Waveguide Investigations with Millimicrosecond Pulses

Pulse testing techniques have been employed to advantage in waveguide investigations in numerous ways. The importance of better resolution through the use of short pulses has always been apparent and, from the first, equipment was employed which used as short a pulse as possible. Radar-type apparatus using magnetrons and a pulse width of about one-tenth microsecond has seen considerable use in waveguide research, and many of the results have been published. 1,2 35 36 THE BELL SYSTEM TECHNICAL JOURNAL, JANUARY 1 9 5 6 To improve the resolution, work was initiated some time ago by S. E. Miller to obtain measuring equipment which would operate with much shorter pulses. As a result, pulses about 5 or 6 millimicroseconds long became available at a frequency of 9,000 mc. In a pulse of this length there are less than 100 cycles of radio frequency energy, and the signal occupies less than ten feet of path length in the transmission medium. The RF bandwidth required is about 500 mc. In order to obtain such band widths, traveling wave tubes were developed by J. R. Pierce and members of the Electronics Research Department of the Laboratories. The completed amplifiers were designed by W. W. Mumford. N. J. Pierce, R. W. Dawson and J. W. Bell assisted in the design and construction phases, and G. D. Mandeville has been closely associated in all of this work. 2. PULSE GENERATION