移动通信中的智能天线技术

智能天线技术已经成为移动通信领域中最具吸引力的技术之一，它能够根据所处的电磁环境，智能地调节自身参数，抑制干扰，提高天线增益，增加频谱利用率，从而改善移动通信系统的性能。介绍了智能天线的工作原理，阐述了智能天线常用的算法、数字波束成型技术、对系统性能的改善以及在移动通信系统中的应用，最后对智能天线的未来作了展望。     

激光再制造三维运动光束头

基于激光制造技术相关理论，设计并制造了激光同轴转动三维运动光束头。分析了三维运动光束头工艺参数对熔覆效果的影响，并讨论了其在工业应用实验中取得的效果。结果表明，该三维运动光束头能绕竖直轴转动和水平轴摆动;在参数一定的条件下，随着光束头摆动角度的增加，熔覆效果越来越不理想，理想的摆动角度为0°～45°;配合送粉头的粉末流聚焦及焦点可调功能，该光束头可以实现曲轴、螺杆、叶片等复杂型面零件的制造和再制造。     

Chemical Amplification of a Triphenylene Molecular Electron Beam Resist

Molecular resists, such as triphenylene derivatives, are small carbon rich molecules, and thus give the potential for higher lithographic resolution and etch durability, and lower line width roughness than traditional polymeric compounds. Their main limitation to date has been poor sensitivity. A new triphenylene derivative molecular resist, with pendant epoxy groups to aid chemically amplified crosslinking, was synthesized and characterized. The sensitivity of the negative tone, pure triphenylene derivative when exposed to an electron beam with energy 20 keV was ～ 6 × 10^–4 C cm^–2, which increased substantially to ～ 1.5 × 10^–5 C cm^–2 after chemical amplification (CA) using a cationic photoinitiator. This was further improved, by the addition of a second triphenylene derivative, to ～ 7 × 10^–6 C cm^–2. The chemically amplified resist demonstrated a high etch durability comparable with the novolac resist SAL 601. Patterns with a minimum feature size of ～ 40 nm were realized in the resist with a 30 keV electron beam.     

空心高斯光束在梯度折射率介质中的传输特性

利用柯林斯公式推导出空心高斯光束在梯度折射率介质中的传输公式,并利用此解析式进行数值计算和分析,讨论了梯度折射率介质对空心高斯光束传输特性的影响。结果表明,介质梯度折射率对空心高斯光束的传输性质有较大影响。     

Non-Selective SiGe Graphic Epitaxial by MBE

To handle the thermal budget in SiGe BiCMOS process, a nonselective graphic epitaxial technology using molecular beam epitaxial (MBE) has been developed. SEM, AFM, XRD, and dislocation density measurements are carried out. The SiGe film's RMS roughness is 0.45nm, and dislocation density is 0.3×103cm2～1.2×103cm2. No dislocation accumulation exists on the boundary of the windows; this indicates the high quality of the SiGe film. The experiment results show that the technology presented in this paper meets the fabrication requirements of SiGe BiCMOS.     

BPM 技术用于环形电子束位置测量的可行性分析

为了对传输管道半径24mm,电子束半径19mm,厚度3mm 的环形电子束位置开展非阻拦测量,选择了BPM 技 术方案。对比研究了真空管道中环形电子束与位于束团中心的实心束在管道壁上产生的场分布,证明BPM 测量技术可以 用于电流密度均匀分布的环形电子束。采用点密度不均匀性模型,分析了环形电子束角向不均匀性对测量精度的影响。 结果显示,当环形电子束电流密度不均匀性应为10%时,对位置分辨率精度的影响为0.1mm。     

一种可展宽频带的U型切角天线

设计了一种可展宽频带的U型切角天线。将U型贴片天线进行切角处理,改变天线的结构与电流路径,可以有效展宽天线频带,并使其具有良好的阻抗匹配特性。采用HFSS15.0软件对天线模型进行仿真分析,对切角的长度、宽度进行优化,给出了天线的反射系数S11与U型槽尺寸和切角尺寸间的关系。结果表明,优化后的U型切角天线覆盖了整个2.4~2.5 GHz频带范围,电压驻波比VSWR≤2的相对带宽为19%,天线增益达到7 dB,波束宽度为83o左右。     

梯度折射率激光准直器的原理与设计

本文研究用单块抛理型梯度折射率棒透镜作激光准直器的原理、特性和设计。     

Growth of GaAs1−xPx/GaAs and InAsxP1−x/InP strained quantum wells for optoelectronic devices by gas-source molecular beam epitaxy

In this paper we show that pseudomorphically strained heterostructures of InAs _x P_1−x /InP may be an alternative to lattice-matched heterostructures of In_1−x Ga _x As _y P_1−y /InP for optoelectronic applications. We first studied the group-V composition control in the gas-source molecular beam epitaxy (GSMBE) of the GaAs_1-x P _x /GaAs system. Then we studied GSMBE of strained InAs _x P_1−x /InP multiple quantum wells with the ternary well layer in the composition range 0.15 <x < 0.75. Structural and optical properties were characterized by high-resolution x-ray rocking curves, transmission electron microscopy, absorption and low-temperature photoluminescence measurements. High-quality multiple-quantum-well structures were obtained even for highly strained (up to 2.5%) samples. The achievement of sharp excitonic absorptions at 1.06, 1.3 and 1.55μm at room temperature from InAs _x P_1−x /InP quantum wells suggests the possibility of long-wavelength optoelectronic applications.     

高斯光束光学系统的合成

本文在输入、输出空间折射率不相等情况下,分析了对应于不同变换要求的几种高斯光束光学系统的分解方法,阐明各种分解形式的意义。同时,讨论了当给定系统输入、输出空间高斯光束参数时,系统如何实现的问题。