DOI:10.1049/ji-3-1.1944.0020

出版商:IEE    

年代:1944

数据来源: IET

摘要:

In modern microwave technique transmission lines find wide application both for the interconnection of component pieces of equipment, such as oscillators and receivers and aerial systems, and as inductive and capacitive circuit elements within these pieces of equipment. In the former they are normally several wavelengths long, but in the latter only fractions of a wavelength. The analysis of their behaviour has been greatly facilitated by the development of a circle diagram technique, the theory and application of which are discussed.This is followed by a discussion of the fundamental principles underlying the transmission-line equations on which this technique is based, and of the meaning to be attached to the word “impedance” at very high frequencies in respect of terminating attachments to lengths of transmission line. In particular, attention is given to the physical possibility of producing a non-reflecting termination, on one aspect of which there appears to have been widespread misunderstanding.

DOI:10.1049/ji-3-1.1944.0021

出版商:IEE    

年代:1944

数据来源: IET

摘要:

An electronic oscillator is a “machine” for the conversion of d.c. power into a.c. power, with electrons as moving parts. By means of the Maxwell-Poynting theory the conversion process can be localized, and analysed into the elementary contributions of volume elements. Integral relations for the whole valve can be expressed in various forms of which the following lends itself best to physical interpretation: The power consists of three parts. The first is “collector power,” determined entirely by the potentials and currents of the electron collectors. The second is “transit power,” produced by changes of space potential during the flight of the electrons. The third power component is due to electric fields induced by alternating currents. This is negligible under quasi-static conditions, but becomes of the same order as the transit power when the valve itself begins to emit radiation.All methods of producing alternating electron currents can be reduced to emission, deflection or transit time modulation. A threefold division is adopted also for the sources of the electromagnetic field. Space charges and their complementary surface charges play no direct part in power conversion. An exhaustive classification of all power-producing processes under nine headings is obtained, and is applied to a few special examples.

DOI:10.1049/ji-3-1.1944.0025

出版商:IEE    

年代:1944

数据来源: IET

摘要:

A description is given of the calibration of commercial thermocouple milliammeters at frequencies of 100 Mc/s and 700 Mc/s. Errors dependent on current amplitude were found, and were shown to be due to the magnetic properties of the material used for the heater wires. The occurrence is confirmed of frequency-dependent errors, due to the method of constructing the ordinary instruments. Specially made instruments, though superior in respect of these errors, are likely to be of limited usefulness on account of the disturbance which is caused by the inclusion of any such device in a circuit carrying current at very high frequencies.

DOI:10.1049/ji-3-1.1944.0032

出版商:IEE    

年代:1944

数据来源: IET