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Antennas and Propagation for Wireless Communications, 1998. 1998 IEEE-APS Conference on

Date 1-4 Nov. 1998

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  • 1998 IEEE-APS Conference on Antennas and Propagation for Wireless Communications (Cat. No.98EX184)

    Publication Year: 1998
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    Freely Available from IEEE
  • Author index

    Publication Year: 1998, Page(s):181 - 184
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    Freely Available from IEEE
  • Modified quadrifilar helix antennas for mobile satellite communication

    Publication Year: 1998, Page(s):141 - 144
    Cited by:  Papers (4)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (188 KB)

    Quadrifilar helix antennas have gained attention recently as antennas for satellite telephone handsets. Here a modification procedure is introduced for decreasing the length of the quadrifilar helix antenna. Two modified and two non-modified, quadrifilar antennas are designed and measured. The measurement results are shown View full abstract»

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  • A new GPS hexafilar slot antenna

    Publication Year: 1998, Page(s):137 - 140
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (196 KB)

    This paper presents a new GPS slot antenna consisting of six quarter-wavelength resonant slots. Each of the six resonant slots is rolled a half-turn around the cylindrical laminate and maintains constant phase relation to each other to form a right-hand circular polarization to receive GPS satellite signals. The printed cylindrical slot antenna presented is useful in applications where low-profile... View full abstract»

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  • A novel crank quadrifilar slot antenna for GPS hand-held receivers

    Publication Year: 1998, Page(s):133 - 136
    Cited by:  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (192 KB)

    This paper presents a new GPS quadrifilar slot antenna consisting of four quarter-wavelength crank slots. The four resonant crank slots are equally placed around the circumference of a cylindrical laminate and they maintain a constant phase relation to each other to form a right-hand circular polarization to receive GPS satellite signals. This new resonant helical slot antenna has a beamwidth of m... View full abstract»

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  • Asymmetrically fed linear antenna for low-angle VHF/UHF satellite communications

    Publication Year: 1998, Page(s):129 - 132
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (200 KB)

    Compared with the center-fed dipole, an asymmetrically fed linear radiator is shown to offer improved low-angle, satellite communications antenna performance by greatly reducing the severity of the multipath signals near the horizon. Numerical analysis (NEC) and measured data show that the improvement is achieved by increasing the upper/lower half-space energy ratio, particularly in the region nea... View full abstract»

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  • Electromagnetic modeling of radio wave propagation in micro- and pico-cellular environments

    Publication Year: 1998, Page(s):25 - 28
    Cited by:  Papers (6)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (252 KB)

    For new service deployment and expansion and improvement of existing systems accurate path loss prediction in urban micro- and pico-cellular environments is an important design verification step View full abstract»

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  • A field/polarization diversity antenna for portable phones

    Publication Year: 1998, Page(s):125 - 128
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (316 KB)

    The design of a two-element field/polarization diversity antenna for portable phones is considered. The antenna consists of a dipole terminated with a parallel loop capacitor combination. The antenna has a single feed at a point on the loop opposite the junction, and does not require external combining circuitry. The capacitor creates a phase shift between the dipole and loop currents, thereby gre... View full abstract»

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  • Indoor ISM band multipath fading: frequency and antenna diversity

    Publication Year: 1998, Page(s):9 - 12
    Cited by:  Papers (5)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (276 KB)

    The frequency fading characterization of the indoor ISM (902-928 MHz) channel are presented. This includes plots of the frequency-dependence of the fading and calculations of the correlation bandwidth. Finally, the measured diversity performance of three novel dual antenna configurations proposed for an ISM band wireless transceiver handset are presented. The diversity performance of these antenna... View full abstract»

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  • Dynamics of attenuation in equatorial Brazil: 1-year analysis of three 12 GHz Earth-space links

    Publication Year: 1998, Page(s):21 - 24
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (296 KB)

    The dynamic analysis of attenuation is defined as the statistical analysis of time duration and number of events of a given attenuation level being exceeded. The results from the dynamic statistical analysis of one year of radiometric attenuation measurements in three 12 GHz stations located in equatorial Brazil are presented and discussed. Such data and results are very rarely presented in the li... View full abstract»

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  • Radial basis function neural network algorithm for adaptive beamforming in cellular communication systems

    Publication Year: 1998, Page(s):53 - 56
    Cited by:  Papers (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (192 KB)

    A smart antenna based on a neural network implementation of the optimum Wiener solution for the problem of adaptive interference nulling using circular arrays is presented. Modem cellular satellite mobile communications systems and GPS systems suffer from different sources of interference which limit system capacity. This paper develops a fast tracking system to constantly track the mobile users, ... View full abstract»

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  • Improved feed system design for a wideband dipole array

    Publication Year: 1998, Page(s):97 - 100
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (248 KB)

    A high power, wideband HF phased array is being constructed as part of the High Frequency Active Auroral Research Program (HAARP) in Galkona, Alaska. Extensive testing of a demonstration prototype (DP) version of the array discovered undesirable feed resonance effects at discrete frequencies and excessive tower currents under simulated scanned conditions. Analyses and subsequent measurements point... View full abstract»

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  • Tapered coplanar-strip antenna

    Publication Year: 1998, Page(s):121 - 124
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (308 KB)

    In this paper, the design and performance characteristics of a new, compact, wideband, tapered coplanar-strip antenna are presented. This antenna can be utilized for narrowband and wideband applications. The antenna design is based on Chebyshev impedance transformation theory. The design and measured performance characteristics of this antenna are described View full abstract»

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  • Multimode rectangular microstrip antenna for GPS applications

    Publication Year: 1998, Page(s):149 - 151
    Cited by:  Papers (4)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (316 KB)

    Hand-held GPS receivers have revolutionized navigation for the dismounted soldier. This paper presents the experimental development of a single-element, multimode rectangular microstrip antenna capable of forming a spatial null. Using fundamental and higher order modes within a single microstrip patch radiator, a relatively simple, low-cost adaptive antenna capable of forming a null in the vicinit... View full abstract»

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  • Electromagnetic ground-wave field of vertical antennas

    Publication Year: 1998, Page(s):5 - 8
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (180 KB)

    Communication between the shore and a ship and between ships makes use of frequencies from 1 to 30 MHz. The analysis presented provides new simple formulas for the ground wave along the surface of the sea. These include not only the range in which the surface of the sea is well-approximated by a plane but also the range where accurate account must be taken of the curvature of the spherical Earth. ... View full abstract»

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  • Evaluation of radio propagation parameters for field strength prediction using neural networks

    Publication Year: 1998, Page(s):17 - 20
    Cited by:  Papers (3)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (384 KB)

    Radio propagation models for field strength prediction are essential for designing and installing a mobile radio communications system. Typical backpropagation neural network (BPN) models with different input parameters are developed and used to evaluate and assess the relative importance of a set of radio propagation parameters for field strength prediction. The NN models are trained on data meas... View full abstract»

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  • Adaptive base station antennas for mobile communication systems

    Publication Year: 1998, Page(s):49 - 52
    Cited by:  Papers (4)  |  Patents (15)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (224 KB)

    There has been a rapid increase in the number of mobile communication users, resulting in an equally rapid need for increased capacity in the networks. Extensive research and development work on advanced base station antennas for mobile communication is in progress at Ericsson. This includes both active and adaptive antenna systems. With the introduction of active antenna products, it is now possi... View full abstract»

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  • Validation of FDTD handset and head patterns by measurement

    Publication Year: 1998, Page(s):93 - 96
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (328 KB)

    This paper compares the principal plane radiation patterns of a portable radio handset at 850 MHz computed with the finite difference time domain method with measured radiation patterns. The agreement for the handset in isolation is excellent. The computed patterns of the handset operating near a box model of the head are compared with measured patterns with very good agreement. Finally the comput... View full abstract»

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  • Pattern nulling synthesis based on adaptive array theory

    Publication Year: 1998, Page(s):65 - 68
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (232 KB)

    A novel algorithm for adaptive pattern null synthesis which is based on the Gram-Schmidt orthogonalization is proposed. It uses the element nulling vector method which not only maintains all the advantages of pattern null synthesis but also has a small increase in the pattern sidelobe level for suppressing the wideband clutter and setting up a wide notch. Compared with the original algorithms, whe... View full abstract»

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  • FDTD analysis of human head-mobile phone interaction in terms of specific absorption rate calculations and antenna design

    Publication Year: 1998, Page(s):85 - 88
    Cited by:  Papers (5)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (312 KB)

    In this study, the finite-difference time-domain (FDTD) method is used to model mutual effects of a mobile phone and a human head in terms of both biological effects and antenna design. A discrete human head model and a hand-held receiver with various antennas mounted on top of it, are located within a three dimensional (3D) FDTD algorithm is built in Cartesian coordinates. Near fields are simulat... View full abstract»

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  • A hybrid MoM/FDTD technique for studying human head/antenna interactions

    Publication Year: 1998, Page(s):81 - 84
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (400 KB)

    As advances in numerical methods for solutions to Maxwell's equations accelerate, larger and more complex electromagnetic problems are becoming tractable at an astounding rate. The science of computational electromagnetics (CEM) gains inertia with each passing day. The maturing field of CEM research has sprouted various branches of research. The finite-difference time-domain (FDTD) method, introdu... View full abstract»

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  • Dielectric resonator antenna technology for wireless applications

    Publication Year: 1998, Page(s):117 - 120
    Cited by:  Papers (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (360 KB)

    This paper features some of the recent advances in dielectric resonator antenna technology at the Communications Research Centre, Ottawa, Canada. Several novel elements are presented offering significant enhancements to parameters such as impedance bandwidth, circular polarization bandwidth, gain, or coupling to feed structures. A variety of linear and planar arrays are also presented to illustrat... View full abstract»

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  • Analysis of elliptical microstrip patch antenna by considering attachment mode of current

    Publication Year: 1998, Page(s):175 - 179
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (180 KB)

    We present an analysis of a microstrip elliptical patch fed by coaxial cable using the moment method. After finding the exact Green's function, the input impedance is calculated by employing the reaction integration method and the moment method in the spectral domain together and proving its validity compared with experimental values. The attachment mode is used to consider the singularity and the... View full abstract»

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  • The circularly polarized cylindrical patch

    Publication Year: 1998, Page(s):145 - 148
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (248 KB)

    The paper presents a new type of antenna with a dipole-like radiation pattern and circular polarization. The antenna is a cylindrical patch antenna fed by a coaxial line, with a special geometry which generates the circular polarization. The configuration was optimized so it would generate the minimum axial ratio in the azimuthal plane where the pattern is omnidirectional. The antenna proposed is ... View full abstract»

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  • An analysis of radio signal level variations in strong multipath indoor environment

    Publication Year: 1998, Page(s):29 - 32
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (360 KB)

    Dipole antenna performance in a strong multipath environment due to multiple reflections is discussed. A method of computing the field distribution inside a room of arbitrary dimensions and electric characteristics of the walls is proposed. Measurements for different transmitter-receiver configurations and polarizations are presented. Based on computer simulation and measurement results some concl... View full abstract»

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