共查询到20条相似文献,搜索用时 15 毫秒
1.
Weikai Su Wei Hong ZhengHau Zhu YunYi Wang 《International Journal of Infrared and Millimeter Waves》1992,13(12):1925-1941
In this paper, the scattering parameters of a waveguide cross junction loaded with a metallic post in the center are analyzed for the first time by using the Method of Lines. The homogeneous boundary condition of the third kind and curved boundary are introduced in the formulation. Numerical results are in good agreement with the experimental data. The scattering parameters at Ka-band and W-band of the cross junctions loaded with metallic posts of different radii are presented. It is shown from the numerical results that loaded with metallic posts is an effective means for adjusting the network parameters of the waveguide cross junction to satisfy some special requirements in the design of millimeter wave components. 相似文献
2.
Falin Liu 《International Journal of Infrared and Millimeter Waves》1998,19(8):1103-1112
Based on the mode matching method, the generalized scattering parameters including the fundamental and higher order modes (multi-modes) are obtained for the discontinuity interface of a category of waveguide H-plane discontinuities. Then by using a general port-connection order-decrease method raised by the author, the whole discontinuity including the two interfaces and the intermediate part of finite length or zero length (as is the case for very thin inductive windows or irises) can be combined into one network, and the generalized scattering parameters of this network can be obtained from which the scattering parameters of the fundamental mode can be extracted. If needed, the equivalent circuit parameters can be calculated directly from the scattering parameters. Examples are given to show the validity and versatility of this new method for dielectric filled waveguide, inductive iris and/or window, E-plane metal and/or finline insert, and even the offset E-plane finline insert, etc.. Multiple inserts, windows and irises can also be analysed. 相似文献
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Humberto César Chaves Fernandez José de Ribamar Silva Oliveira Attílio José Giarola 《International Journal of Infrared and Millimeter Waves》1991,12(5):505-519
The Transverse Transmission Line method is used for the characterization of bilateral and unilateral finlines on a semiconductor substrate and in conjunction with the modal method, for the calculation of the scattering parameters due to a step discontinuity on a unilateral finline with a lossless dielectric substrate.Numerical results of the effective dielectric constant, attenuation constant and characteristic impedance for the bilateral and unilateral finlines on semiconductor substrates, and results of scattering parameters of a step discontinuity for unilateral finline, are presented. 相似文献
5.
用离散偶极子近似法,计算了立方粒子随机取向时在几种等效尺度参数下的光散射特性,并与等效球形粒子的光散射特性进行了比较.结果表明:立方粒子和其他非球形粒子与其等效球形粒子光散射特性之间的差别大致相同,说明对于随机取向的非球形粒子的光散射问题,粒子的内在对称性和表面的突变不会带来明显的效果.
关键词: 相似文献
6.
Wei Hong Wen-Xun Zhang 《International Journal of Infrared and Millimeter Waves》1990,11(11):1323-1332
In this paper, the propagation characteristics of NRD waveguide loaded with periodic metallic strips are analyzed in terms of the method of lines. Numerical results show that such structures are most suitable for millimeter wave bandstop filter and NRD waveguide beam scanning leaky wave antenna application. 相似文献
7.
依据矩形波导基模的场分布表达式和电磁边界条件,解析推导了插入金属薄膜后的矩形波导透射系数,建立了考虑介质衬底影响的金属纳米薄膜微波透射系数仿真计算方法及其方块电阻的微波测量方法.运用全波电磁仿真方法对金属纳米薄膜方块电阻的微波测量装置进行了仿真验证,结果表明透射系数幅度与方块电阻的对数之间呈线性关系.采用磁控溅射工艺分别在高阻硅和玻璃两种介质衬底表面制备了不同方块电阻值的银薄膜,并测量其微波透射系数.实测结果表明,提出的方法适用于方块电阻阻值为0.05—0.5?/square的金属薄膜.研究结果对于微纳制造领域的导电薄膜方块电阻表征具有参考价值. 相似文献
8.
Antonio Luiz Pereira de Siqueira Campos 《International Journal of Infrared and Millimeter Waves》2008,29(7):684-692
In this paper, a theoretical analysis of scattering from a doubly frequency selective surfaces (FSS) with dielectric and metallic
losses in the millimeter wave range is presented. The theoretical analysis involves the solution of the electric field integral
equation relating the induced current in the FSS in the presence of anisotropic dielectric layers. The method of moment is
employed to obtain numerical results. The frequency selective surface structure considered is composed by conducting patch
elements sandwiched between two anisotropic dielectric layers. Three different anisotropic materials are considered: Epsilam-10,
Alumina, and Sapphire. The sapphire presents low losses when compared with the other two dielectric materials. The most common
metals, as copper and aluminum, are considered in this analysis. None significant metallic losses were observed for any considered
metal. Numerical results are presented for the scattering characteristics and for dielectric and metallic losses parameters. 相似文献
9.
给出电磁波导的对偶变量变分原理,并采用对偶棱边元对波导的横截面进行半解析离散. 将波导中沿纵向均匀的区段视为子结构,运用基于Riccati方程的精细积分算法求出其出口刚度阵,然后与不均匀区段的常规有限元网格拼装即可对波导不连续性问题进行求解. 半解析对偶棱边元的采用可以在最大程度上对有限元网格进行缩减,并且能够在不增加计算量的前提下任意增加子结构的长度,从而可以将截断求解区域的人工边界设置在距离不均匀区段充分远的地方,极大地减少了近似边界条件所带来的误差. 数值算例证明这种方法具有很高的精度与效率.
关键词:
波导的不连续性
半解析辛分析
对偶棱边元
精细积分 相似文献
10.
用精细积分法对含各向异性介质的波导不连续性问题进行了数值模拟与分析. 从矢量波动方程相对应的单变量变分形式出发, 推导出了含有各向异性介质波导横截面离散系数矩阵的表达式, 引入对偶变量, 在Hamilton体系下, 利用精细积分法求出出口刚度矩阵, 进行有限元拼装, 求解了含各向异性介质的波导不连续性问题. 算例表明了该方法的准确性和高效性. 利用本文方法还讨论了介电系数和导磁系数张量的各个分量对波导传输特性的影响.
关键词:
波导不连续性
各向异性介质
Hamilton体系
精细积分法 相似文献
11.
A. D. Zakharenko 《Acoustical Physics》2002,48(2):166-170
An approach based on the redistribution of acoustic energy between waveguide modes is used to state the inverse problem of sound scattering from small compact inhomogeneities in a shallow-water waveguide. Numerical results are presented. 相似文献
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Angular-modulated spatial distribution of ultrahigh-order modes assisted by random scattering
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In designing an optical waveguide with metallic films on a nanometer scale, the random scattering by the natural roughness of the thin film is always ignored. In this paper, we demonstrate that for the ultrahigh-order modes (UOMs) in the symmetric metal cladding waveguide, such a scattering leads to drastic variations in their spatial distribution at different incident angles. Owing to the high mode density of the UOMs, the random scattering induced coupling can be easily related to different modes with different propagation directions or wavenumbers. At small incident angles, the intra-mode coupling dominates, which results in a spatial distribution in the form of concentric rings. At large incident angles, the inter-mode coupling plays the most important role and leads to an array-like pattern. Experimental evidence via optically trapped nanoparticles support the theoretical hypothesis. 相似文献
14.
Xu Shanjia Wu Xinzhang P. Boege H. Schäfer C. R. Becker R. Geick 《International Journal of Infrared and Millimeter Waves》1993,14(10):2155-2190
The scattering characteristics of 3-D discontinuity consisting of II-VI-epitaxial layer grown on lossy dielectric substrate inserted in the waveguide with gaps are investigated in detail by the method which combines the multimode network theory with the rigorous mode matching procedure. The experimental data verify the accuracy and the effectiveness of the present method. 相似文献
15.
Experimental studies of extraordinary light transmission through periodic arrays of subwavelength square and rectangular holes in metal films
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We fabricate a series of periodic arrays of subwavelength
square and rectangular air holes on gold films, and measure the
transmission spectra of these metallic nanostructures. By changing
some geometrical and physical parameters, such as array period, air
hole size and shape, and the incident light polarization, we verify
that both global surface plasmon resonance and localized waveguide
mode resonance are influential on enhancing the transmission of
light through nanostructured metal films. These two resonances
induce different behaviours of transmission peak shift. The
transmission through the rectangular air-hole structures exhibits an
obvious polarization effect dependent on the morphology. Numerical
simulations are also made by a plane-wave transfer-matrix method and
in good consistency with the experimental results. 相似文献
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V. Kalesinskas A. Konstantinov V. Shugurov 《International Journal of Infrared and Millimeter Waves》1998,19(12):1773-1781
The paper presents a rigorous solution of the scattering problem by a circular dielectric and perfectly conducting cylinders of any radius and any height in the rectangular waveguide oriented perpendicularly to a wall. The method is based on the representation of fields in waveguide and dielectric medium by cylindrical eigenfunctions and application of boundary conditions on surfaces of the cylinder to evaluate the fields inside and outside the cylinder. The reflection and transmission coefficients are expressed through the fields. As an example the reflection and transmission coefficients versus frequency for various dielectric and metallic cylinders are computed. The comparison of numerical with experimental data is presented. 相似文献
18.
利用时域有限差分方法研究了亚波长金属波导TE波的传播特性和基于异常透射现象的干涉特性.对各种参量对驻波特性的影响及两列波导间的耦合特性进行了分析.研究发现,TE波在波导中传播时存在截止宽度,如果波导宽度小于截止宽度,TE波在波导中不能传播;如果波导宽度大于截止宽度,TE波的传播距离将随波导宽度变大而突然增加.当波导宽度达到或大于半波长时,TE波可以在波导中正常传播.金属波导的截止宽度与金属的吸收系数成正比.此外,由于光在亚波长金属波导透射时的异常透射现象,在亚波长金属波导中产生了TE波的干涉现象,能形成驻波. 相似文献
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Bhartia Prakash 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》1976,4(1):69-71
The electromagnetic scattering from a bounded plasma column in a rectangular waveguide is investigated. Using image and boundary value techniques, equations are formulated for reflection, transmission and attenuation coefficients. Numerical results obtained from computations are in good agreement with results obtained using alternative formulations elsewhere. 相似文献