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Antennas and Propagation Magazine, IEEE

Issue 6 • Date Dec. 2000

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Displaying Results 1 - 12 of 12
  • RCS measurements and results of an engine-inlet system design optimization

    Publication Year: 2000 , Page(s): 16 - 23
    Cited by:  Papers (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (637 KB)  

    A number of papers have been published on the prediction of backscatter from engine-inlet-type structures. Measured data used to verify these predictions mostly consists of backscattered data from canonical structures, e.g., cylindrical waveguide cavities. In this paper, measured backscattered data for an unmanned aerial vehicle-type engine-inlet system is presented. The effects of the application of radar-absorbing materials to the engine-inlet system on the contribution to the RCS is discussed, and data measured in a compact-range facility are presented. View full abstract»

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  • Faster than Fourier: ultra-efficient time-to-frequency-domain conversions for FDTD simulations

    Publication Year: 2000 , Page(s): 24 - 34
    Cited by:  Papers (14)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (899 KB)  

    This tutorial compares several methods of converting from the time to the frequency domain for FDTD simulations. Applications include calculations of field or power distributions, antenna impedance, and radiation patterns. The traditional Fourier-transform methods are compared to two methods based on the solution of linear equations. This tutorial describes how to program and use these techniques, and evaluates their effectiveness for several applications, including analysis of a millimeter-resolution human model underneath a 60-Hz power line, antenna-radiation pattern and impedance calculations, the calculation of the coupling of a cellular telephone to the human head, and geophysical-prospecting simulations. View full abstract»

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  • Correction

    Publication Year: 2000 , Page(s): 74
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (59 KB)  

    First Page of the Article
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  • Reviews and Abstracts

    Publication Year: 2000 , Page(s): 88 - 89
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (201 KB)  

    First Page of the Article
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  • Implementation issues for three-dimensional vector FEM programs

    Publication Year: 2000 , Page(s): 100 - 107
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (572 KB)  

    Theoretical and practical issues that impact on the development of (especially) three-dimensional vector finite-element (FEM) programs are discussed. The theory of vector elements is briefly reviewed, and some troublesome aspects are highlighted: in particular, the interpretation of the degrees of freedom. The choice of element shape is briefly addressed, as is the evaluation of the elemental matrices. Several useful references are provided in this context. Data structures appropriate for a three-dimensional code are outlined, as is the issue of establishing mesh interconnectivity. The topics of mesh generation and linear algebra are very briefly considered. The paper concludes with some comments on post-processing, in particular, the computation of fields within the FE mesh View full abstract»

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  • An illustrative equivalence theorem example

    Publication Year: 2000 , Page(s): 132 - 135
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (196 KB)  

    Discusses the field equivalence principle where a fictitious cylindrical surface is involved. Field plots obtained from numerical results are given View full abstract»

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  • On the design of a dual-band base station wire antenna

    Publication Year: 2000 , Page(s): 144 - 151
    Cited by:  Papers (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (512 KB)  

    A dual-band base station wire-antenna design is presented. The MoM and the simulated-annealing technique, for optimizing the antenna geometry, are used. The procedure starts from the design of a primary radiator, consisting of a dielectric covered driven dipole and a parasitic element. A Chebyshev antenna array is checked in both the 900 and 1800 MHz frequency bands, with and without the appropriate feed network. All the electrical characteristics, as well as the patterns of the antenna, are presented View full abstract»

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  • Visualizing near-field energy flow and radiation

    Publication Year: 2000 , Page(s): 46 - 54
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (592 KB)  

    Computed near-field values of Poynting's vector and electric and magnetic field intensities for a linear dipole are displayed in a way that aids visualization of the radiation process. The fields are computed for time-harmonic excitation, but are shown as a function of time to demonstrate the spatial ebb and flow of the fields around the dipole. By this means, the distinction between near and radiation fields is made clearer, and the shedding of energy by the dipole can be observed View full abstract»

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  • Pencil-beam pattern synthesis with a uniformly excited multi-ring planar antenna

    Publication Year: 2000 , Page(s): 70 - 74
    Cited by:  Papers (12)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (288 KB)  

    In this paper, we describe the synthesis of pencil-beam power patterns for antennas composed of concentric rings of uniformly excited circular patches. The synthesis is performed by simulated annealing, varying the radii of the patch rings so as to optimize performance parameters. Examples illustrate the potential of the method View full abstract»

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  • PCs for AP and other EM reflections

    Publication Year: 2000 , Page(s): 92 - 98
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (460 KB)  

    After a brief introduction to far field analysis of radiation sources (FARS), the author discusses its extension to the time domain (TDFARS) and the validation of CEM results. Other topics discussed include: EM transient analysis, software verification and validation, and error analysis View full abstract»

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  • A bit system that guarantees better accuracy for monopulse antenna detection systems

    Publication Year: 2000 , Page(s): 82 - 86
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (240 KB)  

    Accurate integration and calibration of well-designed components can compensate for time-varying errors in a monopulse antenna system. A switchable four-port bit system, using a balanced four-way splitter and four balanced, electronically controlled, fast switches, make it possible to know the signal location measured by the monopulse antenna with very great accuracy in the presence of these errors View full abstract»

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  • Torque-bias profile for improved tracking of the Deep Space Network antennas

    Publication Year: 2000 , Page(s): 35 - 45
    Cited by:  Papers (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (576 KB)  

    Measurements at the drives of the NASA Deep Space Network (DSN) antennas indicated that the small gap between gear teeth was causing backlash at the gearboxes and elevation bullgear. Left uncorrected, backlash will deteriorate the antenna's pointing precision. At DSN, the backlash was eliminated by implementing two identical drives that impose two nonidentical torques (a.k.a. torque bias, or counter-torque). The difference between these two torques depends on the antenna load, and is shaped by the drive's electronic circuits. The paper explains the shaping principles of the circuit, and shows how the circuits can be modified to improve the antenna dynamics under external disturbances View full abstract»

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The IEEE Antennas and Propagation Magazine covers all areas relating to antenna theory, design, and practice.

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Mahta Moghaddam