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Antennas and Propagation Magazine, IEEE

Issue 2 • Date April 2012

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Displaying Results 1 - 25 of 76
  • [Front cover]

    Publication Year: 2012 , Page(s): c1
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  • [Advertisement]

    Publication Year: 2012 , Page(s): c2
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  • Table of contents

    Publication Year: 2012 , Page(s): 3
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  • Information for contributors

    Publication Year: 2012 , Page(s): 4
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  • [Magazine staff]

    Publication Year: 2012 , Page(s): 5 - 6
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  • AP-S Officers and Administrative Committee

    Publication Year: 2012 , Page(s): 7
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  • Feature articles and contributions solicited

    Publication Year: 2012 , Page(s): 7
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  • President's Message

    Publication Year: 2012 , Page(s): 8 - 9
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  • Editor's Comments

    Publication Year: 2012 , Page(s): 8,292 - 296
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  • An Overview of the Theory and Applications of Metasurfaces: The Two-Dimensional Equivalents of Metamaterials

    Publication Year: 2012 , Page(s): 10 - 35
    Cited by:  Papers (41)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (5576 KB)  

    Metamaterials are typically engineered by arranging a set of small scatterers or apertures in a regular array throughout a region of space, thus obtaining some desirable bulk electromagnetic behavior. The desired property is often one that is not normally found naturally (negative refractive index, near-zero index, etc.). Over the past ten years, metamaterials have moved from being simply a theoretical concept to a field with developed and marketed applications. Three-dimensional metamaterials can be extended by arranging electrically small scatterers or holes into a two-dimensional pattern at a surface or interface. This surface version of a metamaterial has been given the name metasurface (the term metafilm has also been employed for certain structures). For many applications, metasurfaces can be used in place of metamaterials. Metasurfaces have the advantage of taking up less physical space than do full three-dimensional metamaterial structures; consequently, metasurfaces offer the possibility of less-lossy structures. In this overview paper, we discuss the theoretical basis by which metasurfaces should be characterized, and discuss their various applications. We will see how metasurfaces are distinguished from conventional frequency-selective surfaces. Metasurfaces have a wide range of potential applications in electromagnetics (ranging from low microwave to optical frequencies), including: (1) controllable “smart” surfaces, (2) miniaturized cavity resonators, (3) novel wave-guiding structures, (4) angular-independent surfaces, (5) absorbers, (6) biomedical devices, (7) terahertz switches, and (8) fluid-tunable frequency-agile materials, to name only a few. In this review, we will see that the development in recent years of such materials and/or surfaces is bringing us closer to realizing the exciting speculations made over one hundred years ago by the work of Lamb, Schuster, and Pocklington, and later by Mandel'shtam and Veselago. View full abstract»

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  • Changes of Address or Delivery Problems

    Publication Year: 2012 , Page(s): 35
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  • Getting the magazine by air freight

    Publication Year: 2012 , Page(s): 35
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  • Analysis of the Human Head Interaction in Handset Antennas with Slotted Ground Planes

    Publication Year: 2012 , Page(s): 36 - 56
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (5063 KB) |  | HTML iconHTML  

    The interaction between the human head and handset antennas needs to be taken into account, since mobile phones have to be functional, and, at the same time, guarantee biological compatibility. The present research analyzed the performance of several handset antennas with different slotted ground planes in free space and also in the presence of the human head. The main objective was to compare the measured bandwidth and efficiency in both environments (free space and human interaction), and the impact on the measured SAR (Specific Absorption Rate) of such antennas as functions of the slot configuration in the ground plane and the antenna's location. Results showed that slots may be useful for increasing bandwidth and efficiency while keeping similar SAR values compared to the non-slotted ground plane. Changing the antenna's location was a good way to achieve a significant SAR reduction. In some cases, when the antenna was at the lower edge of the ground plane (down position), the SAR could be reduced by a factor of two. Impedance, efficiency, and radiation patterns were measured and analyzed with a phantom head in order to understand the human head's effect on the antenna's performance. Although all antennas suffered from changes, shorted-end slots were more robust for human interaction than open-ended slots. View full abstract»

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  • Analysis of Multilayered Periodic Structures Using a Hybrid FDTD/GSM Method

    Publication Year: 2012 , Page(s): 57 - 73
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2412 KB) |  | HTML iconHTML  

    An efficient algorithm for computing the scattering properties of multilayered periodic structures using a hybrid Finite-Difference Time-Domain/Generalized Scattering Matrix (FDTD/GSM) technique is described. In this technique, the constant-horizontal-wavenumber approach is used to compute the scattering parameters of each periodic layer. A complete Floquet harmonic analysis of the periodic structure is presented, where propagation and evanescent behaviors of Floquet harmonics are studied. In addition, guidelines for selection of higher-order harmonics for a certain layer separation are provided. The scattering matrix of each layer, including proper Floquet harmonics, is then cascaded together with those of the other layers to obtain the generalized scattering matrix of the entire structure. The validity of this algorithm was verified through several numerical examples, including frequency-selective surfaces (FSS) with different periodicities and under different incidence angles. The numerical results showed good agreement with the results obtained from the FDTD simulation of the entire structure, while the new procedure saved computational time and storage. View full abstract»

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  • Miniaturized RFID/UWB Antenna Structure that Can be Optimized for Arbitrary Input Impedance

    Publication Year: 2012 , Page(s): 74 - 87
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2729 KB) |  | HTML iconHTML  

    This paper presents a novel planar antenna structure with miniaturization capability that fits in a small area, and which can be designed towards any arbitrary input impedance, for RFID applications. The proposed antenna has three main parts: the feeding loop, the extension parts that work mainly as the radiator, and the connection between these parts. This antenna structure can be integrated with RFID tags to increase the reading range of the tags. A sample antenna set containing one scavenging antenna at 915 MHz for wireless powering, and one UWB antenna at 5.5 GHz with a 500 MHz bandwidth, were designed with the proposed antenna structure to be used in an RFID/UWB tag. This antenna set occupied an area of 11 × 18 mm2. It achieved a measured reading range of 110 cm, for a realized gain of -16 dBi. The radiation pattern of the proposed antenna, integrated with an RFID chip, was measured and compared with simulations in the E and H planes, showing good agreement. View full abstract»

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  • Multi-Beam Reflector Antenna System Combining Beam Hopping and Size Reduction of Effectively Used Spots

    Publication Year: 2012 , Page(s): 88 - 99
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2164 KB)  

    This paper describes a concept combining beam hopping and size reduction of effectively used spots that can be implemented on multiple-beam antennas to improve their performance, namely the carrier-to-interference ratio, the minimum directivity, and the roll-off. The expected impact on antenna RF performance is demonstrated based on simplified models. A more-realistic focal-array-fed reflector antenna is also presented, based on a cell-reuse scheme of 12 reduced to four (one-third of the coverage receiving all the available bandwidth according to a cell-reuse scheme of four at a given instant), with performance in line with the simplified model. This specific design enabled improving the antenna's performance without drastically increasing its complexity: the minimum directivity and C/I were respectively 1.67 dB and 3.65 dB higher when compared to a standard antenna implementation with a cell-reuse scheme of four. View full abstract»

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  • Time-Domain Far-Field Analysis of Radiation Sources and Point-Source Coherence

    Publication Year: 2012 , Page(s): 100 - 108
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2449 KB) |  | HTML iconHTML  

    A procedure called FARS (Far-field Analysis of Radiation Sources) has been previously described by the author as a means of determining the quantitative contribution per unit length or per unit area to the power radiated from some object in either the frequency domain or the time domain. Just as frequency-domain and time-domain solutions provide complementary perspectives of general electromagnetic phenomena, so do Frequency-Domain FARS (FDFARS) and Time-Domain FARS (TDFARS) for their particular applications. For example, a time-domain solution enables separating various effects due to their different time delays to the far field. TDFARS can thus be useful in demonstrating the effect of the time-space coherence of propagating charge/current pulses as they meet, when propagating along a perfectly conducting wire. Some results concerning this effect are included, as well as their correlation with the time variation of current and charge energy measures. View full abstract»

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  • Double-Tuned Impedance Matching

    Publication Year: 2012 , Page(s): 109 - 116
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3254 KB) |  | HTML iconHTML  

    In the 1940s, Harold Wheeler developed the principles of double-tuned impedance matching in a simple form. These relationships are not well known. They are very useful for the antenna designer in providing a structured approach to obtain near-maximum bandwidth for narrowband and moderate-band antennas with a specified VSWR limit, using a practical arrangement of tuning elements. Wheeler first developed relationships for single-tuned impedance matching, which relate the fractional bandwidth to the antenna's Q and the maximum-permissible reflection-coefficient magnitude (or VSWR). He used the results of single-tuned impedance matching to derive the relationship for double-tuned impedance matching. Wheeler's double-tuned impedance-matching relationship is the best overall measure of the achievable fractional bandwidth for an antenna. Double tuning is practical, and provides more than double the fractional bandwidth of single-tuned impedance matching. One example of double-tuned impedance matching is presented. A comparison to recently published results for single-tuned impedance matching verifies that double tuning more than doubles the fractional bandwidth of single-tuned impedance matching. View full abstract»

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  • High temperature dielectric constant and loss tangent measurements [advertisement]

    Publication Year: 2012 , Page(s): 117
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  • Chapter News

    Publication Year: 2012 , Page(s): 118 - 120
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  • International Siberian Conference on Control and Communications SIBCON-2011

    Publication Year: 2012 , Page(s): 121 - 122
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  • A Note from the Distinguished Lecturers' Chair

    Publication Year: 2012 , Page(s): 122
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  • IEEE AP-S Chapter and Joint Chapter Chairs

    Publication Year: 2012 , Page(s): 123
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  • AP-S Distinguished Lecturer Program for 2011-2012

    Publication Year: 2012 , Page(s): 124
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  • AP-S Distinguished Lecturer Program

    Publication Year: 2012 , Page(s): 125 - 132
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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