Analysis of Oversized Sliding Waveguide by Mode Matching and Multi-Mode Network Theory

Transmission and reflection coefficients of hybrid modes in the sliding waveguide are discussed on the basis of mode matching method and multi-mode network theory. It is confirmed that the decrease in power of < 0.2% at 84 GHz is obtained for 2 cm in gap of the sliding waveguide which is composed of the corrugated waveguide with 88.9 mm diam. and the smooth-wall waveguide with 110 mm diam. At the sliding length near multi-half-wavelength in vacuum, transmission and reflection powers in the sliding waveguide change slightly, because the very small amount of standing wave in high higher-mode is produced resonantly in the gap.     

Analysis of High Power Millimeter Wave Waveguide Mode Converters with Input Mode Mixture

Based on the coupled mode theory, this paper presents the study on the influence of input mode mixture in circular oversized waveguide mode converters. Three kinds of commonly used waveguide mode converters, including the waveguide mode converters with varying wall radius or small axis perturbations, and the waveguide mode converters with bent structures, are taken as the examples. The results show that the spurious input modes do not simply superimpose onto the output modes, and in some cases they may deteriorate the conversion efficiency for the main output mode. Methods for transforming such spurious input mode mixture simultaneously into the main output mode are also presented in this paper.     

一种分析波导系统不连续性的数值计算方法

本文介绍一种分析波导不连续性的数值计算方法 ,采用有限差分法和共轭梯度法对根据矢量偏微分算子理论得出的电磁波基本方程进行求解 ,由此计算出反射系数和传输系数 ,文中以加载金属膜片的矩形波导为例说明了这一计算过程     

Analysis of a Post Discontinuity in an Oversized Circular Waveguide

This paper presents the analysis of scattering characteristics of a radially directed thin post in a circular waveguide using the method of moments. Electric type dyadic Green's function has been used to compute the scattered field in a circular waveguide considering variation of current only in the axial direction of the post. Simulated data on return loss and power coupling in the dominant mode and higher order modes have been compared with the data computed using Ansoft's High Frequency Structure Simulator. The data on return loss and coupling for the incident ${rm TE}_{11}$ mode have been compared with experimental data.      

E- and H-Plane Bends for High-Power Oversized Rectangular Waveguide

A study is presented of theoretical and experimental results of E- and H-plane bends for high-power oversized rectangular waveguide having cross-section dimensions in the range between 1..5 and 2.5 free space wavelengths. It is expected that waveguides having these dimensions will be able to transmit 50 to 100 kW of average power at X-band without water cooling. The transmission of at least 5.0 MW of peak power at X-band without pressurization is also a design objective. Dimensions for bends having low-mode conversion loss were determined by numerical integration of the coupled transmission line equations. The dominant TE/sub 10//spl square/ mode and four spurious modes were considered in these calculations. The results obtained for both constant curvature and sinusoidally shaped E- and H-plane bends are presented. A compact H-plane constant curvature bend is described for which the ratio of centerline radius to waveguide width is equal to 1.48. The measured mode conversion loss to the TE/sub 20//spl square/, TE/sub 30//spl square/, and TE/sub 40//spl square/ modes for an experimental model having a width equal to 2.25 inches was less than -20 dB in the frequency range from 7.0 to 11.0 Gc/s.     

圆形槽波导-波纹圆形槽波导模式变换器的仿真设计

应用基于有限元方法的仿真软件HFSS,分析和设计了圆形槽波导-波纹圆形槽波导模式变换器。变换器由具有渐变波纹深度的波纹圆形槽波导构成,可实现TE11到HE11的模式转换。分析表明,变换器的长度和第一个波纹的深度是影响其性能的主要因数。在保持变换器优化长度不变的条件下,调整波纹周期、增加波纹数目和波纹宽度对改善变换器的性能效果不明显。所设计的具有5个渐变深度波纹的模式变换器,在中心频率36GHz上回损可达30dB。变换器实测的结果与仿真分析之结论吻合较好。     

几种新型的Buck—Boost变换器的合成

从传输机制说明单管升降压变换器（如Buck-Boost、SPEIC、Cuk）中元件承受的电压和电流应力高的原因,并根据这一机制,采用变换器合成的方式,提出了一系列的双管Buck-Boost变换器。这类变换器根据输入输出条件,可以分别工作于Boost模式和Buck模式,起到降低元件应力的作用。     

一种光波导的新颖数值算法的分析

本文采用了一种新颖的数值算法用来模拟计算光波导器件,主要以集成光学中重要的器件单元劈形与Y分岔为例,通过对数值计算引起的传播常数的误差以及传输系数的分析,对算法进行了简要评估,并将算法定量地与广为使用的有限差分光束传输法（FD－BPM）做了对比,从而突出了该算法的优点与不足之处。     

新型快速波导缝隙天线设计方法

对馈电网络和天线的散射矩阵进行级联,推导了互耦条件下阵列天线输入端口散射参数和天线实际激励分布的计算方法。基于该方法,提出了一种新型快速波导缝隙天线设计方法,并设计了一副12 元宽边纵缝一维波导缝隙天线。测试结果表明,在9. 82 ~10. 21 GHz 内反射系数和副瓣电平分别优于-15 dB 和-28 dB。测试结果与计算、仿真结果吻合良好,验证了该方法的准确性和有效性。     

Highly Accurate Synthesis of Fiber and Waveguide Bragg Gratings by an Impedance Reconstruction Layer-Aggregation Method

We present a novel method for the synthesis of complex fiber Bragg gratings (FBGs) which is based on an impedance reconstruction layer aggregation technique. The method takes as a starting point the accurate approximation of the sinusoidal perturbation (uniform or nonuniform) of the refractive index by local step functions by means of an inverse Fourier series relationship. This reduces the otherwise continuous scattering to only two points per local period and thus, the maximum spatial resolution as limited by the Nyquist criterion is achieved and there is no need to lump various periods of the FBG into an equivalent mirror. The main advantage brought by the method is the possibility of synthesizing structures containing defects or discontinuities of the size of the local period, a feature which yields different results with priorly reported methods to which the one reported here can be considered as complementary. In addition, this enhanced spatial resolution allows the synthesis of very strong FBG devices providing convergent solutions. We illustrate this fact by demonstrating the synthesis of a flat-top filter with a maximum reflectivity of 99.999%. The method renders directly the refractive index profile n(z) as it does not rely on the coupled mode theory since the grating is reconstructed using a V-I matrix formulation. The method is simple and its complexity is equivalent to those previously reported in the literature. Examples are given which prove that perfect reconstruction is achieved in both simple and complex grating profiles. Although a layer aggregation is presented here, the layer peeling (i.e., moving time frame) version of this algorithm is straightforward.     

Analysis and Design of TE/sub 11/-to-HE/sub 11/ Corrugated Cylindrical Waveguide Mode Converters

A theoretical parametric study is given of a TE/sub 11/-to-HE/sub 11/ mode converter consisting of a section of cylindrical corrugated waveguide with varying slot depth. The analysis makes use of modal field-matching techniques to determine the scatter marks of the mode converter from which we deduce its propagation properties. It is shown that a mode converter consisting of only five slots achieves a return loss better than 30dB over the band 2.7相似文献   

基于PWM变换器的新型无源无损软开关

详细分析了一种基于PWM变换器的新型无源无损软开关，并给出了其最优化设计步骤。通过一台满载输出功率为900w的带有该无源无损软开关的Boost变换器验证了其开关管实现零电流开通和零电压关断，并与传统的Boost变换器比较，验证其具有较高的效率。     

波导系统模式的分析与鉴别

介绍了现有各种模式分析的方法,比较了它们各自的特点,认为模式耦合鉴别方法具有实时性与动态性的优点,尤其适合高功率微波系统应用。     

电流控制模式Boost电路分岔的数值分析

研究了电流模式下Boost DC/DC变换器,以电感电流作为分岔参数的分岔混沌现象,通过数值计算得出不同电容值下的分岔图,从而验证了理论分析的可靠性。     

A Systematic Method for the Stability Analysis of Multiple-Output Converters

The dynamics of multiple-output dc-dc converters are discussed. A multi-input-multi-output (MIMO) feedback system model incorporating effects of the output fluctuation is derived for the converter. Based on system theoretic tools, a set of stability conditions is obtained for the MIMO model; the result is used to formulate a stable margin. A practical five-output converter was selected for illustration of the proposed analytic tool. The effects of the input filter and coupled inductor on system stability margin are investigated.     

Novel Efficient De-blocking Method for Highly Compressed Images

Due to coarse quantization, block-based discrete cosine transform（BDCT） compression methods usually suffer from visible blocking artifacts at the block boundaries. A novel efficient deblocking method in DCT domain is proposed. A specific criterion for edge detection is given, one-dimensional DCT is applied on each row of the adjacent blocks and the shifted block in smooth region, and the transform coefficients of the shifted block are modified by weighting the average of three coefficients of the block. Mean square difference of slope criterion is used to judge the efficiency of the proposed algorithm. Simulation results show that the new method not only obtains satisfactory image quality, but also maintains high frequency information.     

理想匹配层及模式匹配法分析多段平面光波导结构

将理想匹配层（PML）吸收边界条件和模式匹配法用于多段平面光波导结构分析，给出了一种改进的平面光波导结构的PML吸收边界条件，并对光波导的光场分布进行数值模拟，所得结果表明了PML吸收边界条件应用于多段平面光波导结构分析的有效性。该方法也可用于分析复杂结构的平面光波导。     

理想匹配层及模式匹配法分新多段平面光波导结构

将理想匹配层(PML)吸收边界条件和模式匹配法用于多段平面光波导结构分析,给出了一种改进的平面光波导结构的PML吸收边界条件,并对光波导的光场分布进行数值模拟,所得结果表明了PML吸收边界条件应用于多段平面光波导结构分析的有效性.该方法也可用于分析复杂结构的平面光波导.     

聚合物环形波导弯曲损耗的改进计算

在大部分集成光学器件中,都会用到弯曲波导,而如何控制波导弯曲产生的损耗。便成了影响这些光学器件性能的关键。应用有效折射率和传输矩阵法相结合,基于matlab平台,数值计算出聚合物PMMA环形波导的弯曲损耗。此外,还针对聚合物PMMA波导制备工艺,提出了通过对包层折射率的修饰,使得弯曲损耗减小的简便方法。这为聚合物PMMA弯曲波导的设计提供了一种有用的优化思路。