硅基狭缝脊形波导的几何尺寸对光场分布的影响

文中采用时域有限差分模拟的方法,研究了狭缝脊形波导中狭缝的宽度、狭缝两侧波导的宽度以及狭缝的深度对狭缝脊形波导光场分布的影响。在狭缝脊型波导中, 随着狭缝宽度的增加, 其归一化光功率先增大后减小;同样,光功率随着狭缝两侧波导的增加也呈现出先增加后减小的现象;随着狭缝刻蚀深度的增加,归一化光功率是逐渐增大的。通过比较狭缝中归一化光功率的值,将其影响量化,进一步找到最合适狭缝脊形波导的几何尺寸。实验结果表明,当狭缝的宽度为40 nm,两侧波导的宽度为220 nm,狭缝刻蚀深度为220 nm时,归一化光功率达到最大值为13.54 %。该仿真结果有助于优化狭缝脊形波导与调制器制造和集成。     

导体半平面上双边激励缝隙的并矢格林函数

将导体半平面上的缝隙分解为无限小的水平缝和轴向缝，根据导体半平面上单边激励的无限小缝隙的辐射场，利用求积分的鞍点法，得到了导体半平面上双边激励的缝隙的并矢格林函数在远区的渐近解。根据该并矢格林函数，就可以分析TSA天线的极化及交叉极化特性。     

分布式TDMA网络的时隙设计技术

时隙分配是分布式TDMA组网的一个基础性工作,直接影响到Adhoc网络的性能。为支持低延迟数据业务,通常选择TDMA组网技术,但常规的固定时隙TDMA网络对时隙的利用率较低。提出了一种基于跳频的固定时隙分配和动态时隙分配相结合的TDMA时隙资源管理技术,有效地解决了TDMA网络的不同类型用户信息传输时隙分配问题。     

盲槽孔板的设计及加工方法探讨

文章主要针对盲槽产品的制作流程及加工方法的控制作探讨,盲槽孔主要是利用已经钻好槽孔板和半固化片与另一张板进行压合形成。压合盲槽板时半固化片上所钻的槽孔大小设计/品质及半固化片本身流胶量严重影响成品盲槽的品质,本次主要以影响盲槽孔品质的几个因素作实验层别:半固化片槽孔大小分别比成品槽孔单边大0.4mm、0.6mm、0.8mm;PP厚度0.0375mm×3张;PP铣槽孔时叠板数为6、9、12。结论:半固化片槽孔单边大0.8mm最优,1.5mil厚的PP铣板叠板数9张时铣出的PP压合后槽孔品质符合要求,叠板数越少铣槽的效果越好;介层总厚度相同时,PP选用的张数越少压合时流胶越少,盲槽孔孔形越好。     

一种抑制波导窄边缝隙阵列天线交叉极化的方法

为了抑制波导窄边缝隙阵列天线交叉极化电平,采用一种在波导外壁开非倾斜缝隙、在波导内壁开倾斜缝隙的方法。利用电磁仿真软件HFSS进行仿真,得到孤立缝隙与阵中单个缝隙的电导函数。设计了一个47单元X波段波导窄边缝隙均匀直线阵列,与常规缝隙阵列相比,天线交叉极化电平降低了6.8 dB。     

Output performance of a slot in a waveguide with dielectric insert of finite length

Characteristics of a narrow longitudinal slot positioned over a dielectric insert of finite length completely filling the cross section of a rectangular waveguide have been investigated. The magnetic field excited by a slot in the dielectric insert in the area directly under the slot was determined. Internal admittance of the slot and its energy parameters were numerically investigated.     

表面波放电狭缝天线辐射电磁场的三维数值分析

针对平板型表面波放电等离子体源,建立了表面波放电狭缝天线辐射电磁波模型,对狭缝天线辐射电磁场分布进行了三维数值计算,并与表面波电磁场进行对比分析,讨论了平板型表面波放电机理。结果表明:整个狭缝天线阵激发的电磁场是每个狭缝天线激发电磁场的线性叠加;狭缝天线阵直接激发的电磁场强度在临近波导壁面处很大,并且随着空间距离的增大迅速衰减;狭缝天线阵直接激发和表面波的电场均远大于各自的磁场,分析电、磁场对带电粒子的力作用时可以忽略磁场力的作用;表面波电磁场远大于狭缝天线阵直接辐射的电磁场,强电磁场范围也远大于狭缝天线阵直接激发的强电磁场范围,等离子体有增强电磁场强度、扩大强电磁场范围的作用。     

Determination of the multi‐slot transmission in Bluetooth systems with the estimation of the channel error probability

Bluetooth is an open specification for a technology to enable short‐range wireless communications that operate in an ad hoc fashion. Bluetooth uses frequency hopping with a slot length of 625 μs. Each slot corresponds to a packet and multi‐slot packets of three or five slots can be transmitted to enhance the transmission efficiency. However, the use of multi‐slot packet may degrade the transmission performance under high channel error probability. Thus, the length of multi‐slot should be adjusted according to the current channel condition. Segmentation and reassembly (SAR) operation of Bluetooth enables the adjustment of the length of multi‐slot. In this paper, we propose an efficient multi‐slot transmission scheme that adaptively determines the optimal length of slots of a packet according to the channel error probability. We first discuss the throughput of a Bluetooth connection as a function of the length of a multi‐slot and the channel error probability. A decision criteria which gives the optimal length of the multi‐slot is presented under the assumption that the channel error probability is known. For the implementation in the real Bluetooth system, the channel error probability is estimated with the maximum likelihood estimator (MLE). A simple decision rule for the optimal multi‐slot length is developed to maximize the throughput. Simulation experiment shows that the proposed decision rule for the multi‐slot transmission effectively provides the maximum throughput under any type of channel error correlation. Copyright © 2005 John Wiley & Sons, Ltd.     

Analysis of Slot Characteristics in Slotted Single-Mode Semiconductor Lasers Using the 2-D Scattering Matrix Method

We use the two-dimensional (2-D) scattering matrix method (SMM) to analyze the slot characteristics in slotted single-mode semiconductor lasers and compare the results with those calculated by the one-dimensional transfer matrix method (TMM). The analysis shows that the 2-D SMM is required to accurately account for the measured results. Using the 2-D SMM simulation, we find that there is almost no reflection at the interface from slot to waveguide while a large reflection exists at the interface from waveguide to slot, and the power loss is much larger than the power reflected. For a single slot, the slot width has little influence on the slot reflectivity, which coincides with the measured results. The reflection and transmission of the slot are found to be exponentially dependent on the slot depth     

Full-wave analysis of broad wall slot's Characteristics in rectangular waveguides

A rigorous analysis of the resonant characteristics for a broad wall waveguide slot by using the finite-difference time-domain method is presented. Four types of slots including a radiating longitudinal shunt slot, a longitudinal/transverse coupling slot, a centered-inclined coupling slot and a compound coupling slot are analyzed. Lots of slot characteristics such as the resonant length, scattering parameters and normalized admittance in different offsets, tilt angles or slot sizes are obtained. Because the shape of slots is a rectangle with rounded ends in practical fabrication, an accurate modeling and computation for the slots with rounded ends is implemented, and the resonant lengths calculated coincide well with the Stegen's measured data and method of moments results. From these computed results, it is found that all the resonant characteristics of the slots with rounded ends are significantly different from those with normal rectangular ends.     

浅析V槽上金

无铅时代的到来,板材也正在逐步向无铅体系板材过渡,随之也带来一些负面影响;有铅板材开V槽后进行沉镍金,没有出现V槽上金;无铅板材开V槽后进行沉镍佥,断续出现V槽上金;从板材、刀具、沉镍金工艺三个方面实践论述V槽上金的原因分析及解决办法。     

Size reduction of cavity-backed slot antennas

A technique for reducing the dimensions of the cavity of a cavity-backed slot antenna (CBSA) is presented, which facilitates proper fabrication and integration of miniaturized slot antennas on multilayer substrates. This is accomplished by replacing the solid metal around the traditional slot antennas with a specific metallic pattern that can be viewed as a series of parallel strip lines placed around the slot antenna. This metallic pattern is then modified by designing the parallel strips in a compact fashion to reduce the overall antenna dimensions and obtain a reduced-size CBSA. It is shown that, for a simple straight slot antenna, the overall occupied volume of the modified cavity backing the slot antenna can be reduced by more than 65% without affecting the high radiation efficiency of the antenna. A number of traditional cavity backed slot antennas and the proposed modified CBSAs are designed, fabricated, and measured. The reduced-size CBSAs show a very low input VSWR, low cross-polarized radiation levels, and high radiation efficiency. Despite their small ground plane size, the proposed cavity backed slot antennas have front-to-back ratio (FTBR) values in the range of 6-7 dB.     

波导终端缝隙对的分析

在小型波导缝隙阵设计中，采用匹配缝隙是减少终端损失、提高天线效率的关键技术之一。本文给出了矩形波导终端匹配缝隙对的分析。该缝隙对是由波导宽壁上的纵缝和横缝构成的。基于等效原理和并矢格林函数建立了缝隙对的耦合积分方程组，然后作数值求解。计算了缝隙对的反射特性与辐射特性，给出了缝隙对口面电场的幅值和相位以及波导驻波比随缝隙长度和频率的变化曲线。本文的计算结果可用于圆极化波导缝隙阵的设计     

一种高速通信系统动态时隙分配设计

为了满足高速通信系统网络实时、动态性的要求,提出一种动态时隙分配方案,引入时隙成块分配思想,给出动态时隙块的分解与合并的方法,最后给出时隙动态调整工作流程。     

Analytic design of conformal slot arrays

A completely analytic design process has been developed for small slot arrays which accounts for the varying effect of mutual coupling as a function of element position. A previously developed theory for the design of small arrays has been extended to include conformal dielectric-filled waveguide slot arrays. Computer software has been assembled which enables calculation of the slot geometries required to implement a specified aperture distribution and input impedance condition. The slot self- and mutual admittances are calculated numerically, thus eliminating the traditional measured slot data from the design process. This design technique has been applied to conformalX-band slot arrays on cylinders of a few wavelengths diameter. The arrays consist of multiple dielectric-filled waveguides, each of which is a narrow-band standing-wave linear array of longitudinal shunt slots. The computerized design process adjusts the length and offset of each slot in the total array until the desired aperture distribution and impedance match are achieved. A flow diagram of the design program and test results from experimental arrays are presented.     

On the conceptual utility of current flow lines in waveguides

Surface currents in waveguide walls have been very useful in gaining physical insight into the mechanism of waveguide slot coupling from the waveguide modal fields, to the slot radiator and into free space. If the slot interrupts the current flow lines, it will couple to the waveguide field and if the slot is parallel to the current flow lines, the slot will not couple and causes only minor perturbation to the waveguide field. This heuristic concept is extremely useful for the innovation of new or different slot radiators. Examples of the utility of current flow lines in circular waveguide and parallel plate radial transmission lines and how they suggest a class of reflectors with circular caustics are discussed.     

波导宽边辐射缝隙的全波分析

使用时域有限差分法 (FDTD法 )对矩形波导上单个辐射缝隙的特性进行了严格分析 ,得出在不同缝隙偏置、缝隙宽度和波导壁厚条件下缝隙的谐振长度、散射参数以及等效归一化导纳等特性 ,并对‘谐振状态’的定义做了讨论 ,为高性能波导缝隙天线阵的设计提供参考     

基于HFSS的波导裂缝有源导纳的计算方法

提出一种基于商业软件HFSS仿真得到的开缝波导散射参数来提取辐射缝隙自导纳和有源导纳的方法。根据传输线理论．给出了通过散射参数计算孤立缝隙自导纳的公式．同时给出了考虑互耦的有源导纳方程．利用牛顿迭代法求解此方程得到裂缝的有源导纳值。该方法非常适合于波导天线阵的设计．有效地提高了天线阵的设计效率.     

Admittance of a waveguide radiating into stratified plasma

A slot covered by a stratified plasma is assumed to radiate into a wide waveguide instead of free space. The slot admittance approximates the free space admittance of the slot for waveguide diameters exceeding 6 to10lambda. For thick plasma layers the computed slot admittance checks with earlier admittance calculations for a laterally unbounded plasma. When approximating a plasma profile of a typical hypersonic re-entry, a multilayer plasma model in a wide waveguide appears to provide a more accurate slot admittance than a single-layer approximation in a laterally unbounded geometry.     

一种展宽波导缝隙阵列天线驻波带宽的新方法

辐射缝隙导纳和耦合缝隙阻抗的频率特性,是影响缝隙阵列天线驻波带宽的主要因素。以改善整个缝隙阵阻抗匹配频率特性为出发点,提出了一种展宽波导缝隙阵列天线驻波带宽的新方法,即选择合适的辐射缝隙的总导纳常数。仿真分析表明,改变后的缝隙阵列天线的驻波带宽有了较大改善,其与理论分析的结果是一致的。