Radio direction changes and variations of audibility

As a result of a large number of systematic measurements on direction of incoming signals, using loop reception, variations of considerable magnitude in the apparent direction and occurring within short periods of time are found. Their dependence on length and character of wave are studied. There are certain possible theories of transmission proposed to account for the observed phenomena, notably reflection at the atmospheric "isothermal layer" (6.2 miles or 10 kilometers high), and the production of rotating fields at the receiving station.