共查询到20条相似文献,搜索用时 46 毫秒
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Kwan-Ho Lee Chi-Chih Chen Teixeira F.L. Lee R. 《Antennas and Propagation, IEEE Transactions on》2004,52(8):1983-1991
A detailed analysis of ultrawide-band (UWB), dual-polarized, dielectric-loaded horn-fed bow-tie (HFB) antennas is carried out using the finite-difference time-domain (FDTD) method. The FDTD model includes realistic features of the antenna structure such as the feeding cables, wave launchers, dielectric loading, and resistive-film loading. Important antenna characteristics that are usually difficult to obtain via measurements can be obtained more directly from this FDTD model. Since the HFB antennas under consideration are intended for ground penetrating radar (GPR) applications, the effects of the half-space medium are also investigated. The simulated results serve to verify the performance of the HFB antenna design, and to optimize various antenna parameters. 相似文献
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The finite-difference time-domain (FDTD) method is considered a versatile and efficient tool for the solution of Maxwell's equations in complex structures for any time dependence. We show an antenna feed model suitable for performance evaluation of a cavity-backed slot antenna using the FDTD technique. The gap voltage and the coaxial feed models are examined, and their input characteristics and absolute gains are compared. Analytical results show that the input characteristics are estimated with fewer time steps for the coaxial model than for the conventional gap voltage model. Furthermore, we show how to calculate absolute gains and radiation patterns using the coaxial model and a sinusoidal voltage source at the desired frequency. The computed results of the absolute gain converge after the fifteenth period of the voltage source for the coaxial model and are in good agreement with the experimental results. On the other hand, the absolute gain is observed to fluctuate when the gap voltage model is used. The performance evaluation and comparison reveals that the coaxial model is an appropriate feed model for use in the analysis of the performance of the cavity-backed slot antenna using the FDTD technique. The good agreement of the FDTD results with the experimental measurements demonstrates the effectiveness of the model and the method proposed 相似文献
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Nishioka Y. Maeshima O. Uno T. Adachi S. 《Antennas and Propagation, IEEE Transactions on》1999,47(6):970-977
This paper presents a full-wave analysis of a ground penetrating radar (GPR) using the finite-difference time-domain (FDTD) method. The antenna treated here consists of a resistor-loaded bow-tie antenna, which is covered with a rectangular conducting cavity of which inner walls are coated partially or fully with ferrite absorber. Some techniques are introduced into the FDTD analysis to obtain the accurate results and to save the computer resources. The validity of the FDTD analysis is confirmed experimentally. Furthermore, the effects of the ferrite absorber on the GPR characteristics are theoretically investigated in detail. The FDTD results indicate that the remarkable improvement of the antenna characteristics for the GPR system cannot be attained by the ferrite absorber 相似文献
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Omiya M. Hikage T. Ohno N. Horiguchi K. Itoh K. 《Antennas and Propagation, IEEE Transactions on》1998,46(12):1853-1858
A cavity-backed slot antenna is thought to be one of the most suitable elements for the wireless transmission of microwave energy. A design technique is developed for the cavity-backed slot antenna using the finite-difference time-domain (FDTD) method. The technique is effective in characterizing antenna performance such as the input impedance and the far-field pattern since it takes into account the geometry of the feeder as well as the cavity. We present a method that overcomes difficulties when the FDTD method is used to design the antenna. Moreover, we discuss how to determine the calculation parameters used in the FDTD analysis. Several numerical results are presented, along with measured data, which demonstrate the validity, efficiency, and capability of the techniques. The paper proposes a new prediction method for the frequency characteristics of the cavity-backed slot antenna, which applies computational windows to time-sequence data. It is emphasized that windowing the slow decaying signal enables the extraction of accurate antenna characteristics. We also discuss how to estimate the antenna patterns when we use a sinusoidal voltage excitation 相似文献
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Susceptibility characterization of a cavity with an aperture by using slowly rotating EM fields: FDTD analysis and measurements 总被引:1,自引:0,他引:1
Murano K. Sanpei T. Fengchao Xiao Chen Wang Kami Y. Drewniak J.L. 《Electromagnetic Compatibility, IEEE Transactions on》2004,46(2):169-177
This paper describes the evaluation of the susceptibility of a cavity with an aperture using the finite-difference time-domain (FDTD) method and experimentally. To reduce the computing time, the FDTD method is used for the radiation from the cavity and the susceptibility is obtained by using the reciprocity theorem. The cavity used here is modeled after a full-tower desktop enclosure with a 3.5-in bay. The susceptibility characteristics are evaluated by measuring outputs of a monopole antenna and transmission lines installed in the cavity. The susceptibility characteristics, using a three-dimensional (3-D) map, are studied from the computed and the measured results by applying slowly rotating electromagnetic fields to the cavity on a turntable. Measured and modeled results are in good agreement, indicating the merits of the proposed approach for susceptibility/immunity evaluation. Moreover, some discussions are made to check the susceptibility mechanism. 相似文献
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A concentric microstrip triangular-ring antenna structure using the log-periodic principle for increasing the impedance bandwidth of the microstrip patch antenna is described. The finite-difference time-domain (FDTD) method is applied to analyze the proposed structure. A special technique to model the slanted metallic boundaries of the triangular ring has been used in the general FDTD algorithm to avoid the staircase approximation. The method improves the accuracy of the original FDTD algorithm without increasing the complexity. The radiation patterns at different frequencies over a wide bandwidth are obtained experimentally 相似文献
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Shi-Chang Gao Le-Wei Li Tat-Soon Yeo Mook-Seng Leong 《Vehicular Technology, IEEE Transactions on》2002,51(1):28-36
The characteristics of a dual-frequency compact antenna, which uses a rectangular microstrip patch with a shorting pin, are studied. Compared with the conventional rectangular patch antenna, this antenna can achieve both a significant reduction of antenna size and a dual-frequency operation with a single feed. A detailed parameter study is performed. The theoretical analysis is based on the finite-difference time-domain (FDTD) method. The FDTD codes are developed and validated by measurement results. One antenna has been designed and fabricated, and the comparisons between the measured results and the calculated results are provided. The effects of several antenna parameters on two resonant frequencies, frequency ratio, and radiation pattern characteristics of the antenna have been analyzed and compared. The results of the return loss are also presented. It is shown that various frequency ratios (2.82-4.23) can be obtained by varying the design parameters of this antenna. Several design curves are also presented 相似文献
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The finite-difference time-domain (FDTD) method is used to analyze a dielectric leaky-wave antenna comprising metal strips etched on a rectangular dielectric rod. The radiation patterns of the leaky-wave antenna with and without the transition are determined by using FDTD. The effects of the launching discontinuity on the performance of the antenna are discussed. In addition, the application of the perfectly matched layer (PML) technique to the three-dimensional (3-D) dielectric waveguide and its performance, compared to those of the Mur's (1981) first-order and super-absorbing Mur's first-order absorbing boundary conditions (ABCs) are described. In addition, the effects caused by perturbation on the wave propagation characteristics of dielectric waveguide are also discussed. The FDTD results are verified by a W-band experiment and found to be in good agreement 相似文献
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以鱼骨天线为实例,使用时域有限差分(FDTD)数值算法建立了鱼骨天线、建筑物和不同地面的仿真模型,分析并仿真了建筑物处于不同方位时对短波天线辐射特性的影响,以及不同地面对短波天线辐射特性的影响。数值仿真结果与参考文献和商用软件计算结果一致。 相似文献
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Parallel particle swarm optimization and finite- difference time-domain (PSO/FDTD) algorithm for multiband and wide-band patch antenna designs 总被引:6,自引:0,他引:6
This paper presents a novel evolutionary optimization methodology for multiband and wide-band patch antenna designs. The particle swarm optimization (PSO) and the finite-difference time-domain (FDTD) are combined to achieve the optimum antenna satisfying a certain design criterion. The antenna geometric parameters are extracted to be optimized by PSO, and a fitness function is evaluated by FDTD simulations to represent the performance of each candidate design. The optimization process is implemented on parallel clusters to reduce the computational time introduced by full-wave analysis. Two examples are investigated in the paper: first, the design of rectangular patch antennas is presented as a test of the parallel PSO/FDTD algorithm. The optimizer is then applied to design E-shaped patch antennas. It is observed that by using different fitness functions, both dual-frequency and wide-band antennas with desired performance are obtained by the optimization. The optimized E-shaped patch antennas are analyzed, fabricated, and measured to validate the robustness of the algorithm. The measured less than - 18 dB return loss (for dual-frequency antenna) and 30.5% bandwidth (for wide-band antenna) exhibit the prospect of the parallel PSO/FDTD algorithm in practical patch antenna designs. 相似文献
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FDTD calculation of wide-band antenna gain and efficiency 总被引:1,自引:0,他引:1
Absolute gain and radiation efficiency are calculated using the finite-difference-time-domain (FDTD) method. The method described utilizes pulsed excitation, so that wideband results are available from a single FDTD computation. The approach is demonstrated for a simple wire antenna geometry, and is validated by comparison with results obtained using the method of moments 相似文献
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介绍了一种由折叠臂偶极天线和并联介质块组成的小型化超宽带天线。分析了天线的辐射机理,应用时域有限差分(FDTD)方法和完全匹配层(PML)技术对天线的辐射特性进行了研究。计算结果表明:驻波系数小于3时,天线的阻抗带宽达到2.4GHz(3~5.4GHz),并且辐射脉冲保形性较好,可用于无载波超宽带无线数据通信系统。 相似文献
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A dielectric rod antenna based on an image NRD guide fed by a slot in the broad wall of a rectangular waveguide is proposed. This configuration is developed for the use in the design of an array of this antenna. The antenna characteristics are investigated using the finite difference time domain (FDTD) technique. Measured results at 30 GHz band are presented to validate the numerical analysis. 相似文献
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A review of the finite-difference time-domain (FDTD) method is presented and then employed to model and predict the radiation patterns of three basic configurations of mobile antennas. The directive gain and the input impedance are also calculated. The antennas' configurations considered are a quarter-wavelength monopole mounted on a conducting box, a bent-slot half-wavelength dipole flush mounted on a conducting box, and a quarter-wavelength monopole mounted on the top of an automobile. Three-feed models are discussed and the contour integral is used to model the wire antenna. Transformation of the near field data, resulting from the FDTD, to obtain the radiation patterns is discussed based on the equivalence principle. The radiation patterns obtained using the FDTD compare well with published results 相似文献
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Finite-difference time-domain method for antenna radiation 总被引:1,自引:0,他引:1
The finite-difference time-domain (FDTD) method is used to model and predict the radiation patterns of wire and aperture antennas of three basic configurations. A critical step in each is the modeling of the feed. Alternate suggestions are made and some are implemented. The first antenna is a quarter-wavelength monopole and the second is a waveguide aperture antenna. In both bases the antenna is mounted on ground planes, either perfectly conducting or of composite material. The results obtained using the FDTD technique are compared with results obtained using the geometrical theory of diffraction (GTD) and measurements. The third configuration of interest is a pyramidal horn antenna. To model the flared parts of the horn, a staircase approximation was applied to the antenna surface. The computed radiation patterns compared well with measurements 相似文献