天线开关管频率特性的计算机辅助设计

该文以集总参数元件为理论模型,给出天线开关(TR)管频率特性的理论表达方程组,用FORTRAN语言对它们进行了模拟计算;给出了参差调谐、非四分之一波导波长耦合线以及元件损耗等一些非标准因素对频带特性的影响,给出了四元件TR管的参差调谐及耦合线长度的最佳值,并与试验结果进行了比较;在程序设计中采用了计算机自动选择最佳参数以及屏幕图形方式技术直接显示计算曲线的方法。该文所采用的理论模型及计算方法也适用于一般微波滤波器的分析模拟。     

用放射性示踪法在天线开关放电中研究气体的清除

在天线开关放电中,放射性的示踪气体被用于研究高频激励气体的清除过程。这种放射性的示踪技术用于预放TR管和ATR管中,提供计算石英管的有效放电面积和予计工作寿命的方法。在金属壁的TR管中,这种示踪技术用来研究放电的主要吸收机理和临界面积亦是有用的。     

含有石英放电管的厚谐振窗的频率特性的研究

正 本文叙述的含有石英放电管的厚谐振窗是用在大功率TR开关管中作为输入窗的,有时也可以单独作为大功率TR开关管。本文从实验上研究了这种窗体的谐振频率f0和带宽△f/f0与窗体几何尺寸的关系。本实验得到的改变两窗口间的距离和窗体的厚度对f0和△f/f0的影响的曲线尚未见有文献报道。因此,它们对于设计这种类型的大功率TR开关管有一定的参考价值。 窗口间距离和窗体厚度可以改变的实验模型如图1所示。整个窗体是由两个精密加     

脉冲功率电路参数对RSD开关预充时间的影响研究

文章介绍了高功率半导体脉冲功率开关-反向开关晶体管（Reversely Switched Dynistor,RSD）的工作原理,分析了RSD脉冲功率电路的特性。由磁开关的电压电流,得到了磁开关的动态电感与电流的量化曲线,在MATLAB仿真平台,分别建立了磁开关动态电感模型、RSD脉冲功率电路模型。计算了主回路元件参数对RSD开关的预充时间TR的影响。计算结果表明,主回路电阻负载在0.01～1Ω变化时,TR变化很小,主回路电感和1Ω以上的主回路电阻对TR影响较明显,计算结果与实验结果最大误差为5%,表明通过低压试验结果的计算,可较准确地预测高压试验的TR。     

孪生TR开关管相位特性的研究

本文从实验上研究了平衡天线开关中孪生TR管的两单管间的相位差对开关接收损耗和接收驻波比的影响。结果表明,当两单管间的相位差大于30°时,则接收损耗将大于0.5dB,接收驻波比也相应增大。文中还将实验结果和理论计算作了比较。 本文还研究了由三级插入式放电管组成的孪生TR管中各级管子的相位与整管相位的关系;结果表明,这个关系近似地符合相位叠加原则。     

现代雷达系统用的电子管

近代雷达系統的主要发展趋势是晶体管化,但采用許多种特殊用途的电子管也能使系統获得良好的性能。文中介紹了几种典型的脉冲雷达用的电子管:脉冲磁控管、同軸磁控管、頻率抖动磁控管、旋转調諧磁控管、泊管、特高頻功率放大管、正交場放大管、多腔速調管、行波速調复合管、反射速調管、大功率行波管、耦合腔行波管、低噪声行波管、超高功率管、TR管、予放TR管、ATR管、复合TR管以及雷达指示器用的阴极射线管。     

TR组件自动测试系统设计

TR组件待测数据量和需计算数据量大、控制信号繁琐,构成测试系统的仪表较复杂,需要设计全自动TR组件测试系统以满足相控阵雷达研制需求。根据被测TR组件工作特点,本文详细介绍了测试系统组成和测试原理,测量精度的计算。     

微波管工厂与电子测量

1.前言目前工厂制造的微波管有许多种。以前有从栅控式电子管(孩管在低于微波的频率下使用)发展起来的板极管(一种超高频三极管)以及速调管、磁控管、行波管、返波管等,而且应用的例子还很少,目前正在制造磁控放大管——特高频功率放大管和交叉场放大管等。此外,还生产了相当多的充气开关放电管(TR管、ATR管、Pre TR管)等,特别用于雷达等的发射接收转换。这样,由于种类多,其工     

无源TR管放电保护特性的实验研究

介绍了雷达接收机用气体放电管－TR管的结构和工作机理,给出X波段某型无源TR管在不同峰值功率、脉冲宽度和重复频率X波段微波信号作用下的放电特性测试方法,研究了其对大功率微波信号的压缩作用;从实验角度获取了透过功率、脉冲宽度与入射功率、脉宽和重复频率的关系,重点分析了其对高峰值功率、低重复频率微波短脉冲信号的放电特性,得出其对大动态微波短脉冲接收装置的放电保护性能;为无源TR管改型设计、HPM短脉冲雷达体制的技术可行性论证和当前雷达设备抗电磁辐射能力验证研究提供了参考数据。     

超宽带传输参考接收机的性能研究

分析了超宽带传输参考(TR)接收机的原理和优势,针对UWB通信应用在多个比特传输中信道基本不变的特点,将TR信号集合扩展为一帧几个参考信号和多个数据信号,提出了一种改进TR接收机。文中对基本TR接收机和改进TR接收机的性能进行了理论分析,并采用IEEE的CM1、CM2多径信道模型进行了性能仿真,结果表明,综合考虑性能、传输效率和成本,改进TR接收机优于基本TR接收机。     

Comparison of degradations in radar system sensitivities due to TR tube and TR limiter

The degradation of radar system sensitivities due to the TR tube and the TR limiter are calculated. A general expression relating to the various parameters of the TR tube and the TR limiter and noise figure of the receiver is derived from the condition that the TR limiter will be more sensitive than the TR tube with keep-alive, KA. In particular, the TR limiter may be less sensitive than the TR tube with KA due to the higher insertion loss of the TR limiter. The much longer life of the TR limiter, however, may be the deciding factor for its use in a radar receiver.     

A new concept in microwave gas switching elements

A gas switching tube commonly known as a TR tube is an RF energy switch, the operation of which is a function of incident power level. Switch operation is achieved by gaseous ionization. The major problem in the design of gas switching devices has been that of achieving simultaneously a short recovery time and a low arc loss. This problem has been eliminated by the development of the device described in this paper. The design objective was to produce a self-contained TR window for operation at very high powers. The arc loss developed by conventional tube design at these high power levels would be sufficient to melt any known window material. The design of this device is such that the ionizable gas blanket takes the form of a thin-walled cylinder suspended in the iris in a dielectric cylinder. This configuration presents a smaller volume of gas with a reduced cross section and a much shorter diffusion length. These changes result in lower leakage power, faster recovery time, and reduced arc loss. As finally developed, the window does not involve glass-to-metal or ceramic-to-metal seals. The problem of metal sputtering or outgassing is therefore eliminated. By a unique spring pressure support, the problem of strain developed by differences of thermal coefficients of expansion is eliminated. The open-ended design of the cylinder provides excellent facilities for cooling the window. Prototype units have been successfully operated in "L" Band at power levels considerably in excess of 15 mw peak power and 30 kw average power. These units exhibited recovery times of 5 to 20 µsec with high-level attenuation of 26 to 35 db and arc loss below the level of present measuring techniques, i.e., < 0.02 db. A practical window for these high powers with a loaded Q of less than 1.5 has been fabricated.     

On noise generated in ignitors of TR tubes

The noise generated by a dc glow discharge inside a coaxial ignitor embedded in a standard X-band TR stage has been studied experimentally and the results analyzed. The noise variation due to changes in physical dimensions, notably the dc and RF gap length, have been experimentally measured and a physical explanation presented to account for the phenomenon. Dependence on dc current, pressure, and gas type was also measured in controlled experiments. It is shown that the generated noise and the coupling of this noise to the microwave transmission line is a critical function of the tip shape and insertion depth of the solid cone into the coaxial ignitor cone. This effect is due to the interception of the charge carriers by the apex of the solid cone. This interception creates a noise current whose axis makes an angle with thebar{E}vector of a propagating mode(s). When this angle is small and the discharge current large, the noise energy in the transmission line becomes large. Data showing a linear dependence of generated noise with ignitor current provides strong evidence that this is shot noise. Calculations of the available thermal power per cycle and the shot noise power per cycle are summed and compared with each other and with experimental values. These calculations further indicate the dominance of shot noise power under experimental conditions simulating a practical TR tube. Conclusions regarding techniques for the development of ultralow noise TR's are given.     

“电气控制与PLC”课程中疑难指令的教学探讨

本文针对欧姆龙CPM1A系列PLC的TR、微分与非微分指令形式、顺序控制步转换条件等教学难点进行了深入剖析。结合梯形图实例讨论了TR作用、指令的微分与非微分形式的意义、顺序控制步转换条件中上步控制位的作用及常用指令LD N容易忽视的问题。所作分析有益于克服PLC教学难点,提升教学效果。     

Efficient computation of marginal reliability-importance forreducible+ networks

Marginal reliability importance (MRI) of a link with respect to terminal-pair reliability (TR) is the rate to which TR changes with the modification of the success probability of the link. It is a quantitative measure reflecting the importance of the individual link in contributing to TR of a given network. Computing MRI for general networks is an NP-complete problem. Attention has been drawn to a particular set of networks (reducible networks), which can be simplified to source-sink (2-node) networks via 6 simple reduction rules (axioms). The computational complexity of the MRI problem for such networks is polynomial bounded. This paper proposes a new reduction rule, referred to as triangle reduction. The triangle reduction rule transforms a graph containing a triangle subgraph to that excluding the base of the triangle, with constant complexity. Networks which can be fully reduced to source-sink networks by the triangle reduction rule, in addition to the 6 reduction rules, are further defined as reducible⁺ networks. For efficient computation of MRI for reducible⁺ networks, a 2-phase (2-P) algorithm is given. The 2-P algorithm performs network reduction in phase 1. In each reduction step, the 2-P algorithm generates the correlation, quantified by a reduction factor, between the original network and the reduced network. In phase 2, the 2-P algorithm backtracks the reduction steps and computes MRI, based on the reduction factors generated in phase 1 and a set of closed-form TR formulas. As a result, the 2-P algorithm yields a linearly bounded complexity for the computation of MRI for reducible⁺ networks. Experimental results from real networks and benchmarks show the superiority, by two orders of magnitude, of the 2-P algorithm over the traditional approach     

在超高真空中用加热银管获得纯氧的方法和气体的质谱分析

正 (一)引言 我们知道,在真空条件下可以由化学反应产生氧,例如,加热氧化亚铜、氧化锰或过氧化钡等;也可通过真空阀门向真空室内放入纯氧;而通过加热银管向系统内放入高纯氧则是较简便的方法,这是本文所要讨论的内容。当然,更新的获取高纯氧的方法是用氧化钙稳定氧化锆作渗透膜。 (二)实验技术和结果 我们的实验系统如图1所示。它包括抽速为60l/s的三极式溅射钛离子泵(日本     

Ga阶梯分布改善快速晶闸管耐压特性

利用开管扩Ｇａ系统，分段控制掺杂量，使杂质Ｇａ在硅中形成阶梯形分布，用于快速晶曾管的研制，理论分析与测试结果表明，器件阻断耐压值比原高分布提高２００Ｖ左右，且通态特性和动态特性保持优良。实验证明，Ｇａ的阶梯分布是的晶闸管后条新途径。     

Non-Gaussian smoothing of low-count transmission scans for PET whole-body studies

A non-Gaussian smoothing (NGS) technique is developed for filtering low count transmission (TR) data to be used for attenuation correction (AC) of positron emission tomography (PET) studies. The method is based on a statistical technique known as the generalized linear mixed model that allows an inverse link function that avoids the inversion of the observed transmission data. The NGS technique has been implemented in the sinogram domain in one-dimensional mode as angle-by-angle computation. To make it adaptive as a function of the TR count statistics we also develop and validate an objective procedure to choose an optimal smoothing parameter. The technique is assessed using experimental phantoms, simulating PET whole-body studies, and applied to real patient data. Different experimental conditions, in terms of TR scan time (from 1 h to 1 min), covering a wide range of TR counting statistic are considered. The method is evaluated, in terms of mean squared error (MSE), by comparing pixel by pixel the distribution for high counts statistics TR scan (1 h) with the corresponding counts distribution for low count statistics TR scans (e.g., 1 min). The smoothing parameter selection is shown to have high efficiency, meaning that it tends to choose values close to the unknown best value. Furthermore, the counts distribution of emission (EM) images, reconstructed with AC generated using low count TR data (1 min), are within 5% of the corresponding EM images reconstructed with AC generated using the high count statistics TR data (1 h). An application to a real patient whole-body PET study shows the promise of the technique for routine use.