Wideband modelling and measurement of trans-ionospheric radar waveform propagation

A propagation model has been developed to simulate the corruption of wideband radio waveforms (such as radar chirps) as they pass through a non-homogeneous ionosphere. The ionosphere is modelled by a series of phase changing screens and a split-step parabolic equation method is used to describe the propagation of the complex electromagnetic field in planes normal to the propagation vector. Wideband characteristics of the channel are calculated by propagating spectral components of the waveform spectrum through the phase screens and then reconstituting the signal at the ground via a Fourier transformation into the time (delay) domain. By estimating the ionospheric drift velocity, the channel scattering function (signal power vs Doppler frequency and time delay) is calculated for a given satellite orbit and pulse repetition frequency (PRF).