共查询到20条相似文献，搜索用时 15 毫秒
1.
An accurate impedance matrix interpolation technique based on the surface integral equation (SIE) is presented for the analysis of wireless communication antennas over wide frequency bands. The first‐order derivative of the impedance matrix at the internal frequency is considered in the cubic polynomial‐based interpolation scheme, thus the novel impedance matrix interpolation scheme will provide high accuracy and high efficiency over a frequency band. To demonstrate the efficiency and accuracy of the proposed method, numerical results for planar inverted F antennas (PIFA) and a wideband E‐shaped patch antenna are presented. Good agreement among the interpolation results, exact MoM solutions, finite element method (FEM) solutions, and measured data is observed over the bandwidth. Besides, dimensions of the feeding probe are also studied to investigate their effect on the input impedance and radiation patterns. © 2010 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2010. 相似文献
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In this paper, the multiple refraction phenomenon is investigated on the boundary of a scalar impedance surface (SIS) and a tensor impedance surface (TIS). When a surface wave (SW) propagates on the SIS and radiates to the boundary of the TIS, the propagation direction of it is changed and the refraction phenomenon is accrued. The method that is proposed in this paper can predict the multiple refraction for the SW. Moreover, another analytical method is introduced for designing the proposed structure which the double refraction (DR) occurs at arbitrary angles on it. Using it, a sample of the structure is designed by printed circuits in 15.2GHz and the results are verified by the full‐wave simulation and measurement. The results are shown that in the structure, DR is occurred in 2° and 22° as predicted. The proposed method can provide many applications such as design of SW power dividers based on the TISs, impedance surface based waveguides, holographic antennas, and feeding of array antennas. 相似文献
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Raimi Dewan M.K.A. Rahim M.R. Hamid M.F.M. Yusoff N.A. Samsuri N.A. Murad K. Kamardin 《国际射频与微波计算机辅助工程杂志》2017,27(6)
Artificial Magnetic Conductor (AMC) is a type of implemented metamaterial in several antennae and microwave design applications. By utilizing the unique characteristics of metamaterials which do not exist naturally, the performance of various microwave devices can be enhanced. This article elaborates on the technical perspective and recent works on AMC for antenna applications. The technical perspective discusses the theoretical aspects, simulation design procedures, and the measurement setup used to characterize the AMC unit cell. Subsequently, various recent works of antenna design that involve the incorporation of AMC are discussed thoroughly. Each of the recent works is highlighted with specific performance enhancements that can be achieved with the introduction of AMC. The conventionally narrow band property of AMC, which is the bandwidth at which the radiation characteristics and directivity of the antenna can be manipulated, is discussed. The property limits the applications of AMC in wideband antenna applications. One of the techniques to improve the narrow band AMC as the ground plane is discussed in detail. The employment of AMC has solved many issues whilst overcoming the typical limitations in conventional antenna designs. 相似文献
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A. A. Omar 《国际射频与微波计算机辅助工程杂志》2012,22(2):153-158
This article combines the Galerkin method of moments with the complex image technique to find the current distribution, input impedance, return loss, and frequency bandwidth of a half‐wave dipole near a human head. It also finds the specific absorption rate distribution inside the human head which is modeled as three planar layers of lossy dielectrics. Comparisons with IE3D commercial simulator verify the accuracy and speed of the proposed method. It is found that the input resistance of the dipole is significantly reduced as the dipole is brought closer to the human head causing a reduction in the frequency bandwidth. The proposed method can be modified to solve other types of antennas on different human head planar geometries. © 2011 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2012. 相似文献
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Ezzeldin A. Soliman 《国际射频与微波计算机辅助工程杂志》2007,17(6):533-541
A novel method is presented in this article for calculating the sensitivities of the impedance and excitation matrices of the method of moments. The proposed method evaluates the required derivatives with respect to a design variable semi‐analytically. It is demonstrated that one matrices' fill is enough to achieve the required sensitivities. Two such fills would be necessary to obtain similar results using the conventional finite‐difference approximation method. A microstrip patch antenna example is used to demonstrate the validity of the proposed method. By comparing its results with those obtained using finite‐difference numerical approximation, a high degree of agreement is observed. The accuracy of the numerical approximation is found to be sensitive to the selected value of perturbation. © 2007 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2007. 相似文献
6.
采用全波矩量法及两步准静态算法研究了MIT无线输电系统取得最大传输效率时谐振线圈的磁场和电场分布,并通过HFSS有限元仿真软件定量分析了人脑对该系统电磁辐射的吸收情况。研究结果表明,系统输入功率为400 W时,谐振线圈的最大磁场和最大电场分别为9.376 3×10-3 A/m,1.52×102 V/m,磁场强度符合国际非电离辐射保护委员会规定的标准值,电场强度则大于规定标准值;在距发射线圈100mm处,人脑局部吸收辐射率最大值为7.038 9×10-6 W/kg,小于国际非电离辐射保护委员会规定的标准值。 相似文献
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Metamaterial surfaces offer a wide range of advantages in terms of antenna design. One such metamaterial is designed to capture the benefits of both high‐impedance surfaces as well as artificial magnetic surfaces. The confluence of both these properties delivers an added advantage to planar antennas by delivering high gain and directivity simultaneously. Bidirectional radiation pattern has been transformed to a directional radiation pattern by placing the metamaterial as substrate beneath the antipodal bowtie antenna. In addition, zero separation between the antenna and metasurface ensures low profile. The proposed design has been verified both by simulation and measurement which have shown an improvement on gain of 3.2 dBi with an almost steady gain response inside the resonating band of the antenna which lies between 12 and 16 GHz. 相似文献
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The multi‐dimensional asymptotic waveform evaluation (MD‐AWE) method is proposed as an extension of the conventional one dimensional asymptotic waveform evaluation (1D‐AWE) method. It can be applied in parameter analysis of structures, particularly with multiple variables, at which repeated calculations are required. The MD‐AWE is proposed at first, and then an adaptive hopping technique similar to the complex frequency hopping (CFH) technique to expand the approximation region of MD‐AWE is delivered, and this technique also helps to reduce the memory usage by taking lower order of MD‐AWE. In the end, two examples are given with good results, which show the efficiency and accuracy of the proposed method. © 2008 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2008. 相似文献
10.
In this article, wire antennas installed on electrically large structures are modeled by surface–surface configuration. The surface–surface configuration is applied to the hybrid method of moments–physical optics (MoM‐PO) to solve electromagnetic radiation problem of wire antennas mounted on electrically large conducting platform. Numerical results for the arbitrary shaped perfectly electric conducting are considered. Compared with the wire–surface configuration, the surface–surface configuration is easy to ensure the current continuity at the junction and maintain the required good accuracy. Additional complex basis functions are not required in surface–surface junction model compared with wire–surface junction model. © 2010 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2010. 相似文献
11.
A theoretical treatment of electro‐thermally induced passive intermodulation (PIM) is developed for printed dipole antennas, yielding an expression of third‐order intermodulation distortion based on the surface current distribution. The simulation procedure of third‐order PIM products with the full‐wave frequency‐domain method was given to evaluate the PIM level. In particular, the PIM dependencies on input power, two‐tone frequency separation, and substrate parameters are analyzed leading to design guidelines for low distortion antennas. It is shown in this paper that the thermal factors have a noticeable impact on the PIM power generated by printed dipole antennas. Finally, two antenna samples are fabricated on different substrates, Rogers 5880 and FR4, and a two‐tone test at 2‐GHz band using a reflective PIM test system is reported. The PIM evaluation method and the design guidelines to reduce the PIM on printed antennas proposed in this paper are of great significance for telecommunication systems. 相似文献
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Sembiam R. Rengarajan 《国际射频与微波计算机辅助工程杂志》2013,23(4):430-436
Waveguide‐fed slot arrays in standing wave mode have been employed successfully in space based remote sensing radars because of their high efficiency, ease of deployment and their ability to withstand the radiation environment. Although the bandwidth requirement in such systems is minimal, at Ka band and above manufacturing tolerances in the order of 1 mil (25 μm), achieved in the dip brazing process, may affect their performance. To produce designs that are less sensitive to manufacturing tolerance, genetic algorithm (GA) optimization is employed in conjunction with a full wave analysis utilizing the method‐of‐moments solution to the pertinent integral equations of slot apertures of a planar array. In this work, a single 8 × 10 sub‐array of an interferometric antenna, proposed previously for a planetary mapping application, was investigated. The array was first designed by the Elliott's procedure and subsequently the design parameters were perturbed by GA optimization using the moment method analysis. The fitness parameter is a weighted function of return loss and gain over a number of frequencies in the operating band. A matching waveguide section consisting of inductive irises is also optimized using GA and mode matching technique. Optimum designs producing nearly constant gain and good return loss over 6% bandwidth are found to be less sensitive to manufacturing tolerance than the initial Elliott design. © 2013 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2013. 相似文献
13.
A point‐wise approach that can be used efficiently in the numerical solution of Electric Field Integral Equations is introduced. The algorithm is based on the so‐called magic distance concept, which defines exactly the point‐to‐point equivalent of a four‐dimensional integral. Magic distance values are rigorously obtained in the electrostatic case and their usefulness is demonstrated. The concept is generalized to the electrodynamic case, resulting in a family of very simple “magic‐distance inspired” algorithms that maintain the overall accuracy of Galerkin formulations without appreciable deterioration in the overall accuracy. © 2013 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2013. 相似文献
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A new set of entire‐domain basis functions for the numerical solution of corner‐truncated patch antennas via a method of moments (MoM) algorithm is proposed in this article. The basis functions used here allow improvement of the computational efficiency and/or the accuracy of the numerical method, compared to the analysis techniques previously presented in the literature and commonly employed in practical designs. Some numerical results showing the capabilities of the new basis functions proposed here and good agreement with the measurements are also presented. © 2005 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2005. 相似文献
15.
《国际计算机数学杂志》2012,89(2):279-288
In this paper the order of convergence of the evolution operator method used to solve a nonlinear autonomous system in ODE's [2] is investigated. The order is found, to be 2N+1 where N comes from the [N+1,N] Pade approximation used in the method. The order is independent of the choice of the weight function. 相似文献
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A systematic synthesis procedure for ridge waveguide branch line couplers in both E‐plane and H‐plane configurations is presented. Ridge waveguides are chosen to benefit from their wide mono‐mode band and compact size compared to rectangular waveguides. Equivalent circuit parameters are used to synthesize the coupler sections. Rigorous mode matching method is used for full‐wave analysis and optimization of the couplers. Ridge couplers both in empty waveguide and Low Temperature Co‐fired Ceramic “LTCC” technology are designed using the proposed method and the design is verified with another numerical method. A prototype is built and its response is measured to verify the approach. © 2008 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2008. 相似文献
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Elson Agastra Claude Dedeban Giacomo Guarnieri Stefano Maddio Giuseppe Pelosi Christian Pichot Stefano Selleri 《国际射频与微波计算机辅助工程杂志》2011,21(5):551-559
In this article, an algorithm able to deal at the same time with wire frame and surface patch models for the method of moments in time domain is presented. After a unified theory combining both models, attention is focused on stability dependence issues on the time basis function chosen and on other algorithm parameters. An accurate analysis of time interpolation functions and of their time filtering properties is provided. © 2011 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2011. 相似文献
18.
直接应用三维矩量法求解旋转对称目标的电磁散射特性计算效率较低,计算机内存耗费大,利用其结构特点可降维获得一种更为有效的计算方式。然而对于电大目标,这种改进依然是不够的。文中根据旋转对称目标矩量法（ BOR-MOM）中电流的分解特征,构建了一种基于切比雪夫近似的高阶基函数,将电流的切向分量和方位角分量分别以该高阶基函数展开后应用矩量法求解。实验结果表明：高阶BOR-MOM算法在低剖分下,具有很高的计算精度,计算效率和存储耗费得到了较大改善。 相似文献
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Continuous scanning leaky‐wave antenna (LWA) based on second‐mode spoof surface plasmon polaritons (SSPPs) excitation has been proposed and validated in this article. Different from the existing modulation methods, connecting axisymmetric rectangular modulation is adopted to excite the ?first harmonic. In this way, the slow‐wave bound on the surface of the transmission line is converted into a radiation wave in space. To the authors' knowledge, this is the first presentation of LWA design utilizing second‐mode SSPPs excitation. In the range from 5.0 to 9.0 GHz, the proposed LWA realizes continuous scanning from ?54° ~ 11° with a quasi‐omnidirectional beam in the vertical plane. A prototype of the proposed antenna is fabricated and measured, and the measured results show good agreement with the simulated. The proposed LWA has potential applications in communication systems and radars. 相似文献