Wideband scattering functions for HF ionospheric propagation channels

A physically based method has been developed to simulate the wideband HF io nospheric propagation channel relevant to the case of wideband spread spect rum HF communications and also other HF applications such as digital broadc asting and over-the-horizon radar, It is based on the consideration and sol ution of the equations governing pulse signal propagation through a fluctua ting time varying random ionosphere. The wideband scattering function has b een constructed as the appropriate Fourier transform of the correlation fun ction of a channel impulse response. Numerical codes have been written, whi ch allow numerical simulation of the wideband scattering function of the HF sky wave ionospheric fluctuation channel for any given model of the backgr ound ionosphere and time varying ionospheric turbulence with an anisotropic inverse power law spatial spectrum and frozen drift of the ionospheric inh omogeneitics. When employed in the simulation of the scattering function fo r real conditions of propagation, the method provides the possibility of an alysing the propagation effects for different relative bandwidths of the ba ckground channel, fluctuating channel and transmitted pulse. The effects of the transmitted pulse bandwidth and anisotropy of the irregularities have been studied. The numerical results have been obtained and presented, which demonstrate the contribution of the effects enumerated in the wideband sca ttering function of the HF ionospheric channel. (C) 2001 Elsevier Science L td. All rights reserved.