The two-frequency, two-time coherence function for the fluctuating ionosphere: wideband pulse propagation

This article presents a numerical investigation of the two-frequency, two-lime coherence function for HF wave propagation in the fluctuating ionosphere. Earlier published results of numerical calculations, with an empirical plane-stratified background ionosphere and a power-law spectrum of the electron density fluctuations, show that the coherence function in general has a rather complicated behaviour and that it does not fall off quickly with increasing difference frequency. Under these circumstances, the case of wideband pulses requires particular considerations which are presented in this article. The shape of a wideband pulse is generally represented by two items, namely the contributions from the fluctuational and coherent components of the field that has passed through the fluctuating ionosphere. (C) 1997 Elsevier Science Ltd.