Shielding Effects in Thin-Film Integrated Circuits

The shielding effect of a thin (or thick) film ground plane on two film conductors has been theoretically investigated by viewing the problem as that of determining the scattering matrix coefficients of a microstrip directional coupler in terms of various transmission-line parameters. The effect of resistive losses in the film conductors and ground plane are considered and methods of systematically determining all transmission parameters have been evolved. Recently published equations for the design of coupled microstrips are used to determine pertinent transmission-line parameters. These results can serve as a guide to designers of thin-film integrated circuits, wherein undesired coupling levels can be predicted and optimum circuit layouts can be determined.     

EMP对电子电路的影响及其防护

EMP对电子电路的正常工作构成了严重的威胁,其防护日显重要。根据电磁脉冲的特点分析了EMP对电子电路的损伤模式及其危害程度评估,最后给出了相应的防护措施,重点介绍了保护电路的应用,并对实际例子进行了分析。     

基于屏蔽暗箱窗口法材料快沿电磁脉冲屏蔽效能测试*

为满足材料强电磁脉冲场屏蔽效能的测试需求,搭建了基于屏蔽暗箱窗口法的材料电磁脉冲屏蔽效能测试系统.首先采用连续波对某种金属织物材料进行了频域测试,通过测试空箱和加载材料内部场强大小,计算了该材料的频域屏蔽效能.然后采用快上升沿电磁脉冲源对该材料进行了时域测试,计算了强场作用下材料的峰值屏蔽效能.对测得的时域信号进行降噪处理和快速傅里叶变换(FFT),得到了该材料频域屏蔽效能曲线,与频域试验所测曲线进行了对比,结果基本一致.实验表明该测试系统能够可靠评价强电磁脉冲作用下材料的屏蔽效能.     

基于箱体法材料电磁脉冲场屏蔽效能测试研究

为准确评价屏蔽材料在强电磁脉冲环境中的屏蔽效能,提出了一种基于屏蔽暗箱窗口法的材料电磁脉冲屏蔽效能时域测量方法。该方法将带有测试窗口的屏蔽箱体置于GTEM 室内,被测屏蔽材料安装在屏蔽箱的测试窗口上,利用置于腔体中心的单极子天线测量耦合进腔体的电磁脉冲电压波形,对测得的时域电压信号进行快速傅里叶变换( FFT) ,得到了被测材料频域屏蔽效能曲线。与频域测试结果进行了对比,结果基本一致。实验表明该测试系统可以有效减小局部增强效应对测量精度的影响,能够可靠评价强电磁脉冲作用下材料的屏蔽效能。     

地下工程中金属门非核电磁脉冲屏蔽效能研究

以圆形截面坑道为简化模型,运用旋转对称体时域有限差分法将三维问题转化为二维问题处理,计算了地下防护工程口部金属门对高功率微波、超宽带电磁脉冲的屏蔽效能,分析了门缝大小、门框嵌入岩土介质深度对屏蔽效能的影响,确定了场泄漏的主要途径.计算结果表明,门对坑道中不同的传输波模具有不同的屏蔽效能;泄漏场主要是通过门框的绕射进入工程内部,门缝的泄漏较小,门缝大小以及门框嵌入岩土介质的深度对屏蔽效能的影响是次要的;另外,通过门的泄漏场在工程内部迅速衰减;HPM的载频越高,UWB的脉宽越窄,门的屏蔽效能越好.最后对数值计算结果和实验测得数据进行了比较,二者吻合较好,证实了数值计算的有效性.     

贯穿设备屏蔽层线缆电磁脉冲响应研究

提出了一种获取电子设备壳体屏蔽层外接线缆电磁脉冲耦合响应的计算方法。首先,以壳体屏蔽层为分割点,将贯穿线缆分为内外两部分,根据基本传输线理论和戴维南等效原理,得到内外两段线缆的等效电路模型。然后,利用Agrawal散射电压模型分析了外等效电路的端口负载频域响应,并根据该负载响应得出了内部线缆等效电路的端口负载频域响应。最后,以高空核爆电磁脉冲的IEC标准波形为计算波形,通过傅里叶变换方法求解了内部端口上的时域响应,并分析了线缆几何参数和终端负载对响应波形的影响。     

"平台",浮出水面--访爱立信移动平台有限公司总裁

爱立信移动平台有限公司总裁桑迪(Sandeep Chennakeshu)博士在移动电话行业的研发领域成绩斐然。在过去的19年中，他一直从事该领域的工作。1996年，桑迪博士荣获了爱立信年度发明家奖，还在全球拥有170项专利。他于1994年加盟爱立信，先后担任了诸多高级技术与管理职务：他所从事的领域包括：TDMA、GSM、CDMA、PDC、WCDMA、蓝牙以及卫星技术。     

System-generated EMP

The state of the art of system-generated electromagnetic pulse (SGEMP) is reviewed with particular emphasis on the empirical laws of photoelectron emission current and the analytical and numerical techniques employed for the calculation of currents and charges induced on the surface of a system such as a satellite.     

EMP susceptibility insights from aircraft exposure to lightning

Examines the interactions of natural lightning and the nuclear electromagnetic pulse (EMP) with aircraft. The propositions that one can use normal exposure to lightning to provide information on EMP protection, and deliberate exposure to lightning to test EMP protection are evaluated. The rarity of encountering lightning, its random occurrence and variability (necessitating extensive onboard instrumentation), and its apparent deficiency in energy at the high frequencies make the use of lightning for an EMP surveillance or test impractical     

电磁脉冲对射频接收机威胁分析

射频接收机是现代电子系统中最重要的组成部分,应用在通信、导航等许多领域。射频接收机一般位于天线后端,直接发送和接收空间中的各种电磁信息。然而,由于接收机可以接收到任何信息,因此它也极易被干扰,如高功率噪声和电磁脉冲。首先分析了电子设备的电磁环境,然后主要以射频接收机为对象,将电子系统模块化建模,分析在空间环境中遭遇电磁脉冲攻击时的受损情况,最后通过系统建模仿真,分析了电磁脉冲对射频接收机后端系统的损坏情况。     

Shielding Characterization of Metallic Enclosures With Multiple Slots and a Thin-Wire Antenna Loaded: Multiple Oblique EMP Incidences With Arbitrary Polarizations

Shielding effectiveness (SE) of metallic rectangular enclosures with thin slots and a thin-wire antenna loaded by an impedance, illuminated by multiple electromagnetic pulses (EMPs) simultaneously, is investigated using a hybrid finite-difference time-domain (FDTD) method. In order to enhance the simulation efficiency of the FDTD algorithm, accurate formulas for handling multiple thin slots, a thin-wire antenna, and a lumped network are integrated together. Numerical results show that for real metallic enclosures, their shielding performance is very sensitive to the variations in direction and polarization angle of the incident EMPs. However, at a given frequency, the resistance and inductance loaded at the terminal of a thin-wire antenna have little effect on the SE level. For two, three, as well as more EMP incidences, common-frequency interferences will result in strong inner field resonance in the enclosure.      

受散热制约的屏蔽技术

如果我们想尽办法,系统仍然不能满足它的电磁兼容性(EMC)要求,可以采用屏蔽-一种非常有效的干扰抑制技术.我们只需在干扰电路的周围加上均匀、连续的封闭体,问题即可解决.这是目前唯一不会带来负面影响的干扰抑制技术,它在减少辐射发射的同时,也降低了敏感度.由于屏蔽技术不涉及电路内部,因而它在解决EMC问题的同时不会影响电路的高速正常工作.     

A Transformation Method from Voltage-Mode OP-Amp-RC Circuits to Current-Mode Gm-C Circuits

A new transformation method is presented and used to transform voltage-mode op-amp-RC circuits to current-mode Gm-C ones. The proposed method enables the generation of high-performance Gm-C filters that benefit from the advantages of good and well-known op-amp-RC structures and the advantages of the current-mode circuits, and at the same time feature electronic tunability, high frequency capability, and monolithic integration ability. An attractive feature of the proposed method is that it results in Gm-C structures with only grounded capacitors in spite of the presence of floating capacitors in the original op-amp-RC circuits and it utilizes a small number of transconductors. Moreover, simultaneous multiple outputs are easily available in the transformed current-mode Gm-C circuits.     

电爆装置的电磁脉冲响应

介绍了电爆装置在电磁脉冲环境下的感应电流响应特征。分别进行了MIL-STD-461F 环境下,同种电爆装置不 同脚线长度情况下,感应电流的变化;以及同种脚线长度,不同脉冲环境,电爆装置感应电流的分布情况;研究了不同 脉冲环境,不同脚线长度对电爆装置感应能量的影响,对于实际测试和理论开展都有一定的意义。     

Shielding TCP from last hop wireless losses

The pervasiveness of the transport control protocol (TCP) and the proliferation of wireless local area networks (WLAN) of the 802.11 type make the topic of TCP performance over last hop wireless networks very relevant. The Snoop protocol, a link layer solution introduced several years ago to improve the performance of TCP in this scenario, has been shown to neglect its benefits to the most widely used TCP version, TCP SACK. In this paper, we introduce the TCP SACK‐Aware Snoop protocol to address this problem. Our results indicate that the TCP SACK‐Aware Snoop protocol improves the performance of TCP SACK by around 30% compared with the original Snoop protocol and by about 8% in an environment where no TCP enhancing mechanism is in place. In addition, we introduce further modifications to the proposed protocol to make its advantages available to any TCP sender. We also show that the mechanism does not introduce unfairness among TCP sources and somewhat protects TCP against UDP traffic. Our results show important throughput improvements to all TCP versions and demonstrate that the TCP SACK‐Aware Snoop protocol shields TCP from last hop wireless losses providing throughtput values very close to the maximum possible. Copyright © 2006 John Wiley & Sons, Ltd.     

EMP simulators for various types of nuclear EMP environments: An interim categorization

Nuclear EMP environments have various forms depending on the location of the nuclear detonation and the location of the system exposed to the EMP environment. One can simulate these environments with various degrees of completeness on such systems. A simulator produces an EMP environment on a system of interest in a manner which can be related to the type of nuclear weapon detonation being simulated. There are many types of EMP simulators, some of which have been realized in one or more existing EMP simulators. Some types of EMP simulators only exist conceptually at the present time. This note discusses the basic types or categories of EMP simulators. Such categories are based on the electromagnetic geometry of the simulator structure and electrical sources, including the location of the system under test and other nearby materials significantly influencing the electromagnetic fields. The various types of simulators are suitable for simulating different types of nuclear EMP environments. A particular type of EMP environment can be simulated with different degrees of completeness depending on the type of simulator used. In this note we only consider nonnuclcar types of ernegy sources, and in some cases high energy photon and electron sources. The EMP simulators considered range from ones which illuminate entire systems, down to ones which drive individual penetrations into systems. Not considered here are techniques for testing individual components or "black boxes" or driving the system at some intermediate point along an internal coupling path.     

Electro-Optical System for EMP Measurement

An electro-optical system is described for measuring the E-field component of electromagnetic pulses (EMP) produced by an EMP-simulator. Typical rise time of these pulses is down to 10 ns, measured E-field strength from 1-500 kV/m. The measurement device consists of a He-Ne-Laser as the light source, fiber optics as the transmitter with a length of up to some hundred meters, a Pockels-cell with two polarizers as the sensor modulating the light intensity in dependence of E-field strength, and a photodiode with preamplifier and storage oscilloscope as the detector. The wide E-field range can be measured by capacitively coupling the E-field to the Pockels-cell via pairs of plane antennas with variable area. Measurements are shown of pulses produced by a laboratory simulator and a field simulator.