Polarisation of Echoes from the Heaviside Layer

Abstract

ONE of the most fruitful methods of investigating the Heaviside layer is that originated by Breit and Tuve, in which a series of short impulses of the order of 0.2 of a millisecond in duration are transmitted and the direct ray and echoes reflected at nearly normal incidence are observed at a neighbouring station. The echo patterns observed are often very complex and it has been found that a single F layer echo, say, is often split into two fairly closely spaced components. This has been attributed by Appleton to the double refraction suffered by a ray in passing through the ionised regions of the upper layer.