. This impedance is close to the conjugate of the RFID chip's input impedance. The different mounting materials tested were cardboard, a paper block, plastic, wood, a bottle of tap water, and a glass bottle. The measurement results indicated a maximum range of eight meters for materials with a low permittivity, and a maximum range close to two meters for denser materials or materials with a higher permittivity. View full abstract»

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  • The Unwinding of a Transformer

    Page(s): 20 - 30
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    The usefulness of passive radio-frequency identification (RFID) and general passive sensor technology is currently limited by relatively low field strengths due to regulations, giving a notoriously short reader-to-tag link range. The energizing and thus communication strength from receiver to detector depends on the amount of dc voltage that a chip can rectify from an interrogating electromagnetic field. Voltage-amplification/rectification methods employ multi-stage charge pumps, using nonlinear circuit components that incur significant losses, with diminishing returns for increasing stages. In RFID/sensor technology, where field strength is limited by regulations, technology, or distance, there is an opportunity for an alternate approach to RF-generated dc voltage. The proposed solution uses the Ferranti effect, where, for certain lengths and distributed parameter values, the voltage amplitude at the receiving end of a transmission line is greater than that of the sending end. As the Ferranti effect is typically an issue in high-voltage, low-frequency, long-distance power transmission, this problem poses significant design puzzles at RFID frequencies, transmission-line lengths, and voltage scales. By extending the formalism of the relevant transmission-line theory to the domain of common microstrip structures, microstrip transmission lines have been investigated and tested to demonstrate the effect. Because significant voltage gains (between two and five times the input amplitude) have been observed at a number of frequencies in the practical or RFID application range, it is concluded that the Ferranti effect is indeed a viable means of voltage amplification for RFID and related passive sensor applications. View full abstract»

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  • Change of address or delivery problems

    Page(s): 30
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  • To All IEEE Life Members

    Page(s): 30
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  • Getting the magazine by air freight

    Page(s): 30
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  • A CPW-Fed Printed Loop Antenna for Ultra-Wideband Applications, and its Linear-Array Performance

    Page(s): 31 - 40
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2736 KB) |  | HTML iconHTML  

    A small CPW-fed loop antenna is described. The single antenna has a measured relative impedance bandwidth of 70%. Radiation patterns show stable co-polar and low cross-polar characteristics within the specified bandwidth. The small size of the radiator (0.5λ at 13.6 GHz) makes it suitable for being used in linear-array applications. The linear-array performance of the antenna is investigated by means of simulations and measurements. The mutual coupling in the array environment is reduced by means of slots placed on the antenna's surface. The impedance bandwidth is almost preserved after the antennas are embedded in an array environment. The radiation patterns of the array is also investigated by means of simulations and measurements. View full abstract»

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  • Cognitive-Radio Systems for Spectrum, Location, and Environmental Awareness

    Page(s): 41 - 61
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1862 KB) |  | HTML iconHTML  

    In order to perform reliable communications, a system needs to have sufficient information about its operational environment, such as spectral resources and propagation characteristics. Cognitive-radio technology has capabilities for acquiring accurate spectrum, location, and environmental information, due to its unique features such as spectrum, location, and environmental awareness. The goal of this paper is to give a comprehensive review of the implementation of these concepts. In addition, the dynamic nature of cognitive-radio systems - including dynamic spectrum utilization, transmission, the propagation channel, and reception - is discussed, along with performance limits, challenges, mitigation techniques, and open issues. The capabilities of cognitive-radio systems for accurate characterization of operational environments are emphasized. These are crucial for efficient communications, localization, and radar systems. View full abstract»

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  • A Multi-Feed Receiver in the 18 to 26.5 GHz Band for Radio Astronomy

    Page(s): 62 - 72
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (4220 KB) |  | HTML iconHTML  

    A large-bandwidth, state-of-the-art multi-feed receiver has been constructed to be used on the new 64 m Sardinia Radio Telescope (SRT) (http://www.srt.inaf.itl), an antenna aiming to work from 300 MHz to 100 GHz with an almost continuous frequency coverage. The goal of this new receiver is to speed up the survey of the sky with high sensitivity in a frequency band that is very interesting to radio astronomers. In the meantime, the antenna erection has been finalized, and the receiver has been mounted on the Medicina 32 m antenna to be tested (http://www.med.ira.inaf.itl). We present a complete description of the system, including a dedicated backend, and the results of the tests. View full abstract»

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  • On the Reflection Characteristics of a Reflectarray Element with Low-Loss and High-Loss Substrates

    Page(s): 73 - 89
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (6854 KB) |  | HTML iconHTML  

    This paper revisits the loss phenomenon (particularly, the dielectric loss) for a microstrip patch in reflectarray mode, and discusses the reflection characteristics (magnitude and phase) for a reflectarray element with low- and high-loss substrates. First, the dielectric losses that occur in a lossy slab backed by a perfect electric conductor are both analytically and numerically investigated. Using similar numerical analysis, the reflectarray element (a patch on top of a slab backed by a conductor) is characterized, based on dielectric losses and reflection behavior. It is observed that for low-loss substrates, the dielectric loss decreases with increasing substrate thickness (as previously suggested in the literature). More importantly, for high-loss substrates, the dielectric loss no longer follows the expected trend (decreasing loss with increasing substrate thickness). The dielectric loss becomes a complex phenomenon, involving the dielectric loss tangent and substrate thickness. It is therefore noted that it is important to recognize the well-behaved and misbehaved phase-swing region for high-loss substrates for a reflectarray element. A simple circuit-model representation is provided for the reflectarray element. The anomalous phase behavior observed for high-loss substrates is explained using pole-zero analysis. Waveguide measurements are performed to quantify these reflectarray losses for low- and high-loss substrates. Finally, the loss mechanisms in a patch reflectarray (scattering mode) are compared to a patch antenna (radiation mode), using parameters such as reflection power and radiation efficiency, and similar loss mechanisms for both structures are apparent. View full abstract»

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  • A Novel Split-Step Parabolic-Equation Package for Surface-Wave Propagation Prediction Along Multiple Mixed Irregular-Terrain Paths

    Page(s): 90 - 97
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    A novel MATLAB™-based split-step parabolic-equation (SSPE) propagation package is introduced for the prediction of electromagnetic surface-wave attenuation along multiple mixed irregular and lossy paths. The impedance boundary condition is implemented via the discrete mixed Fourier transform (DMFT). Irregular terrain modeling is handled via coordinate transformation. Tests are performed along sea paths including smooth and hilly islands. Comparisons with ITU Recommendations and a Finite-Element-Method (FEM) based numerical propagator are given. View full abstract»

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  • Chapter News

    Page(s): 98 - 99
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    First of all, on behalf of the IEEE Antennas and Propagation Society, I would like to congratulate Prof. Kam Weng Tam and his team at the University of Macau on the successful formation of the IEEE Macau Section Antennas & Propagation and Microwave Theory & Techniques Joint Societies Chapter. View full abstract»

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  • AP-S Distinguished Lecturer Program for 2009–2010

    Page(s): 100
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    The full abstracts of the Distinguished Lecturers' talks and the Lecturers' biographies appeared in the June 2009 issue of the Magazine. This information can also be obtained by sending an email request to info.distlect.ap@ieee.org, or via a link at http://www.ieeeaps.org. View full abstract»

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  • Ultra-Low-Sidelobe-Level Concentric-Ring-Array Pattern Synthesis Using Bessel Neural Networks [Antenna Designer's Notebook]

    Page(s): 102 - 105
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    The present paper proposes a new approach to constrained optimal pattern synthesis for a circular ring array with ultra-Iow-sidelobe levels. The approach uses an artificial neural network (ANN) with hidden Bessel activation functions, trained using the Levenberg-Marquardt (LM) algorithm. The proposed approach is capable of producing minimal sidelobe levels for an arbitrary pattern shape using only a few iterations, and without high memory requirements as compared to existing alternatives. View full abstract»

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  • Design, Development, and Fabrication of a Traveling-Wave Antenna on a Conical Surface

    Page(s): 106 - 109
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1646 KB) |  | HTML iconHTML  

    A novel design methodology is illustrated, along with the fabrication technique for a wrap-around antenna in the C band on a conical surface. The methodology illustrates an attempt to achieve broadband performance with a thin conformal antenna. An attempt is also made to fabricate such an antenna on the parent body by a progressive lamination process of the layers. Experimental results are shown for the antenna fabrication technique. 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.

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Meet Our Editors

Editor-in-Chief
Mahta Moghaddam