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Antennas and Propagation, IEEE Transactions on

Issue 11 • Date Nov. 2006

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Displaying Results 1 - 25 of 35
  • Table of contents

    Page(s): C1 - 3049
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  • IEEE Transactions on Antennas and Propagation publication information

    Page(s): C2
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  • Guest Editorial for the Special Issue on Wireless Communications

    Page(s): 3050 - 3054
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  • Compact Six-Sector Antenna Employing Three Intersecting Dual-Beam Microstrip Yagi–Uda Arrays With Common Director

    Page(s): 3055 - 3062
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    A novel compact planar six-sector antenna suitable for wireless terminal is presented. Our new antenna design yields low-profile and extremely compact multisector antennas since it allows microstrip Yagi-Uda array antennas to share director elements. Two microstrip Yagi-Uda array antennas are combined to form a unit linear array that has feed elements at both ends, only one of which is excited at any one time, and the other is terminated. A numerical analysis shows that applying a resistive load to the feed port of the terminated element is effective in reducing the undesired radiation. The radiation pattern of a six-sector antenna, which employs three intersecting unit linear arrays, is investigated, and the optimum termination condition is identified. From the results of measurements, it is found that our antenna achieves high gain, at least 10 dBi, even though the undesired radiation is suppressed. It is shown that the radiation pattern suitable for a six-sector antenna can be obtained even with a 1.83 wavelength diameter substrate, i.e., the area is 75% smaller than that of a regular antenna with six individual single-beam microstrip Yagi-Uda arrays in a radial configuration View full abstract»

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  • Study and Reduction of the Mutual Coupling Between Two Mobile Phone PIFAs Operating in the DCS1800 and UMTS Bands

    Page(s): 3063 - 3074
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    Several solutions are presented to reduce the mutual coupling between two planar inverted-F antennas (PIFAs) working in close radiocommunication standards and positioned on a finite-sized ground plane modeling the printed circuit board (PCB) of a typical mobile phone. First, the two PIFAs are designed on separate PCBs to, respectively, operate in the DCS1800 and UMTS bands. In a second step, they are associated on the top edge of the same PCB. Realistic arrangements are then theoretically and experimentally studied. Finally, several solutions are investigated to maximize the isolation. They consist in inserting a suspended line between the PIFAs' feedings and/or shorting points. All along this paper, several prototypes are fabricated and their performances measured to validate the obtained IE3D moment method-based simulation results View full abstract»

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  • Compact Ultrawideband Rectangular Aperture Antenna and Band-Notched Designs

    Page(s): 3075 - 3081
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    A simple and compact ultrawideband (UWB) aperture antenna with extended band-notched designs is presented. The antenna consists of a rectangular aperture on a printed circuit board ground plane and a T-shaped exciting stub. The proposed planar coplanar waveguide fed antenna is easy to be integrated with radio-frequency/microwave circuitry for low manufacturing cost. The antenna is successfully designed, implemented, and measured. A compact aperture area of 13 times23mm2 is obtained with promising performances, including broadband matched impedance, stable radiation patterns, and constant group delay. The correlation between the mode-based field distributions and radiation patterns is discussed. Extended from the proposed antenna, three advanced band-notched (5-6 GHz) designs are also presented as a desirable feature for UWB applications View full abstract»

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  • Mutual Coupling Compensation in UCAs: Simulations and Experiment

    Page(s): 3082 - 3086
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    In a beamforming system, mutual coupling among the elements can significantly degrade the system performance. However, the mutual coupling effects can be compensated if an accurate model of mutual coupling is available. This paper utilizes a mutual coupling matrix model to compensate mutual coupling in the beamforming of a uniform circular array. In addition, a circular array of dipoles was built and measurements were performed. The predictions are compared with measurements, and verified with results from full-wave simulations View full abstract»

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  • A Switchable Multiple Beam Antenna for GSM-UMTS Base Stations in Planar Technology

    Page(s): 3087 - 3094
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    A broadband antenna for GSM1800-UMTS base stations with multiple switchable beams in azimuth is presented in this paper. The multiple beams are obtained by means of a broadband Butler matrix. The radiating element is broadband and consists of two stacked patches. The elevation pattern is shaped with null filling and upper lobe reduction that has been achieved by means of a broadband corporate feed network implemented in microstrip technology. Photographs and measurements of the manufactured prototypes are presented confirming that the design of all of the elements is correct View full abstract»

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  • An Integrated Phased Array Antenna Design Using Ferroelectric Materials and the Continuous Transverse Stub Technology

    Page(s): 3095 - 3105
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    In this paper, a new integrated phased array antenna system employing the ferroelectric materials technology for electronic beam steering capabilities is described. The design integrates a ferroelectric coplanar waveguide phase shifter with the continuous transverse stub (CTS) array. The phase shifter employs a multi-dielectric substrate and includes a thin layer of silicon dioxide between the signal conductors and the ferroelectric material to reduce the insertion losses and produce good impedance matching. The coplanar waveguide-based multi-dielectric layer design demonstrated an effective ferroelectric biasing architecture and exhibited an increase in figure of merit by up to 8deg/dB from that of the direct metallization approach. An integrated two elements phased array antenna is developed and demonstrates linearly polarized radiation with +/-20deg of beam scanning between the unbiased and biased states of the ferroelectric phase shifter View full abstract»

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  • Reverberation Chamber for Antenna Measurements: Modeling Using Method of Moments, Spectral Domain Techniques, and Asymptote Extraction

    Page(s): 3106 - 3113
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    Large reverberation chambers (RCs) have proved to be useful for measuring the performance of small antennas and terminals for wireless communications, and it is therefore important to be able to model them numerically to control accuracy. This paper describes a method of moments approach for analyzing wire antennas and other metallic objects in a large RC. The RC is treated as a rectangular perfect electric conducting cavity, and the Green's function is constructed by using a spectrum of plane waves and imaging combined with periodic boundary conditions. The code has been validated by comparison with measurements and other computer codes View full abstract»

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  • Statistical Analysis of the Multiple Scattering Radio Channel

    Page(s): 3114 - 3124
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    The concept of multiple scattering radio propagation channels-in contrast to the conventional single (Rayleigh) scattering-has been proposed and found to be a fitting model in certain propagation scenarios. Except for some special cases, expressions for the amplitude distribution of such channels are unknown. In this paper, we derive distribution functions for the amplitude of the general multiple scattering radio channel. Rice, Rayleigh, and double-Rayleigh distributions are special cases of the general result. We also derive a computationally simple moment-based estimator for the parameters of the distribution. In addition to the measurement analysis of multiple scattering propagation channels, our results can also be applied in the performance evaluation of communication schemes over such media View full abstract»

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  • Capability of 3-D Ray Tracing for Defining Parameter Sets for the Specification of Future Mobile Communications Systems

    Page(s): 3125 - 3137
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    Three-dimensional (3-D) ray tracing has advanced to such a degree that it can provide channel parameters like delay spread, Doppler spread, angular spread, and distribution functions of long- and short-term fading with high accuracy for fixed to mobile and mobile to mobile communications. These parameters are absolutely required during the specification phase of future mobile communications systems in order to define the air interface and a variety of other relevant system parameters. This paper describes state-of-the-art ray tracing capabilities. A 3-D ray tracing model developed at the Universitaumlt Karlsruhe is presented. Important characteristic channel parameters are briefly discussed. Based on these parameters the model is verified by wideband nondirectional and directional measurements at 2 and 5.2 GHz, respectively, showing a good agreement. The proposed 3-D ray tracing model can therefore be used in order to extract parameter sets for the specification of future mobile communications systems and to optimize existing ones View full abstract»

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  • A Novel Measurement-Based Algorithm for Coverage Prediction of Urban and Suburban Cells in Wireless Networks

    Page(s): 3138 - 3142
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    A novel approach is proposed to predict the coverage of urban and suburban cells in wireless networks. By this approach, the propagation loss between any two points along the virtual propagation path from the base-station to the mobile-station within a predicted area can be deduced in an average sense with reasonable accuracy, based on an a priori series of measurements, finite and limited in extent, taken along the periphery of this area. The effectiveness of the proposed method has been demonstrated using experiments under various radio environments in Guang Dong, China. It was shown that the prediction results were approximately consistent with independent checking samples View full abstract»

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  • Channel Characterization of Indoor Wireless Personal Area Networks

    Page(s): 3143 - 3150
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    The wireless channel for nomadic diversity-based wireless networks operating at 1.9 GHz is characterized. Using a 1 times 2 wideband measurement chain, four typical indoor office and industrial environments have been investigated: a corridor, an office room, a laboratory room and a large industrial hall. The measurement equipment is constituted by an 80-MHz transmitter. At the receiver, two omnidirectional antennas are connected to a wideband channel sounder through a switch, in order to measure an estimate of the instantaneous vector channel. Special attention is given to the experimental procedure itself, so as to take into account the specificity of nomadic systems (as opposed to usual mobile systems). The measurement analysis reveals that the shadowing, Rician K-factor and delay-spread are lognormally distributed. A path-loss model is derived, and cross-correlations between K-factor, delay-spread and shadowing are analyzed. The channel correlations at the user terminal or at the access point are also derived, and related to the individual channel characteristics View full abstract»

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  • A Comprehensive Standardized Model for Ultrawideband Propagation Channels

    Page(s): 3151 - 3166
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    A comprehensive statistical model is described for ultrawideband (UWB) propagation channels that is valid for a frequency range from 3-10 GHz. It is based on measurements and simulations in the following environments: residential indoor, office indoor, builtup outdoor, industrial indoor, farm environments, and body area networks. The model is independent of the used antennas. It includes the frequency dependence of the path gain as well as several generalizations of the Saleh-Valenzuela model, like mixed Poisson times of arrival and delay-dependent cluster decay constants. A separate model is specified for the frequency range below 1 GHz. The model can thus be used for realistic performance assessment of UWB systems. It was accepted by the IEEE 802.15.4a Task Group as standard model for evaluation of UWB system proposals. This paper also presents a critical assessment of the applicability of the model and possible generalizations and improvements View full abstract»

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  • On the Use of Reverberation Chambers to Simulate a Rician Radio Environment for the Testing of Wireless Devices

    Page(s): 3167 - 3177
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    With the proliferation of wireless devices in recent years, there is a growing need to test the operation and functionality of these various devices in different multipath environments, ranging from line-of-sight environment to a pure Rayleigh environment. In this paper we discuss how a reverberation chamber can be used to simulate a controllable Rician radio environment for the testing of a wireless device. We show that by varying the characteristics of the reverberation chamber and/or the antenna configurations in the chamber, any desired Rician K-factor can be obtained. Expressions for the desired K-factor as a function of the chamber and antenna characteristics will be presented. Experimental results are presented to illustrate the validity of these expressions, to show how the reverberation chamber can be used to simulate different multipath environments, and to show the realization of a controlled K-factor test facility. We present both a one-antenna and a two-antenna test configuration approach View full abstract»

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  • Conditions for Direction-Independent Distortion in UWB Antennas

    Page(s): 3178 - 3183
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    Many measures for the assessment of ultrawideband (UWB) antenna performance have previously been presented. Nevertheless, it remains to be succinctly stated exactly what constitutes an ideal UWB antenna. Here, one particular criterion, direction-independent distortion, and the conditions required to satisfy it are presented. We show that the realized gain (i.e., gain including mismatch) must be a separable function of angle and frequency, and that the phase pattern must satisfy a narrow set of restrictions. Within certain restrictions, the property of direction-independent distortion is independent of input waveform. We show that the class of antennas known as "maximum directivity" antennas is one type of antenna that satisfies these requirements. Three numerical examples are given, including an unloaded linear dipole, a resistively loaded linear dipole, and a resistively loaded tapered dipole. The examples show that the unloaded linear dipole does not at all satisfy the requirements for direction-independent distortion while both loaded dipoles do, with the loaded tapered dipole satisfying the requirements exceedingly well View full abstract»

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  • Correlation-Based Pattern Stability Analysis and a Figure of Merit for UWB Antennas

    Page(s): 3184 - 3191
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    Combining the concepts of pulse fidelity, time-domain correlation patterns, and frequency-domain pattern stability, we propose the concept of frequency-domain correlation patterns and a figure of merit, called pattern stability factor (PSF), to characterize pattern stability of wideband antennas. The frequency-domain correlation pattern represents the relationship between radiation in a reference direction to radiation in all other directions of interest, over a specified bandwidth. With practical examples, we demonstrate that this tool is very useful when selecting a single transfer function (and a reference direction) for the antenna when designing or optimizing an ultrawideband (UWB) system. Careful selection of the reference direction is crucial for antennas with relatively less stable patterns, but even antennas with relatively stable patterns can perform poorly overall if an inappropriate reference direction is chosen. The PSF represents the overall pattern stability of an antenna for a specific bandwidth and a range of directions. It is useful as a quantitative measure: a) to compare the suitability of different antennas for a given wideband or multiband application; b) to assess pattern stability improvement methods; and c) to quantify the effect of packaging, etc., on stability. We also propose the concept of PSF bandwidth and show how it can be used to identify stable frequency bands of a given antenna within its impedance bandwidth, and how it compares with the impedance bandwidth of some UWB antennas View full abstract»

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  • Textile UWB Antennas for Wireless Body Area Networks

    Page(s): 3192 - 3197
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    A new ultrawideband (UWB) textile antenna designed for UWB wireless body area network (WBAN) applications is presented. Unlike previous textile antennas, these antennas offer a direct integration into clothing due to a very small thickness (0.5 mm) and flexibility. We have realized two different designs of textile antennas: coplanar waveguide fed printed UWB disc monopole and UWB annular slot antenna. To our knowledge, these are the first textile UWB antennas reported in the open literature. Measured return loss and radiation pattern characteristics of textile UWB antennas agree well with simulations. Moreover, measured transfer functions show that these textile antennas possess excellent transient characteristics, when operating in free space as well as on the human body. They can operate in the entire UWB band approved by the Federal Communications Commission (3.1-10.6 GHz) View full abstract»

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  • Characterization and Modeling of Temporal Variations on an Ultrawideband Radio Link

    Page(s): 3198 - 3206
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    The development of efficient ultrawideband (UWB) systems for high-rate wireless links requires an accurate knowledge of the radio propagation mechanisms. Anticipated usage scenarios in office or residential environments predict a significant impact of mobile persons on the UWB radio link. However, the issue of temporal variations in the UWB propagation channel has been scarcely investigated so far. This paper presents a study of the time variance of a UWB channel induced by the motion of people, with a specific focus on the main path of a line-of-sight radio link. A real-time measurement campaign involving moving scatterers was performed in the 4-5 GHz band, in a hallway of a typical office building. The analysis of measured data, regarding the shadowing effect and fast signal fluctuations, provides a detailed description of the phenomena involved in a time varying UWB channel. As a result, a model is described for the temporal variations observed on the main propagation path in a fixed UWB link, accounting for both the nonstationary attenuation due to obstructing people and the small-scale signal variations due to scattered propagation paths View full abstract»

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  • A Channel-Based Statistical Approach to Antenna Performance in UWB Communications

    Page(s): 3207 - 3215
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    An analysis of the joint antenna-channel problem in ultrawideband communications is carried out in order to provide tools for the performance evaluation of antennas while taking into account the system architecture and the radio link scenarios. Owing to the stochastic character of channels and of antenna close environment, a statistical approach to the problem based on discrete channel models is favored. The distinction between gain and dispersion effects is highlighted, both in a nondirectional and in a fully directional channel model. It is shown that antenna distortion generally has a small effect, but for coherent pulse detection it provides an extra gain in dense multipath channels with respect to ideal antennas and low density channels View full abstract»

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  • A Time Reversal Transmission Approach for Multiuser UWB Communications

    Page(s): 3216 - 3224
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    We propose and evaluate the performance of the time reversal technique in impulse radio ultrawideband (UWB) communications. The evaluation was based on measured channel impulse responses of a 4times1 multiple input single output (MISO) system in the UWB frequency bandwidth of 3 to 5 GHz with both vertical and horizontal polarization at the receiver. The results show that there is a great potential in combining time reversal and UWB technique with respect to both reducing the receiver complexity and improving the system performance. Simultaneous communication is illustrated with 5 users, each with a bit error rate (BER) of less than 10-3 at an average signal to noise ratio (SNR) of 15 dB View full abstract»

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  • Impact of Matching Network on Bandwidth of Compact Antenna Arrays

    Page(s): 3225 - 3238
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    We analyze the impact of the matching network on compact multiple-input multiple-output systems. Existing studies have found that the matching network has a significant influence on the performance of multiple antenna systems when the antennas are in close proximity. However, none has examined the wide-band case. In this paper, we investigate the wide-band performance of four different matching networks for multiple dipole antennas. The performance of the matching networks is given in terms of the bandwidths of correlation and matching efficiency, which are extensions of the single-antenna concept of bandwidth to multiple antenna systems. We also investigate the impact of the propagation conditions on the matching and bandwidth. For a uniform two-dimensional (2-D) angular power spectrum, we find that while individual-port matching can achieve in excess of 3% fractional correlation bandwidth for envelope correlation of 0.5 at an antenna separation of 0.01lambda, multiport matching is required for efficiency bandwidth to exist for a return loss of -6 dB. Moreover, even with multiport matching, both correlation and efficiency bandwidths decrease drastically at small antenna separations. At 0.01lambda, the correlation and efficiency bandwidths are 0.4% and 0.2%, respectively. Similar evaluations were performed for measured outdoor-to-indoor channels with moderate to small 2-D angular spreads. We find that the efficiency advantage of multiport matching over individual-port matching diminishes with decreasing angular spread View full abstract»

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  • Experiments With Compact Antenna Arrays for MIMO Radio Communications

    Page(s): 3239 - 3250
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    Realizing antenna arrays that preserve channel capacity in multiple-input multiple-output (MIMO) radio communications is a challenge because of the detrimental effects of mutual coupling. The fact that mutual coupling becomes more pronounced as antenna spacing decreases is therefore a critical issue with compact arrays used in portable MIMO radios. The contributions made in this paper include the realization of compact MIMO arrays designed to preserve channel capacity and the characterization of these compact arrays' performance in field measurements using MIMO radios. A multiport metric is used to characterize the compact arrays in a way that more appropriately measures array performance under MIMO signalling conditions than the traditional scattering matrix characterization. Field measurements show the extent and proportion of the effect that correlation and radiation efficiency have on MIMO channel capacity. The compact arrays' strong performance in field measurements is explained by their ability to preserve the MIMO channel's eigenstructure. Results also show that mutual coupling prevents channel capacity from scaling linearly with the number of antennas. Guidelines for compact MIMO array design are given with supporting results from field measurements View full abstract»

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  • Optimization of Linear Multielement Antennas for Selection Combining by Means of a Butler Matrix in Different MIMO Environments

    Page(s): 3251 - 3264
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    An optimized linear multielement antenna (MEA) is presented for selection combining schemes that improves the selection diversity gain and selection diversity capacity in medium and low multipath environments, with respect to the performance achieved with a simple uniform linear array (ULA) using omnidirectional antennas, while it performs equally as well as a ULA in highly scattered environments. An analytical investigation based on the analysis of the correlation coefficients, together with simulations and extensive measurements, have been carried out for different fading multiple-input multiple-output environments ranging from line of sight (LOS) to non-LOS. Two MEAs are compared: a simple ULA with omnidirectional antennas and a MEA combining a ULA and a Butler matrix. The measurement results show that the nature of the proposed MEA is such that it is adaptive to any propagation scenario by simultaneously taking advantage of beamforming gain and signal diversity gain View full abstract»

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Aims & Scope

IEEE Transactions on Antennas and Propagation includes theoretical and experimental advances in antennas.

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Meet Our Editors

Editor-in-Chief                                                 Kwok W. Leung