1. D0020 D regiont That part of the ionosphere in which the D layer tends to form.

2. The region between Earth's surface and the ionospheric D-layer behaves thus like a waveguide for VLF- and ELF-waves.

3. This means that a vertically polarized incident wave after reflection at the ionospheric D-layer converses to a vertically and a horizontally polarized wave.

4. P0980 Polar cap absorption Effect on radio waves in high latitudes, caused by a sudden increase in the electron concentration in the D layer of the ionosphere.