This paper addresses the estimation of the height of a point scatterer over a sea surface via multipath exploitation for a High Range Resolution radar that is using pulse range compression, such as Synthetic Aperture Radars. We first focus our attention on the physical model, in particular on the specular/diffuse reflection coefficients, this coefficients being derived from the empirical Miller Brown and Vegh model. The gravity waves are also simulated since they modify the acquisition geometry such as the local grazing angle. Secondly, the signal model is derived, thus allowing an easy derivation of the time delays (direct echo and replicas), these time delays being converted into a height estimation for possible automatic ship recognition applications. Our algorithm is a non-conventional radar signal processing, in other words it uses the backscattered pulse over before range compression and demodulation. The aim of the paper is to understand for which radar and sea parameters, as well as acquisition scenes, it is possible to extract the scatterer height information using the multipath of the backscattered electromagnetic wave.

In this paper, a new method is proposed to retrieve target reflectors heights for maritime surveillance applications. Multipath propagation over sea surface is used to retrieve the height information for each target reflectors. Firstly, radar raw data with multipath propagation are simulated. The backscattered electric field from a marine scene is predicted with physical models for the environment and the target. The scene is made of given wind conditions, a linear sea surface and a boat, as a set of point reflectors. Multipath propagation is included with the so-called Four-Path Model. Secondly, height estimation of target reflectors is realized by estimating temporal delays between neighbouring paths of the multipath propagation pattern. Performances of the height estimation algorithm for only one reflector are studied with regards to noise levels.

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