摘要:

A description is given of important improvements and modifications which have been made in the design of a flat television tube. In the new form, magnetic components have been eliminated and considerable structural simplifications have been made. An electrostatic deflection system is described which is capable of giving deflection angles of ±60°, and a mathematical model of such a system is developed. The design of the electrostatic collimator which follows the deflection system is treated mathematically, and results of measurements on experimental models of both components of the tube are described. The action of the scanning array which provides the frame scan is discussed.

DOI:10.1049/piee.1968.0087

出版商:IEE    

年代:1968

数据来源: IET

摘要:

A theoretical and experimental investigation into narrow-bandwidth microwave rejection filters, which can be constructed from simple, standard microwave components, is described. Suppression factors of at least 50dB at resonance are possible, and the bandwidth can be easily controlled. A simple form of analysis, which indicates clearly the effects of variation in the parameters, gives good agreement with experimental measurements. The possibility of using a 2-cavity system to obtain a slightly broader frequency response and a very low insertion loss, at the expense of a lower suppression factor at the centre frequency, is indicated.

DOI:10.1049/piee.1968.0088

出版商:IEE    

年代:1968

数据来源: IET

摘要:

The noise performance of transistor mixers at high frequencies is investigated by first considering the signal processes in the mixer. A knowledge of the mixer signal performance, and consideration of the various noise sources in the transistor, allows calculation of expressions for the mixer noise figure and optimum source resistance. The effects of variation in operating conditions are discussed, and, in particular, it is shown that, at very high frequencies, the mixer noise figure increases rapidly with collector current. Expressions for mixer and amplifier noise figure are compared and the basic differences are discussed.

DOI:10.1049/piee.1968.0090

出版商:IEE    

年代:1968

数据来源: IET

摘要:

Shockleys's theory of the junction field-effect transistor with step-junction transitions is reviewed and improved. Estimates of the effect of channel-length modulation on the output conductance and drain-to-gate capacitance are obtained. Theoretical results for both the constant mobility and field-dependent mobility cases are presented and are compared with experimental measurements made on a commercial planar field-effect device.

DOI:10.1049/piee.1968.0091

出版商:IEE    

年代:1968

数据来源: IET

摘要:

A propagation mechanism is discussed which comprises two reflections from a horizontally-stratified, partially-reflecting layer. Such a layer located appreciably below the ‘crossover height’ (i.e. the height of intersection of the horizon rays from the terminals) may cause an enhancement of signal strength which exceeds that obtained with a single reflection from a similar layer at the crossover height. This mechanism appears to give a satisfactory explanation for the experimental results obtained by Lane and Sollum in a study of layer-mode propagation over two radio paths, of length 139 and 309km, the shorter being over land and the longer partly over sea.

DOI:10.1049/piee.1968.0092

出版商:IEE    

年代:1968

数据来源: IET

摘要:

An asynchronised synchronous machine is a combination of a doubly excited synchronous machine and an automatic control system, and it overcomes some of the basic disadvantages inherent in a synchronous machine. The paper describes some analogue-computer studies in which the steady-state and transient characteristics of an asynchronised synchronous machine are examined from the point of view of power generation.

DOI:10.1049/piee.1968.0093

出版商:IEE    

年代:1968

数据来源: IET

摘要:

The application of theo-d-qtransformation (due to Park) to the induction-machine equations is used to develop a set of equations suitable for use with a digital computer in the analysis of dynamic performance. The method of calculation is designed to be compatible with those already in use for the analysis of synchronous-machine behaviour and makes use of a novel equivalent circuit. An account is given of measurements taken on a range of laboratory motors to determine the variation of the principal parameters of the equivalent circuit with slip and voltage. A method of analysis is discussed which allows an adequate representation of an induction motor to be included in stability studies. The measured performance shows good agreement with that predicted using the computer program for the case where a small motor is fed from a larger machine which has lost synchronism, and an indication of the effect of neglecting some of the corrections is included.

DOI:10.1049/piee.1968.0094

出版商:IEE    

年代:1968

数据来源: IET

摘要:

In order to study the influence of terminal capacitors on the transient behaviour of an induction machine, differential equations are developed in which the nonlinear effect of magnetic saturation is taken into account. Theoretical results obtained from a digital-computer solution of these equations are compared with experimental measurements on a 7.5hp motor. The transients investigated are those (a) following disconnection and reconnection to the supply with power-factor-correcting capacitors; (b) following disconnection and reconnection to the supply of the machine operated as a capacitor-excited induction generator; (c) during capacitor and magnetic braking of the motor.

DOI:10.1049/piee.1968.0095

出版商:IEE    

年代:1968

数据来源: IET

摘要:

The general phenomenon of voltage collapse or instability at the load end of transmission links is introduced with reference to previous work, and the induction motor is seen to be the critical constituent of system loads. The power/voltage and reactive-power/voltage characteristics of power-system loads are predicted and accurately represented by polynomial expressions which are used in the analysis of radial transmission links fed from infinite busbars. Graphs summarising the critical load voltages and the corresponding short-circuit levels for various transformer tap ratios are given and are general in application; these are based on thedV/dZcriterion for voltage stability. It is shown that, although tap changing to raise the load voltage increases the critical length of the link, it also reduces the margin between normal operating voltage and the voltage at the onset of instability. The effects of the injection of reactive power by static capacitors are discussed, together with the effect of the induction-motor content of the loads. The use of thedEs/dVrcriterion as advocated in the Russian literature is discussed.

DOI:10.1049/piee.1968.0096

出版商:IEE    

年代:1968

数据来源: IET

摘要:

Partitioning techniques for the nodal-impedance methods of the power-system network load-flow solution are derived and classified. The techniques include normal matrix inversion using partitioning and successive inverse modification, the topological or diakoptic and the algebraic partitioning principles. The paper shows how, without reference to network graph theory, these principles follow from simple rearrangement of the matrix iterative procedures.

DOI:10.1049/piee.1968.0100

出版商:IEE    

年代:1968

数据来源: IET