Inspec keywords: ionospheric electromagnetic wave propagation; HF radio propagation; F-region; electromagnetic wave reflection; ionospheric techniques; radio direction-finding; plasma density; interplanetary magnetic fields; electron density; geomagnetic variations; measurement errors

Other keywords: polar-cap ionosphere; measurements; geomagnetic activity; geomagnetic parameters; interplanetary magnetic field; directional components; convection; large HF bearing errors; high-latitude ionosphere; large electron-density gradients; overdense plasma; HF signal propagation; high-latitude auroral arcs; propagation paths; very high-latitude receiving site; received signal bearing; tilted reflecting surfaces; great circle path; polar cap; F-region ionosphere

Subjects: F-region; Ionospheric electromagnetic wave propagation; Radionavigation and direction finding; Interplanetary magnetic fields; Geomagnetism and geoelectricity; Radiowave propagation; Atmospheric, ionospheric and magnetospheric techniques and equipment