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Antennas and Propagation, IEEE Transactions on

Issue 1 • Date Jan. 2004

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Displaying Results 1 - 25 of 57
  • Table of contents

    Page(s): c1 - 1
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  • IEEE Transactions on Antennas and Propagation publication information

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  • Deployable antenna with 10-m maximum diameter for space use

    Page(s): 2 - 11
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (800 KB) |  | HTML iconHTML  

    This paper describes a large deployable antenna which is used at L-, C-, and Ka-bands on an artificial satellite in space. The main reflector with 10-m maximum diameter is formed using the tensioned truss concept which was proposed by one of the authors. The mechanical structure of the antenna is briefly explained and a more detailed description given of the electrical design of the antenna and the verification method of electrical characteristics. This antenna was successfully launched and deployed in space in 1997 and is used for a Space VLBI mission. View full abstract»

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  • The design of classical offset Dragonian reflector antennas with circular apertures

    Page(s): 12 - 19
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (288 KB) |  | HTML iconHTML  

    The vector aperture field of classical offset Dragonian dual-reflector antennas is derived using geometrical-optics concepts. This field then yields the equivalent paraboloid of the geometry. From these results, the conditions for an axially symmetric equivalent paraboloid, when a circular aperture is assumed, are obtained. A complete step-by-step geometrical-optics-based design procedure for optimum classical offset Dragonian antennas with circular apertures is then presented (i.e., zero geometrical-optics cross-polarization and minimum spillover). This procedure is demonstrated by two design examples. View full abstract»

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  • Gravitational deformation of a reflector antenna measured with single-receiver holography

    Page(s): 20 - 25
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (392 KB) |  | HTML iconHTML  

    Holographic measurements of deformations in a large antenna reflector are described. The deformations were brought about by changing elevation angle and gravitational loading. A phase-switching arrangement was used, which allowed a single, already installed and operating receiver to be shared by both the main antenna signal and a reference signal. Natural H2O masers in our galaxy were used as signal sources, and a reference antenna was attached rigidly to the antenna under test so as to move with it. Observing techniques are described that accommodate changes in source elevation angles and antenna feed position while acquiring a data set. View full abstract»

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  • Numerical and experimental analysis of circular-end wire bow-tie antennas over a lossy ground

    Page(s): 26 - 35
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (456 KB) |  | HTML iconHTML  

    This paper presents a numerical and experimental analysis of a wire bow-tie antenna situated horizontally near a lossy ground. The antenna is basically an array of identical wire dipoles having a common feed point and equal angular separation between two neighboring wires. This antenna is particularly suitable for ultrawide-band applications as it possesses a wideband property and allows a simple realization of resistive loading. It also provides a possibility to easily vary the antenna flare angle for the purpose of antenna matching or to adjust its footprint. In this work a theoretical model of the antenna is developed and verified experimentally. The wires are modeled as a tape-like structure by triangular patches and the antenna is analyzed using a mixed-potential integral equation formulation. Moreover, time-domain solutions are computed using the Fourier transformation, and a time-window technique is employed to calculate the antenna characteristic impedance. Using the model a comprehensive analysis of the antenna performance is carried out. View full abstract»

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  • A new dielectric grating antenna at millimeter wave frequency

    Page(s): 36 - 44
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (864 KB) |  | HTML iconHTML  

    The development of a dielectric grating antenna at Ka band is presented. The antenna performance is analyzed using perturbation analysis and a numerically based commercial software. The effect of the grating profile and various dimensions on the performance is presented. Based on the analytical results a rectangular profile grating antenna is designed. The antenna is optimized, fabricated and measured. Close agreement between the simulated and measured results is obtained. View full abstract»

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  • Design of dual-polarized L-probe patch antenna arrays with high isolation

    Page(s): 45 - 52
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1024 KB) |  | HTML iconHTML  

    An experimental study of a dual-polarized L-probe patch antenna is presented. The antenna is designed to operate at around 1.8 GHz. A "dual-feed" technique is introduced to achieve high isolation between two input ports. The proposed antenna has an impedance bandwidth of 23.8% (SWR≤2), 15% (SWR≤1.5) and an isolation over 30 dB. In array designs, techniques for improving the isolation between two adjacent elements of an antenna array are also investigated. A two-element array with more than 30 dB isolation is designed and tested. View full abstract»

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  • Highly efficient unidirectional twin arc-slot antennas on electrically thin substrates

    Page(s): 53 - 58
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (312 KB) |  | HTML iconHTML  

    Unidirectional, highly-efficient planar twin arc-slot antenna elements backed by a reflector are presented. The theoretical radiation efficiency is as high as 99.9%. This high efficiency is achieved because the proposed slot geometry reduces the coupling to the parallel-plate TEM mode effectively in all directions on the substrate plane. A corporate-fed as well as a compact, center-fed, twin arc-slot elements have been implemented and tested. The parallel-plate TEM substrate patterns for a representative twin arc-slot element have been measured and compared with those of a corresponding straight twin-slot element. It was verified that the parallel-plate TEM mode, coupled from the proposed twin arc-slot element is greatly reduced in all directions. The measured gain improvement when a back-reflector is added is found to be about 2.8 dB, further validating this high efficiency. In addition to the high radiation efficiency, the proposed twin arc-slot element is more compact compared to the corresponding, straight, full-wavelength twin-slot element, making it well-suited for two-dimensional antenna arrays. View full abstract»

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  • A wide-band small size microstrip antenna proximately coupled to a hook shape probe

    Page(s): 59 - 65
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (432 KB) |  | HTML iconHTML  

    A rectangular shorted patch is designed to achieve a wideband performance and size reduction. The patch size is reduced to 25% of the full size patch with over 30% matching bandwidth. A hook shape probe excites the patch approximately. The effect of hook parameters is investigated. A comparison between the L-shape and the hook-shape probe is given. Some of the numerical results are verified experimentally. A 16 elements array is analyzed with different feeding arrangements indicating an improvement of the array performance. View full abstract»

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  • Broad-band dual-frequency microstrip patch antenna with modified Sierpinski fractal geometry

    Page(s): 66 - 73
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    A dual-frequency antenna based on the Sierpinski fractal with two parasitic patches to enhance the impedance bandwidth is presented. An electrical circuit model formed by RLC resonators is proposed to learn about the antenna physical behavior and to achieve the dual band operation minimizing a trial-and-error numerical/measurement proofs. The antenna has been designed using a method of moment commercial code and has been experimentally tested, obtaining two bands with a broad bandwidth and similar radiation patterns. View full abstract»

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  • CPW-fed stacked microstrip antennas

    Page(s): 74 - 83
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    This paper presents a systematic parameter study of aperture-coupled stacked patch antennas fed by coplanar waveguide. These antennas are to be used at millimeter-wave frequencies in the 30-GHz range. The influence of the most important design parameters, such as patch dimensions, aperture dimensions, and substrate thicknesses, was studied extensively. It has been found that these antennas can easily be impedance-matched by tuning the dimensions of the excitation slot and adding a small tuning stub. In this way, an antenna element with a -10 dB impedance bandwidth of 36.8% has been designed. Furthermore, the results of this parameter study have allowed to formulate some general guidelines concerning the design of this type of antenna element. View full abstract»

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  • Polarization-agile microstrip antenna array using a single phase-shift circuit

    Page(s): 84 - 87
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (208 KB)  

    A novel polarization-agile microstrip antenna array is proposed, in which the polarization agility from linear to circular polarization for the whole array is realized easily by controlling a single phase-shift circuit. Using the corner-fed square patch element, a new 16 element dual-polarized array with high isolation and low cross-polarization is designed and analyzed by the extended multiport network method. A special FET phase shifter circuit is created, where 0° or 90° phase shift between dual ports is electrically switched. Experimental results are presented to verify the theory, and measured circularly-polarized radiation patterns show a boresight axial ratio of 0.5 dB. Another experiment that connects a low noise amplifier together with the phase-shift circuit is also introduced, realizing both polarization agility and power amplification with one active circuit. View full abstract»

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  • Analysis of Gunn integrated annular ring microstrip antenna

    Page(s): 88 - 97
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    The analysis conducted on Gunn integrated annular ring microstrip antenna and evaluation of various parameters such as input impedance, voltage standing-wave radio voltage standing wave ratio (VSWR), return loss, bandwidth, radiation pattern, beamwidth, etc., as a function of bias voltage and threshold voltage reveals that the Gunn loaded patch offers wider tunability, better matching, enhanced radiated power as compared to the patch alone. Bandwidth of the Gunn loaded patch improves to 11.07% over the 7.9% bandwidth of the patch whereas the radiated power is enhanced by 3.7 dB as compared to the patch. View full abstract»

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  • Termination-dependent diversity performance of coupled antennas: network theory analysis

    Page(s): 98 - 105
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (224 KB) |  | HTML iconHTML  

    A new analysis of mutually coupled diversity antenna systems is presented that includes the effects of coupling on the radiation pattern and received power. This analysis, based upon the network scattering parameters, makes use of the singular value decomposition to both specify the characteristics of and analyze terminated antenna networks. The approach facilitates a simplified proof of the multiport conjugate matching condition as well as development of expressions for diversity performance as a function of various impedance terminations. Application of the analysis to coupled dipole antennas characterized using full-wave electromagnetic analysis leads to a comprehensive examination of the diversity performance obtainable for such antennas under different termination conditions. The results from this paper reveal that for closely spaced antennas, the termination can play a noticeable role in determining the diversity gain offered by coupled antennas. View full abstract»

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  • Smart antennas based on spatial multiplexing of local elements (SMILE) for mutual coupling reduction

    Page(s): 106 - 114
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (296 KB) |  | HTML iconHTML  

    A new method for reducing mutual coupling in a smart antenna array using patch antenna elements is proposed. In a recently introduced smart antenna architecture, the spatial multiplexing of local elements (SMILE) scheme, the newly proposed array feed network affects mutual coupling. It is demonstrated that proper design of the feed network may reduce mutual coupling significantly, yielding nearly ideal radiation characteristics. Numerical solutions are used to study and optimize the currents on the surface of a four-element C-band patch antenna array and feed network. Radiation patterns of the same array with different feed networks are also computed. Results show a reduction in sidelobe level of several decibels, increased accuracy in beam pointing during scan, and improved depth and placement. View full abstract»

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  • A low-cost electrical beam tilting base station antennas for wireless communication system

    Page(s): 115 - 121
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (584 KB) |  | HTML iconHTML  

    A multifunctional feeding network is presented in this paper. It contains a one-to-eight Wilkinson-based power divider and eight microstrip lines backed with slot array. In addition, the moveable card printed with seven metal strips serves as a novel phase shifter. By dynamically moving the card, we can adjust the number and shielding area of the slot array and then alter the distribution of phase angle at each port of the feeding network accordingly. For example, in our application, we can have a progressive phase difference between the ports of feeding network and dynamically adjust them by changing the degree of perturbation on the slots array. The characteristic of beam tilting has been carefully examined by measuring the phase angle at each port and also by the far-field radiation pattern of the patch antenna array integrated with this novel phase shifter, in various perturbation conditions. The reliable, easily fabricated, and low-cost characteristics show its potential applications in the base-station antenna design. View full abstract»

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  • Crossed-dipole arrays for asynchronous DS-CDMA systems

    Page(s): 122 - 131
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    In this paper, the use of a crossed-dipole array is proposed in joint space-time channel estimation for asynchronous multipath direct sequence code division multiple access (DS-CDMA) systems. The polarization diversity offered by such an array, unlike linearly polarized arrays, is able to detect and estimate any arbitrary completely polarized signal path. By utilizing the polarization information inherent in the received signal to construct the polar-spatio-temporal array (polar-STAR) manifold vector, the accuracy and resolution of the polar-STAR parameters' estimation are significantly improved, and its signal detection capability is enhanced. To alleviate the need for a multidimensional search in the polarization space, a computationally efficient joint polarization-angle-delay channel parameter estimation algorithm is proposed for a "desired user" that operates in an asynchronous multiuser and multipath environment. The proposed algorithm, which can be seen as an application of MUSIC-type techniques, is based on combining a two-dimensional STAR-Subspace type technique with a set of analytical equations and is supported by representative examples and computer simulation studies. View full abstract»

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  • Power pattern synthesis of reconfigurable conformal arrays with near-field constraints

    Page(s): 132 - 141
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1080 KB) |  | HTML iconHTML  

    A conformal array power pattern synthesis technique is presented which makes it possible to take into account near-field constraints and to reconfigure the radiated pattern by controlling only the phases of the excitation coefficients. Far-field pattern specifications are given by masks while near-field constraints are given by prescribing the maximum allowable field intensity at points arbitrarily located in a given near-field region. The amplitude of the excitations, common to all radiated beams, and the phases corresponding to each one are obtained as a result of the synthesis algorithm. View full abstract»

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  • Spiraphase-type reflectarrays based on loaded ring slot resonators

    Page(s): 142 - 153
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (656 KB) |  | HTML iconHTML  

    Reflective periodic arrays based on loaded ring slot resonators are analyzed. A full-wave mathematical model is developed and numerical results are presented. It is proven that the reflection angle for the normally incident circularly polarized wave can be effectively controlled by proper positioning of reactive loads in ring slot resonators. Analysis of the reflection characteristics of the Ka band one-layer reflectarray results in a conclusion that the incident wave can be effectively redirected in the directions determined by elevation angles as high as 65° with conversion coefficient better than -1.5 dB. It is also shown that the usage of the multilayer reflectarray leads to a considerable improvement in the reflection characteristics when it is compared with the one-layer reflectarray. The method of the waveguide simulator has been used to verify the developed mathematical model. View full abstract»

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  • A retro-directive antenna array with phase conjugation circuit using subharmonically injection-locked self-oscillating mixers

    Page(s): 154 - 164
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (656 KB) |  | HTML iconHTML  

    In this paper, a novel phase conjugation circuit and its application to retro-directive antennas are presented. The phase conjugation circuit uses a balanced circuit structure with subharmonically injection locked self-oscillating mixers oscillating at ω. In the operation, an input signal at ω/2 is converted to its conjugated signal with no external source required for LO signal pumping, and the output signal frequency is locked at the same frequency of the input signal. The developed phase conjugation circuit is implemented with active antennas to become a retro-directive antenna array. Both the theoretical and measured results of phase conjugation and retro-directive performance are shown in good agreement. View full abstract»

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  • Improved coupled wave analysis of two-dimensional planar multiple gratings

    Page(s): 165 - 171
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (320 KB) |  | HTML iconHTML  

    An improved coupled wave approach is presented for the analysis of diffraction behavior of a two-dimensional spatially periodic or almost periodic dielectric layer illuminated by TE polarized plane waves. This method applies to any simultaneous composition of arbitrarily modulated planar transmission gratings with any permittivity in neighboring regions. Two major improvements have been made. In the first part, the eigenvalues and eigenvectors of coupled wave system of equations are first-order corrected to reduce the inherent errors generated by neglecting second-order derivatives. In the second part, a scattering matrix method is used to model the effect of boundaries. Using this method, the applicability range of coupled wave approach is extended to higher modulation depths and thicker grating layers. The main advantages of the proposed method compared with rigorous coupled wave analysis are ease of simulation, ease of extension to multiple grating structures, and increased speed. Results are presented for single and multiple grating structures, and comparisons with results obtained using rigorous coupled wave analysis are made to verify the accuracy of the proposed method. View full abstract»

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  • Polarization properties of the GPS signal scattered off a wind-driven ocean

    Page(s): 172 - 188
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    A Global Positioning System (GPS) transmitter-receiver pair form a bistatic radar for ocean remote sensing when the receiving platform carries a downlooking antenna capable of collecting the GPS signal scattered off the ocean surface. The aggregate GPS signal scattered by the ocean and received in a general bistatic configuration has been calculated for representative geometries and a variety of wind speeds and directions, using the integral equation method (IEM) combined with a realistic ocean correlation function (spectrum). The role of polarization of the reflected signal is investigated and its dependence on wind speed and direction is analyzed to assess its suitability as a detector of the wind vector. The complexity of the scattering calculations is handled by an efficient integration scheme based on combining Gaussian quadrature with a local interpolation of the surface correlation function. Additionally, since a large number of scattering contributions are required the code has been parallelized for efficiency. Some relevant features of the parallelization scheme are outlined. View full abstract»

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  • Scattering by multilayer isorefractive elliptic cylinders

    Page(s): 189 - 196
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (304 KB) |  | HTML iconHTML  

    An analytical solution to the plane-wave electromagnetic scattering by multilayer elliptic cylinders is derived in the case of isorefractive materials. For these materials, a recursive solution similar to the solution for the multilayer circular cylinder is obtained. Moreover, it will be shown that the matrix-based recursive procedure for common dielectrics reduces to the present solution in this particular case. Finally, a number of numerical examples and comparisons will be provided. View full abstract»

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  • A fast physical optics (FPO) algorithm for high frequency scattering

    Page(s): 197 - 204
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (608 KB) |  | HTML iconHTML  

    A novel algorithm referred as the fast physical optics (FPO) for computing the back-scattered field over a range of aspect angles and frequencies is presented. The computation is performed in the framework of the conventional physical optics approximation appropriate for the high frequency scattering regime. The proposed algorithm is, also, directly applicable to fixed angle bistatic configurations and a variety of single scattering formulations. The method comprises two steps. First, a decomposition of the scatterer into subdomains and computation of the pertinent scattering characteristics of each subdomain. Second, interpolation, phase-correction and aggregation of the scattering patterns of the subdomains into the final pattern of the whole body. A multilevel algorithm is formulated via a recursive application of the domain decomposition and aggregation steps. The computational structure of the multilevel algorithm resembles that of the FFT. The proposed method is especially suited for generation of synthetic data for radar imaging simulation. View full abstract»

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

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Editor-in-Chief                                                 Kwok W. Leung