A time reversal parabolic equation based localization method in evaporation duct

Abstract

Evaporation duct is a multipath environment on the sea, which tends to distort the signals, causes lower localization accuracy or even affects the normal work of radar when using the traditional localization algorithms. This paper presents a localization method in time reversal parabolic equation based on the radiation pattern loading. It could effectively handle the effects of evaporation duct and adaptively compensate the signal distortion, form time reversed waves matched with the propagation environment, and lead to a robust focusing and localization of the target. This method uses multipath effects flexibly to increase the effective aperture of antenna array for super resolution. In addition, it has a good tolerance in element spacing leading to a sparse array configuration which is more practical on the sea and widens its application fields. Simulation results show that the azimuth resolution in evaporation duct with the same aperture array has been improved 2 times more than in the free space by using this method; when 30λ is adopted as the element spacing, the sidelobe levels can be kept below -8.96 dB, so ghost images are effectively suppressed. The proposed method has strong robustness and high accuracy, thus may be useful in many practical applications, such as communication, search and rescue, pre-warning system on the sea, etc.