Modeling the received signal for the Canadian over-the-horizon-radar

The detection performance of high frequency over-the-horizon radar (HF OTHR) systems is heavily influenced by the presence of radar clutter that originates by Bragg backscatter from plasma structures in the aurora zone, denoted as auroral clutter. The work in [1] developed a data model for the clutter seen by HF OTHR system. The model uses a geometric optics approach to determine the power spectral density (PSD) of the radar signal phase as a function of space and Doppler. However, in that approach the space-Doppler spectrum focuses on a single transmit-receive ray path. This, in turn, forces the clutter to occupy a very narrow notch in Doppler. This issue was addressed in [1] by multiplying the resulting clutter signal with a series of random Doppler shifts per pulse thereby introducing a Doppler spread in the clutter. In this paper we present an extension of this model for auroral clutter wherein the clutter is modelled as a superposition of multiple rays each of which, individually, satisfies the model in [1]. The paper also addresses the modelling of the target return that is not addressed in [1]. The target model presented here uses the power spectrum approach to estimate the angle-Doppler spread due to signal propagation through the ionosphere.