By Topic

Antennas and Propagation, IEEE Transactions on

Issue 4 • Date April 2000

Filter Results

Displaying Results 1 - 22 of 22
  • Theory of line-source radiation from a metal-strip grating dielectric-slab structure

    Publication Year: 2000 , Page(s): 556 - 564
    Cited by:  Papers (26)  |  Patents (12)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (294 KB)  

    This paper describes the fundamental theory of line source radiation from a source on a dielectric slab backed by a metal-strip grating. A continuous phased-array (CPA) method is applied to treat the analytic and numerical problems of antenna interaction with periodic structures. Both TE and TM mode cases for a one-dimensional strip grating are investigated. It is found that the strip grating on the dielectric surface may result in surface wave elimination and may also be used to support leaky waves. It is shown that high-efficiency and high-gain antennas on a dielectric substrate are possible with such metal-strip gratings. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Comments on "Simple and accurate formula for the resonant frequency of the equilateral triangular microstrip patch antenna

    Publication Year: 2000
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (31 KB)  

    For original paper by Kumprasert and Kiranon see IEEE Trans. Antennas Propagat., vol.42, p.1178-9 (1994 August). Discusses the calculation of the resonance frequencies and provides some corrected calculations. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Sparsity and conditioning of impedance matrices obtained with semi-orthogonal and bi-orthogonal wavelet bases

    Publication Year: 2000 , Page(s): 473 - 481
    Cited by:  Papers (10)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (308 KB)  

    Wavelet and wavelet packet transforms are often used to sparsify dense matrices arising in the discretization of CEM integral equations. This paper compares orthogonal, semi-orthogonal, and bi-orthogonal wavelet and wavelet packet transforms with respect to the condition numbers, matrix sparsity, and number of iterations for the transformed systems. The best overall results are obtained with the orthogonal wavelet packet transforms that produce highly sparse matrices requiring fewest iterations. Among wavelet transforms the semi-orthogonal wavelet transforms lead to the sparsest matrices, but require too many iterations due to high condition numbers. The bi-orthogonal wavelets produce very poor sparsity and require many iterations and should not be used in these applications View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Gain enhancement of a pyramidal horn using E- and H-plane metal baffles

    Publication Year: 2000 , Page(s): 529 - 538
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (576 KB)  

    A technique for enhancing the gain of a wide-flare angle pyramidal horn is described. The gain of the antenna is increased by placing simple metal strips or baffles inside the horn near its throat. Two baffles, an E- and an H-plane baffle, are described and analyzed. The baffles are first analyzed through two-dimensional (2-D) numerical calculations and then through measurements in an experimental X-band horn. Each baffle enhances the antenna's gain in the respective plane. When the baffles are implemented together the gain enhancement is additive in decibels. The numerical calculations and measurements show that baffles can he used to significantly reduce the size of pyramidal horn antennas View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Electromagnetic diffraction of an obliquely incident plane wave by a right-angled anisotropic impedance wedge with a perfectly conducting face

    Publication Year: 2000 , Page(s): 547 - 555
    Cited by:  Papers (14)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (436 KB)  

    The diffraction of an arbitrarily polarized electromagnetic plane wave obliquely incident on the edge of a right-angled anisotropic impedance wedge with a perfectly conducting face is analyzed. The impedance tensor on the loaded face has its principal anisotropy axes along directions parallel and perpendicular to the edge, exhibiting arbitrary surface impedance values in these directions. The proposed solution procedure applies both to the exterior and the interior right-angled wedges. The rigorous spectral solution for the field components parallel to the edge is determined through the application of the Sommerfeld-Maliuzhinets technique. A uniform asymptotic solution is provided in the framework of the uniform geometrical theory of diffraction (UTD). The diffracted field is expressed in a simple closed form involving ratios of trigonometric functions and the UTD transition function. Samples of numerical results are presented to demonstrate the effectiveness of the asymptotic expressions proposed and to show that they contain as limit cases all previous three-dimensional (3-D) solutions for the right-angled impedance wedge with a perfectly conducting face View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A path integral time-domain method for electromagnetic scattering

    Publication Year: 2000 , Page(s): 565 - 573
    Cited by:  Papers (15)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (412 KB)  

    A new full wave time-domain formulation for the electromagnetic field is obtained by means of a path integral. The path integral propagator is derived via a state variable approach starting with Maxwell's differential equations in tensor form. A numerical method for evaluating the path integral is presented and numerical dispersion and stability conditions are derived and numerical error is discussed. An absorbing boundary condition is demonstrated for the one-dimensional (1-D) case. It is shown that this time domain method is characterized by the unconditional stability of the path integral equations and by its ability to propagate an electromagnetic wave at the Nyquist limit, two numerical points per wavelength. As a consequence the calculated fields are not subject to numerical dispersion. Other advantages in comparison to presently popular time-domain techniques are that it avoids time interval interleaving and it does not require the methods of linear algebra such as basis function selection or matrix methods View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Accurate model of arbitrary wire antennas in free space, above or inside ground

    Publication Year: 2000 , Page(s): 482 - 493
    Cited by:  Papers (13)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (668 KB)  

    An accurate model of wire antennas in free space, above or inside lossy ground is presented in which the current is assumed to flow on the surface of the wire and the testing is also performed on the surface. To replace the traditional delta-gap source, a more accurate source model is developed by using the Huygens' principle. From this principle and reciprocity theorem, a variational formulation of the input admittance is derived. When the triangle function is chosen as both basis and weighting functions, all the elements of impedance matrix and source vector are formulated in closed forms, which can be rapidly computed. Several numerical results are given. Comparing with measured data, both the current distribution and input impedance by this model are more accurate than those of delta-gap model View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Proposal of method for estimating received signal characteristics in mobile communication environments

    Publication Year: 2000 , Page(s): 539 - 546
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (168 KB)  

    A method for estimating the received signal characteristics (MERS) is developed. The MERS aims at estimating the received power and the fading spectrum at the mobile in mobile communication environments. In MERS, these characteristics are estimated on the basis of both an angular probability density distribution (APD) of wave arrival and a radiation pattern. The APD can also be estimated under arbitrary environmental conditions in the MERS. For the estimation of the APD of wave arrival, a novel propagation model is proposed in this paper. The model consists of an environment model that represents the statistical features of the configuration of buildings along streets and a path model that represents geometrical propagation paths from a transmitting point to a receiving point on the streets. The estimated results of the received signal characteristics are compared with the measured ones. It is proved that the received power and the fading spectrum can be closely estimated View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A truncated Floquet wave diffraction method for the full wave analysis of large phased arrays. I. Basic principles and 2-D cases

    Publication Year: 2000 , Page(s): 594 - 600
    Cited by:  Papers (38)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (240 KB)  

    This two-part sequence deals with the formulation of an efficient method for the full wave analysis of large phased array antennas. This is based on the method of moments (MoM) solution of a fringe integral equation (IE) in which the unknown function is the difference between the exact solution of the finite array and that of the associated infinite array. The unknown currents can be interpreted as produced by the field diffracted at the array edge, which is excited by the Floquet waves (FWs) pertinent to the infinite configuration. Following this physical interpretation, the unknown in the IE is efficiently represented by a very small number of basis functions with domain on the entire array aperture. In order to illustrate the basic concepts, the first part of this sequence deals with the two-dimensional example of a linearly phased slit array. It is shown that the dominant phenomenon fur describing the current perturbation with respect to the infinite array is accurately represented in most cases by only three diffracted-ray-shaped unknown functions. This also permits a simple interpretation of the element-by-element current oscillation, which was described by other authors View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Signal-processing techniques to reduce the sinusoidal steady-state error in the FDTD method

    Publication Year: 2000 , Page(s): 585 - 593
    Cited by:  Papers (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (268 KB)  

    Techniques to improve the accuracy of the finite-difference time-domain (FDTD) solutions employing sinusoidal excitations are developed. The FDTD computational domain is considered as a sampled system and analyzed with respect to the aliasing error using the Nyquist sampling theorem. After a careful examination of how the high-frequency components in the excitation cause sinusoidal steady-state errors in the FDTD solutions, the use of smoothing windows and digital low-pass filters is suggested to reduce the error. The reduction in the error is demonstrated for various cases View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Electromagnetic scattering by nonplanar junctions of resistive sheets

    Publication Year: 2000 , Page(s): 574 - 580
    Cited by:  Papers (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (292 KB)  

    Approximate uniform asymptotic expressions are provided to determine the field scattered by a penetrable wedge illuminated at normal incidence. The wedge is formed by two resistive sheets or two thin dielectric slabs definable as resistive sheets having identical geometric and electromagnetic characteristics. The solution is limited to wedge angles and source positions where internal reflections cannot occur. It is obtained by using a geometrical optics (GO) approximation for the field internal to the slabs and by performing a uniform asymptotic evaluation of the physical optics (PO) radiation integral in the hypothesis that a resistive sheet condition is valid. Samples of numerical results so obtained are presented and compared with other methods to demonstrate the effectiveness of the proposed technique View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Phased-array radiator reflection coefficient extraction from computer waveguide simulator data when grating lobes are present

    Publication Year: 2000 , Page(s): 633 - 635
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (80 KB)  

    Commercially available finite-element software that solves Maxwell's equations for arbitrary three-dimensional bounded structures has enabled phase-array radiator designers to perform waveguide simulator modeling of phased-array radiating elements on the computer very efficiently. Published work on waveguide simulator design has concentrated on array performance in the absence of grating lobes, a requirement for many radar applications. For such simulators, the reflection coefficient of each propagating mode at the waveguide simulator port gives the radiator reflection coefficient at a discrete scan angle. However, the design of limited scan arrays can lead to selection of an array element spacing that allows grating lobes in real space. When a waveguide simulator is modeled on the computer, and a grating lobe is present, the two waveguide modes representing the main lobe and the grating lobe will propagate in the waveguide simulator and they will be coupled together. The simulator port-reflection coefficient of either mode is not the true reflection coefficient seen by the radiating element. We describe a method for extracting the reflection coefficient of the radiating element from the waveguide simulator data when one or more grating lobes are present View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Frequency-domain complementary operators for finite-elements simulation

    Publication Year: 2000 , Page(s): 629 - 631
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (132 KB)  

    A new mesh-truncation technique is introduced for the frequency-domain (time-harmonic) solution of open-region radiation problems. The technique is based on the complementary operators method (COM), where two independent solutions are averaged to eliminate first-order boundary reflections. The dual complementariness in the frequency domain is achieved by introducing a discrete-domain operator that achieves the objective of ∂t in the original time-domain development of COM View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Dispersion compensation for Huygens' sources and far-zone transformation in FDTD

    Publication Year: 2000 , Page(s): 494 - 501
    Cited by:  Papers (10)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (408 KB)  

    The equivalence principle is utilized for generation of both incident plane waves and for near- to far-zone transformation in the finite-difference time-domain (FDTD) method. Small errors will appear due to numerical dispersion when a plane wave is generated by Huygens' sources using an analytical expression for the incident field. These errors can be derived from the numerical dispersion relation in the frequency domain. By using a second-order approximation of the numerical wavenumber it is shown that a simple approximative time-domain compensation procedure for the dispersion can be derived. This has been implemented in a Huygens' source routine and in a time-domain near- to far-zone transformation routine. It is shown that this compensation significantly reduces the errors produced when calculating far-zone scattered fields of low amplitude. It is also shown that it is sufficient to compensate either the Huygens' sources or the time-domain near- to far-zone transformation with respect to dispersion. For validation, plane wave propagation through empty space and scattering of a dipole have been studied View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A truncated Floquet wave diffraction method for the full-wave analysis of large phased arrays .II. Generalization to 3-D cases

    Publication Year: 2000 , Page(s): 601 - 611
    Cited by:  Papers (32)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (416 KB)  

    For pt.I see ibid., vol.48, no.3, p.594-600 (2000). This paper deals with the generalization to three-dimensional (3-D) arrays of the truncated Floquet wave (TFW) diffraction method for the full-wave analysis of large arrays. This generalization potentially includes arrays consisting of microstrip excited slots, cavity-backed apertures, and patches. The formulation is carried out first by deriving an appropriate fringe integral equation (IE) and next by defining entire domain basis functions in terms of global-array functions shaped as TFW diffracted rays whose analytical expression is derived on the basis of prototype canonical problems. The efficiency and the accuracy of this method is demonstrated by comparison with the results of an element-by-element full wave approach for a rectangular slot array View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Full-wave analysis of planar stratified media with inhomogeneous layers

    Publication Year: 2000 , Page(s): 631 - 633
    Cited by:  Papers (16)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (136 KB)  

    In this paper, the dyadic Green's functions for an inhomogeneous isotropic grounded slab embedded in an unbounded isotropic half-space fed by an electric three-dimensional (3-D) point-source based on the equivalent two-port circuit representation along the axis normal to the stratification is presented. The working case is extensively investigated by deriving important information on the radiation of the structure and on how to control the radiation on the horizon plane. Numerical results are also presented showing the effects of the electromagnetic parameters on radiation pattern of the integrated structure View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Calculation of ring-shaped phase centers of feeds for ring-focus paraboloids

    Publication Year: 2000 , Page(s): 524 - 528
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (196 KB)  

    Some primary feeds such as the hat feed radiate around the feed waveguide, which also acts as an axial support tube. Such feed antennas have phase centers in the form of rings rather than points. This paper presents a formula to calculate the location of the ring-shaped phase center. The optimum reflector is a ring-focus paraboloid with the ring focus coinciding with the ring-shaped phase center. The phase center formula is applied to two versions of the hat feed and it is shown that the aperture efficiencies can be improved by up to 0.5 dB when optimum ring-focus paraboloids are used instead of point-focus paraboloids View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Application of the matrix pencil method for estimating the SEM (singularity expansion method) poles of source-free transient responses from multiple look directions

    Publication Year: 2000 , Page(s): 612 - 618
    Cited by:  Papers (22)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (272 KB)  

    The matrix pencil method has been utilized for estimating the natural resonances from different transient responses recorded along multiple look directions as a function of time after the incident field has passed the structure. The novelty of this article is that a single estimate for all the poles are done utilizing multiple transient waveforms emanating from the structure along multiple look directions. The SEM poles are independent of the angle at which the transient response is recorded. The only difference between the various waveforms are that the residues at the various poles are of different magnitudes. Some of the residues may even be zero for some of the poles indicating that the contribution from certain SEM poles may not be significant along that look direction. Here all the waveforms are utilized providing a single estimate for the poles without performing an arithmetic mean of the various waveforms View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Performance analysis of an automated E-pulse target discrimination scheme

    Publication Year: 2000 , Page(s): 619 - 628
    Cited by:  Papers (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (300 KB)  

    An automated E-pulse scheme for target discrimination was initially presented by Ilavarasan et al. (1993) without an analytic performance evaluation. Assuming that target responses are contaminated with white Gaussian noise, an automated E-pulse scheme is rigorously analyzed to yield a reliable measure of performance. The discrimination performance of this automated E-pulse scheme is determined quantitatively through the use of energy discrimination numbers (EDNs). Statistics of the EDNs are evaluated analytically to derive the probability of correct identification. The probability of identification as a function of signal-to-noise ratio (SNR) is evaluated using the theoretical scattering data for all potential targets to predict the performance of the automated E-pulse scheme. These theoretical results are corroborated by direct simulation of the discrimination scheme. In addition, the probability density functions of the EDNs are presented providing new physical insights into E-pulse performance as a function of target geometries and SNR View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Radiation pattern computation of cavity-backed and probe-fed stacked microstrip patch arrays

    Publication Year: 2000 , Page(s): 502 - 509
    Cited by:  Papers (13)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (336 KB)  

    In this paper, two different methods based on Floquet's harmonic expansion of the electromagnetic field in half-space are proposed to determine the active element pattern of infinite planar arrays. They allow us to obtain the radiating characteristics without the limitations of the conventional method from the active reflection coefficient. Both are applied to analyze the scan performance in the case of probe-fed and cavity-backed microstrip arrays from its generalized scattering matrix (GSM), computed previously with a full wave numerical procedure. Numerical results are presented and compared with other techniques View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Equivalent hyperboloid (ellipsoid) and its application

    Publication Year: 2000 , Page(s): 581 - 584
    Cited by:  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (124 KB)  

    Analogous to the equivalent paraboloid, the equivalent hyperboloid (ellipsoid) for dual quadratic surface reflector antennas is derived. The condition that the equivalent reflector is center fed is also derived. The numerical example shows that a reflector geometry that satisfies this center fed condition is a good initial antenna geometry to design a shaped dual reflector antenna View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Analysis of transient electromagnetic scattering phenomena using a two-level plane wave time-domain algorithm

    Publication Year: 2000 , Page(s): 510 - 523
    Cited by:  Papers (45)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (644 KB)  

    A fast algorithm is presented for solving electric, magnetic, and combined field time-domain integral equations pertinent to the analysis of surface scattering phenomena. The proposed two-level plane wave time-domain (PWTD) algorithm permits a numerically rigorous reconstruction of transient near-fields from their far-field expansion and augments classical marching-on in-time (MOT) based solvers. The computational cost of analyzing surface scattering phenomena using PWTD-enhanced MOT schemes scales as O(NiNs2/3 log Ns) as opposed to 𝒪(NtNs2) for classical MOT methods, where Nt and Ns are the numbers of temporal and spatial basis functions discretizing the scatterer current. Numerical results that demonstrate the efficacy of the proposed solver in analyzing transient scattering from electrically large structures and that confirm the above complexity estimate are presented View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.

Aims & Scope

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

Full Aims & Scope

Meet Our Editors

Editor-in-Chief                                                 Kwok W. Leung