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Antennas and Propagation Magazine, IEEE

Issue 1 • Date Feb 2005

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Displaying Results 1 - 25 of 54
  • Random radio: an answer to the puzzle

    Publication Year: 2005 , Page(s): 138 - 139
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (782 KB)  

    In the random radio puzzle, imagine an early "ham" trying to assemble an oscillatory RLC circuit by randomly grabbing a resistor, a capacitor, and an inductor out of separate boxes filled respectively with resistors, capacitors, and inductors of various values. The problem of providing a solution for the probability that the resulting circuit will oscillate is presented in the paper. View full abstract»

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  • In Memoriam: Carlyle J. Sletten

    Publication Year: 2005 , Page(s): 181
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    Freely Available from IEEE
  • Meetings and Symposia

    Publication Year: 2005 , Page(s): 140 - 144
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  • Teaching ethics in the engineering design process: a legal scholar's view

    Publication Year: 2005 , Page(s): 146 - 151
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    Engineering ethics are a critical "gap filler" in the regulation of technology. Engineers, as "professionals," are given professional autonomy in promoting risky activities, based on a promise that they will act in the public interest. The legal system, both in regulation and liability, puts constraints on the design process, but often leaves gaps that must be filled by ethical precepts. The conflict between the public interest and the private interest of the engineer is often most acute in the acceptance or rejection of relatively rare risks in the design of products. Rare risks normally involve the greatest uncertainty of injury. These rare risks of catastrophic injury can fall "under the radar" of regulatory systems, or technological advances may make regulatory systems obsolete. The other major risk category are "system risks," in which individual engineers assume that some other party will take care of the risk. Teaching engineers to recognize and deal with these risks is critical. In particular, reliance on regulatory approval may be inadequate. Designing products that hold paramount the public safety must be the benchmark for engineering ethics. View full abstract»

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  • A MATLAB-based visualization package for planar arrays of isotropic radiators

    Publication Year: 2005 , Page(s): 156 - 163
    Cited by:  Papers (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1313 KB)  

    This article introduces a simple MATLAB antenna package (ANTEN_GUI) for the visualization of the radiation patterns, beamforming, and beam-steering capabilities of user-designed planar arrays of isotropic radiators. The package can be used as an educational aid, especially in antennas and propagation lectures. View full abstract»

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  • Modal impedances of planar, non-complementary, N-fold symmetric antenna structures

    Publication Year: 2005 , Page(s): 110 - 116
    Cited by:  Papers (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1111 KB)  

    Planar N-arm rotationally symmetric antennas are commonly used in applications that demand wideband, multiple-mode, dual-polarization, and conformal geometries. Antennas included in this category are spirals, log-periodic dipole arrays, bow-tie antennas, and sinuous structures. An analytic expression for the modal impedances of these complementary planar structures has been available for many years. This paper extends the theory to non-complementary planar /V-fold symmetric antennas, and provides equations valid for any arm-to-gap width ratio, arm width, expansion rate, and low-loss electrically thin substrate materials. The equations are based on quasi-TEM coplanar stripline theory, and provide a band-averaged approximation of the input impedance of the antenna for each characteristic mode of operation. Predicted modal impedances are compared to spiral antenna measurements. In addition, a procedure for accurately measuring the dielectric constant of the substrate material is discussed. View full abstract»

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  • Sardinia radio telescope (SRT): instrumentation research and development

    Publication Year: 2005 , Page(s): 178 - 180
    Cited by:  Papers (2)
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  • IEEE-USA

    Publication Year: 2005 , Page(s): 199 - 201
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  • Information for Contributors

    Publication Year: 2005 , Page(s): 4
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  • Inexpensive upgrade of base-station dumb antennas by two magnetic loops for "blind" adaptive downlink beamforming

    Publication Year: 2005 , Page(s): 189 - 193
    Cited by:  Papers (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (979 KB)  

    A simple scheme is herein proposed to upgrade an older base-station's "dumb" antennas for use in an adaptive space-division frequency-reuse downlink, with no expensive retrofitting of each "dumb" antenna with its own rake receiver. This scheme adds only two horizontally oriented loops (plus an optional vertically oriented dipole) to a base station's 120°-azimuth sector, each with a temporal (not space-time) rake receiver. Such a pair (or triad) of diversely polarized but collocated antennas can estimate an incident mobile-source's uplink direction of arrival, based on which the existing "dumb" antennas can beam-form towards the mobile in downlink transmission. View full abstract»

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  • An overview of ultra-wideband microwave imaging via space-time beamforming for early-stage breast-cancer detection

    Publication Year: 2005 , Page(s): 19 - 34
    Cited by:  Papers (104)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1757 KB) |  | HTML iconHTML  

    Ultra-wideband (UWB) microwave imaging has recently been proposed for detecting small malignant breast tumors. In this article, we review the current research status of this approach. First, we introduce the concept of microwave imaging via space-time (MIST) beamforming and related signal-processing algorithms. The objective of these signal-processing techniques is to form a spatial image of scattered microwave energy, and to identify the presence and location of malignant lesions from their scattering signatures. Next, we present numerical studies based on finite-difference time-domain simulations to demonstrate the efficacy of MIST beamforming for detecting small malignant breast lesions in both prone and supine configurations. Finally, the experimental feasibility of UWB microwave imaging is demonstrated using an initial imaging prototype and multilayered breast phantoms. View full abstract»

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  • Matching of equivalent field regions

    Publication Year: 2005 , Page(s): 56 - 61
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (956 KB) |  | HTML iconHTML  

    In aperture problems, integral equations for equivalent currents are often found by enforcing matching of equivalent fields. The enforcement is made in the aperture surface region adjoining the two volumes on each side of the aperture. In the case of an aperture in a planar perfectly conducting screen, having the same homogeneous medium on both sides and an impressed current on one side, an alternative procedure is relevant. We make use of the fact that in the aperture the tangential component of the magnetic field due to the induced currents in the screen is zero. The use of such a procedure shows that equivalent currents can be found by a consideration of only one of the two volumes into which the aperture plane divides the space. Furthermore, from a consideration of an automatic matching at the aperture, additional information about tangential as well as normal field components is obtained. We compare the two procedures in this tutorial article. View full abstract»

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  • The risk of acoustic neuromas from using cell phones

    Publication Year: 2005 , Page(s): 183 - 185
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (934 KB) |  | HTML iconHTML  

    In a recently reported study, an elevated risk of acoustic neuromas, a benign tumor of the auditory nerve, was found among persons in Sweden with 10 or more years of cell-phone use. There was no association with use less than 10 years, nor for other measures of use, such as cumulative hours of use or cumulative number of calls made. Tumors occurred more frequently on the side of the head on which the cell phone was typically used. Given the recent introduction and popularization of digital phones - this study used five years as the time since first regular use - these results provide only limited guidance with regard to the risk of short-term use of cell phones or exposure to wireless radiation, and do not indicate the relative risk from using an analog or digital phone alone. View full abstract»

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  • Reviews and Abstracts

    Publication Year: 2005 , Page(s): 118 - 119
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    Freely Available from IEEE
  • AP-S Officers and Administrative Committee

    Publication Year: 2005 , Page(s): 6
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  • Feeling guilty?

    Publication Year: 2005 , Page(s): 166
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  • Chapter News

    Publication Year: 2005 , Page(s): 92 - 99
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  • Report on ultra-wideband and ultra-shot impulse signals Workshop 2004

    Publication Year: 2005 , Page(s): 193 - 196
    Cited by:  Papers (1)
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  • Magazine Staff

    Publication Year: 2005 , Page(s): 5
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  • A novel approach to complex target recognition using RCS wavelet decomposition

    Publication Year: 2005 , Page(s): 35 - 55
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2029 KB) |  | HTML iconHTML  

    A novel approach to complex target recognition using wavelet decomposition of the radar cross section is introduced. The analysis technique is presented, and it shown how it can be implemented using MATLAB software. Applications in the radar field are then investigated, both for simple and complex targets. The results obtained show that this technique is very promising and yields recognition levels difficult to achieve with any other available technique. View full abstract»

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  • Wave propagation in ray-chaotic enclosures: paradigms, oddities and examples

    Publication Year: 2005 , Page(s): 62 - 81
    Cited by:  Papers (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1968 KB) |  | HTML iconHTML  

    Ray chaos, characterized by eventual exponential divergence of originally nearby multi-bounce ray trajectories, is an intriguing phenomenon. It can be observed in several electromagnetic wave propagation scenarios: both very complex (e.g., urban areas) and very simple (e.g., a stadium-shaped cavity) scenarios. This paper contains a compact review of known results on wave propagation in ray-chaotic scenarios. Attention is focused principally on two-dimensional simple paradigms of internal ray chaos ("ray-chaotic billiards"), with emphasis on possible implications for high-frequency wave dynamics ("ray-chaotic footprints"). General concepts, tools, and numerical examples are discussed, and their potential relevance to current challenges in electromagnetic engineering is noted. View full abstract»

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  • Computational cost estimations and comparisons for three methods of applied electromagnetics (MoM, MAS, MMAS)

    Publication Year: 2005 , Page(s): 121 - 129
    Cited by:  Papers (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1237 KB) |  | HTML iconHTML  

    The computational costs of three numerical techniques used in electromagnetics, namely the moment method (MoM), the method of auxiliary sources (MAS), and its modified version (MMAS), are estimated for various calculation schemes and configurations. Both surface and volumetric problems are considered. The number of multiplications required for the system-matrix fill is calculated and added to the algorithmic cost of the matrix inversion. The Green's function singularity extraction is also taken into account, particularly for the MoM. The original integrals are transformed into the local (area or volume) coordinate systems, and are subsequently evaluated on the basis of standard numerical quadrature schemes. For the surface integral equation (SIE), some calculations using either the well-known Duffy transformations or some analytical-numerical integration schemes are also presented (expressions are available only for the scalar potential integral case). For the MAS and MMAS, the matrix fill is shown to be much faster, since no time-consuming integrations are involved. The analysis is applied to various objects, such as a perfectly conducting (PEC) parallelpiped, a PEC sphere, and a microstrip patch antenna, and useful conclusions are drawn on the relative efficiency of the three methods. View full abstract»

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  • Splendid Social Events

    Publication Year: 2005 , Page(s): 15 - 18
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  • IEEE AP-S International Symposium and USNC/URSI Meeting Special Sessions

    Publication Year: 2005 , Page(s): 14
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  • Intellectual Property and Patent Abstracts

    Publication Year: 2005 , Page(s): 168 - 175
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The IEEE Antennas and Propagation Magazine covers all areas relating to antenna theory, design, and practice.

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Editor-in-Chief
Mahta Moghaddam