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Antennas and Propagation Magazine, IEEE

Issue 6 • Date Dec. 2006

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Displaying Results 1 - 25 of 71
  • IEEE Antennas and Propagation Magazine - Dec. 2006

    Publication Year: 2006 , Page(s): 1
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  • Table of contents - Vol 48 No 6

    Publication Year: 2006 , Page(s): 3
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  • Information for Contributors

    Publication Year: 2006 , Page(s): 4
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  • Magazine Staff

    Publication Year: 2006 , Page(s): 5
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  • Feature Articles and Contributions Solicited

    Publication Year: 2006 , Page(s): 6
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  • Our Feature Articles [Editor's comments]

    Publication Year: 2006 , Page(s): 7 - 241
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  • President's Message

    Publication Year: 2006 , Page(s): 7 - 8
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  • 2007 IEEE AP-S International Symposium

    Publication Year: 2006 , Page(s): 9 - 11
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  • Announcement - 2007 Raj Mittra Travel Grants

    Publication Year: 2006 , Page(s): 12
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  • Patch-antenna miniaturization using recently available ceramic substrates

    Publication Year: 2006 , Page(s): 13 - 20
    Cited by:  Papers (9)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (5092 KB) |  | HTML iconHTML  

    The recent availability of high-contrast, low-loss ceramic materials provides us with possibilities for significant antenna miniaturization. This paper explores the use of low-temperature co-fired-ceramic (LTCC) substrates in producing a miniaturized patch-antenna design. Of particular interest in the design are parameters such as substrate thickness, input impedance, radiation efficiency, and bandwidth due to the high-contrast ceramic. We propose a thick substrate to increase bandwidth. However, the substrate is truncated to mitigate surface-wave loss, with possible texture to provide dielectric-constant control for improved impedance matching. Utilizing these proposed design modifications, a miniaturization factor of more than eight was achieved, with a return-loss half-power bandwidth greater than 9%. Moreover, respectable gain was maintained, given the achieved miniaturization View full abstract»

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  • Correction: "A mixed-path groundwave field-strength prediction virtual tool for digital radio broadcast systems in medium and short wave bands," vol. 48 no. 4 Aug. 2006, pp. 19- 27

    Publication Year: 2006 , Page(s): 20
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  • The differentiated on-surface poynting vector as a measure of radiation loss from wires

    Publication Year: 2006 , Page(s): 21 - 32
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (8309 KB) |  | HTML iconHTML  

    This article explores use of the on-surface Poynting vector to investigate the power flow at the surface of various thin wires, excited as antennas or scatterers. By differentiating the axial Poynting vector at the wire's surface, the rate of change of power flow in the current and charge along a perfectly electrically conducting (PEC) wire can be determined. The idea being explored is to see if a change in axial power flow can reveal anything about possible power loss due to radiation. The results from the differentiated Poynting vector are normalized with those obtained from an approach developed by the author called FARS (far-field analysis of radiation sources). Two antenna-excitation models are investigated for a straight-wire dipole: the usual tangential E-field model, and a two-wire transmission-line feed. Comparison of FARS and the differentiated Poynting vector results for a 10-wavelength dipole shows them to agree to within 10% relative to end peaks in the distribution of spatial radiation, except in the vicinity of the antenna's feed point. Both also show that radiation occurs not only near the feed point and ends of the antenna, but is distributed along its length, being associated with maxima of the current standing wave. Results presented for antennas such as a bent-wire dipole, circular and square loops, and for a straight-wire scatterer demonstrated the effects of shape and excitation on the distributed radiation View full abstract»

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  • A novel lightweight dual-frequency dual-polarized sixteen-element stacked patch microstrip array antenna for soil-moisture and sea-surface-salinity missions

    Publication Year: 2006 , Page(s): 33 - 46
    Cited by:  Papers (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (8894 KB) |  | HTML iconHTML  

    The main motivation for this paper is to discuss the development of a novel compact and light-weight dual-frequency, dual linearly polarized, high-efficiency, stacked-patch microstrip-array antenna for use in standalone aircraft-based remote sensing applications. Results from simulation, fabrication, and testing of a sixteen-element stacked-patch array antenna, optimized for an L-band frequency of operation, are presented. The design center frequencies were 1.26 GHz and 1.413 GHz with 10 MHz and 25 MHz bandwidths in each band, respectively. Due to the large number of design parameters and demanding design requirements of beam-efficiency, sidelobe levels, and polarization characteristics, particle-swarm optimization (PSO) and finite-difference time-domain (FDTD) simulations were used for synthesis and analysis. Cancellation techniques, based on symmetry, were applied to the antenna ports, with a custom-built feed network to reduce cross polarization. Simulations and measurement results from a spherical near-field test facility confirmed excellent performance of the array configuration, with a beam efficiency of greater than 90%, isolation better than -35 dB, and cross polarization in the main beam of the array better than -40 dB. From the sixteen-element array simulations and experimental verifications, one of the objectives of the present study is to suggest the possibility of using customized dual-frequency, dual-polarized arrays as potential feeds for reflectors to replace the traditionally used conical horns for future soil-moisture and sea-salinity missions View full abstract»

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  • Bandwidth optimization of an integrated microstrip circulator and antenna assembly. 1

    Publication Year: 2006 , Page(s): 47 - 56
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (6358 KB) |  | HTML iconHTML  

    A methodology for integrating a wideband circulator with a wideband antenna is considered herein. To accomplish this integration effectively, the conditions for perfect circulation are examined, whereby the port impedances of the circulator are allowed to be complex, treated as part of the design of the circulator, and couched in terms of network-scattering parameters. This approach allows for the design of a single matching network that interfaces between the circulator and the antenna, and effects a complex-to-complex impedance match for maximum power transfer. Simulation and experimental data for a stand-alone circulator and a compact circulator/antenna assembly are presented to validate the design methodology. The data shows that return loss and isolation on the order of 20 dB over a 4 GHz bandwidth about a 14 GHz center frequency was achievable, without the need of any post-fabrication adjustments View full abstract»

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  • Empirical analysis of a 2 x 2 MIMO channel in outdoor-indoor scenarios for BFWA applications

    Publication Year: 2006 , Page(s): 57 - 69
    Cited by:  Papers (14)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (8215 KB) |  | HTML iconHTML  

    The unquestionable advantages of multiple-input multiple-output (MIMO) systems are having a strong influence on the development of new wireless systems, both in wireless local-area networks (WLANs), and in those designed to offer broadband fixed wireless access (BFWA) services in wireless metropolitan-area networks (WMANs). The MIMO channel characterization in different environments and for different operating frequency bands is a crucial factor in the design of new systems and standards, and for adequate planning of existing systems. This article makes two main contributions. First, the experimental characterization of a 2 times 2 MIMO channel at a frequency of 2.4 GHz in a canonical outdoor-indoor scenario is presented. The channel characterization performed includes the analysis of the spatial correlation between the MIMO system subchannels and its impact on the channel capacity. Second, on the basis of the capacity results obtained, a proposal is made for the use of a 2 times 2 MIMO system in outdoor-indoor scenarios for BFWA applications in metropolitan environments. The proposal is based on the experimentally verified hypothesis that the path loss due to building penetration can be practically compensated for by the diversity gain of 2 times 2 systems View full abstract»

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  • Simplified calculation of ground losses in low- and medium-frequency antenna systems

    Publication Year: 2006 , Page(s): 70 - 81
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (6956 KB) |  | HTML iconHTML  

    Calculations of ground losses are paramount in obtaining the best performance of a monopole antenna in the low- (LF) and medium-frequency (MF) bands. Ground losses are usually computed numerically, due to difficulties in the mathematical formalism. The novel approach here permits obtaining simple analytical expressions for ground-loss calculations that can be useful for determining the behavior of the ground plane. As a first approximation, the monopole antenna is placed on a perfect electrically conducting (PEC) ground plane in order to obtain the antenna current distribution and the near magnetic field, taking into account the non-zero-radius effect of the monopole. Next, the near magnetic field is used to determine the surface-current density on the ground plane below the antenna. This is divided into two zones: (1) the artificial ground plane, where either a radial-wire ground screen or a metallic layer is used to increase the soil's conductivity; and (2) the natural ground plane or bare soil up to a circular boundary a half wavelength from the antenna's base. The power dissipation is calculated from the artificial and natural ground-plane surface-current densities, and the ground-plane loss resistance is obtained. Also, an effective conductivity is defined as a measure of the ground plane's effectiveness, and the cases of quarter-wave monopoles and short top-loaded antennas are analyzed. Some results are validated by means of numerical computations and moment method simulations View full abstract»

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  • International mapping of antenna-measurement facilities

    Publication Year: 2006 , Page(s): 82 - 86
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3144 KB) |  | HTML iconHTML  

    This paper presents a comprehensive international mapping of antenna-measurement facilities. This initiative, conducted within the framework of the Antenna Centre of Excellence (ACE) of the European Union, is oriented toward all institutions having research, development, or operational activities in the field of antenna measurements. It has been established to provide the scientific and industrial community with an efficient means to improve and facilitate their research and development activities in the field of antennas. The mapping will constitute a new service for all potential users of antenna measurements, in particular from the wireless communication industry, to identify and contact antenna-measurement facilities. The first phase of the mapping showed a significant and encouraging reaction to this initiative, with more than 50 European facilities currently registered. The next phase aims at the integration of non-European institutions View full abstract»

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  • 2007 International Symposium on Antennas and Propagationca - Final Call for Papers

    Publication Year: 2006 , Page(s): 87
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  • Announcement of ISAP2007 Young Scientist Travel Grants / AP-S Election Results

    Publication Year: 2006 , Page(s): 88
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  • Chapter News [AP-S]

    Publication Year: 2006 , Page(s): 90 - 94
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  • AP-S Distinguished Lecturer Program for 2005-2006

    Publication Year: 2006 , Page(s): 95
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  • North-American Radio Science Meeting - July 22-26, 2007

    Publication Year: 2006 , Page(s): 96 - 97
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  • EMTS 2007 Call for Papers [July 26-28, 2007]

    Publication Year: 2006 , Page(s): 98
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  • EuCAP'06: A feather in Europe's cap / Where the antenna researchers got their signals straight

    Publication Year: 2006 , Page(s): 100 - 104
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  • IEEE 2007 International Symposium on Microwave, Antenna, Propagation, and EMC Technologies For Wireless Communications (MAPE 2007)- Announcement and Call for Papers

    Publication Year: 2006 , Page(s): 106
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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