非均匀电离层中VLF辐射源在海面上产生的场

用于对潜通讯的星载的ＥＬＦ／ＶＬＦ发射天线处于３００￣４００ｋｍ高度的电离层Ｆ２层。本文将星载的天线理想化为一偶极子，电离层看成随高度变化的非均匀各向异性等离子体，分析计算了ＶＬＦ发射天线在海面上产生的场。     

低纬电离层闪烁与扩散F

同步卫星４ＧＨＺ电视信号和ＶＨＦ信标信号电离层闪烁与其附近的电离层扩散Ｆ资料进行比较，说明低纬电离层闪烁与扩散Ｆ有关正相关关系。     

LM331压频变换器的原理及应用

介绍了集成电路ＬＭ３３１的结构和特点，分析了Ｖ／Ｆ和Ｆ／Ｖ电路的工作原理，同时也给出了一些应用的例子。     

高压RESURF LDMOSFET的实现

利用ＲＥＳＵＲＦ技术，使用常规低压集成电路工艺，实现了适用于ＨＶＩＣ、耐压达１０００Ｖ的ＬＤＭＯＳＦＥＴ。本文介绍了该高压ＬＥＭＯＳＦＥＴ的设计方法、器件结构、制造工艺测试结果，此外，本文还从实验和分析的角度探讨了覆盖在漂移区上面的金属栅－金属栅场板长度ＬＦ对ＲＥＳＵＲＦ器件耐压的影响。     

深亚微米MOSFET二维数值模拟的若干结果

对溶亚微米器件，由于工作电压下降，要求重新确定ＬＤＤ和常规ＭＯＳＦＥＴ在ＶＬＳＩ中的作用。本文从基本器件数理方程发出，对深亚微米常规及ＬＤＤ ＭＯＳＦＥＴ的器件特性、热载流子效应及短沟道效应进行了二维稳态数值模拟，指出了常规和ＬＤＤ ＭＯＳＦＥＴ各自的局限性，明确了在深亚微米ＶＬＳＩ中，ＬＤＤ仍然起主要作用。     

用精确数字模拟方法建立激光对准模型

该文叙述了对准装置的三维计算机模拟技术和一些范例的计算。这项技术的开发为未来ＶＬＳＩ技术的发展，找到了对准和套刻精度问题的答案。分析的根据是通用的有限元电磁波传播码ＥＭＦＩｅｘ，它严格地模拟三维对准标记光的散射。Ｎｉｋｏｎ激光步进机对准（ＬＳＡ）装置作为模拟仪器，模拟了套刻误差和信号形状，研究了理想化的不对称金属标记的情况，表明严密模拟的初步结果，与以前所用的一维菲涅耳近似法有着实质性区别。     

用于高频回波探测的小型环天线的设计与应用

为了节省研发成本,缩短研发周期,方便电离层流动观测,设计了可用于1MHz~30MHz电离层回波探测的环天线,对该天线进行了辐射性能的仿真和天线阻抗的测量,设计了有源天线的前端信号放大电路。配合通用软件无线电平台USRP,组成了电离层高频回波探测系统,电离层扫频回波探测实验结果显示该天线能够宽频率范围工作,具有应用价值。     

片式高压多层瓷介电容器最新进展

片式高压多层瓷介电容器（ＭＬＣＣ）的研制生产水平已达额定直流电压０．５～２０ｋＶ。额定交流电压２２０～１１００Ｖ，标称电容量范围为：０．５ｐＦ～０．１５μＦ（Ｃ０Ｇ），４７ｐＦ～２．２μＦ（Ｘ７Ｒ）。产品技术标准尚未统一纳入国际标准体系。高压ＭＬ－ＣＣ在Ｖ－Ｃ、ＴＶＣ（温度、偏压、容量关系）、耐电压及电晕等性能和试验方法方面有特殊要求，设计制造技术有独到之处。高压ＭＬＣＣ的包装和使用须严格控制工艺过程。     

FO－560传真机故障检修实例

ＦＯ－５６０传真机故障检修实例邓圻贵例１故障现象：开机后液晶显示器上无显示，按键操作不起作用。故障检修：ＦＯ—５６０机的液晶显示器（ＬＣＤ）由＋５Ｖ电源供电，ＬＣＤ无显示，说明＋５Ｖ未加到ＬＣＤ上。首先检查电源单元有无＋５Ｖ电压输出。打开后盖板，取出...     

INTERBALL—2卫星MEMO实验观测结果的初步分析

利用ＩＮＴＥＲＢＡＬＬ－２卫星上多分量波测量实验（ＭＥＭＯ）在ＥＬＦ／ＶＬＦ／ＬＦ三个频段进行的高分辨率等离子体波观测结果。通过事件分析，给出了所观测到事件的波传播特性的估值。结果表明：对于极区千米波辐射（ＡＫＲ），Ｒ－Ｘ模式和Ｌ－Ｏ模式可以同时发生。前者在低频段，后者则发生在频率高端，两者传播是在准平行于地磁场方向的波法线方向上。ＶＬＦ嘶声发射表明主要是哨声模式，但其它模式也存在。利用波特性分析     

Radiation resistance of a small filamentary loop antenna in a cold multicomponent magnetoplasma

A study is made of the radiation resistanceRof a small filamentary loop antenna immersed in a cold collisionless uniform multicomponent magnetoplasma. Assuming that the current distribution along the loop is uniform and that the loop axis is parallel to the static magnetic field, an integral expression is derived forRwhich is valid for arbitrary values of driving frequency, plasma composition and density, and static magnetic field strength. The mathematical properties of this integral are such thatRis finite for all values of the driving frequency, including the upper and lower hybrid frequencies as well as the multiple-ion hybrid-resonance frequencies. Application of the integral expression is made to the case of the inner magnetospheric plasma and approximate closed-form expressions are developed forRfor the very low-frequency/extremely low-frequency (VLF/ELF) range in the magnetosphere. Numerical results in the VLF/ELF range are also presented. It is found that the inclusion of multiple ions introduces interesting effects: sharp maxima appear at the gyrofrequency and the multipleion hybrid-resonance frequency associated with each ion, while sharp minima occur at the "crossover" frequencies. It is concluded that the presence of these relative extrema in the radiation resistance presents interesting possibilities for the use of a small loop as a diagnostic tool in a multicomponent plasma.     

Radiation from a generalized antenna in a stratified medium

Exact calculations are made of the electromagnetic field radiated by an arbitrary current distribution in an arbitrary stratified lossy medium. The medium thus characterized can include both a stratified earth and a many layer stratified ionosphere. The results of the investigation, which include the input resistance and the efficiency of the antenna, are useful for designing antennas in the ELF, VLF and LF bands. (The theory is applied to the case of an ELF-ring antenna.)     

水下甚低频导航磁场接收天线设计

通过分析 Alpha 甚低频信号空气—海水跨介质及水下传播规律，重点研究了影响水下磁场天线接收性能的主要噪声源，并给出相应解决措施，提出了甚低频磁场接收天线的设计方案，经测试验证具备水下 20 m 接收甚低频导航信号的能力和可行性。     

透地通信信道特性的研究

由于大地信道稳定,低频透地通信被认为是最可靠的救急通信方式。对环状发射天线情形下分层大地的有关信道特性进行了探讨,以期为该系统设计及工程应用提供有益的指导。     

T型甚低频多调谐发射天线电容与电感研究

甚低频天线理论认为,采用多调谐方式,T型甚低频多调谐天线可以基本按比例增加天线电容,在实际工程中常用五组或六组天线.本文利用甚低频天线输入电抗的实测值,计算了在不同频率下天线所呈现的等效电容和等效电感,研究了T型甚低频发射天线的等效电容、电感、功率容量与天线组数及频率之间的关系.研究结果表明T型甚低频多调谐天线的组数过...     

计算电离层VLF波传输特性的时域有限差分算法

在星载甚低频( VLF)通信技术中,研究甚低频信号在电离层中的传输特性具有重要意义。现有的利用时域有限差分( FDTD)算法研究电离层传输特性大多基于高频脉冲信号,且传播模型相对粗略,计算存在一定误差。为此,建立了更为精确的电离层各向异性传播模型,对常规的FDTD算法引入变步长因子,并用该算法对VLF波在电离层中的场强衰减进行了数值计算,研究了昼夜变化及频率对其传输特性的影响。仿真结果与卫星实测数据对比表明：与常规的FDTD算法以及全波分析方法相比,引入变步长因子的FDTD算法精度更高;在VLF频段,降低频率有利于电磁波穿透电离层,且白天的衰减明显大于夜间;VLF波在射入电离层并穿透D层时衰减严重(30~40 dB),约为F1层中衰减的3倍。     

Electric field sensors in electromagnetic sounding

A staked and an insulated dipole antenna were used to monitor transmissions from a distant very-low-frequency transmitter. The field strength recorded from the staked antenna was found to be much larger than that recorded from the insulated antenna. It is shown that this can be adequately described as magnetic field induction. It is postulated that an insulated antenna is a far better electric field probe for surface impedance investigations including audio magnetotelluric (AMT), controlled source audio magnetotelluric (CSAMT), and VLF sounding techniques     

甚低频系留气球缆绳天线设计实现与效能分析

甚低频系留气球缆绳天线是机动式车载甚低频通信系统的重要组成部分. 该缆绳在作为气球浮空平台系留缆的同时,还需兼具甚低频段电磁波的天线辐射功能. 本文针对甚低频辐射天线的电气特性及物理特性,通过对天线关键参数的计算、不同风速下的缆绳姿态及辐射方向图的设计仿真,在工程上以光电复合系留结构形式进行实现。最终结合理论分析与全系统通信试验数据对甚低频系留气球缆绳天线的辐射效能做出了综合评估,验证了该天线设计的正确性与高效性,为国内甚低频辐射天线的相关研究积累了一定的经验与数据.     

Wave emission from an open-ended cylindrical channel in a coldmagnetoplasma

We study wave emission from a transmitting system consisting of a magnetic-field-aligned cylindrical plasma channel of enhanced density and a loop antenna immersed in it. An ambient medium is assumed to be a cold uniform magnetoplasma. It is found that when the plasma density in the near-antenna zone increases, the total power radiated from the antenna increases considerably due to the efficient excitation of guided modes on the channel. We consider the emission of these modes from the channel end, assuming that the plasma density in the channel decreases gradually with distance from the loop. It is shown that under ionospheric conditions this transmitting system can be useful for improving the antenna coupling to VLF waves of the ambient plasma