Investigation on accurate signal modelling and imaging of the moving target in ground-based forward scatter radar

摘要

The existing signal model and imaging algorithm of the moving target in the forward scatter radar (FSR) are built based on the assumptions that the baseline is long, diffraction angle is small and velocity direction of the target is approximately perpendicular to the baseline. However, the ground-based FSR system is characterised by short baseline and large diffraction angle, and the velocity direction of the target is not always perpendicular to the baseline. Therefore in many cases, the above assumptions introduce significant errors to the imaging results in the ground-based FSR. In the light of the imaging requirements of the moving target in the ground-based FSR, firstly, the current forward scatter (FS) signal model is modified using the high-order approximation method based on the Fresnel-Kirchhoff diffraction formula. The modified signal model considered the effect of high-order terms of Doppler phases, quadratic term of the target profile length, velocity direction of the target and diffraction angle changes, and therefore FS signal of the moving target in the ground-based FSR can be more precisely described. Secondly, the current imaging algorithm is modified based on the modified signal model, and the expressions applicable to precise reconstruction of the target profile in the ground-based FSR are analytically deduced. Finally, the effectiveness of the modified imaging algorithm is validated through the simulation results.