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Antennas and Propagation Magazine, IEEE

Issue 2 • Date April 2007

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Displaying Results 1 - 25 of 51
  • Front cover - IEEE Antennas and Propagation Magazine - April 2007

    Publication Year: 2007 , Page(s): 1
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  • Table of contents - Vol 49 No 2

    Publication Year: 2007 , Page(s): 3
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  • Information for Contributors

    Publication Year: 2007 , Page(s): 4
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  • Magazine Staff

    Publication Year: 2007 , Page(s): 5 - 6
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  • AP-S Officers and Administrative Committee

    Publication Year: 2007 , Page(s): 7
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  • Our Feature Articles [Editor's Comments]

    Publication Year: 2007 , Page(s): 8 - 193
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  • President's Massage

    Publication Year: 2007 , Page(s): 9 - 10
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  • 2007 IEEE Antennas and Propagation Society - Membership Application

    Publication Year: 2007 , Page(s): 11
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  • Wireless propagation in tunnels

    Publication Year: 2007 , Page(s): 11 - 26
    Cited by:  Papers (44)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (9335 KB) |  | HTML iconHTML  

    In this article, we give a presentation of wireless electromagnetic propagation in tunnels. We discuss in depth the characteristics of multimodal propagation. We show analytical models whereby we are able to study electromagnetic fields in tunnels. To complement the analysis, we give an account of experiments performed in the Channel Tunnel between France and England, and the Massif Central in south-central France. We conclude with a discussion of the results, followed by some comments about bandwidth and the possibility of using multiple-input multiple-output (MIMO) systems to improve communication-channel capacity. View full abstract»

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  • Room electromagnetics

    Publication Year: 2007 , Page(s): 27 - 33
    Cited by:  Papers (31)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (4601 KB) |  | HTML iconHTML  

    In analogy with the established discipline of room acoustics, various aspects of diffuse wideband microwave propagation in a room are treated. It is shown that an equivalent to Sabine's equation for reverberation time in a room is valid for the completely diffused field, depending only on the volume, the surface area, and an effective absorption coefficient. An exponential decay of the power as a function of the delay is a consequence of the assumptions. Furthermore, the concept of a reverberation distance is also valid. This is the distance from a transmitting antenna where the received diffuse, randomly scattered power equals the direct line-of-sight received power, such that the diffuse power dominates for distances larger than the reverberation distance. A number of measurements in a large room support the theory with an effective absorption coefficient of 0.5. The power delay profiles around the room from a transmitter in the ceiling vary only in the first arriving part of the impulse, whereas the tail, being dominated by the diffuse field, has the same power level for a given delay and the same decay rate all over the room. It is also a consequence of the theory that the diffuse fields incident on an antenna are uniformly distributed in angle. View full abstract»

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  • Enabling RF/microwave devices using negative-refractive-index transmission-line (NRI-TL) metamaterials

    Publication Year: 2007 , Page(s): 34 - 51
    Cited by:  Papers (9)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (12282 KB) |  | HTML iconHTML  

    Metamaterials are artificially engineered structures with unusual electromagnetic properties. In this article, we review the implementation of isotropic metamaterials that exhibit a negative permittivity and a negative permeability, thus leading to a negative index of refraction. Specifically, the article focuses on transmission-line metamaterials, which are planar structures comprising a network of distributed transmission lines loaded periodically with inductors, L, and capacitors, C, in a "high-pass" configuration. The periodic unit cell is much smaller than the wavelength, thus leading to an effective medium in which the lumped loading elements can be either discrete (chip) or printed. Based on such negative-refractive-index transmission-line (NRI-TL) metamaterials, several RF/microwave devices are presented, including microwave lenses that can overcome the diffraction limit, compact phase-shifting lines and associated broadband series-fed power dividers, electrically small antennas, antenna feed networks and baluns, backward leaky-wave antennas, and high-directivity coupled-line couplers and reflectometers. View full abstract»

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  • Propagation-prediction and site-planning software for wireless communication systems

    Publication Year: 2007 , Page(s): 52 - 60
    Cited by:  Papers (10)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (6317 KB) |  | HTML iconHTML  

    Propagation-prediction and site-planning software for wireless communication networks has been developed. The software has a user-friendly graphical user interface (GUI), and provides calculations for large-scale and small-scale propagation parameters, including path loss (or received power) and delay profiles. Angles of arrival/departure, which are useful for the design of wireless systems employing multiple antennas, are also provided in the simulation. Some of the main features of the software include the use of a computationally efficient ray-tracing approach for simulating propagation in wireless environments, and the fact that users can upload AutoCAD .dxf files for indoor or outdoor environments. Both a single-building floor plan or an entire city layout can be simulated, and the user is provided with the ability to assign wall geometries and electrical parameters. User-defined realistic antenna radiation patterns for both the transmitting and receiving antennas are incorporated in the simulation. Broadband as well as polarization-dependent simulations are also included in the software. View full abstract»

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  • Some scattering results computed by surface-integral-equation and hybrid finite-element - boundary-integral techniques, accelerated by the multilevel fast multipole method

    Publication Year: 2007 , Page(s): 61 - 69
    Cited by:  Papers (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (5863 KB) |  | HTML iconHTML  

    Method-of-moments (MoM) solutions of surface integral equations are especially well suited for scattering computations involving metallic objects. Improved modeling flexibility for dielectric (possibly lossy) and mixed dielectric/metallic bodies is obtained by combining a surface-integral-equation formulation, involving electric and magnetic equivalent surface-current densities, with a volumetric finite-element (FE) model of the dielectric regions. This results in the well-known hybrid FEBI (finite-element-boundary-integral) technique. For many years, hybrid FEBI techniques, as well as stand-alone Bl (surface-integral equation, often just termed MoM) techniques, were restricted to relatively small (with respect to a wavelength) geometries. However, with the development of powerful multilevel fast multipole methods/algorithms (MLFMM/MLFMA), it has become possible to compute a larger variety of practical scattering and radiation problems with the hybrid FEBI-MLFMM technique. In this contribution, we give a short review of our hybrid FEBI-MLFMM approach, with a focus on mixed dielectric/metallic geometries and multiple Bl domains. We then present a variety of scattering results for metallic and mixed dielectric/metallic objects, together with comparisons with measured RCS (radar cross section) data. Broadband computations are used to derive high-resolution range (HRR) profiles of several configurations. View full abstract»

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  • Linear array synthesis using an ant-colony-optimization-based algorithm

    Publication Year: 2007 , Page(s): 70 - 79
    Cited by:  Papers (20)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (5995 KB) |  | HTML iconHTML  

    The aim of this work is to show the use of a well-known type of evolutionary computational optimization technique, ant colony optimization (ACO), in a typical electromagnetic problem: linear array synthesis. To this aim, an algorithm based on the fundamentals of ant colony optimization has been developed. The algorithm uses real numbers. Some examples using different optimization criteria are presented. Also, some guidelines for the use of the algorithm, especially for creating the desirability function, are supplied. The algorithm has been demonstrated to be versatile and useful for this problem. The purpose of the work is to show (via this particular application) the flexibility and easy implementation of this algorithm family, which makes it suitable for use in other electromagnetic optimization problems. View full abstract»

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  • Correction to "The electrically small multi-turn loop antenna with a spheroidal core" [Oct 06 54-66]

    Publication Year: 2007 , Page(s): 80 - 81
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1131 KB) |  | HTML iconHTML  

    In the above titled paper (ibid., vol. 48, no. 5, Oct 06), the authors used an approximation for the core loss resistance that was later found to be invalid for the magnetic-field distribution involved. After a brief outline if the problem, the correct loss resistance is derived and its impact discussed. View full abstract»

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  • Correction in the contribution to the AMTA Corner, "Theory and measurement of backscattering from RFID tags" [Dec 06 212-218]

    Publication Year: 2007 , Page(s): 81
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (662 KB)  

    In the above titled paper (ibid., vol. 48, no. 6, pp. 212-218), Figure 11 was printed incorrectly. The correct figure, which illustrates the differences between tag antennas with various impedance loads, is presented here. View full abstract»

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  • Chapter News

    Publication Year: 2007 , Page(s): 82 - 85
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  • AP-S Distinguished Lecturer Program for 2005-2006

    Publication Year: 2007 , Page(s): 86
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  • In Memoriam: Donald G. Dudley, Jr.

    Publication Year: 2007 , Page(s): 87
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  • Call for Papers - IEEE International Workshop on Antenna Technology 2008: Small Antennas and Novel Metamaterials

    Publication Year: 2007 , Page(s): 88
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  • Design, optimization, and validation of a planar nine-element Quasi-Yagi antenna array for X-band applications [Antenna designer's Notebook]

    Publication Year: 2007 , Page(s): 89 - 96
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (4743 KB) |  | HTML iconHTML  

    A planar antenna array, based on nine identical quasi-Yagi elements, is presented in this paper. Contrary to conventional designs, the feeding network is composed of three-way power dividers, which are carefully designed in order to provide synchronized output signals over a wide frequency range. The use of spline-shaped microstrip lines suppresses coupling effects by parallel lines. Thus, signal distortions within the feeding network are minimized. Compared to conventional designs with eight elements, the additional antenna element will enhance the gain of the array, which is between 10.5 dBi and 13 dBi in the X band. The input return loss of the antenna array is below -15 dB over most parts of the relevant spectrum, with a total bandwidth of 45%. The planar antenna array is well suited as a radiating element in linear phased arrays for multifunction radars, including SAR and MTI. Additionally, the suitability of this antenna for phased-array applications is studied by an experimental setup consisting of five antenna plates. View full abstract»

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  • Measurement of electrically large array antennas in small anechoic chambers [Measurements Corner]

    Publication Year: 2007 , Page(s): 100 - 106
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (4596 KB)  

    A post-processing procedure that yields accurate array-antenna radiation-pattern estimations is described. By resorting to this strategy, measurements of large array antennas inside small anechoic chambers become feasible. The method employs an adequate phase-correction derived from an optical ray approach, under the assumption that the elementary radiators themselves are electrically small and can be measured under far-field conditions inside the relevant anechoic chamber. The effectiveness of the proposed technique is demonstrated by examining the case of a nonuniform linear array antenna. View full abstract»

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  • Changes of Address or Delivery Problems

    Publication Year: 2007 , Page(s): 106
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  • Adaptive Antennas and Receivers (Weiner, M.M., Ed.; 2005) [Reviews and Abstracts]

    Publication Year: 2007 , Page(s): 108 - 110
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  • Antennas and Wireless Propagation Letters (AWPL)

    Publication Year: 2007 , Page(s): 112
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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
Mahta Moghaddam