一种由基本割集矩阵求网络图的方法

对于一个给定的网络图,可以确定对应的网络矩阵。同样,如果给定网络矩阵,也能够画出对应的网络图。本文讨论由基本割集矩阵求网络图的方法,该方法利用基本割集矩阵Q和降价关联矩阵A的关系,由Q得到A,进而画出对应的网络图。本文的讨论可供从事电路教学的教师参考。     

Modal analysis of loaded N-port scatterers

AnN-port loaded scatter is one havingNports to which lumped impedance loads or a load network is connected. Methods are given to determine the characteristic modes of a loaded scatterer and for using them in a modal solution for electromagnetic scattering. A procedure is also given for resonating any given real port current, which makes that current the dominant mode of the loaded scatterer. The theory is formulated both in terms of open-circuit and short-circuit network parameters. A number of numerical examples are given for a wire triangle to illustrate the general theory. Computer programs are available for all procedures discussed.     

GPRS网络建设方案及设计

首先对GRPS系统基本结构进行了简单介绍。其次,根据广东汕头GPRS网络建设工程,详细说明了GPRS网络的设计方案。详细阐述了汕头GPRS网络连接方案、数据配置以及对现有网络的升级方案。最后对GRPS网络建设方案进行了总结。     

焦点移动现象的规律及成因

指出高斯光束人射时国孔衍射场的一般规律．画了不同Nw时衍射场振幅随（H,Pm）变化的函数图形。找到振幅极大值点移动的原因及焦移量的计算公式．     

Broad-Band Quarter-Wave Plates

Analytical expressions are given for the propagation constant for the two orthogonal dominant modes in a square waveguide loaded with a centered slab of dielectric. These are combined to find the differential phase shift in a loaded section. Solutions of these equations are given for polystyrene which enables one to design broad-band quarter wave plates. The problem of transforming from unloaded to loaded guide is discussed and two solutions are given and another suggested. Experimental results are given and it is found that the work in square guide carries over to circular guide almost intact. It is shown that quarter-wave plates may easily be designed to cover a normal waveguide bandwidth.     

Cumulative probability of detection for targets approaching a uniformly scanning search radar

This paper deals with the cumulative detection probability of a search radar when it is scanning uniformly. This is the probability that a target, approaching the radar at a constant radial velocity, is detected at least once by the time it reaches a given range, as distinguished from the more common blip-scan ratio (a single-scan detection probability). It is shown that for constant-velocity targets the range for a given cumulative-detection probability varies as the cube root of the power-aperture product, rather than as the fourth root. Curves of cumulative detection probability, as a function of normalized range, are given for three different target scintillation models. Also, curves of optimum (normalized) frame time, are given as a function of the desired cumulative detection probability for each of the three target scintillation characteristics.     

A generalization of the Pursley-Davisson- Mackenthun universal variable-rate coding theorem

Suppose nature selects a source from among a class of sources according to some prior probability distribution. With respect to a given fidelity criterion and a given distortion level, it is shown that there exists a variable-rate code such that the following is true. It is highly likely that nature will choose a source whose average distortion with respect to the given code achieves the given distortion level and whose average rate is approximately the optimum rate theoretically attainable. Only a very weak assumption has to be made. The assumption is satisfied, for example, for separable metric space alphabets and a distortion measure which is a nondecreasing continuous function of the metric. This generalizes work of Pursley, Davisson, and Mackenthun and settles a conjecture of Pursley and Davisson.     

Intrinsic Attenuation

The name "intrinsic attenuation" is suggested for the concept originally called "intrinsic insertion loss" and reasons for the proposed change are given. Formulas are given to permit calculation of this quantity, given the scattering coefficients of the network. The use of lossless tuners to obtain a bilaterally matched nonreflecting network is described, and the expected reduction in attenuation is discussed. A graph is presented for rapidly estimating this reduction in attenuation, given minimum information about the network. Experimental results for badly mismatched coaxial attenuators show that the losses in the tuners may in some cases prevent one from realizing any reduction in attenuation.     

On the convergence of discrimination information (Corresp.)

A sufficient condition involving a hypothesis of mean-square convergence is given for the convergence of discrimination information. A stronger condition requiring uniform convergence has already been given. An example is given which satisfies the mean-square convergence hypothesis but not the uniform convergence hypothesis.     

Rotating dielectric sphere in a low-frequency field

A general formulation is given for the fields of a rotating body of revolution immersed in an incident wave. A solution is outlined for the low-frequency case, and the solution is worked out for a sphere of given εr.     

Mode coupling in circular-cylindrical system and its application tofingerprint resonators

Coupled-mode equations are given in the circular-cylindrical coordinate system for the evaluation of two-dimensional fingerprint resonators. The general form of coupled-mode equations is outlined. The coupling coefficients are found for transverse electric and transverse magnetic modes. The quality value Q is defined, and a numerical evaluation is given. A detailed derivation of the coupled-mode equations is given     

Tunnel diode reverse characteristics at different temperatures

The tunnel diode characteristics in the reverse direction at low and high temperatures is investigated applying a simplified model of the heavily doped semiconductor junction. In this model momentum is conserved and a calculation of the tunneling probability is made on account of field and image-charge effects on the potential energy barrier.The energy gap of heavily doped germanium is plotted as a function of the impurity concentration at 78 and 300 K. It is suggested that the tunneling current increases with concentration for a given temperature, and with temperature for a given concentration.Our theoretical results are in good agreement with the experiments. The breakdown voltage decreases with temperature for a given reverse current. Finally it is suggested that the tunneling current in the Kane's theory is much larger compared to that given in the present theory and experiments.     

Impedance Transformations For The Generalized Reflection Modulator

A procedure is given for obtaining the impedance transformer which will produce a prescribed pair of phasor reflection coefficients by transformation from a given pair of impedance states terminating the transformer. The transformer may be used in a general two-state reflection modulator: as a phase shifter with phase change at constant amplitude or as an amplitude modulator with level shift at constant or variable phase. The condition governing the reflection coefficients available from a given pair of impedance states is given. Examples and limitations are discussed.     

Dimensions of Microstrip Coupled Lines and Interdigital Structures (Short Papers)

A method is presented for finding dimensions of coupled lines and interdigital structures on microstrip given the electrical properties. Both a graphical approach and computer approach using polynomial approximations are given. These results are within 1 percent of Bryant and Weiss' dimensions for coupled lines for most practical stripwidths and spacings. Experimental data for a 10-percent bandwidth microstrip interdigital filter are given.     

Statistical timing analysis of combinational logic circuits

Efficient methods for computing an exact probability distribution of the delay of a combinational circuit, given probability distributions for the gate and wire delays, are developed. The derived distribution can give the probability that a combinational circuit will achieve a certain performance, across the possible range. This information can then be used to predict the expected performance of the entire circuit. The techniques presented target fast analysis as well as reduced memory requirements. The notion of a correct approximation, based on convex inequality, which never overestimates the percentage of circuits that will achieve any given performance is defined. It is shown that given the assumption that all the topologically longest paths are responsible for the delay, the computation technique provides a correct probabilistic measure in the sense given above. Methods are given to identify and to ignore false paths in the probabilistic analysis, so as to obtain correct and less pessimistic answers to the performance prediction question. Some practical results are given for a number of benchmark combinational circuits     

Computation of the Transmission Line Inductance and Capacitance Matrices from the Generalized Capacitance Matrix

In a recent paper [1], a method for computing the per-unitlength generalized capacitance matrix of a system of dielectric-insulated wires was given. In this-paper, a method for computing the per-unitlength inductance and capacitance matrices used in multiconductor transmission-line models in terms of the elements of the generalized capacitance matrix is given. Certain approximate formulas for large wire separations are also given. Rome Air Development Center.     

An alternative diffraction coefficient for the wedge

A geometrical theory of diffraction (GTD) interpretation of a uniform solution for the wedge given by Mohsen is given. The diffraction coefficients are equal to those given by Kouyoumjian and Pathak except that the Fresnel argument in the two solutions are different. This uniform geometrical theory of diffraction (UTD) result is compared with exact series expansions for a plane wave incident on a90degwedge.     

Singularity Extraction from the Electric Green's Function for a Spherical Resonator (Short Papers)

The electric dyadic Green's function for a spherical resonator is expressed as a sum of two dyadics given in closed form and a dyadic given in the form of a series. The first two dyadics diverge at the source point and they represent a low-frequency approximation for the Green's function, valid up to frequencies moderately lower than the resonant frequency of the dominant mode. The dyadic given in the form of a series is finite at the source and takes into account cavity resonances. It is given either as a one-index series, whose terms are transcendental functions of the frequency, or as a double series, whose terms are rational functions of the frequency. Both series have very good converging properties everywhere inside the cavity.