Objectives  Changes in attitude caused by sailing motion will lead to changes in the probability density of the radar cross section (RCS) of a ship. As such, it is necessary to master the influence degree of various motion conditions on the probability density of the RCS of a ship under grazing incidence.

  Method  Using the quasi-static method, a hydrodynamic and electromagnetic scattering characteristic co-simulation model and calculation process are constructed. A 10 GHz continuous wave at grazing incidence is selected as the radar detection wave threat, and the RCS probability distributions of the ship's body under different statistical times, sea states, speeds, headings and other parameters are compared and analyzed.

  Result  A lognormal distribution model is used to simulate the distribution characteristics of the static RCS of the ship model. The probability distribution of the dynamic RCS is basically stable when the statistical time is longer than 250 seconds. There exists a "burr" phenomenon in the dynamic RCS probability distribution curve under low sea states, following waves or beam sea drifting conditions.

  Conclusion  The effects of the ship's speed on its RCS probability density distribution can be ignored. The influence of the sea wave direction angle on the RCS probability density distribution is obvious only in high sea states. The increase of the sea state makes the RCS distribution probability curve increasingly smooth. Statistical time has a great influence on the RCS probability density distribution, so it is necessary to accumulate sufficient data to carry out a test or simulation that can provide an accurate grasp of a ship's RCS probability distribution characteristics.