The Theory and Practice of Radio Frequency Measurements: a Handbook for the Laboratory and a Textbook for Advanced Students

Abstract

IT is difficult for a wireless worker of to-day, who has been trained along modern lines, to realise how much precision has been introduced into his subject by the development of the thermionic valve. Important radio measurements were made in pre-War days, but in every case strong signals had to be used. The difficulties were largely due to the relative insensitivity of the instruments available for the measurement of high-frequency currents and potentials. But this, of course, did not prevent the pioneers of those days from making the very best use of the instruments at their disposal, and more than twenty years ago Duddell and Taylor, in a classical series of experiments, laid the foundations of the subject of signal measurement by studying the falling-off of signal intensity with increase of distance from a radio transmitter. In these experiments the high-frequency currents produced in a receiving antenna were measured directly with a Duddell thermogalvanometer. Although audible signals were detectable at much greater distances, quantitative observations were possible only up to a distance of 80 miles. In signal strength measurements over long distances, subjective methods involving audibility comparisons had to be used which were not very trustworthy.

The Theory and Practice of Radio Frequency Measurements: a Handbook for the Laboratory and a Textbook for Advanced Students.

By E. B. Moullin. (Griffin's Scientific Textbooks.) Pp. xi + 278. (London: Charles Griffin and Co., Ltd., 1926.) 25s. net.