一种汽车发动机微波点火器的仿真研究

简要介绍了微波点火技术,对四分之一波长同轴谐振腔点火器的发展进行了概述。采用三维电磁仿真软件HFSS模拟了内导体对称环结构的耦合方式。在输入功率为400W时,内导体的顶部电场强度可达到2．3×10^7V／m左右,满足汽车发动机在高达1×10^6Pa气压下激发等离子体火焰的门限条件2．25×10^7V／m。     

冻土用的微波加热装置

本专利所涉及的内容为微波加热材料用的微波加热器。将同轴传输线插进材料中,其一端与微波源耦合。同轴线的另一端盖上短路板,沿外导体开许多辐射孔,使用同轴线可避免空心波导中存在的要求最小尺寸的问题,利用同轴线内导体上的弹簧式定位接触装置,使用同轴线可直接与微波发生器的输出探针相耦合。     

汽车发动机点火性能测试仪设计

点火系统是汽车发动机的核心部件,其工作性能直接影响汽车的动力性、燃油消耗量和尾气排放指标。点火提前角是点火系统的关键参数之一,通过对点火提前角的精确调整,能使发劝机的动力性及经济性达到最佳状态。本文介绍了汽车发动机点火性能测试仪的设计与实现,该测试仪通过测量发动机闭合角和分火角角度,分析发动机分电器和点火器性能,为调整高效的点火提前角提供关键依据。     

微波谐振腔湿度测量同轴环耦合设计与实现

基于微波谐振腔汽轮机内流动湿蒸汽湿度的测量原理,分析了微波谐振腔及同轴线小环耦合的场结构分布,设计出两端带栅网结构的湿度传感器.采用HFSS型微波软件对湿度传感器进行了建模仿真,由此得到场分布及S参数曲线图,以此设计出湿度传感器的结构尺寸.仿真结果表明,该微波谐振腔传感器工作在TE011模式下,谐振频率为9.58 GHz,其Q=1 198,适合作为测试流动湿蒸气的传感器.与采用矩形波导和谐振腔的孔耦合相比,这种新型同轴线耦合装置体积小,对汽轮机设备的开口也小,实用性也强.     

电磁脉冲辐射波模拟器笼形天线的理论和数值研究

采用天线理论和数值模拟方法研究了同轴线馈电的双锥笼形天线辐射特性.通过双锥天线和馈电同轴线的阻抗匹配确定双锥半张角为32°;结合清晰时间的概念,确定双锥笼形天线半径为2.5m.给出了双锥半径2.5m、笼形天线长度50m、末端经过削锥处理、架高15m时的双锥笼形天线在地面上方2m水平面内的辐射场分布,在该平面上40mx60m的区域内,电场最大值为6kV/m,最小值为1.6kV/m;在80m×10m的区域内,电场最大值为82kV/m,最小值为12kV/m.     

同轴线型低通滤波器的设计

该文介绍了同轴线型低通滤波器的设计原理与方法,并以结构二,即同轴线内导体外直径统一,外导体内直径呈阶梯变换实现了截止频率为4GHz的同轴线型低通滤波器。结构二相比于结构一,即外导体内直径统一,内导体外直径呈阶梯变化的优势是其设计简单,体积较小且性能更好。测试结果表明,所制作的同轴低通滤波器有良好的性能指标,在整个通带内插入损耗小于0.4dB,回波损耗大于15dB,在通带外6GHz处的抑制约为36dB,整体满足了设计要求。     

高相位一致性六路微波功分器的设计与测试

利用在谐振腔中添加耦合导体的新方法,解决了传统的带状线功分器需要在前后级进行相位补偿的问题。设计的模型用同轴线作为输入输出端口,再将T 型结构带状线与径向线通过1/4 波长阻抗变换器进行连接,优化设计一种新型的C 波段高相位一致性的六路功分器,测试结果与CST 仿真结果符合较好。在工作频段5. 3～5. 9 GHz 内,输入口回波损耗小于-18. 3 dB,输出口回波损耗小于-15. 3 dB,相位一致性优于依1毅,插损小于0. 2 dB。     

非标准波导-同轴电缆转换组件的研制

介绍了非标准波导-同轴电缆转换组件的设计及Ansoft HFSS仿真.详细阐述了将电缆内导体直接插入同轴谐振腔内进行调配,通过改变短路活塞在波导谐振腔内的位置和λ0/4同轴调谐器在同轴谐振腔内的位置,可实现小电压驻波比、低损耗、结构稳定可靠等优异的技术性能,并给出了实测数据,其主要技术性能优于俄罗斯同类产品的主要技术性能.     

2×8低噪声InGaAs/InP APD读出电路设计

对In0.53Ga0.47As/InP雪崩光电二极管(APD)探测器进行了特性分析.以大阵列研究为基础,结合器件特性设计了一个2×8低噪声读出电路(ROIC),电路主要由电容反馈互阻放大器(CTIA)和相关双采样(CDS)电路单元构成,并对读出电路的时序、积分电容等进行了设计.电路采用0.6 μm CMOS工艺流片,芯片面积为2 mm×2 mm,电荷存储能力为5×107个,功耗小,噪声低,设计达到预期要求.     

高Q超导谐振腔的实验研究

针对频率标准用超导腔的设计,通过理论分析及CST仿真优化得到了一种高Q纯铌超导谐振腔的设计。所设计超导腔工作模式为TM010模,谐振频率为4.452GHz,Q值在液氦温度4.2K时达到3.4×107,在减压降温到2K左右时达到1.9×109,实验结果与设计结果一致,验证了设计的正确性和实验装置的可行性。     

A Radiation Measuring System with Potential Automotive Under-Hood Application

An automotive under-hood radiation antenna system (AURAS) has been developed for measuring the electric and magnetic fields produced in the engine compartment of a vehicle by nanosecond impulse signals radiating from an automotive ignition system. The system consists of two sensors (one E-and one H-field) and a wideband amplifier which is capable of operation between 200 and 1000 MHz. Standard 50-? coaxial transmission lines are used to interface the sensors with laboratory instrumentation. The sensors are designed to measure surface field quantities and their voltage output is made proportional to the incident field by passively loading the sensors with appropriate elements.     

Study of Mode Coupling on Coaxial Resonators

A study of mode coupling phenomenon of coaxial resonators has been conducted with theories.Through establishing the source-free transmission line equation,boundary conditions of the coaxial resonators with a corrugated inner conductor are analyzed.In the end,calculations are performed in a wide range of corrugation parameters for the resonator of the Karisruhe Institute of Technology (KIT) relevant coaxial gyrotron.     

Radiated ignition noise due to the individual cylinders of an automobile engine

It is known that mobile communication systems are susceptible to radio-frequency interference (RFI) generated by automotive ignition systems. In this paper the automotive ignition noise generated by individual engine cylinders is investigated. Using specially designed instrumentation, the pulse amplitude densities of individual cylinder ignition noise are measured and analyzed. It is found that the ignition noise generated by the individual cylinders is not statistically uniform and the modes of the pulse amplitude densities of different cylinders may differ by as much as 30 dB (as measured by an antenna positioned to one side of the vehicle). The measurement procedure and results discussed in this paper may prove to be valuable in the diagnosis of ignition system RFI.     

铁电材料介电常数的测量方法研究

描述了一种基于同轴谐振腔技术测量铁电材料介电常数的原理和方法。将待测样品放置在1/4波长的同轴谐振腔的开路端,通过设计制作尺寸合适的同轴谐振腔以保证在测量频率范围内只存在横向电磁场(TEM)基波,并根据测量的同轴谐振腔TEM基波的谐振频率,计算出相应的样品介电常数以及介电常数随电压的变化。为了精确采样待测样品和同轴谐振腔开路端之间部分所形成的等效电容,分析了电容边缘效应并结合边界元数值算法计算该等效电容。针对主要误差来源(气膜),采用在样品上用导电胶制作电极从而减小气膜对测量的误差影响。实验结果表明这是一种简便而有效的测量铁电材料介电常数的方法。     

Quality factor optimisation of coaxial resonators

The optimum shape of the inner conductor of a coaxial resonator with constant resonance frequency yielding maximum Q is obtained by applying the Rayleigh-Ritz method for the analysis and the conjugate gradient method for function maximisation. The shape of the inner conductor is approximated by a polygon and the resulting quality factor increase is 8.8%     

New M6805 Microcomputers Aim at Automotive Applications

Several new additions to the MC6805 family of microcomputers include features particularly suited for automotive electronics. These devices feature application specific logic for automotive ignition systems and instrumentation designs. The MC6805S2, MC680S3, and MC68705S3 microcomputers are useful for engine ignition controls, where asynchronous events, such as engine speed and spark dwell time must be computed with high accuracy. The MC6805K2 microcomputer features EEPROM for critical data retention when the power source is disconnected. The instrumentation odometer is one such application where the EEPROM feature is mandatory. The MC68HC05C4 (ROM version) and M68HC805C4 (EEPROM version) are the latest general purpose MCU's that also offer many important features for automotive applications. The HCMOS silicon technology allows minimal power dissipation which means the devices can operate in an ambient temperature range of -55 to +125 degrees C. These two devices also feature SCI and SPI serial interface ports. The devices run at a fast 2.1-MHz internal bus speed.     

GaAs m.e.s.f.e.t. prepared by organometallic chemical vapour deposition

GaAs m.e.s.f.e.t.s with gate dimensions of 1.5 ?m × 300 ?m were fabricated in the epitaxial layers grown by organometallic chemical vapour deposition (o.m.c.v.d.) technique. The average saturation velocity in the channel was deduced to be 1.3 × 107 cm/s and is equal to that of epitaxial layers grown by AsCl3 chemical vapour deposition (c.v.d.). The velocity degraded region was confined to within about 350 ? of the interface. A gain of 10 dB and a noise figure of 3 dB with an associated gain of 5.5 dB at 8 GHz were measured.     

聚光系统构形对激光推力器推进性能的影响

在喷管与聚光系统一体化设计时,聚光系统因其同时承担聚光和喷管两项功能而成为激光推力器的重要组成部分。通过改变聚光系统内表面的母线方程,可以改变点火区的大小、形状、点火区与聚光系统内表面的距离及喷管长度等参数,而这些参数都会对激光推力器的推进性能产生影响。针对不同的聚光系统构形建立了相应的点火模型,数值计算与实验结果一致,即当注入能量不超过60 J时,在喷管出口直径相同的条件下,抛物形喷管点聚焦方式比环聚焦方式所获得的冲量耦合系数大,可达38.84×10-5N.s/J;而冲量耦合系数对点火区与聚光系统内表面的距离及喷管长度等参数并不十分敏感。研究结果对于吸气式激光推力器的喷管构形设计具有指导意义。     

GaAs/InGaAs量子点探测器件微光读出研究

GaAs/InGaAs量子点光电探测器,在633 nm激光辐射3.5 nW条件下,器件偏压-1.4 V时,测得响应电流8.9×10-9A,电流响应率达到2.54 A/W,量子注入效率超过90%。基于GaAs/InGaAs量子点光电探测器的高量子注入效率、高灵敏度等特点,采用具有稳定的电压偏置,高注入效率和低噪声特点的CTIA(电容互阻跨导放大器)作为列放大器读出结构,输出部分采用相关双采样(CDS)结构去除系统和背景噪声。实验结果表明,在3.5 nW的微光辐射下,器件偏压为-2.5 V时,50μm×50μm像素探测器与读出电路互联后有7.14×107V/W的电压响应率。