Gain and G/T of multielement receive antennas with activebeamforming networks

A basic system-level model for the gain and G/T of active multielement receive antennas is presented that covers arbitrary beamforming networks and direct radiating arrays, as well as array-fed systems with one or more focusing elements (reflectors or lenses). Since the model is based on measurable parameters and uses definitions, which are consistent with conventional communication system analysis terms, it can be applied directly to the analysis and design of systems using such antennas and can be used to support the specification, design, and test of such antennas as well, measurement possibilities for the basic parameters are discussed and the characteristic parameters of generic active beamforming networks are derived and compared. Finally, the impact of the different parameters on the overall antenna gain and G/T is illustrated by one application example that covers a reconfigurable multifeed reflector antenna with selectable beamwidth. The presented theory has been verified successfully in the frame of a classified EHF antenna development whose details cannot be reported here     

G/T值自动化测试

G/T值是卫星地面接收系统的一项重要指标,常规测试方法耗时、费力、计算量大。通过工程实践详细论述利用射电星法测量地面大型天线系统的G/T值的原理及计算方法,论证G/T值自动化测试的可行性,并对测试过程中引入的测量误差进行了分析,给出G/T值自动化测试的实现方法及测试结果。该方法具有自动化程度高、测试指标精度高、测试速度快等特点,可广泛应用于各种卫星地面接收、航天测控等设备。     

New method for direct G/T measurement using satellite signals

A new possible method for direct G/T measurement using satellite signals is described. A formula for calculation of G/T from Y-factor and down link EIRP measurement is developed. The potential of the method for low G/T measurement is illustrated with possible applicability to Intelsat Standard B and C and ECS earth stations. Possible disadvantages are commented on.     

遥感卫星地面接收站的自动化测试系统

系统品质因数（G／T值）和系统误码特性是衡量系统的重要性能指标,检测系统性能时采用人工测试方法,复杂而耗时。文中介绍通过用射电星原理进行遥感地面站G／T值自动测试方法．以及利用调制、解调模型进行误码率的自动化测试方法。给出了测试原理、测试方案和实际运行效果。     

基于气象卫星数据的我国沿海悬空波导反演方法初步研究

悬空波导的测量方法有直接测量和间接测量两种.传统的直接测量手段只能得到单点的波导信息.间接测量也存在一定的局限性,不能获取高时空分辨率的波导多维空间信息.而静止气象卫星由于其高时空分辨率观测的特点,能对我国沿海海域大气环境进行时空四维监测.文中借鉴国外一种基于气象卫星数据反演悬空波导的方法,利用我国静止气象卫星FY-2G的云分类和云顶温度数据、地面观测数据及探空数据,分析该方法中各影响因素的敏感性,初步检验了该方法在我国沿海的适用性.提出建立本地海域悬空波导反演方法的几个关键问题：①选用高精度云顶温度反演数据;②选择合适规定层（850hPa或700hPa）;③根据本地数据得到一些参量的经验值;④建立本地参数化方案.下一步将寻找更多我国不同沿海海域的事例进行验证,该方法有希望运用到我国沿海大气波导监测中,为我国沿海大气波导监测和反演提供一种新方法新技术.     

太阳能电池并联电阻的一种测量方法

对于用常规工艺制作的大面积太阳能电池，需要经常对电池的并联电阻进行监测。文章描述的从电流的直流模型导出的并联电阻测量方法，只需将电池测量中的部分Ｉ－Ｖ数据进行处理，即可得出电池的并联电阻。     

利用仙后座A测量16m天线G/T值及误差分析

阐述了利用仙后座A测量地球站天线G/T值的原理和基本公式,讨论了其修正因子的计算方法,介绍了用多项式拟合确定任意频率G/T值的方法。给出了C频段16m天线G/T值的测量结果,实测结果同理论计算结果吻合很好。对G/T值的误差进行了分析和估算,其最大均方根误差±0.384dB。     

改进校准技术的转发器输入输出特性测试方法

当卫星发射定点后,必须对在轨卫星通信有效载荷(即转发器)的性能进行测试。输入输出特性是转发器的一项重要技术指标。本文在参考国家标准和INTELSAT测试方案的基础上提出一种改进校准技术的转发器输入输出特性测试方法,详细介绍了该方法的测试原理,同时还提出一种无需精确测量卫星信道传输时延的解决收发信号同步的方法。该方法减少了误差因素,提高了测试精度,而且使在轨测试系统的校准由程序自动执行,提高了测试效率。     

球面近远场和远近场变换算法

天线的远场对于研究天线辐射特性具有重大意义，近场测量技术因其能够避免直接测量远场而得到广泛应用，该技术采用近远场变换获得远场，然而，检验该远场的准确性也是很重要的.为了解决此类问题，文中以球面近场测量为例，提供了一种解决方案.该方案主要探讨了球面波模式展开理论，该理论是实现球面近远场变换算法的关键，其将待测天线在空间建立的场展开成球面波函数之和，天线的加权系数既包含了远场信息也包含了近场信息.因此，不仅能够利用近场测量信息获得远场辐射特性，同样能够利用远场辐射特性反推得到近场处电场，这样就能检验由近远场变换算法得到的远场是否准确.文中首先推算得到了近远场变换公式，随后进一步推算得到远近场变换的公式，最后将本文算法计算结果与FEKO测量结果进行比较，二者吻合良好，从而证实了本文两种算法的有效性.     

Waveguide dispersion measurement technique for single-mode fibersusing wavelength dependence of mode field radius

A waveguide dispersion measurement technique using a simple fitting function for wavelength dependence of the root-mean-square width in the far field and its theoretical measurement error are discussed. Results indicate that waveguide dispersion can be evaluated with theoretical accuracy of 0.5 ps/km/nm using this technique. The waveguide dispersions for conventional and dispersion-shifted fibers have been measured using the far-field pattern method. Good agreement between measured and theoretical values of waveguide dispersion was obtained. Material dispersion and dispersion sensitivity evaluation methods that are applications of this technique are also described     

The sidewall resistor—A novel test structure to reliably extract specific contact resistivity

Conventional contact resistance extraction structures suffer inaccuracies when measuring small values of contact resistivity which are sensitive to small perturbations in device fabrication. This is because two-dimensional current crowding around the periphery of the contact window introduces parasitic resistance components which are not accounted for by the one-dimensional model and which can be much larger than the contact resistance component for low values of specific contact resistivity ρc. Unfortunately, there is no direct method to isolate these parasitics, which makes the extraction of ρcusing the conventional test structures difficult. In this paper, a novel test device, the sidewall resistor, which utilizes the vertical sidewall dimensions, is demonstrated to circumvent these difficulties. The proposed structure has the advantage that a simple one-dimensional (1-D) extraction technique can still be used. The specific contact resistivity between pure Al and N+ polycrystalline Si is accurately extracted with the value of 7.4 × 10^-8Ω.cm². The sidewall resistor is then used to extract the contact resistivity between pure Al and WSi2which turns out to be less than 5 × 10^-9Ω.cm².     

一种基于预测值量测转换的卡尔曼滤波跟踪算法

在雷达目标跟踪中,系统量测信息通常在球坐标系下获得。为了采用经典卡尔曼滤波算法实现有效目标跟踪,通常采用量测转换方法将非线性量测信息转换到直角坐标系中。针对传统量测转换方法基于量测值计算转换误差统计特性而导致的估计结果有偏问题,提出了一种基于预测值的量测转换方法,并将其与卡尔曼滤波算法相结合,获得了一种基于预测值量测转换的卡尔曼滤波跟踪算法。仿真结果表明,与现有的基于量测转换的卡尔曼滤波算法相比,该算法能在不提高运算量的情况下有效改善目标跟踪效果,跟踪精度提升约20%。     

“电气测试技术”课程的特点及电流检测实例

“电气测试技术”是电气类的一门应用技术型课程,其内容以电气测试原理、方法以及传感器等为基础。通过该课程的学习,可以使学生掌握测试系统的构造方法。文章分析了该课程具有的理论性、实践性和综合性的特点,采用了检测电流的几个常用方法作为实例,对课程中的测量方法、误差合成等概念和霍尔传感器原理进行穿插讲解,达到预期的教学效果。     

Simultaneous Determination of Complex Permittivity and Permeability of Columnar Materials With Arbitrarily Shaped Cross Section

An effective simultaneous evaluation method for the complex permittivity and permeability of lossy materials is proposed by applying it to an arbitrarily shaped cross-sectional post placed in a rectangular waveguide. We use one sample and only measure S ₂₁ parameters for two different locations of the sample. The measurement of complex reflection parameter S ₁₁ is not required in this evaluation method. The scheme of electromagnetic field analysis for the evaluation is based on the extended spectral-domain approach combined with the mode-matching method, which is accurate and efficient, and can be flexibly used for the iterative fitting operation for the estimation of material parameters. Sample preparation and setting is significantly easier in this method compared to conventional methods. The error caused by deviations in the setting of a sample is investigated. The estimated values for the sample material by this procedure show good agreement with the results obtained using the conventional method over the X-band.     

Magnetotransconductance mobility measurements of GaAs MESFET's

It is demonstrated that the magnetic field dependence of the transconductance of short-gate GaAs FET's provides a direct means of characterizing the mobility profile of the active layer of the device, which does not require a capacitance measurement, and which is relatively insensitive to the parasitic series resistance associated with the source and drain contacts. The results are shown to be in agreement with those obtained from conventional measurements on a long-gate FET test structure.     

Accurate measurement of small input resistances using aconventional network analyzer

Precise and accurate measurement of input resistance is essential to characterize small antennas whose input resistance is very small. However, this is very difficult because uncertainty, which includes imprecision and inaccuracy, sometimes exceeds the resistance being measured. A method for precise measurement of small input resistance using a conventional network analyzer is presented. Inaccuracy, which includes an actual conductor loss of the antenna under test (AUT), manufacturing error, and the residual systematic errors is then estimated. The former two sources of inaccuracy are obtained by comparing a radiation efficiency measurement of a small loop antenna using the Wheeler cap method with a calculated radiation efficiency. Using these values in the calculation of the input resistance, a true input resistance is acquired. Finally, the actual value of the residual systematic errors for each instrument is estimated by comparison between the true input resistance and the measurement     

空间高分辨率光学系统几何畸变标定技术

遥感相机光学系统畸变系数作为影响相机在轨成像质量的关键因素,其检测精度一直以来都是遥感相机研制过程中的核心环节。传统的测角法主要依靠高精度二维转台,实现了光学系统视场角与像高之间的精准对应,该方法对测试设备和测试环境要求苛刻。随着相机焦距、口径和体积的增大,对于转台设备的尺寸与测量精度也日渐提升,单纯依靠提升测试设备性能无法满足后续各类高性能遥感相机的研制需求,尤其对于垂直装调类超大口径空间高分辨率光学系统,该方法不可行。在传统精密测角法的基础上,提出一种基于干涉原理的空间高分辨率光学系统几何畸变标定技术,相比于传统的精密测角法,该方法在同等测试精度的基础上,具备更广泛的适用性,其不再受限于测试设备的尺寸与精度限制,可同时满足各种类型遥感相机的畸变测试需求。文中详细介绍了该畸变测试方的基本原理、测试方法与误差链路,并对该畸变测试方法进行了应用验证,将结果与传统畸变测试方法进行对照,表明该方法的测试精度满足遥感相机的研制要求且适用范围更广,对航天长焦距大口径遥感相机研制及畸变测试有参考借鉴意义。     

A simple and efficient measurement method for characterizingcapacitance matrix of multilayer interconnection in VLSI

A compact new test structure for direct extraction of components of the capacitance matrix for multilayer interconnections is presented. In this new method, each capacitive component in integrated structures is separately and directly obtained from measurement, and the total pads are kept to eight, independent of the size of the target matrix. As a result of evaluation of measurement errors caused by the asymmetry of structures, this new method can measure components of capacitance matrix with a precision of femto-farad order     

产品质量检测中试验数据异常值的处理

在产品质量检测的一组试验数据中。有时会出现个别的异常值,从直观上看,这个数据要比其它数据小许多或者大很多。在处理试验数据时,对于这样的异常值,是否要剔除？如果单凭直观的判断,似乎缺乏理论上的依据。提出了应用数理统计的方法,对试验数据的异常值进行剔除的观点。     

Quantifying charging damage in gate oxides of antenna structures for WLR monitoring

A new method to quantify the reliability risk for gate oxide with plasma induced charging damage (PID) is established. Based on existing antenna test methodology the quantity of inflicted damage is expressed in a physical meaningful number by means of a simple model applicable for thick oxides (>5 nm).This model takes trap activation, trap filling, detrapping and also traps generation under constant current test condition (“revealing stress”, “diagnostic stress”) into account. For the corresponding development of the measurable external supply voltage with time an equation is derived. Experimental test data from different oxide thicknesses are fitted to this model equation to obtain its main parameters, the cross section values. These cross section values describe the probabilities for the different trap/detrap processes during stress. Cross section values thus found extend published data for lower electric fields to high electric fields necessary for a fast test.The number of plasma induced traps, which was added to the oxide during wafer processing, can now be determined by applying an electron trapping rate (ETR) test method, and combining it with our dynamic trap generation/filling model. The obtained number of PID related traps opens a path to calculate the corresponding reduction of oxide lifetime. Real measurement data are used to illustrate the method and its applicability to fast wafer level reliability (fWLR) monitoring.