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Antennas and Propagation, IEEE Transactions on

Issue 11 • Date Nov. 2004

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  • Table of contents

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

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  • A review of antennas and propagation for MIMO wireless communications

    Page(s): 2810 - 2824
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (640 KB) |  | HTML iconHTML  

    Multiple-input-multiple-output (MIMO) wireless systems use multiple antenna elements at transmit and receive to offer improved capacity over single antenna topologies in multipath channels. In such systems, the antenna properties as well as the multipath channel characteristics play a key role in determining communication performance. This paper reviews recent research findings concerning antennas and propagation in MIMO systems. Issues considered include channel capacity computation, channel measurement and modeling approaches, and the impact of antenna element properties and array configuration on system performance. Throughout the discussion, outstanding research questions in these areas are highlighted. View full abstract»

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  • Harmonic radar transceiver design: miniature tags for insect tracking

    Page(s): 2825 - 2832
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    The design and operation along with verifying measurements of a harmonic radar transceiver, or tag, developed for insect tracking are presented. A short length of wire formed the antenna while a beam lead Schottky diode across a resonant loop formed the frequency doubler circuit yielding a total tag mass of less than 3 mg. Simulators using the method-of-moments for the antenna, finite-integral time-domain for the loop, and harmonic balance for the nonlinear diode element were used to predict and optimize the transceiver performance. This performance is compared to the ideal case and to measurements performed using a pulsed magnetron source within an anechoic chamber. A method for analysis of the tag is presented and used to optimize the design by creating the largest possible return signal at the second harmonic frequency for a particular incident power density. These methods were verified through measurement of tags both in isolation and mounted on insects. For excitation at 9.41 GHz the optimum tag in isolation had an antenna length of 12 mm with a loop diameter of 1 mm which yielded a harmonic cross-section of 40 mm2. For tags mounted on Colorado potato beetles, optimum performance was achieved with an 8 mm dipole fed 2 mm from the beetle attached end. A theory is developed that describes harmonic radar in a fashion similar to the conventional radar range equation but with harmonic cross-section replacing the conventional radar cross-section. This method provides a straightforward description of harmonic radar system performance as well as provides a means to describe harmonic radar tag performance. View full abstract»

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  • Study of ultrawide-band transmission in the extremely high frequency (EHF) band

    Page(s): 2833 - 2842
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (536 KB) |  | HTML iconHTML  

    The growing demand for broad-band wireless communication links and the lack of wide frequency bands within the conventional spectrum, causes us to seek bandwidth in the higher microwave and millimeter-wave spectrum at extremely high frequencies (EHF) above 30 GHz. One of the principal challenges in realizing modern wireless communication links in the EHF band are phenomena occuring during electromagnetic wave propagation through the atmosphere. A space-frequency approach for analyzing wireless communication channels operating in the EHF band is presented. Propagation of the electromagnetic radiation is studied in the frequency domain, enabling consideration of ultrawide-band modulated signals. The theory is employed for the analysis of a communication channel operating at EHF which utilizes pulse amplitude modulated signals. The atmospheric absorptive and dispersive effects on pulse propagation delay, pulse width and distortion are discussed. The theory and model are demonstrated in a study of ultrashort-pulse transmission at 60 GHz. View full abstract»

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  • Propagation of electromagnetic waves at MHz frequencies through seawater

    Page(s): 2843 - 2849
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    The nature of the ocean environment and its vast size has necessitated the development of sophisticated equipment and techniques for various underwater applications including diver-to-diver communications, ROV/AUV docking, communications and oil and gas explorations. To facilitate scientific exploration a wide variety of systems and vehicles have been developed to operate within the shallow continental shelf region or in deep oceans. For successful underwater electromagnetic (EM) wave operation, knowledge is required of the wave transmission properties of seawater over all distances both short and long. This information is required for such activities such as: sensor systems, imaging, position fixing, measurement of speed, obstacle detection and avoidance, guidance, communication of data/voice and remote control. This paper presents a new approach of EM wave propagation through seawater. The experimental results conducted in the laboratory and the real environment of seawater is presented. View full abstract»

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  • A novel horn radiator with high aperture efficiency and low cross-polarization and applications in arrays and multibeam reflector antennas

    Page(s): 2850 - 2859
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (768 KB) |  | HTML iconHTML  

    A step horn structure is presented that yields about 90% aperture efficiency with low cross-polar radiation. It is found that for obtaining high aperture efficiency, the horn aperture should consist of only the TEz type of modes in appropriate amplitudes and phases. The desired TEz modes are produced using multiple steps in the horn walls. The distances between the steps are critical to suppress the undesired TMz modes. Radiation characteristics of high efficiency circular and square horns are presented and potential applications of such high efficiency horns are discussed. View full abstract»

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  • A reconfigurable slot aperture design over a broad-band substrate/feed structure

    Page(s): 2860 - 2870
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1160 KB) |  | HTML iconHTML  

    A novel dual-band reconfigurable aperture (RECAP) design is introduced for operation over a two-octave bandwidth. The proposed RECAP consists of interleaved crossed-slot elements for dual-polarized and broad-band array operation without grating lobes. The dimensions of the array elements can be reconfigured by using radio-frequency switches such as microelectromechanical systems or PIN diodes. The array elements along with the switches are integrated into the top layer of a multilayered composite structure consisting of passive, resistively loaded frequency selective surface (FSS) elements that form a broad-band ground plane system. Excitation is provided through a broad-band balanced/matched feed, and reconfiguration allows for broad-band operation using the same FSS substrate. Besides the FSS substrate, shorting pins can be employed within the cavity to enhance gain performance. Significant analysis and understanding of the FSS/slot array configuration is presented along with measurements that should serve as a reference in future developments of these layered arrays. View full abstract»

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  • A C/ka dual frequency dual Layer circularly polarized reflectarray antenna with microstrip ring elements

    Page(s): 2871 - 2876
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (672 KB) |  | HTML iconHTML  

    This paper reports a dual frequency dual layer circularly polarized reflectarray operating in the C and Ka bands. A 0.5-m right-hand circularly polarized planar reflectarray antenna is designed using microstrip ring elements of variable rotations to achieve a cophasal beam at broadside. The microstrip ring elements are more compact than the traditional reflectarray elements and can minimize blockage for the multilayer multifrequency applications. The highest efficiencies measured are 46% at 7.3 GHz and 38% at 31.75 GHz. The tested cross-polarization levels are -21 dB at 7.3 GHz and -29.2 dB at 31.75 GHz at the broadside direction. The tested results show that the designed ring element is suitable for both the single and dual layer applications with good bandwidth and circularly polarized performance. View full abstract»

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  • Shorting strap tunable stacked patch PIFA

    Page(s): 2877 - 2884
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (640 KB) |  | HTML iconHTML  

    An oppositely shorted dual-band stacked patch planar inverted-F antenna (PIFA) is developed. RF switches are integrated to the shorting straps of the stacked patches to make a tunable PIFA. The L band switch yields 0.45-dB insertion loss and 10-dB isolation bandwidth (BW) of 108% at 1.8 GHz. The tunable PIFA yields 10% frequency tunability BW at 745 MHz when the number of upper radiating patch's shorting straps changes and 20% BW at 1137 MHz when the number of lower radiating patch's shorting straps changes. Independent lower and upper frequency tunings are achieved through this technique. View full abstract»

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  • Analysis of injection-locked antenna array including mutual coupling effects

    Page(s): 2885 - 2890
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (328 KB) |  | HTML iconHTML  

    In this paper, the injection locking performance analysis of dipole antenna array with each element loaded with a two-terminal oscillator is presented. The analysis is based on the nonlinear model of oscillator and the linear model of antenna array considering mutual coupling effects. The locking range of injection signal and the array radiated power are obtained by solving an equivalent multiport network. In general, the solutions include stable and unstable solutions. The Routh-Hurwitz stability criterion is then applied to remove the unstable solutions. Numerical results show that the array performance such as frequency locking range and radiated power by taking into account the array mutual coupling effects is quite different from that of an isolated antenna element. In addition, the influence of antenna element spacing upon array locking parameters in this paper is found to be consistent with other existing theories. View full abstract»

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  • Null steering in phased arrays by controlling the positions of selected elements

    Page(s): 2891 - 2895
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (312 KB) |  | HTML iconHTML  

    A new technique is presented that is capable of steering s in the antenna pattern in the directions of strong interference signals without affecting the main beam. The technique is based on the element position perturbations of selected elements of the antenna array. This technique frees the phase shifters to be used solely for steering the main beam toward the direction of the desired signal. It also freezes the positions of those elements that have insignificant contributions to the s. Our results have shown to be comparable to the results obtained from the method of controlling the positions of all elements. View full abstract»

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  • Efficient electromagnetic analysis of line-fed aperture antennas in thick conducting screens

    Page(s): 2896 - 2903
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    This paper presents a numerical and experimental verification of an approximate but efficient integral equation technique for the scattering by apertures in conducting planes with finite thicknesses. The approach is based on a perturbation method and modified Green's functions that take into account the finite metallization thickness. The computational effort and time needed for solving the problem are the same as in zero-thickness case. When compared to full-wave cavity treatment of thick apertures, the method is (depending on the number of unknowns) at least an order of magnitude faster. The method can be applied even to apertures of arbitrary shapes where computing the cavity's Green's functions is a difficult task. The results of simulations using the new approach show good agreement when compared to both results from full-wave cavity approach and measurements. View full abstract»

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  • Circular aperture pattern synthesis from collapsed equivalent line-source distributions

    Page(s): 2904 - 2911
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (368 KB) |  | HTML iconHTML  

    A novel circular aperture pattern synthesis technique is presented, which enables a linear line-source distribution to be converted to a rotationally symmetric circular aperture distribution, of which any φ-cut radiation pattern is ideally the same as the principal plane pattern of the line-source distribution. Line-source pattern synthesis techniques are numerous and versatile and the technique presented here allows these techniques to be applied to circular apertures as well. This new synthesis method is most compatible with line-source distributions which have zero edge illumination. View full abstract»

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  • A hybrid approach for the optimal synthesis of pencil beams through array antennas

    Page(s): 2912 - 2918
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (528 KB) |  | HTML iconHTML  

    A hybrid approach to the synthesis of excitations and locations of nonuniformly spaced arrays in order to achieve optimal focusing in any given direction is proposed and discussed. The approach takes definite advantage from the convexity of the problem with respect to excitation variables, and exploits a Simulated Annealing procedure as far as location variables are concerned. The corresponding synthesized patterns outperform previously known results in standard benchmark problems. View full abstract»

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  • Planar antenna array control with genetic algorithms and adaptive array theory

    Page(s): 2919 - 2924
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    Planar arrays are successfully employed in radar and communication systems in order to allow three-dimensional-scanning. In the framework of real-time control of antenna arrays, starting from the Applebaum theory, this paper presents an approach based on a customized genetic algorithm aimed at adaptively eliminating interfering signals. Successful applications are presented in order to evaluate the effectiveness of the proposed approach in term of performances and computational complexity. View full abstract»

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  • Multiband single-layer frequency selective surface designed by combination of genetic algorithm and geometry-refinement technique

    Page(s): 2925 - 2931
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1008 KB) |  | HTML iconHTML  

    This paper proposes an optimization-design method for the frequency selective surface (FSS) based on the genetic algorithm (GA) incorporated with a geometry-refinement technique. The present method takes the connectivity condition of the elements into consideration, thereby resulting in an easy fabrication. As an example, we design the multiband single-layer FSS for transmitting L band (1.5 GHz band) and S band (2.5 GHz band) and also reflecting Ka band (20/30 GHz band). The designed FSS has bandwidths broader than previous FSSs. Finally, the validity of the present method is proved by the agreement between the calculated and the measured transmission responses for the designed FSS. View full abstract»

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  • Comparison of fitness landscapes for evolutionary design of dipole antennas

    Page(s): 2932 - 2940
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1904 KB) |  | HTML iconHTML  

    Evolutionary algorithms are powerful optimization and design tools, and the design of fitness function is their crucial phase. The ruggedness of a fitness function landscape has a profound effect on optimization speed. The choice of objectives and penalty coefficients are important problems for evolutionary antenna design, because these parameters influence the ruggedness of the fitness function landscape. In this paper, we analyze several fitness function landscapes for evolutionary design of dipole antennas using the method of basin evaluation. Our approach makes it possible to compare different fitness functions and thus define proper fitness functions for evolutionary antenna design. View full abstract»

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  • The treatment of thin wires in the FDTD method using a weighted residuals approach

    Page(s): 2941 - 2949
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (456 KB) |  | HTML iconHTML  

    In this contribution, the problem of accurately representing thin wires within the finite-difference time-domain (FDTD) mesh is addressed by means of a method based on the weighted residual (WR) interpretation of the FDTD algorithm. Results for wire dipoles and wire transmission lines, obtained using the proposed method, are presented and compared to those obtained using existing techniques. It is shown that the proposed method yields results which are more accurate and are less dependent on the choice of cell size than other approaches and, in addition, lends itself well to being extended for more complicated structures. Details of the calculation of the update equations are given. View full abstract»

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  • Z-transform theory and FDTD stability

    Page(s): 2950 - 2954
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (384 KB) |  | HTML iconHTML  

    In this paper we analyze the stability and the accuracy of finite-difference time-domain (FDTD) algorithms using Z-transform technique. Conventional time-staggered approximation of the time-derivative is replaced by a rational transfer function discrete-time filter. Then a generalized formulation of the FDTD time-stepping is presented. Finally, we show that it is possible significantly reduce the time-sampling error of FDTD algorithm by properly choosing the transfer function coefficients. View full abstract»

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  • Finite-difference and pseudospectral time-domain methods applied to backward-wave metamaterials

    Page(s): 2955 - 2962
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (328 KB) |  | HTML iconHTML  

    Backward-wave (BW) materials that have simultaneously negative real parts of their electric permittivity and magnetic permeability can support waves where phase and power propagation occur in opposite directions. These materials were predicted to have many unusual electromagnetic properties, among them amplification of the near-field of a point source, which could lead to the perfect reconstruction of the source field in an image [J. Pendry, Phys. Rev. Lett. vol. 85, pp. 3966, 2000]. Often systems containing BW materials are simulated using the finite-difference time-domain technique. We show that this technique suffers from a numerical artifact due to its staggered grid that makes its use in simulations involving BW materials problematic. The pseudospectral time-domain technique, on the other hand, uses a collocated grid and is free of this artifact. It is also shown that when modeling the dispersive BW material, the linear frequency approximation method introduces error that affects the frequency of vanishing reflection, while the auxiliary differential equation, the Z-transform, and the bilinear frequency approximation method produce vanishing reflection at the correct frequency. The case of vanishing reflection is of particular interest for field reconstruction in imaging applications. View full abstract»

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  • Approximate Crank-Nicolson schemes for the 2-D finite-difference time-domain method for TEz waves

    Page(s): 2963 - 2972
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    Two implicit finite-difference time-domain (FDTD) methods are presented in this paper for a two-dimensional TEz wave, which are based on the unconditionally-stable Crank-Nicolson scheme. To treat PEC boundaries efficiently, the methods deal with the electric field components rather than the magnetic field. The "approximate-decoupling method" solves two tridiagonal matrices and computes only one explicit equation for a full update cycle. It has the same numerical dispersion relation as the ADI-FDTD method. The "cycle-sweep method" solves two tridiagonal matrices, and computes two equations explicitly for a full update cycle. It has the same numerical dispersion relation as the previously-reported Crank-Nicolson-Douglas-Gunn algorithm, which solves for the magnetic field. The cycle-sweep method has much smaller numerical anisotropy than the approximate-decoupling method, though the dispersion error is the same along the axes as, and larger along the 45° diagonal than ADI-FDTD. With different formulations, two algorithms for the approximate-decoupling method and four algorithms for the cycle-sweep method are presented. All the six algorithms are strictly nondissipative, unconditionally stable, and are tested by numerical computation in this paper. The numerical dispersion relations are validated by numerical experiments, and very good agreement between the experiments and the theoretical predication is obtained. View full abstract»

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  • An accurate scheme for the solution of the time-domain Integral equations of electromagnetics using higher order vector bases and bandlimited extrapolation

    Page(s): 2973 - 2984
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    Despite the numerous advances made in increasing the computational efficiency of time-domain integral equation (TDIE)-based solvers, the stability and accuracy of TDIE solvers remain problematic. This paper introduces a new numerical method for the accurate solution of TDIEs for scattering from arbitrary perfectly conducting surfaces. The work described in this paper uses the higher order divergence-conforming basis functions of Graglia et al. for spatial discretization and bandlimited interpolation functions for the temporal discretization of the relevant integral equations. Since the basis functions used for the temporal representation are noncausal, an extrapolation scheme is employed to recover the ability to solve the problem by marching on in time. Numerical results demonstrate that the proposed method is stable and that it exhibits superlinear convergence with regard to the spatial discretization and exponential convergence with respect to the temporal discretization. View full abstract»

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  • Higher order hierarchical Legendre basis functions for electromagnetic modeling

    Page(s): 2985 - 2995
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (800 KB) |  | HTML iconHTML  

    This paper presents a new hierarchical basis of arbitrary order for integral equations solved with the method of moments (MoM). The basis is derived from orthogonal Legendre polynomials which are modified to impose continuity of vector quantities between neighboring elements while maintaining most of their desirable features. Expressions are presented for wire, surface, and volume elements but emphasis is given to the surface elements. In this case, the new hierarchical basis leads to a near-orthogonal expansion of the unknown surface current and implicitly an orthogonal expansion of the surface charge. In addition, all higher order terms in the expansion have two vanishing moments. In contrast to existing formulations, these properties allow the use of very high-order basis functions without introducing ill-conditioning of the resulting MoM matrix. Numerical results confirm that the condition number of the MoM matrix obtained with this new basis is much lower than existing higher order interpolatory and hierarchical basis functions. As a consequence of the excellent condition numbers, we demonstrate that even very high-order MoM systems, e.g., tenth order, can be solved efficiently with an iterative solver in relatively few iterations. View full abstract»

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  • Study of mixed-order basis functions for the locally corrected Nyström method

    Page(s): 2996 - 3004
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    A high-order locally corrected Nyström (LCN) method employing the mixed-order basis functions proposed by C$80alιs$80kan and Peterson is presented for the electromagnetic scattering by targets composed of both dielectric and conducting bodies. An integral operator based on a combined field formulation for conducting surfaces and a Müller formulation for dielectric surfaces is used. It is found that for general scattering objects, mixed-order basis functions accelerate the convergence of the LCN solution, can eliminate spurious charges, and can significantly reduce the condition number of the impedance matrix. 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