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Antennas and Propagation, IEEE Transactions on

Issue 3 • Date March 2005

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Displaying Results 1 - 25 of 51
  • Table of contents

    Publication Year: 2005 , Page(s): c1 - 897
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  • IEEE Transactions on Antennas and Propagation publication information

    Publication Year: 2005 , Page(s): c2
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  • The relation between creeping waves, leaky waves, and surface waves

    Publication Year: 2005 , Page(s): 898 - 907
    Cited by:  Papers (17)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (456 KB) |  | HTML iconHTML  

    In this paper, we examine the creeping wave propagation wavenumbers, modal impedance, and field behavior on a dielectric coated circular cylinder. The physical interpretation is assisted by comparing the cylinder's pole waves with the leaky waves and surface waves that occur on a flat, grounded dielectric slab. The propagation wavenumbers and modal impedance are computed in the complex wavenumber plane. The cylinder propagation wavenumbers come from a transcendental equation involving Hankel functions, which are entire functions of complex order, whereas for the slab, branch-point singularities are present. This difference is examined, so that one can better understand how a coated cylinder behaves like a flat slab, when the cylinder radius is large. It is found that for the cylinder, the Stokes line for the asymptotic expansion of the Hankel function plays a role that is similar to the planar slab branch cut. View full abstract»

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  • High-impedance surfaces having stable resonance with respect to polarization and incidence angle

    Publication Year: 2005 , Page(s): 908 - 914
    Cited by:  Papers (69)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (336 KB) |  | HTML iconHTML  

    The work presented in this paper concerns a theoretical study on frequency selective surfaces (FSS) with application to artificial magnetic conductors or high-impedance surfaces (HIS). Current realizations of HIS are based on a planar FSS at the interface of a metal-backed dielectric slab either including vertical vias or not. A stable resonance was found for the case of series-resonance grids without vias in the slab. The resonance turns out to be unique in theory for all angles of incidence and both polarizations of plane waves illuminating the HIS. It was shown that vias destroy the stabilization effect and introduce a frequency shift. The analytical model was validated by HFSS simulations. View full abstract»

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  • Electromagnetic waves over half-space metamaterials of arbitrary permittivity and permeability

    Publication Year: 2005 , Page(s): 915 - 921
    Cited by:  Papers (12)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (560 KB) |  | HTML iconHTML  

    Most electromagnetic problems deal with media with unit permeability. However, recent interest in metamaterials necessitated studies of wave characteristics in media with arbitrary permittivity and permeability whose real parts can be positive or negative. This paper presents analysis of wave characteristics on semiinfinite metamaterials. Waves are excited by electric or magnetic line sources, and the problem is separated into the p (TM) and the s (TE) polarization, showing symmetries. The Fourier spectra of the reflection and transmission coefficients are examined and the poles, branch points, and zeros are shown in the real μ-real ε diagram. We clarify the location of poles in proper and improper Riemann Surfaces, and the excitation of forward and backward surface waves, forward and backward Lateral waves, and Zenneck waves, and the relations between Brewster's angle and Sommerfeld poles. We include the behaviors of the backward surface waves and the temporal backward Lateral waves. View full abstract»

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  • Physical and geometrical optics for 2-D rough surfaces with power-law height spectra

    Publication Year: 2005 , Page(s): 922 - 932
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (512 KB) |  | HTML iconHTML  

    Random rough surfaces with slowly decaying power spectral density can have infinite slope variance. Such surfaces do not satisfy the classical curvature criterion for validity of the physical optics (PO) approximation, and the infinite frequency geometrical optics limit or specular point scattering model breaks down. We show for two-dimensional surfaces with infinite slope variance that the Gaussian form of the classical geometrical limit generalizes to a stable distribution function. We also show that the PO integral is insensitive to surface components with spatial frequency above a cutoff wavenumber, which explains past observations that PO can be accurate for surfaces with power law spectra. This result leads to a general validity condition for the PO approximation in the backscattering direction for power-law surfaces, which in the case of a k-4 spectrum requires that the significant slope of the surface be less than 0.03. View full abstract»

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  • Approximate formulas for lateral electromagnetic pulses from a horizontal electric dipole on the surface of one-dimensionally anisotropic medium

    Publication Year: 2005 , Page(s): 933 - 937
    Cited by:  Papers (9)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (248 KB) |  | HTML iconHTML  

    In this paper, approximate formulas are derived for the electromagnetic pulse due to a delta-function current in a horizontal electric dipole on the planar boundary between a homogeneous isotropic medium and one-dimensionally anisotropic medium. The components of the electric field consist of two delta-function lateral pulses which decrease with the amplitude factor ρ-2 and travel along the boundary with different velocities and different amplitudes. Also, it is noted that the formulas for the time-dependent magnetic field components obtained by Fourier transforms from the approximate formulas in the frequency domain are not adequate. View full abstract»

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  • A stochastically optimized adaptive procedure for the location of MAS auxiliary monopoles: the case of electromagnetic scattering by dielectric cylinders

    Publication Year: 2005 , Page(s): 938 - 947
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (680 KB) |  | HTML iconHTML  

    A genetically optimized technique that fully automates the potentially laborious allocation of the auxiliary monopoles for the method of auxiliary sources (MAS) is presented for the problem of electromagnetic (EM) scattering by isotropic dielectric cylinders with various cross sections. The proposed technique uses as input information not only the geometry of the scatterer but also the exciting field and the material properties of the cylinders are implicitly taking part in the optimization procedure. The resulting auxiliary surfaces, where the simulating monopoles are situated, are appropriately adapted to the original boundary surface and the MAS modeling is greatly facilitated. In addition, certain considerations are taken into account in order to avoid undesirable numerical dependencies between the fictitious monopoles. Finally, the accuracy of the numerical method combined with overdetermined systems of equations is examined for isotropic cylinders of various geometries and dielectric characteristics. View full abstract»

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  • A phase-space beam summation formulation for ultrawide-band radiation. II: a multiband scheme

    Publication Year: 2005 , Page(s): 948 - 957
    Cited by:  Papers (13)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (720 KB) |  | HTML iconHTML  

    The ultrawide-band (UWB) beam summation representation introduced in Part I of this two-part sequence, is extended here to make it more efficient for excitations with bandwidths that are larger than one octave. The main features of the basic formulation in Part I were: 1) utilization of overcomplete windowed Fourier transform (WFT) frames to construct the beam lattice (or skeleton) that is independent of the frequency; 2) the use of isodiffracting Gaussian beams (ID-GBs) provides the snuggest frame representation, and thus stable and localized expansion coefficients, for all frequencies; 3) the ID-GBs can readily be tracked in the ambient medium and, due to the ID property, their propagation parameters are calculated only once and then can be used for all frequencies. Although the basic formulation can accommodate large bandwidths, it becomes increasingly less efficient at the low end of the frequency spectrum where the overcompleteness increases. The self-consistent multiband beam-summation scheme presented here extends and generalizes the basic formulation of Part I by dividing the excitation band into one-octave sub-bands and applying the UWB beam expansion of Part I in each band. This is done, though, via a novel self-consistent scheme wherein the beam sets at the lower bands are decimated subsets of those at the highest band, so that only the set of beam-propagators at the highest band needs to be traced, while for the lower bands one uses properly decimated subsets. This approach requires less beam elements at the lower frequency bands and thus keeps the overcompleteness (oversampling) in all the bands below a given level. As in Part I, we provide the guidelines for choosing the expansion parameters and then demonstrate the effectiveness of the new scheme via a numerical example of UWB focused aperture whose frequency band spans several octaves. View full abstract»

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  • The performance of the maximum ratio combining method in correlated rician-fading channels for antenna-diversity signal combining

    Publication Year: 2005 , Page(s): 958 - 964
    Cited by:  Papers (9)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (320 KB) |  | HTML iconHTML  

    The performance of the maximum ratio combining method for the combining of antenna-diversity signals in correlated Rician-fading channels is rigorously studied. The distribution function of the normalized signal-to-noise ratio (SNR) is expanded in terms of a power series and calculated numerically. This power series can easily take into account the signal correlations and antenna gains and can be applied to any number of receiving antennas. An application of the method to dual-antenna diversity systems produces useful distribution curves for the normalized SNR which can be used to find the diversity gain. It is revealed that signal correlation in Rician-fading channels helps to increase the diversity gain rather than to decrease it as in the Rayleigh fading channels. It is also shown that with a relative strong direct signal component, the diversity gain can be much higher than that without a direct signal component. View full abstract»

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  • The influence of complex material coverings on the quality factor of simple radiating systems

    Publication Year: 2005 , Page(s): 965 - 970
    Cited by:  Papers (22)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (344 KB) |  | HTML iconHTML  

    The influence of material coverings on the antenna quality factor is investigated for radiators formed by thin electric or magnetic line sources. It is shown that thin uniform and symmetric layers of arbitrary passive materials (including Veselago, left-handed, or double-negative materials) cannot help to overcome the bandwidth limitations imposed by the amount of energy stored in the antenna reactive field. Alternative possibilities offered by complex composite materials in the antenna design are identified. View full abstract»

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  • Dispersion analysis of the three-dimensional complex envelope ADI-FDTD method

    Publication Year: 2005 , Page(s): 971 - 976
    Cited by:  Papers (14)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (384 KB) |  | HTML iconHTML  

    In this paper, numerical dispersion properties of the three-dimensional complex envelope (CE) alternate-direction implicit finite-difference time-domain (ADI-FDTD) method are studied. The variations of dispersion errors with propagation direction, ratio of carrier to envelope frequencies, and spatial and temporal steps are presented. It is found that the CE ADI-FDTD scheme have much better accuracy and efficiency over the ADI-FDTD, especially with a higher ratio of carrier to envelope frequencies. Therefore, the CE ADI-FDTD is recommended for use in efficient narrow bandwidth electromagnetic modeling. View full abstract»

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  • Double-beam parallel-plate slot antenna

    Publication Year: 2005 , Page(s): 977 - 984
    Cited by:  Papers (10)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1120 KB) |  | HTML iconHTML  

    This paper presents the design and prototyping of a double-beam linear polarized parallel-plate slot antenna at 12-GHz band. Each beam is separated 27.7° and 27.3°, respectively, from broadside direction. Two different radiation patterns are generated, exciting the parallel plate from opposite sides. The radiating elements are composed by three parallel slots, the central slot is close to the resonance, while the side ones are designed to minimize the reflection inside the parallel plate. The length of the slots in the same row is kept constant (periodic walls), and the distance between columns is equal to 0.7 times the wavelength. The designs of the feeding networks and the design of the array of slots generate both beams, pointing toward Hispasat and Astra satellites simultaneously, at the same frequency band. The feeding networks are two microstrip circuits that excite two linear arrays of 24 patches, placed at both sides of the antenna, and generate both quasi-TEM mode plane waves inside the parallel-plate waveguide, propagating from one side to the other. View full abstract»

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  • Study and design of a capacitively coupled polymeric internal antenna

    Publication Year: 2005 , Page(s): 985 - 993
    Cited by:  Papers (9)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (752 KB) |  | HTML iconHTML  

    A capacitively coupled polymeric internal antenna is introduced for Bluetooth or GPS applications. Such an antenna can be easily fabricated on a flexible film substrate and attached to the inside surface of the plastic housing of a portable wireless device, such as a PDA. The proposed antenna saves critical space on the printed circuit board (PCB) and eliminates the need for a vertical contact feed. Thus manufacturing is also simplified and cost is reduced. Practical examples of utilizing such a concept for Bluetooth (2.45 GHz) and GPS (1.575 GHz) applications are provided. The antenna system requires a small coupling plate (as small as 4 by 4 mm2) that can be easily surface mounted on a PCB. The solution proposed provides wideband operation satisfying Bluetooth functionality with good radiation pattern and gain. View full abstract»

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  • Bandwidth enhancement and size reduction of microstrip slot antennas

    Publication Year: 2005 , Page(s): 994 - 1003
    Cited by:  Papers (108)  |  Patents (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1000 KB) |  | HTML iconHTML  

    Reduced size microstrip monopole slot antennas with different slot shapes-straight, L and inverted T, and placed on a small ground plane, are investigated. The ground plane size is 50 mm×80 mm, which is about the size of a typical PC Wireless card. Detailed simulation and experimental investigations are conducted to understand their behavior and optimize for broadband operation. It is shown that, the variation in the slot shape, from straight to L and T shapes, helps in generating additional resonances, which when coupled to the original resonances of the slot, further increases impedance bandwidths. The bent shapes of the L and T slots reduce their height and provide more space on the ground plane for electronics. A mirror image dual L-slot antenna, placed at two adjacent corners of the ground plane, is also investigated and optimized for the polarization diversity. They provide an impedance bandwidth of 87%, with near orthogonal radiation characteristics. The measured impedance bandwidths (S11=-10 dB) of up to 60%, 84%, and 80% are achieved for these straight, L and inverted T slots respectively, by suitably selecting their design parameters. The simulation results are in good agreement with the experimental data considering several practical issues. View full abstract»

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  • Comparative study on the mutual coupling between different sized cylindrical dielectric resonators antennas and circular microstrip patch antennas

    Publication Year: 2005 , Page(s): 1011 - 1019
    Cited by:  Papers (13)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (568 KB) |  | HTML iconHTML  

    A systematic comparative study on the mutual coupling (S21) between dielectric resonator antennas (DRAs) and microstrip patch antennas is presented. The mutual coupling between two cylindrical probe-fed DRAs is studied for different radius to height (a/L) ratios. It is found that the mutual coupling decreases with the radius to height ratio. Comparison between mutual coupling of probe-fed cylindrical DRAs and circular microstrip patch antennas with different dielectric substrates are also studied. The mutual coupling between DRAs is 2 dB stronger than between microstrip patch antennas when the patch is etched on a dielectric substrate of a dielectric constant close to the permittivity of the DRA. The mutual coupling of the circular patch antennas reduces with the dielectric constant of the substrate. View full abstract»

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  • Compact slot and dielectric resonator antenna with dual-resonance, broadband characteristics

    Publication Year: 2005 , Page(s): 1020 - 1027
    Cited by:  Papers (61)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (432 KB) |  | HTML iconHTML  

    The goal of this study is to improve the bandwidth of a miniaturized antenna. The proposed technique combines a slot antenna and a dielectric resonator antenna (DRA) to effectively double the available bandwidth without compromising miniaturization or efficiency. With proper design it is observed that the resonance of the slot and that of the dielectric structure itself may be merged to achieve extremely wide bandwidth over which the antenna polarization and radiation pattern are preserved. In addition, using the DRA, a volumetric source, improves the radiation power factor of the radiating slot. A miniaturized antenna figure of merit (MAFM) is defined to simultaneously quantify aspects of miniaturized antenna performance including the degree of miniaturization, efficiency, and bandwidth. Figures for various common types of antennas are given and compared with that of the proposed structures. In order to determine the effects of varying design parameters on bandwidth and matching, sensitivity analysis is carried out using the finite-difference time-domain method. Numerous designs for miniaturized slot-fed dielectric resonator antennas are simulated and bandwidths exceeding 25% are achieved. Two 2.4 GHz antennas are built, characterized, and the results compared with theory. View full abstract»

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  • Excitation of dielectric resonator antennas by a waveguide probe: modeling technique and wide-band design

    Publication Year: 2005 , Page(s): 1028 - 1037
    Cited by:  Papers (9)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (688 KB) |  | HTML iconHTML  

    Analysis of a dielectric resonator antenna (DRA) fed by a waveguide probe is presented. The probe is excited by the dominant mode of a waveguide and extends into the DRA through an aperture in the waveguide wall. The DRA has, in general, an arbitrary shape and resides on an infinite ground plane, which coincides with the exterior of the waveguide broad wall. A simple and efficient analysis procedure is implemented where the problem is divided into two parts. In the upper part, the input impedance of the DRA excited by a coaxial probe is obtained with respect to the feeding position on the ground plane independent of the waveguide part. Then the input impedance is transformed to the waveguide part as a concentrated load at the end of the probe connected to the waveguide wall. The effect of the wall thickness is taken into account by modeling the section of the probe passing through the waveguide wall as a coaxial cable transmission line supporting the transverse electromagnetic mode. Thus the DRA input impedance is transferred from the ground plane reference to the waveguide inner wall reference. Results obtained using the method of moments are compared with those obtained using the finite-difference time-domain method and exhibit very good agreement. The procedure is used to achieve a bandwidth of 50% for a stacked DRA excited by a waveguide probe. View full abstract»

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  • Design of electrically small wire antennas using a pareto genetic algorithm

    Publication Year: 2005 , Page(s): 1038 - 1046
    Cited by:  Papers (26)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (680 KB) |  | HTML iconHTML  

    We report on the use of a genetic algorithm (GA) in the design optimization of electrically small wire antennas, taking into account of bandwidth, efficiency and antenna size. For the antenna configuration, we employ a multisegment wire structure. The Numerical Electromagnetics Code (NEC) is used to predict the performance of each wire structure. To efficiently map out this multiobjective problem, we implement a Pareto GA with the concept of divided range optimization. In our GA implementation, each wire shape is encoded into a binary chromosome. A two-point crossover scheme involving three chromosomes and a geometrical filter are implemented to achieve efficient optimization. An optimal set of designs, trading off bandwidth, efficiency, and antenna size, is generated. Several GA designs are built, measured and compared to the simulation. Physical interpretations of the GA-optimized structures are provided and the results are compared against the well-known fundamental limit for small antennas. Further improvements using other geometrical design freedoms are discussed. View full abstract»

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  • Low Q electrically small linear and elliptical polarized spherical dipole antennas

    Publication Year: 2005 , Page(s): 1047 - 1053
    Cited by:  Papers (64)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (296 KB) |  | HTML iconHTML  

    Electrically small antennas are generally presumed to exhibit high impedance mismatch (high VSWR), low efficiency, high quality factor (Q); and, therefore, narrow operating bandwidth. For an electric or magnetic dipole antenna, there is a fundamental lower bound for the quality factor that is determined as a function of the antenna's occupied physical volume. In this paper, the quality factor of a resonant, electrically small electric dipole is minimized by allowing the antenna geometry to utilize the occupied spherical volume to the greatest extent possible. A self-resonant, electrically small electric dipole antenna is presented that exhibits an impedance near 50 Ohms, an efficiency in excess of 95% and a quality factor that is within 1.5 times the fundamental lower bound at a value of ka less than 0.27. Through an arrangement of the antenna's wire geometry, the electrically small dipole's polarization is converted from linear to elliptical (with an axial ratio of 3 dB), resulting in a further reduction in the quality factor. The elliptically polarized, electrically small antenna exhibits an impedance near 50 Ohms, an efficiency in excess of 95% and it has an omnidirectional, figure-eight radiation pattern. View full abstract»

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  • Approximate calculation of time-domain effective height for aperture antennas

    Publication Year: 2005 , Page(s): 1054 - 1061
    Cited by:  Papers (10)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (512 KB) |  | HTML iconHTML  

    The time-domain (TD) effective height is a space-time vector operator recently introduced to describe the performance of ultrawide-band antennas. Since generally obtained by measurements or intensive numerical modeling, it is represented through a large set of data not very suitable to the evaluation of the whole TD link. For the particular class of aperture-radiating antennas of separable shapes, such as slot, open-ended waveguides and horns, this paper proposes a systematic TD processing of the aperture field, involving model-based deconvolution and parameter estimation, at the purpose of an efficient calculation and a more manageable representation of the effective height. Following the idea at the base of modal near to far field transformation, as previously presented by the authors, the processing of the aperture impulse response is here addressed with a particular care to the fast varying early transient. The corresponding time-dependent Radon transforms are then approximated by semi-analytical formulas whose accuracy is discussed as for the aperture size and frequency limits. The proposed methods, which are much faster than the conventional approach, are demonstrated by some examples. View full abstract»

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  • Physical optics analysis of beam waveguides using auxiliary planes

    Publication Year: 2005 , Page(s): 1062 - 1068
    Cited by:  Papers (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (368 KB) |  | HTML iconHTML  

    A physical optics (PO) method is presented which in two steps calculates the scattered field of a reflector or a lens in a beam waveguide (BWG). The first step involves a calculation of a set of currents on an auxiliary plane and the second step a field calculation from this current set. The method is named A-PO that refers to the calculation of PO currents on an Auxiliary plane. A-PO is less accurate than PO for sidelobe analysis, but useful for first-pass analysis of the main beam region in a BWG where it is significantly faster than standard PO. Two examples show that the co-polar as well as cross-polar radiation in a submillimeter BWG can be efficiently determined 40 dB below peak. View full abstract»

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  • A new accurate design method for millimeter-wave homogeneous dielectric substrate lens antennas of arbitrary shape

    Publication Year: 2005 , Page(s): 1069 - 1082
    Cited by:  Papers (40)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1824 KB)  

    The synthesis and the optimization of three-dimensional (3-D) lens antennas, consisting of homogeneous dielectric lenses of arbitrary shape and fed by printed sources, are studied theoretically and experimentally at millimeter(mm)-wave frequencies. The aim of the synthesis procedure is to find a lens profile that transforms the radiation pattern of the primary feed into a desired amplitude shaped output pattern. This synthesis problem has been previously applied for dielectric lenses and reflectors. As far as we know, we propose, for the first time, to adapt and implement it for the design of substrate lens antennas. The inverse scattering problem is solved in two steps. In the first one, the geometry of the 3-D lens is rigorously derived using geometrical optics (GO) principles. The resulting second-order partial-differential equation is strongly nonlinear and is of the Monge-Ampe`re (M.A) type. The iterative algorithm implemented to solve it is described in detail. Then, a surface optimization of the lens profile combined with an analysis kernel based on physical optics (PO) is performed in order to comply with the prescribed pattern. Our algorithms are successfully validated with the design of a lens antenna radiating an asymmetric Gaussian pattern at 58.5 GHz whose half-power beamwidth equals 10° in H plane and 30° in E plane. The lens is illuminated by a microstrip 2×2 patch antenna array. Two lens prototypes have been manufactured in Teflon. Before optimization, the measured radiation patterns are in very good agreement with the predicted ones; nevertheless, the -12 dB side lobes and oscillations appearing in the main lobe evidence a strong difference between the desired and measured patterns. This discrepancy is significantly reduced using the optimized lens. View full abstract»

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  • Study of behavior of digital modulations for beam steerable reflectarray antennas

    Publication Year: 2005 , Page(s): 1083 - 1097
    Cited by:  Papers (9)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2768 KB) |  | HTML iconHTML  

    This paper investigates the bit error rate (BER) performance of digital modulations in a system with a scanning reflectarray antenna. A reflectarray causes intersymbol interference (ISI) in a digitally modulated signal, its phase shifters' phase errors cause signal distortion, and its phase shifters' phase transient causes beam pattern degradation during direction switching. In this paper, composite signal models of the reflectarray are established for both static and transient states. Due to different feed-to-element distances and the element-to-observation distances, different delays exist in signal components. These delays cause ISI whose effect is analyzed and evaluated. Effects of phase shifters' phase errors and phase transient during beam switching are also analyzed and evaluated. Numerical calculations and simulations are performed. The analytical and simulation results for an example reflectarray at fc=26.5 GHz and bit rate of 1.325 Gbps show that the BER degradation due to ISI is proportional to the symbol rate and the loss ranges from about 1 dB to around 2 dB in Eb/No, depending on original Eb/No, for BPSK, QPSK, 8PSK, and 16QAM. The phase error effect is negligible for lower order modulations and is unacceptable for higher order modulations such as 64QAM and 256QAM. The degradation due to phase transient effect is about 2 dB for BPSK and QPSK. View full abstract»

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  • Scan impedance of RSW microstrip antennas in a finite array

    Publication Year: 2005 , Page(s): 1098 - 1104
    Cited by:  Papers (1)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (456 KB)  

    Scan impedances of finite reduced surface wave (RSW) arrays are studied. Center element scan impedances of linear arrays and two-dimensional (2-D) square lattice arrays are calculated and compared with those of conventional microstrip arrays. Results show that compared with conventional microstrip arrays, broadside scan impedance of RSW arrays has less variation and converges much faster when the array size increases. Scan performance of the linear and 2-D square lattice RSW arrays are also studied. Results show that the RSW array can avoid the scan blindness (when the array spacing is greater than 0.5λ0) and the scan impedance has much less variation than that of conventional microstrip array with the same array spacing. However, due to the size limitation of RSW elements, the grating lobes cannot be avoided. Hence, the scan region is limited to about 20° (with 0.75λ0 array spacing). Compared with conventional microstrip arrays with 0.5λ0 array spacing, the results show no favor to RSW arrays. 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