Space Reflection Research Articles

Imperfections in Active Transmission Lines

The effect of discrete imperfections on the behavior of active transmission lines (i.e., lines with distributed gain) is considered. Two cases are studied: 1. Lines with identical, equally spaced reflectors. The transmission and reflection gains versus frequency are studied as functions of the magnitude of the reflectors. Limits on the magnitude of the reflectors to guarantee stability are investigated. 2. Lines with random reflectors, having random position and/or magnitude. The statistics of the transmission are studied; in particular, the average value and the variance and covariance of the transmission are determined for small reflections. If the reflections become large enough, instability may occur, and these calculations may become invalid. Stability of active distributed systems is studied in a companion paper.1

Measurement of Atmospheric Attenuation at Millimeter Wavelengths

A frequency-modulation radar technique especially suited to measurement of atmospheric attenuation at millimeter wavelengths is described. This two-way transmission method employs a single klystron, a single antenna and a set of spaced corner reflectors whose relative reflecting properties are known. Since the method does not depend on measurements of absolute antenna gains and power levels, absorption data can be obtained more readily and with greater accuracy than by the usual one-way transmission methods. Application of the method is demonstrated by measurements in the 5-mm to 6-mm wave band. The results have made it possible to assign an accurate value for the line-breadth constant of oxygen at atmospheric pressure; the constant appropriate to the measurements lies between 600 and 800 MCS per atmosphere.