The Role of the Propagation Environment in HF Electronic Warfare

摘要

The HF propagation channel is characterized by its inextricable relationship to the ionospheric medium; and because the medium is variable in both space and time, the channel is itself a temporally and spatially-varying entity. The nature of the channel has been the subject of continuous investigation over the years and models of propagation effects have been developed to assist in communication system design and in operational frequency management. HF communication system sensitivity to ionospheric disturbances is well known and the role of the benign ionosphere in affecting efficient skywave communication is acknowledged. NRL is investigating various remote sensing schemes including terrestrial-oblique and satellite-borne ionosonde to serve as update tools in the specification of the ionosphere. It has been shown by NRL tests that ionospheric specifications using these tools may be useful over an extended geographical zone. Furthermore, temporal extrapolation (i.e., forecasting) may be satisfactory for up to 24 hours provided the forecast is not obviated by unexpected intense solar and magnetic activity. Following identification of certain well known propagation principles, this paper outlines how quasi-real time propagation data may be utilized to engage in operationally-viable propagation tactics.