Propagation Effects on HF Skywave MIMO Radar

MIMO technology has been suggested as an eective tool to overcome some of the issues typical of conventional OTH skywave radars. The advantages of the application of MIMO technology to HF Skywave radars is based on the transmission of multiple linearly independent waveforms and their separation at the receiver. Notwithstanding, the high instability of the ionosphere is responsible for severe signal fading and degradation that can prevent the separation with consequences on the radar performance. The present thesis is concerned with the problem of the eects of ionospheric propagation, which are analyzed from a theoretical point of view at rst, through the description of the ionosphere morphology and the disturbances that aect the ionospheric electron density structure. The relation between structural variations in the ionosphere and the transmitted signal parameters has been then derived. A radar signal simulator has been realized accordingly to the signal model proposed in the thesis. The results of the thesis concern three dierent aspects of propagation in HF MIMO radars. The orthogonality of the transmitted waveforms after ionospheric propagation is analyzed rst, while the eects of ionospheric propagation on the results of conventional beamforming is studied secondly. The performance of the radar receiver are evaluated in terms of ROCs in case of multipath propagation and compared to the single path case.