By Topic

Antennas and Propagation, IEEE Transactions on

Issue 10  Part 2 • Date Oct. 2003

Filter Results

Displaying Results 1 - 25 of 37
  • Comments on "Analysis of elliptical microstrip patch antenna considering attachment mode"

    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (143 KB)  

    For original article by Jung and Seo, see IEEE Trans. Antennas Propag., vol.50, p.888-90 (2002). The paper by Jung and Seo presented a moment method solution of an elliptical patch antenna with emphasis on inclusion of the attachment mode around the probe/patch junction. In this comment, Deshpande points out that very similar work on the elliptical microstrip antenna was published by Bailey and Deshpande (1985), and a comparison is given. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Semantics of dyadic and mixed potential field representation for 3-D current distributions in planar stratified media

    Page(s): 2778 - 2787
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (678 KB)  

    The full spectral electric dyadic Green's function for three dimensional current distributions in planar stratified media can be obtained straight from Maxwell's equations. By following a physical reasoning analogous with the free space case but using general derivative relations for multilayered Green's functions, we derive a "basic" mixed potential form with a simple vector potential kernel but multiple scalar potential kernels, and also obtain the well established single scalar potential formulations with a dyadic vector potential kernel. Mixed potential forms are thus arrived at without the a priori introduction of scalar and vector potential, or choice of gauge condition. The nonuniqueness of the scalar potential kernel and the dyadic nature of the scalar and/or vector potentials are believed to be clarified by the proposed approach. A discussion of the different formulations focuses on physical meaning and numerical consequences for the solution of integral equations. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Single-layer single-feed dual-frequency circular microstrip antenna with an offset open-ring slot

    Page(s): 3010 - 3012
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (289 KB)  

    A novel dual-frequency design of a single-layer single-feed circular microstrip antenna with an offset open-ring slot is demonstrated. For the proposed design, an offset open-ring slot is embedded in the circular patch. By selecting a suitable radius of the circular patch enclosed by this offset open-ring slot, a dual-frequency operation with its two operating modes excited with the same polarization planes is obtained. The frequency ratio of the two frequencies is within a range of about 1.22 to 2.17. The measured results show that similar broadside radiation patterns are obtained and the variations of antenna gain are small for frequencies within the two resonant modes. Details of the antenna design and the experimental results obtained for the dual-frequency performance are presented. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Low-cost broadband circularly polarized patch antenna

    Page(s): 3006 - 3009
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (342 KB)  

    A novel single-feed broadband circularly polarized patch antenna is proposed. The proposed antenna has a simple structure, consisting of a corner-truncated square radiating patch, an L-shaped ground plane, and a probe feed. Through a via hole in the vertical ground of the L-shaped ground plane, the radiating patch is easily excited by a probe feed oriented in the same plane as the patch, and circular polarization (CP) radiation over a wide frequency range (>10%) is achieved. Experimental results of a constructed prototype with the center operating frequency at about 2500 MHz showed that the antenna has an impedance bandwidth (1.5:1 VSWR) of about 30%, a 3-dB axial-ratio CP bandwidth of about 10.4%, and a gain level of 8.5 dBi or larger within the CP bandwidth. In addition to the low cost of the proposed antenna due to its simple structure, the obtained CP performance is among the best that have been reported for single-feed single-element patch antennas. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A wideband L-probe patch antenna array with wide beamwidth

    Page(s): 3012 - 3014
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (476 KB)  

    The design and characteristics of a wide-beamwidth, wide-bandwidth patch antenna fed by an L-shaped probe is presented. The novelty in this design is the incorporation of a folded patch with a U-shaped cross section, the dimensions of which can be optimized to achieve an impedance bandwidth of 20% (SWR < 1.5) and a H-plane beamwidth of 103°. The antenna finds application as a cellular base station antenna covering both CDMA and GSM bands from 824-960 MHz. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A modified Dolph-Chebyshev approach for the synthesis of low sidelobe beampatterns with adjustable beamwidth

    Page(s): 3014 - 3017
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (339 KB)  

    A new method for the synthesis of low sidelobe beampatterns is presented, which enables beamwidth and sidelobe level to be adjusted with relative independence. Unlike existing methods for the synthesis of arbitrary beampatterns, the proposed method is based on a modification of the Dolph-Chebyshev design and requires only a few parameters to be optimized, regardless of the array size. Due to its much lower complexity, the method is implementable in wireless communications applications requiring fast and cheap, adaptive algorithms for low sidelobe arrays. The method is applicable, for instance, to the design of adaptive sector-like antennas with uniform circular arrays (UCAs), and to the design of quasi-steering-invariant beampatterns with uniform linear arrays (ULAs). View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Designing a 161-element Ku-band microstrip reflectarray of variable size patches using an equivalent unit cell waveguide approach

    Page(s): 2953 - 2962
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1181 KB)  

    We present an equivalent unit cell waveguide approach (WGA) to designing a multilayer microstrip reflectarray of variable size patches. A normal incidence of a plane wave on an infinite periodic array of radiating elements is considered to obtain reflection coefficient phase curves for the reflectarray's elements. It is shown that this problem is equivalent to the problem of reflection of the dominant TEM mode in a waveguide with patches interleaved by layers of dielectric. This waveguide problem is solved using a field matching technique and the method of moments (MoM). Based on this solution, a fast computer algorithm is developed to generate reflection coefficient phase curves for a multilayer microstrip patch reflectarray. The validity of the developed algorithm is tested against alternative approaches and Agilent high frequency structure simulator (HFSS). Having confirmed the validity of the WGA approach, a small offset feed two-layer microstrip patch array is designed and developed. This reflectarray is tested experimentally and shows good performance. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Physical optics models for the backscatter response of road-surface faults and roadside pebbles at millimeter-wave frequencies

    Page(s): 2862 - 2868
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (847 KB)  

    Theoretical models, based on the physical optics (PO) approximation, are presented to predict the backscatter response of road-surface faults and roadside pebbles. Two types of surface faults are considered, cracks and potholes. By applying the PO model, the backscattering coefficients of a road-surface crack are approximated by the radar cross section (RCS) per unit length of a lossy dielectric cylinder. For a road-surface pothole with a simple geometry, its RCS is estimated by the coherent sum of the backscattered fields from the pothole edges with significant backscatterers. The backscatter response of roadside pebbles is a combination of the surface scattering from surface roughness and the volume scattering from a layer of rock particles. The surface scattering is depicted by the integral equation method, a simplified second-order iterative physical optics approximation. The hybrid scattering model based on the theory of vector radiative transfer is employed to predict the volume scattering. The validity of the theoretical models is examined by comparing the simulation results with experimental data from the University of Michigan, where backscatter measurements at W-band frequencies were conducted on road-surface faults and roadside pebbles at near grazing incidence angles (74°-88°) (Sarabandi, K. et al., ibid., vol.45, p.1679-88, 1997; Li and Sarabandi, ibid., vol.47, p.851-61, 1999). View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Analysis of multilayered printed frequency selective surfaces by the MoM/BI-RME method

    Page(s): 2830 - 2836
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (753 KB)  

    This paper presents an efficient method for the analysis of printed periodic structures, consisting of a multilayered array of metal patches in a stratified dielectric medium, illuminated by a uniform plane-wave. These structures are widely used as frequency selective surfaces and mirrors. The analysis is based on the solution of an integral equation by the method of moments (MoM) with entire-domain basis functions. The basis functions are calculated numerically by the boundary integral-resonant mode expansion (BI-RME) method. The patches may have an arbitrary shape, and both metal conductivity and dielectric losses are considered. Some examples are reported to show the accuracy and rapidity of the proposed method. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Mutual coupling calibration of DBF array with combined optimization method

    Page(s): 2947 - 2952
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (415 KB)  

    This paper introduces a new concept - space equalization - into mutual coupling calibration of a digital beamforming (DBF) array. Based on the concept, the combined optimization method (COM) is developed to minimize element pattern errors in specified narrow angles and keep global errors being suboptimum. By constructing the cost function of COM properly, the complete equations are derived for the calculation of the calibration matrix. Experimental results show that COM calibrates element errors efficiently in constrained narrow space and eliminates mutual coupling errors and channel gain and phase errors in a broad angle region. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Chiral cover effects on microstrip antennas

    Page(s): 2891 - 2898
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (502 KB)  

    By exploiting a rigorous variational formulation, we point out the main effects of a chiral cover on a cavity backed microstrip patch antenna. A hybrid finite element-boundary integral method is employed to solve numerically the electromagnetic problem modeled by a variational functional. The dependence of the resonance frequency on the cover thickness and on the chirality admittance of the material is first investigated. In more detail, it is demonstrated that a chiral cover permits reducing the antenna dimensions, compared to an isotropic one, for a fixed working frequency. Then, through several numerical examples, we also investigate the variation of gain properties, cross-polarization levels, radiation resistance, radiation efficiency, and radar cross-section. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A plane wave expansion of spherical wave functions for modal analysis of guided wave structures and scatterers

    Page(s): 2801 - 2805
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (479 KB)  

    A new finite plane wave series expansion for spherical wave functions of the first kind is presented in this paper. The formulation converts the spherical wave function described in the spherical coordinate system into a series of plane wave functions represented in the Cartesian coordinate system. The series expansion will be very useful in modal analysis of three dimensional guided wave structures and scatterers containing planar boundary surfaces. For a given range of orders m and degree n and for a region with |r~| View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A different perspective on taper efficiency for array antennas

    Page(s): 2963 - 2967
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (282 KB)  

    Taper efficiency is a relative figure of merit for antenna arrays giving the loss of directivity due to array amplitude and phase weighting. The derivation of the standard formula for antenna array taper efficiency proceeds from the definition of antenna directivity given the assumption that the array elements are spaced a multiple of half wavelengths apart. We derive a more physically intuitive definition of the taper efficiency of an array by starting from the communication link range equation. We do not require any assumption regarding element spacing. We find that the taper efficiency is equal to the ratio of beamformer signal gain to noise gain divided by the ratio of the same gains when the beamformer is uniformly weighted, where gain includes the contributions from all active and passive components within the beamformer. This definition is edifying, since an array's amplitude weighting and directivity are manifested primarily within the beamformer. We show that our formula reduces to the standard formula for three examples. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Problem-independent enhancement of PML ABC for the FDTD method

    Page(s): 3002 - 3006
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (370 KB)  

    A problem independent approach to the improvement of perfectly matched layers (PML) for the classical Yee's finite-difference time-domain (FDTD) method is proposed. First, the spatially polynomial PML variables are allowed to vary at different exponent rates. Second, lossy termination walls are used. It is shown that each of the approaches or their combination enhances the performance of the PML in the termination of open/radiation problems as well as in the termination of high-frequency structure ports. The proposed modification in the PML variable profiles adds a new degree of freedom in their definition and leads to lower numerical reflections in comparison with the commonly used profiles for Yee's FDTD method. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Analysis of a hard strip-loaded conical horn by the method of generalized scattering matrices

    Page(s): 2918 - 2925
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (593 KB)  

    A hard-walled conical horn fed in the TE11-mode from a regular circular waveguide is analyzed. The hard wall is formed by a dielectric layer with cylindrical inner surface loaded with longitudinal conducting strips. The analysis is carried out by using a stepwise representation of the horn with subsequent application of the method of generalized scattering matrices in combination with the method of factorization. The approach used refines values of the limiting aperture efficiency by 5 to 15% for diameters up to 3.2 wavelength in comparison with the underrated data based on the Kirchhoff method, and reveals the effect of the sharp worsening of the hard horn performance at some values of the horn length caused by resonances of the strip-line mode excited in the loaded section. Beyond the resonance points, the aperture efficiency remains relatively high (from 80 to 85%), and the crosspolar level is a few decibels lower than that of a standard smooth-walled horn. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • On the analysis of resonators using finite-difference time-domain techniques

    Page(s): 2885 - 2890
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (316 KB)  

    Because a resonator with perfect electrically conducting (PEC) walls has no complications with absorbing boundary conditions and, for canonical geometries, the resonant frequencies are trivial to find, resonators are often used for analyzing the performance of finite-difference time-domain (FDTD) methods. However, when testing the performance of boundary implementations in an FDTD scheme, one should compare to the resonant frequencies of a "perfect" discretized resonator (not to the mode frequencies in the continuous world). On the other hand, when testing the dispersion properties of a method, the resonant frequencies for some structures can be obtained directly from the dispersion relation, thus obviating the need for any simulation. Here, we demonstrate how the dispersion relation can be used to obtain all the resonant frequencies of a rectangular resonator modeled with the Yee algorithm. Furthermore, it is shown that modes that are degenerate in the continuous world can split into distinct modes in FDTD resonators, while modes that are separate in the continuous world can combine in FDTD resonators, thus yielding extra or missing modes. Analytic results are verified using numerical simulations. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Microstrip antennas integrated with electromagnetic band-gap (EBG) structures: a low mutual coupling design for array applications

    Page(s): 2936 - 2946
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1196 KB)  

    Utilization of electromagnetic band-gap (EBG) structures is becoming attractive in the electromagnetic and antenna community. In this paper, a mushroom-like EBG structure is analyzed using the finite-difference time-domain (FDTD) method. Its band-gap feature of surface-wave suppression is demonstrated by exhibiting the near field distributions of the electromagnetic waves. The mutual coupling of microstrip antennas is parametrically investigated, including both the E and H coupling directions, different substrate thickness, and various dielectric constants. It is observed that the E-plane coupled microstrip antenna array on a thick and high permittivity substrate has a strong mutual coupling due to the pronounced surface waves. Therefore, an EBG structure is inserted between array elements to reduce the mutual coupling. This idea has been verified by both the FDTD simulations and experimental results. As a result, a significant 8 dB mutual coupling reduction is noticed from the measurements. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A novel method for predicting site dependent specific rain attenuation of millimeter radio waves

    Page(s): 2987 - 2999
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (817 KB)  

    There is a need for validation and improvement of propagation prediction methods for the safe design and operation of millimeter radio communication systems. At this frequency range, propagation related degradation is primarily caused by rainfall. Our goal is an improved method for predicting specific attenuation due to rainfall. A general method for establishing the relationship between rainfall rate and specific attenuation is developed. Drop size distributions (DSDs) measured by a Joss distrometer are analyzed, and three climate classification parameters, rain rate, DSD median, and DSD mode, are used in the development of the new methods. These parameters are investigated as candidate classes to categorize drop size distributions. Categories of the classes are then established to improve the long-term DSD estimate. The typical long-term DSD is used to derive new prediction methods that are compared with observed attenuation. The influence of wind on the rainfall measurements is studied, and a corresponding correction is suggested, reducing the prediction error significantly. Testing of the three new methods using measurements at 40 and 60 GHz shows noticeable improvement over the method recommended by the International Telecommunication Union (ITU) using measurements at 60 GHz at deep attenuation. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Reflection and transmission by reinforced concrete - numerical and asymptotic analysis

    Page(s): 2852 - 2861
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (848 KB)  

    To model the reflection and transmission properties of reinforced concrete, we develop a method of moments/Green's function (MoM/GF) model for a wire grid embedded in a lossy dielectric slab. Since the scattering by a wire grid is dominated by wires that are parallel to the incident electric field, a two-dimensional (2D) model with a grid of straight, parallel wires is used. The number of wires is finite, but can be large. The dielectric slab can be thin or thick, and it is of infinite transverse extent. The source and field points are in the near field. The wire currents are solved for by the MoM. Certain Green's functions for the dielectric slab are evaluated by two different methods: 1) exact numerical evaluation of Sommerfeld integrals (SI); 2) the high frequency asymptotic approximation, via the saddle point method, which yields the geometrical optics (GO) result. We explore the range dependence and angular dependence of the reflected and transmitted fields. The influence of surface waves and wire-wire interactions is also examined. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Wide-band truncated tetrahedron dielectric resonator antenna excited by a coaxial probe

    Page(s): 2913 - 2917
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (459 KB)  

    A truncated tetrahedron dielectric resonator antenna is examined numerically and experimentally. The tetrahedron base is an equilateral triangular over a ground plane and excited by a coaxial probe to provide a broad side radiation pattern. Three different configurations are analyzed: the truncated tetrahedron when the wide base is attached to the ground plane, the narrow base attached to the ground plane, and the equitriangular cylinder. Results are verified experimentally and numerically. The tetrahedron with narrow base attached to the ground plane achieves wide-band performance for the impedance match and the radiation patterns of about 40%. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Well-conditioned MLFMA formulation for closed PEC targets in the vicinity of a half space

    Page(s): 2822 - 2829
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (456 KB)  

    The multilevel fast multipole algorithm (MLFMA) is applied to the problem of scattering from a closed perfect electric conductor (PEC) in the presence of a half space. The combined-field integral equation (CFIE) employs a new electric-field integral equation (EFIE) formulation, robust to a high basis-function sample rate, relative to wavelength. The new EFIE formulation is discussed, as is its implementation in the context of a CFIE MLFMA analysis for closed PEC targets. Several example results are presented, in which comparisons are made to traditional MLFMA formulations. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A surface integral equation formulation for low-frequency scattering from a composite object

    Page(s): 2837 - 2844
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (564 KB)  

    A surface integral equation formulation is derived for low-frequency scattering from a composite object. This formulation allows those algorithms for finding the loop-tree basis on simple surfaces to be applied to the complicated interfaces of a composite object. By including the residue term in the K operator, the present formulation induces the interface boundary conditions automatically, and the resultant matrix equation can be solved directly without using the O(N2) number-of-unknowns-reduction scheme. Numerical results validate that the algorithm is stable even at extremely low frequencies and for closely spaced structures. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Surface-wave radar and its application

    Page(s): 3000 - 3002
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (241 KB)  

    Following a brief review of the problem of detecting drug-carrying aircraft approaching the United States from South America, a short description is given of over-the-horizon radar that makes use of radar pulses reflected from the ionosphere. An alternative, surface-wave radar, is then described beginning with the complete formulas for the electric field transmitted by a vertical dipole erected on the surface of the sea. The backscattered field of a small airplane and of a boat are calculated and the fields received by the array determined. Arrays of vertical dipoles are then described for sending radar pulses along the surface of the Gulf of Mexico. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Detection of buried inhomogeneous elliptic cylinders by a memetic algorithm

    Page(s): 2878 - 2884
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (430 KB)  

    The paper studies the application of a global optimization procedure to the detection of buried inhomogeneities. The object inhomogeneities are schematized as multilayer infinite dielectric cylinders with elliptic cross sections. An efficient recursive analytical procedure is used for the forward scattering computation. A functional is constructed in which the field is expressed in a series solution of Mathieu functions. Starting with the input scattered data, the iterative minimization of the functional is performed by a new optimization method called memetic algorithm. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Effective resonance representation of propagators in complex ducts-a multiresolution and homogenization approach

    Page(s): 2754 - 2760
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (583 KB)  

    We use the multiresolution homogenization theory to study the effective resonances representation of transient electromagnetic propagation in complex random multilayer ducts. The theory permits explicit choice of the smoothing (homogenization) scale, and can be applied to a wide range of micro-scale properties. The analytical study is based on a Wroskian equivalence result, which establishes the relation between the "true" Wronskian W and that of the homogenized problem W(eff). Since the roots of W in the complex ω plane constitute the duct resonance, the Wronskian equivalence theorem is used as a basic apparatus for the effective resonance study. With this, the time-domain spectral properties of the multiresolution homogenization formulation are studied analytically and demonstrated numerically. Effective representations of reflection from complex random multilayer ducts are considered. 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