Investigations on ultra-high frequency electromagnetic oscillations

Dawton, Ralph H.V.M. (1944). Investigations on ultra-high frequency electromagnetic oscillations. University of Birmingham. Ph.D.

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Abstract

The Thesis opens with an introduction to electrical resonators and some instruments which are special to the centimeter region of wavelengths. The excitation of resonators by the principle of the velocity modulation of electrons is then given and it is followed by a brief mention of velocity modulated oscillators and magnetron oscillators. Little specific mention is made in these sections of the author's work. A reference is however made to an early split anode 3 cm. magnetron and also to a tunable velocity modulated oscillator. These were made by him before such tubes had passed the experimental stage. The development of magnetrons required some
simple but reliable method of measuring pulsed high tension power. Some satisfactory methods developed by the author are described. To prevent there being any possible doubt, these power measurements were checked by careful measurement of the heat developed in the magnetron. To examine the electric fields within resonators and feeder lines small test probes and loops are necessary. These probes and loops require a consideration of the various types of rectifiers, detector instruments and high frequency matching sections. All are discussed both from their simplicity of design and from their performance.
For the design of 3 cm. magnetrons, whose output system was to be matched to the standard fitting used in the Services, an accurate standing wave measuring instrument was built. The errors occurring in these instruments are examined and shown to be negligible only under certain conditions of operation. The general properties of wave guides and coaxial cables are given prior to an account of the author's experiments on the measurements of magnetron output powers. Mention of preliminary work on power measurement is made and is followed by a full description of a rugged glass contained helical absorber suitable for low or for high power routine measurements. Full details of the calibration of the absorbers is given. There are also details of a calorimeter for coaxial output valves and also for wave guide output valves. These instruments have given a trouble free performance for nearly two years and are eminently suited for use in factories for testing the quality of the valves produced. The increase in the output powers tram magnetrons soon necessitated a complete redesign in the output system. The author's experiments on what was, as far as he is aware, the first 3 cm. wave guide output valve are included.

Type of Work:	Thesis (Doctorates > Ph.D.)
Award Type:	Doctorates > Ph.D.
Licence:
College/Faculty:	Faculties (to 1997) > Faculty of Science
School or Department:	Department of Physics
Funders:	None/not applicable
Subjects:	Q Science > QC Physics T Technology > TK Electrical engineering. Electronics Nuclear engineering
URI:	http://etheses.bham.ac.uk/id/eprint/7678

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