Abstract :
It has been known for a long time that signals from strong commercial stations can be received in the skip zone. Early investigations with a short-wave Adcock direction-finder showed that the signals within the skip zone are in general characterized by absence of bearing. The present paper is a complete investigation into the causes of such effects. It was found that they are due to momentary irregularities and small clouds in the E region of the ionosphere. These irregularities produce scattered signals. The investigation, first carried out with the Adcock direction-finder, was later made more definite and accurate by using short impulses from highpowerstations. The later investigations entirely confirmed the original deductions. The effects of such scattering on long-distance transmission, direction-finding, etc., are discussed. The phenomenon is considered to be a major factor in practically all transmissions.
