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Application of the array scanning method in Periodic Structures with Large Periods

ELECTROMAGNETICS 2015年第5期35卷 293-309页

作者： Bakhtafrouz, Ahmad Borji, Amir Isfahan Univ Technol Dept Elect & Comp Engn Esfahan *** Iran Sharif Univ Technol Dept Elect Engn Tehran Iran

The problem of aperiodic excitation of periodic structures with periods larger than a half-wavelength is revisited. A large number of antennas and other electromagnetic wave propagation problems fall within this category. Because of overlapping branch cuts, the conventional path deformation techniques employed in application of the array scanning method for this type of problem fail when the period is larger than a half-wavelength. A new method based on the subdivision of the integration path and using the double exponential quadrature formula is introduced to alleviate this problem and apply the array scanning method to structures with an arbitrary spatial period. To demonstrate the application of the new method and to validate the results, reflection and transmission coefficients of a frequency selective surface excited by a single electric dipole are calculated. Near fields of the frequency selective surface with aperiodic excitation are obtained and compared with those of a commercial electromagnetic simulator. The proposed method, similar to the path deformation technique, which is applicable to small periods, shows considerable advantage in terms of computational time and memory requirement.

关键词： aperiodic sources array scanning method double exponential quadrature rule frequency selective surface periodic structures

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Electromagnetic modeling of damaged fiber-reinforced laminates

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JOURNAL OF COMPUTATIONAL PHYSICS 2020年 409卷 109318-000页

作者： Liu, Zicheng Li, Changyou Zhong, Yu Lesselier, Dominique Univ Paris Saclay Lab Signaux & Syst CNRS Cent Supelec F-91190 Gif Sur Yvette France UiT Arctic Univ Norway Dept Phys & Technol Klokkargardsbakken 35 N-9019 Tromso Norway Northwestern Polytech Univ Dept Elect Engn Xian 710129 Peoples R China ASTAR Inst High Performance Comp Singapore 138632 Singapore

As a prerequisite to nondestructive testing of damaged fibered laminates, the Green's function, corresponding with an undamaged structure, and the electromagnetic fields associated with the damaged one are investigated herein. For the undamaged fibered laminate, benefiting from the periodicity of the fibers within each layer, the field solution follows the scattering-matrix-based method using the Floquet theorem. Yet, the periodicity is destroyed by the analytical source (for the Green's function) or by damages, and the Floquet theorem cannot be directly applied to compute the associated scattering matrices. The array scanning method is introduced to that effect. Inserting fictitious sources to get a quasi-periodic source array, the modeling approach for undamaged laminates can be used to compute the field with the source array, the integration of which cancels the effects of the fictitious sources and yields the Green's function. With the multipole method, field disturbances by damages, which include missing, displaced, shrunk, and expanded fibers and circular inclusions inside fibers, are accurately modeled by setting equivalent sources inside sound fibers, and the array scanning method applies. Modeling accuracy and efficiency of the approaches are illustrated by numerical simulations. (C) 2020 Elsevier Inc. All rights reserved.

关键词： Nondestructive testing Fibered laminates Multipole method array scanning method Green's function Equivalence theory

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Input impedance and radiation pattern of a resonant dipole embedded in a two-dimensional periodic leaky-wave structure

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IET MICROWAVES ANTENNAS & PROPAGATION 2015年第14期9卷 1567-1573页

作者： Bakhtafrouz, Ahmad Borji, Amir Isfahan Univ Technol Dept Elect & Comp Engn Esfahan *** Iran Sharif Univ Technol Dept Elect Engn Tehran *** Iran

array scanning method (ASM) is employed to study the input impedance and radiation pattern of a two-dimensional periodic leaky-wave antenna (LWA). The antenna consists of a narrow horizontal strip dipole of arbitrary length underneath a two-dimensional (2D) periodic screen of metallic patches, which acts as a partially reflective surface (PRS), and backed by a ground plane. First, the Green's function in the presence of the 2D array of metallic patches is calculated by means of the ASM and then the current distribution and input impedance of the source dipole are calculated through the electric field integral equation and method of moments. The far-field pattern is computed using the reciprocity theorem. Compared to the Hertzian dipole, which is the only type of source that has been considered in the literature, the resonant dipole substantially improves the performance of periodic LWA in terms of radiated power, efficiency and bandwidth. Numerical results are given for a resonant dipole over the frequency range of 60-70 GHz and compared with those obtained from commercial softwares, FEKO (R) and Ansys HFSS (R), showing an excellent agreement with considerable improvement in terms of memory usage and computational speed.

关键词： leaky wave antennas antenna radiation patterns dipole antenna arrays millimetre wave antenna arrays Green's function methods electric field integral equations method of moments input impedance radiation pattern resonant dipole two-dimensional periodic leaky-wave structure array scanning method ASM two-dimensional periodic LWA narrow-horizontal strip dipole arbitrary length 2D periodic screen two-dimensional periodic screen metallic patches partially reflective surface PRS ground plane Green function 2D array source dipole electric field integral equation method-of-moments far-field pattern reciprocity theorem Hertzian dipole radiated power FEKO software HFSS software frequency 60 GHz to 70 GHz

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Thick Vivaldi Antenna for Focal Plane Applications

Thick Vivaldi Antenna for Focal Plane Applications

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IEEE International Symposium on Antennas and Propagation (APSURSI)/USNC/URSI National Radio Science Meeting

作者： Sarkis, Remi Craeye, Christophe Veidt, Bruce Catholic Univ Louvain ICTEAM B-1348 Louvain Belgium Natl Res Council Penticton Ottawa ON K1A 0R6 Canada

ISBN: (纸本)9781424495610

This communication deals with the design of metal only thick Vivaldi antenna, hollow inside to host a Low Noise Amplifier adjacent to the antenna, that is suitable to focal plane array devoted to radio astronomy. The impedance frequency band of the array goes from 0.75 GHz to 1.5 GHz and has a half-power beam width of 60 degrees over the same frequency band. Numerical simulations have been carried out to study the radiation patterns using the method-of-Moments approach for infinite array simulations, followed by the implementation of fast numerical methods combining the array scanning method with Macro basis Functions for the simulation of an array consisting of 5x5 elements.

关键词： component focal plane array taper slot antenna vivaldi 3D infinite array simulation array scanning method macro basis functions

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Thick Vivaldi Antenna for Focal Plane Applications

Thick Vivaldi Antenna for Focal Plane Applications

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2011 IEEE International Symposium on Antennas and Propagation(APSURSI 2011)

作者： Remi Sarkis Christophe Craeye Bruce Veidt ICTEAM Universite catholique de Louvain. Louvain-la-Neuve Belgium National Research Council Penticton Canada

ISBN: (纸本)9781424495627;9781424495634

关键词： component focal plane array taper slot antenna vivaldi 3D infinite array simulation array scanning method macro basis functions Vivaldi antennas half-power beamwidth Radiation patterns Focal plane arrays Numerical methods simulating Frequency bands Moment of force arrays ANTENNA antennae

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Input Impedance of Nonperiodic Sources Exciting 1-D Periodic Shielded Microstrip Structures

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IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES 2010年第7期58卷 1796-1806页

作者： Valerio, Guido Burghignoli, Paolo Baccarelli, Paolo Galli, Alessandro Sapienza Univ Rome Dept Elect Engn I-00184 Rome Italy

The input impedance of nonperiodic sources that excite a periodically loaded shielded microstrip line is studied numerically with a rigorous method-of-moments approach based on the array scanning method. Both a delta-gap voltage and an impressed vertical current sheet are considered to be idealized sources exhibiting different symmetry properties. Their input impedances, calculated according to either a power-voltage or a power-current definition, are compared with the Bloch impedance of the dominant mode excited along the structure in a wide frequency range encompassing different propagation regimes of the dominant and of the first higher order mode. Numerical results, validated also through independent full-wave codes, provide physical insight and quantitative information on the mode excitation efficiency and input-impedance features of finite sources in a periodic microstrip environment.

关键词： array scanning method input impedance periodic structures nonperiodic sources numerical methods

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Convergence Analysis of ASM-FDTD method

Convergence Analysis of ASM-FDTD Method

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2010 IEEE International Symposium Antennas and Propagation/CNC-USNC/URSI Radio Science Meeting

作者： Qiang, Rui Chen, Ji Univ Houston Dept Elect & Comp Engn Houston TX 77004 USA

The convergence properties of ASM-FDTD are discussed. It is shown the accuracy of this method is greatly dependant on the choice of sampling rate for calculating the spectral domain integral.

ISBN: (纸本)9781424449682

The convergence properties of ASM-FDTD are discussed. It is shown the accuracy of this method is greatly dependant on the choice of sampling rate for calculating the spectral domain integral.

关键词： ASM-FDTD method array scanning method convergence analysis convergence of numerical methods finite difference time-domain analysis finite difference time-domain analysis sampling methods sampling rate spectral domain integral

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On the excitation of a closely spaced array by a line source

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IMA JOURNAL OF APPLIED MATHEMATICS 2007年第4期72卷 476-497页

作者： Thompson, I. Linton, C. M. Loughborough Univ Technol Dept Math Sci Loughborough Leics England

An infinite row of periodically spaced, identical rigid circular cylinders is excited by an acoustic line source which is parallel to the generators of the cylinders. A method for calculating the scattered field accurately and efficiently is presented. When the cylinders are sufficiently close together, Rayleigh-Bloch surface waves that propagate energy to infinity along the array are excited. An expression is derived which enables the amplitudes of these surface waves to be computed without requiring the solution to the full scattering problem.

关键词： array scanning method line source multiple scattering periodic array Rayleigh-Bloch surface wave

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Full-wave analysis of periodic microstrip lines excited by an aperiodic delta-gap source

Full-wave analysis of periodic microstrip lines excited by a...

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IEEE/MTT-S International Microwave Symposium

作者： Rodriguez-Berral, R. Valerio, G. Mesa, F. Baccarelli, P. Burghignoli, P. Galli, A. Univ Seville Dept Appl Phys 1 Seville Spain Univ Rome Dept Elect Engn Rome Italy

ISBN: (纸本)9781424406876

A study is presented of the current excited on a printed periodic structure by a single aperiodic source. In particular, both completely shielded and open microstrip lines periodically loaded with gaps are considered, excited by a delta-gap voltage source. The aperiodicity of the source does not allow for a direct application of the Floquet theorem. The array scanning method (ASM) is then applied, which reduces the aperiodic problem to an integral superposition of suitable Floquet-periodic problems. Efficient numerical implementations of the ASM are developed, for both the shielded and the open cases, based on the method of moments with entire-domain basis functions. Numerical results are presented for dispersion features and Bloch modes supported by the periodic microstrip line and for the current excited by the source in different frequency ranges corresponding to passband and stopband regimes of the fundamental perturbed quasi-TEM mode.

关键词： aperiodic sources array scanning method method of moments microstrip line periodic structures

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An efficient method to determine Green's functions of a two-dimensional photonic crystal excited by a line source - The phased-array method

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IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES 2002年第5期50卷 1380-1391页

作者： Caloz, C Skrivervik, AK Gardiol, FE Univ Calif Los Angeles Dept Elect Engn Los Angeles CA 90095 USA Ecole Polytech Fed Lausanne Electromagnetism & Acoust Lab CH-1015 Lausanne Switzerland

A novel and efficient method to determine Green's functions in photonic crystals (PCs), i.e., the phased-array method (PAM), is presented. The PAM is a combination of the plane-wave method and the array-scanning method, which is both more flexible and computionally faster than the eigenmodes expansion method. A complete derivation of the electric- and magnetic-field Green's functions associated, respectively, with an infinite electric and magnetic current line exciting a two-dimensional PC is given. Although the developments are presented only for a line source, the PAM can be extended to a dipole source. Thus, the PAM represents a promising method for the analysis of printed-circuit elements or antennas on PC materials. Numerical results for the Green's functions are shown for different positions of the source and a discussion about radiation patterns, asymptotic behaviors, and convergence characteristics is proposed.

关键词： array scanning method Green's functions phased-array method photonic bandgaps photonic crystals plane-wave method

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