Experimental studies of the propagation of very short radio waves

The paper presents a survey of the experimental work on the propagation of very short waves, and especially of centimetre waves, carried out in this country during the war. Although much of the paper is necessarily descriptive, and by no means all the problems are solved, it has been written with the aim of providing the radio engineer with applicable results where they have been established. After referring to the main differences in propagation characteristics between these waves and longer radio ground-waves, the state of the art at the beginning of the war is briefly noted and the development of the war-time experimental work is outlined. Some simple theoretical characteristics are then described to provide a background for the experimental results which follow. Preliminary experimental studies over land and sea paths are described, with a summary of the tentative conclusions to which they led. The main experimental programme consisted of measurements of 3-cm, 9-cm, and 3¿-m waves over sea paths 57 miles and 200 miles in length; and of 9-cm waves over a single 38-mile land path. The measurements were continuous over some of these paths for periods between two and three years; and, particularly as regards detailed correlation with meteorological measurements, the work is still in progress. In a concluding Section some investigations into special aspects of very-short-wave propagation are described; data on reflection from sea and land, and on the effect of obstacles, are included in this Section.