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Antennas and Propagation Magazine, IEEE

Issue 4 • Date Aug. 2011

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Displaying Results 1 - 25 of 88
  • [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): 8,270 - 272
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  • President's Message

    Page(s): 8 - 11
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  • 2012 IEEE International Symposium on Antennas and Propagation and USNC/URSI National Radio Science Meeting

    Page(s): 12
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  • Instructions for AP-S and URSI Authors

    Page(s): 13
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  • AP-S General Topics

    Page(s): 14
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  • Steering Committee

    Page(s): 15
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  • Photoresist-Based Polymer Resonator Antennas: Lithography Fabrication, Strip-Fed Excitation, and Multimode Operation

    Page(s): 16 - 27
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (6324 KB) |  | HTML iconHTML  

    Artificially modified materials are becoming increasingly important in antenna design. Attractive features make polymer composites very promising materials for improving the fabrication process and antenna performance. In this study, a photosensitive polymer composite is utilized to fabricate precise dielectric-resonator antenna structures using deep-X-ray lithography. The multimode operation and miniaturization aspects of strip-fed composite antennas with very low permittivity (εr <; 5 ) are investigated for the first time. The prototype antenna offers a -10 dB impedance bandwidth of 48%, from 18.8 GHz to 30.7 GHz, and gain in the range of 5 dBi. The nonradiating modes are removed by the special boundary conditions enforced by the vertical strip. Stable radiation patterns and low cross-polarization levels over the entire impedance bandwidth are therefore preserved. Further improvements in impedance bandwidth are presented, and the antenna performance and fabrication processes are discussed. View full abstract»

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  • Getting the Magazine by Air Freight

    Page(s): 27
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  • Changes of Address or Delivery Problems

    Page(s): 27
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  • To All IEEE Life Members

    Page(s): 27
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  • Coherence, Compressive Sensing, and Random Sensor Arrays

    Page(s): 28 - 39
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    Random sensor arrays are examined from a compressive-sensing (CS) perspective, particularly in terms of the coherence of compressive-sensing matrices. It is demonstrated that the maximum sidelobe level of an array corresponds to the coherence of interest for compressive sensing. This understanding is employed to explicitly quantify the accuracy of array source localization as a function of the number of sources and the noise level. The analysis demonstrates that the compressive-sensing theory is applicable to arrays in vacuum, as well as in the presence of a surrounding linear medium. Furthermore, the presence of a surrounding media with known properties may be used to improve array performance, with this related to phase conjugation and time reversal. Several numerical results are presented to demonstrate the theory. View full abstract»

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  • Radio-Electric Validation of an Electronic Cowbell Based on ZigBee Technology

    Page(s): 40 - 44
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1889 KB) |  | HTML iconHTML  

    The tracking of cows in large, extensive farms, as well as the possibility of checking on some veterinary data in real time, could open new business horizons for meat producers. A proposal for an electronic cowbell is presented, in order to provide an inexpensive technical solution for the exploitation of such free-running cattle. The idea is based on Zig Bee technology, which a rapidly developing technology. Different rural environments have been analyzed from propagation measurements, and an estimate of the number of network nodes (or “motes”) and the cost of the system is presented. View full abstract»

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  • Design of an Edge-Coupled Dual-Ring Split-Ring Resonator

    Page(s): 45 - 54
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (4684 KB) |  | HTML iconHTML  

    Electric permittivity and magnetic permeability control electromagnetic wave propagation through materials. In naturally occurring materials, these are positive. Artificial materials exhibiting negative material properties have been reported: they are referred to as metamaterials. This paper concentrates on a ring-type split-ring resonator (SRR) exhibiting negative magnetic permeability. The design and synthesis of the SRR using the genetic-algorithm approach is explained in detail. A user-friendly graphical user interface (GUI) for an SRR optimizer and estimator using MATLAB™ is also presented. View full abstract»

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  • Low-Cost Procedure for Radar-Imaging Simulation

    Page(s): 55 - 62
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    A low-cost radar-imaging procedure is presented in this work. The method starts from a surface-current-density solution obtained from a simulation at a given frequency. Under these conditions, the geometry is efficiently subdivided into cells, using an octree-based decomposition. The procedure assigns to each cell the reflectivity given by the scattered fields in one direction due to the subdomains contained inside it. A high-resolution result is obtained that may be displayed either directly as a three-dimensional view, or else by projecting to represent two-dimensional images and profiles. View full abstract»

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  • Compact Circularly Polarized Symmetric-Slit Microstrip Antennas

    Page(s): 63 - 75
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (6345 KB) |  | HTML iconHTML  

    Compact symmetric-slit square microstrip-patch antennas are proposed for circularly polarized (CP) radiation. A symmetric slit on a patch radiator can be used for circularly polarized radiation with a compact size. Various slit shapes embedded along the four diagonal directions on the patch radiators are realized for compact circularly polarized symmetric-slit microstrip antennas based on a single feed. Circularly polarized radiation is achieved by slightly varying the slit's circumference along one of the diagonal axes. The performance and sizes of the proposed antennas with various slit shapes are studied and compared. The proposed antennas were designed on a low-loss Rogers RO4003C substrate and on low-cost lossy FR4 substrate. The 3-dB axial ratio (AR) and 10-dB return-loss bandwidths of the antenna on the FR4 substrate were larger compared to those of the antenna on the RO4003C substrate. The gain of the antenna on the RO4003C substrate was higher compared to that of the antenna on the FR4 substrate with a fixed overall antenna size. The measured 10-dB return loss and 3-dB axial-ratio bandwidths were 3.85% and 1.5%, respectively, with a maximum gain of around 0.8 dBic, for the antenna on the FR4 substrate. For the antenna on the RO4003 substrate, the measured 10-dB return loss and 3-dB axial-ratio bandwidths were 1.5% and 0.5%, respectively, with a maximum gain of around 3.4 dBic. View full abstract»

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  • Comparison of 1.8 GHz Cellular Outdoor Measurements with AWAS Electromagnetic Code and Conventional Models Over Urban and Suburban Regions of Northern India

    Page(s): 76 - 85
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2917 KB) |  | HTML iconHTML  

    Propagation modeling is an important component of system design, and helps to avoid surprises when the actual service begins, in the case of wireless systems. Testing of various available models with experimentally generated data helps to identify a suitable model that can be deployed for the design of a future generation of mobile communication systems. This requires raising new data sets, which can be achieved by conducting experiments. With this objective, the present study reports the narrowband signal-level measurements of 11 GSM base stations in the urban, dense urban, and suburban regions of Delhi, in northern India. Comparison of the observed data was carried out with electromagnetic models such as AWAS, and other empirical models, such as ITU-R, Cost 231 Hata, Walfisch-Ikegami, and Dmitry. Based on the comparisons, mean prediction errors and standard deviations were deduced. High-path-loss exponents close to the base station were observed. The AWAS electromagnetic code and ITU-R methods showed good agreement with the observed results, compared with other methods. View full abstract»

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  • Chapter News

    Page(s): 86 - 87
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  • Report on Outreach Program at KIIT Bhubaneswar, India

    Page(s): 88
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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
W. Ross Stone