DOI:10.1049/piee.1965.0001

出版商:IEE    

年代:1965

数据来源: IET

DOI:10.1049/piee.1965.0002

出版商:IEE    

年代:1965

数据来源: IET

摘要:

The scattering matrix is now sufficiently well known to become a useful tool in formalising the discussion of circuit behaviour in terms of wave concepts. Some examples are given to illustrate the utility of the scattering approach in describing the operation of such devices as circulators, hybrid junctions and negative-impedance, amplifiers. The treatment is aimed at the circuit engineer who is conversant with the matrix methods of circuit analysis yet unfamiliar with the application of scattering methods to the class of problem in which wave concepts are a real advantage.

DOI:10.1049/piee.1965.0003

出版商:IEE    

年代:1965

数据来源: IET

摘要:

The paper considers the influence of orbital parameters on the economic provision of simultaneous multiple interconnections between large numbers of earth stations in a global communication-satellite system.In order to provide direct communication between many countries which may be widely separated geographically, and also to avoid certain technical problems, it is most important to provide the interconnections wherever practicable on a one-hop basis. It is also desirable that each earth station shall work simultaneously to as few satellites as possible.These requirements can most readily be met by a system of geostationary satellites. However, such a system may prove unacceptable from other points of view (e.g. that of transmission delay).From an examination of the relations between coverage zones, orbital parameters and number of satellites required, it is concluded that large coverage zones may also be obtained with relatively few satellites by using systems in which each satellite follows the same earth track as its predecessor. The coverage provided by a number of such systems is discussed.

DOI:10.1049/piee.1965.0004

出版商:IEE    

年代:1965

数据来源: IET

摘要:

Ionospheric propagation at medium frequencies depends almost entirely on the ordinary wave, which is, in general, elliptically polarised. This paper describes coupling losses which occur when this wave is transmitted and received with vertical aerials, it also discusses additional losses caused by changes of polarisation when intermediate earth reflections occur. Formulas are given, permitting the various losses to be estimated; these are necessarily approximate, because they are based on the simple ray-theory approach. By way of example, curves are given showing the calculated losses for one typical frequency and angle of incidence.

DOI:10.1049/piee.1965.0005

出版商:IEE    

年代:1965

数据来源: IET

摘要:

The general principles of a proposed logic system using magnetic films are described. Groups of binary storage cells are coupled by means of short planar conducting loops close to the film on a conducting substrate. A theoretical analysis is made of the current induced in the loop when a storage cell on it is read. Currents of 250mA, decaying to 50mA in the first 10ns, are expected. Experiments on the properties of a short loop coupling the cells are described, the measured currents being in general agreement with those predicted over the possible range of measurement, provided that the effects of the substrate in setting film cells are separated from the effects of the loops. It is concluded that, although a complete logic system could be made using the proposed technique, the rapid decay of the currents used to set the cells would require the use of very fast pulse generators, and the system could not complete economically with conventional transistor logic of the same speed. The experiments show the practical possibility of two forms of nondestructive-readout store.

DOI:10.1049/piee.1965.0006

出版商:IEE    

年代:1965

数据来源: IET

摘要:

The determination of the resistance of plane dissipative layers by impedance measurement is treated. Special attention is devoted to the range 1–104Ω per square at 7Gc/s. Formulas are derived from transmission-line theory by making certain approximations, and the ranges of validity of these approximations are discussed. For 10–300Ω per square, a simple graphical method is given. Experimental results show that the h.f. and d.c. resistances for two kinds of layers agree, but that a third kind shows substantial differences between the two resistances.In an Appendix a formulation of the input impedance of transmission lines is proposed that is specially suitable for transmission lines consisting of sections with different propagation coefficients.

DOI:10.1049/piee.1965.0007

出版商:IEE    

年代:1965

数据来源: IET

DOI:10.1049/piee.1965.0008

出版商:IEE    

年代:1965

数据来源: IET

摘要:

In blast-cooled electrical machines in aircraft, the minimum permissible mass flow of cooling air, the electrical output, the air outlet pressure (a function of aircraft altitude), the air inlet temperature (a function of aircraft speed and altitude) and the pressure drop across the machine are all related to each other. Experimental data concerning these quantities are obtained from rating tests on a prototype machine, and are generally presented graphically by means of a ‘rating-data chart’.This paper describes a new form of rating-data chart, consisting of four component graphs. It has been derived from the heat-transfer and pressure-drop correlation equations of the physical system, and it expresses mass flow as a function of electrical output, pressure and temperature, and pressure drop as a function of mass flow, pressure and temperature. This form of presentation enables it to cover accurately the wide ranges of pressure and temperature which obtain in modern high-performance aircraft. The accuracy of the new form of chart has been assessed from charts for five machines, and is considerably greater than that of the simpler form of chart generally used at the present time.

DOI:10.1049/piee.1965.0010

出版商:IEE    

年代:1965

数据来源: IET

摘要:

Postwar developments in building have increased the importance of automatic controls for heating and air-conditioning installations because of the demand for comfortable environmental conditions and the large potential saving of fuel obtainable with appropriate controls. The reasons why the actual performance of heating controls is often unsatisfactory are considered.The characteristics of buildings and heating systems affecting the design and selection of automatic controls are discussed, and the principal elements of control systems are described, particular attention being devoted to improvements considered necessary to overcome difficulties in application.The application of these elements to typical systems of electrical heating, conventional central heating and air conditioning is then considered, and the paper concludes by discussing the problems of installation and maintenance and demonstrates how these can be alleviated by suitable design procedures.

DOI:10.1049/piee.1965.0011

出版商:IEE    

年代:1965

数据来源: IET