Simon Ramo

Currents Induced by Electron Motion

A method is given for computing the instantaneous current induced in neighboring conductors by a given specified motion of electrons. The method is based on the repeated use of a simple equation giving the current due to a single electrons movement and is believed to be simpler than methods previously described.

Electrostatic Electron Microscopy. I

This paper, consisting of three parts, describes investigations made with the objective of developing a simplified, practical microscope of the type which yields magnified images of transparent specimens with a resolving power superior to that of the best light microscopes. The first part deals with the general problem of design, including the electron gun and the imaging lenses. A later part will describe a completed instrument embodying many of the results of the investigations.

Electrostatic Electron Microscopy. II

This paper is a continuation of the description of problems arising in the development and design of an electrostatic electron microscope. The present article discusses depth of focus, lens and field stops, shielding, manufacturing tolerances, the choice of the number of stages of magnification, and alternative methods of viewing and recording the final image. A following paper will describe a completed instrument.

Propagation of Electromagnetic Waves in a Space Charge Rotating in a Magnetic Field

A theoretical discussion is presented of the transmission of electromagnetic waves of the symmetrical, transverse magnetic type by a space charge of uniform density, rotating under the influence of a uniform magnetic field. It is shown that the space charge presents to the wave an effective dielectric constant less than unity. By appropriate choices of magnetic field, the dielectric constant can be reduced to zero and can even become negative, so that the wave undergoes attenuation as it passes through the space charge. Experiments are described on the control of the propagation constants of 470‐megacycle waves by variation of the dielectric constant of the rotating space charge medium. The results obtained are in agreement with the theoretical predictions.

Electrical concepts at extremely high frequencies

Some of the characteristics of electricity when the frequency of alternation reaches the range of billions of cycles per second are discussed in relation to the physical pictures of basic electrical concepts, such as current flow along conductors, in tubes, and in circuits which are being evolved by engineers in the high-frequency field. As applied to high-frequency phenomena, some of these concepts now are being modified or broadened in order that more accurate pictures may be obtained.

A New Postgraduate Course in Industry in High-Frequency Engineering

THOSE FIELDS of engineering which utilize high-frequency electric currents and electronic devices have long ago graduated from the trial and error stage. The empirical experimenter who is ingenious and observant will always be useful, especially in some new and fruitful phase of the art not yet well understood. However, reliance has for many years been placed upon the ability of the engineer to design analytically upon a sound basis in the underlying theory and analytical tools are recognized as valuable aids and guides in laboratory work.

Synthesis of a High Frequency Reactance

Foster’s reactance theorem (1) provides the necessary information for the synthesis of the most general dissipationless reactance provided the frequency range is such that lumped reactances, namely inductance coils and condensers, are available. At the higher frequencies these are difficult to obtain practically and the impedence elements must be treated in design as the transmission lines with distributed inductance and capacity which they truly are.