一种雷达副瓣匿影概率的仿真方法

副瓣匿影技术是一种重要的雷达抗干扰手段,副瓣匿影概率是其一项关键指标。本文在瑞利信号模型下,推导了副瓣匿影时的信号模型,得到了虚警概率的表达式,给出了检测概率的仿真方法。仿真实验结果表明,该方法能够较好地对副瓣匿影时的检测概率和匿影概率进行仿真。     

分布式数字合成阵列主辅波束优化

针对分布式数字合成阵列中高副瓣效应导致的多目标探测困难的问题,给出了一种分布式数字接收阵列合成的总体设计技术,一方面利用凸优化数字波束加权设计方法,抑制主波束副瓣;另一方面利用副瓣匿影技术及多匿影波束分段设计方法,实现对副瓣方向干扰的抑制。文中通过检测理论和数值计算给出了系统性能分析,并通过两部合成数字阵列的外场跟飞试验验证了方法的有效性。     

有源相控阵天线子阵划分对旁瓣匿影性能影响

由于缺少旁瓣匿影性能评估的统一标准,子阵划分对旁瓣匿影性能影响研究较少。对此,本文提出旁瓣匿影性能评估参量——旁瓣匿影率,其本质是计算满足旁瓣匿影要求区域占整个方向图区域的比例。其中保护通道直接利用子阵级数据通过加权非相参积累方式构建,可实现保护通道的自适应干扰抑制,支撑干扰条件下的自适应旁瓣匿影。实验表明,子阵划分非均匀性越强,子阵数越多,扫描角越小,有源相控阵天线的旁瓣匿影率越高,旁瓣匿影性能越好。     

一种旁瓣匿影天线系统设计

旁瓣匿影是相控阵雷达采用的一种典型抗干扰技术。天线系统是旁瓣匿影的核心硬件设备,其设计直接关系到匿影波束能否有效压制干扰信号。针对目前旁瓣匿影容易出现的波束覆盖穿刺等问题,文中设计了一种旁瓣匿影天线系统,它包括全向匿影天线、低噪放耦合模块。通过匿影天线与低噪放集成设计提高匿影链路的干噪比。全向匿影天线采用方位全向双极化天线设计,水平极化匿影天线采用扁波导缝隙全向天线,垂直极化匿影天线采用扁平双锥全向天线。仿真结果表明,两种天线可实现方位向水平极化与垂直极化的全向覆盖。经实测验证,匿影波束能完整覆盖主天线副瓣区,可有效提升雷达系统的抗干扰能力。     

激光匿影器的设计

给出了匿影技术的定义,在分析激光接收系统工作环境的基础上,说明了匿影技术对完善激光接收系统的性能具有重要意义;介绍了匿影技术的工作原理和匿影技术实现的电路设计,并重点分析了匿影处理电路的时序关系和匿影信号脉冲宽度的选择.     

极化干扰对雷达抗干扰性能的影响

随着雷达电子战攻防博弈的发展,极化干扰给雷达反干扰措施带来了新的挑战,文中分析了极化干扰对雷达副瓣对消功能、副瓣匿影功能、干扰源感知功能、干扰源定位功能、极化滤波功能以及其他有关反干扰功能的影响机理,并给出了部分试验验证结果,最后文章提出了应对极化干扰的有关建议和措施。     

雷达旁瓣相消和旁瓣匿影抗干扰技术

自适应旁瓣相消（ASLC）是雷达抗有源干扰的有效方法。它采用空间滤波技术，通过辅助接收通道在干扰方向形成波束图的零点．实现对干扰信号的抑制；而旁瓣匿影则可以用来对付另一类由天线副瓣进入接收机的干扰．包括脉冲型干扰、强目标回波、杂波干扰等。本文论述了自适应旁瓣相消和旁瓣匿影的基本原理，实现方案，并对仿真结果进行了分析。     

基于旁瓣匿影的抗密集假目标干扰研究

针对脉冲压缩雷达中旁瓣匿影技术门限判决规则简单、抗干扰能力差的问题,首先基于脉冲压缩雷达旁瓣匿影的一般结构,对旁瓣匿影门限选择进行了理论分析,推导了匿影门限、检测门限与雷达探测性能的关系;然后,着重针对密集假目标干扰覆盖目标回波后错误匿影的问题,提出了一种“二次判决”方法,该方法对超过匿影门限的距离单元进行再次判决。仿真结果表明,该方法能够在正常抑制干扰的同时,解决目标信号被匿影而丢失的问题。     

盲源分离在雷达抗主瓣干扰中的应用研究

主瓣干扰位于雷达主瓣内,干扰信号通常很强,会严重影响雷达探测性能.常用的副瓣匿影和副瓣对消措施难以奏效.文中给出了盲源分离抗干扰信号模型,在此基础上提出了基于矩阵联合对角化特征矢量的盲源分离抗主瓣干扰算法,并给出了不同信噪比条件下主瓣干扰抑制的仿真结果.仿真结果表明,在信噪比大于-15 dB的条件下,干扰抑制比能达到10 dB以上.该方法能有效降低主瓣干扰对雷达探测性能的影响,具有良好的应用前景.     

舰载雷达自适应匿影方法研究

在介绍和分析固定脉宽匿影方式局限性基础上,提出了一种自适应调整脉宽匿影方法,对其工作原理、流程及最长延时进行了研究和探讨。该方法能够根据气象和海况变化,自适应调整匿影延时,消除同载体雷达对电子侦察设备的干扰,充分发挥电子侦察的效能,同时缩短匿影模块维修时间,具有较强的应用价值。     

Preparation and Characterization of TaN ALD Precursors

High purity organic-tantalum precursors for thin film ALD TaN were synthesized and characterized.Vapor pressure and thermal stability of these precursors were studied.From the vapor pressure analysis,it was found that TBTEMT has a higher vapor pressure than any other published liquid TaN precursor,including TBTDET,TAITMATA,and IPTDET.Thermal stability of the alkyl groups on the precursors was investigated using a 1H NMR technique.The results indicated that the tertbutylimino group is the most stable group on TBTDET and TBTEMT as compared to the dialkylamido groups.Thermal stability of TaN precursors decreased in the following order:TBTDET ＞ PDMAT ＞ TBTEMT.In conclusion,precursor vapor pressure and thermal stability were tuned by making slight variations in the ligand sphere around the metal center.     

Curved crystal spectrometer for the measurement of X-ray lines from laser-produced plasmas

In order to diagnose the laser-produced plasmas, a focusing curved crystal spectrometer has been developed for measuring the X-ray lines radiated from a laser-produced plasmas. The design is based on the fact that the ray emitted from a source located at one focus of an ellipse will converge on the other focus by the reflection of the elliptical surface. The focal length and the eccentricity of the ellipse are 1350 mm and 0.9586, respectively. The spectrometer can be used to measure the X- ray lines in the wavelength range of 0.2-0.37 nm, and a LiF crystal （200） （2d = 0.4027 nm） is used as dispersive element covering Bragg angle from 30° to 67.5°. The spectrometer was tested on Shengnang- Ⅱ which can deliver laser energy of 60-80 J/pulse and the laser wavelength is 0.35 μm. Photographs of spectra including the 1 s2p ^1P1-1s^2 ^1S0 resonance line（w）, the 1s2p ^3P2-1s^2 1S0 magnetic quadrupole line（x）, the 1s2p ^3P1-1 s^2 ^1S0 intercombination lines（y）, the 1 s2p ^3S~1-1 s^2 ^1S0 forbidden line（z） in helium-like Ti Ⅹ Ⅺ and the 1 s2s2p ^2P3/2-1 s622s ^2S1/2 line（q） in lithium-like Ti Ⅹ Ⅹhave been recorded with a X-ray CCD camera. The experimental result shows that the wavelength resolution（λ/△ 2） is above 1000 and the elliptical crystal spectrometer is suitable for X-ray spectroscopy.     

Electronic Structure of Semiconductor Nanocrystals

This paper reviews our recent development of the use of the large-scale pseudopotential method to calculate the electronic structure of semiconductor nanocrystals, such as quantum dots and wires, which often contain tens of thousands of atoms. The calculated size-dependent exciton energies and absorption spectra of quantum dots and wires are in good agreement with experiments. We show that the electronic structure of a nanocrystal can be tuned not only by its size,but also by its shape. Finally,we show that defect properties in quantum dots can be significantly different from those in bulk semiconductors.     

Critical Stage Rule-Based Real Time Dispatch（RTD）System in Highly-Mixed-Products （HMP） FAB

An improving utilization and efficiency of critical equipments in semiconductor wafer fabrication facilities are concerned. Semiconductor manufacturing FAB is one of the most complicated and cost sensitive environments. A good dispatching tool will make big difference in equipment utilization and FAB output as a whole. The equipment in this paper is In-Line DUV Scanner. There are many factors impacting utilization and output on this equipment group. In HMP environment one of the issues is changing of reticule in this area and idle counts due to load unbalance between equipments. Here we'll introduce a rule-based RTD system which aiming at decreasing the number of recipe change and idle counts among a group of scanner equipment in a high-mixed-products FAB.     

GaAsSb/InAlAs PA DHBTs Grown by Production MBE

The epi material growth of GaAsSb based DHBTs with InAlAs emitters are investigated using a 4 × 100mm multi-wafer production Riber 49 MBE reactor fully equipped with real-time in-situ sensors including an absorption band edge spectroscope and an optical-based flux monitor. The state-of-the-art hole mobilities are obtained from 100nm thick carbon-doped GaAsSb. A Sb composition variation of less than ± 0.1 atomic percent across a 4 × 100mm platen configuration has been achieved. The large area InAlAs/GaAsSb/InP DHBT device demonstrates excellent DC characteristics,such as BVCEO＞6V and a DC current gain of 45 at 1kA/cm2 for an emitter size of 50μm × 50μm. The devices have a 40nm thick GaAsSb base with p-doping of 4. 5 × 1019cm-3 . Devices with an emitter size of 4μm × 30μm have a current gain variation less than 2% across the fully processed 100mm wafer. ft and fmax are over 50GHz,with a power efficiency of 50% ,which are comparable to standard power GaAs HBT results. These results demonstrate the potential application of GaAsSb/InP DHBT for power amplifiers and the feasibility of multi-wafer MBE for mass production of GaAsSb-based HBTs.     

Noise character analysis and the restraint of self-pulsation laser diodes

We calculate the Langevin noise sources of self-pulsation laser diodes, analyze the effects of active region noise and saturable-absorption region noise on the power fluctuation as well as period fluctuation, and propose a novel method to restrain the noise effects. A visible SIMULINK model is established to simulate the system, The results indicate that the effects of noise in absorption region can be ignored; that with the increase of DC injecting current, the noise effects enhance power jitter, and nevertheless, the period jitter is decreased; and that with external sinusoidal current modulating the self-pulsation laser diode, the noise-induced power jitter and period jitter can be suppressed greatly. This work is valuable for clock recovery in all-optical network.     

High-quality single-crystal CdSe nanoribbons and their optical properties

Large-scale synthesis of single-crystal CdSe nanoribbons is achieved by a modified thermal evaporation method, in which two-step-thermal-evaporation is used to control CdSe sources＇ evaporation. The synthesized CdSe nanoribbons are usually several micrometers in width, 50 nm in thickness, and tens to several hundred micrometers in length. Studies have shown that high-quality CdSe nanoribbons with regular shapes can be obtained by this method. Room-temperature photolumines-cence indicates that the lasing emission at 710 nm has been observed under optical pumping （266 nm） at power densities of 25-153 kW/cm^2. The full width half maximum （FWHM） of the lasing mode is 0.67 nm     

Propagation of hermite-cosh-gaussian beams passing through ABCD optical system with an annular aperture

By using the expansion of the aperture function into a finte sum of complex Gaussian functions, the corresponding analytical expressions of Hermite-cosh-Gaussian beams passing through annular apertured paraxially and symmetrically optical systems written in terms of ABCD matrix were derived, and they could reduce to the cases with squared aperture. In a similar way, the corresponding analytical expressions of cosh-Gaussian beams through annular apertured ABCD matrix were also given. The method could save more calculation time than that by using the diffraction integral formula directly.     

Influence of polarization extinction ratio on distributed polarization coupling detection

Distributed polarization coupling in polarization-maintaining fibers can be detected by using a white light Michelson interferometer. This technique usually requires that only one polarization mode is excited. However, in practical measurement, the injection polarization direction could not be exactly aligned to one of the principal axes of the PMF, so the influence of the polarization extinction ratio should be considered. Based on the polarization coupling theory, the influence of the incident polarization extinction on the measurement result is evaluated and analyzed, and a method for distributed polarization coupling detection is developed when both two orthogonal eigenmodes are excited.     

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正Communications—VLSI Researches and industries of telecommunications have been growing rapidly in the last 20 years and will keep their high growing pace in the next decade.The involved researches and developments cover mobile communications,highway and last-mile broadband communication,domain specific communications,and emerging D2D M2M communications.Radio communication steps into its