採用經驗海波頻譜模擬海風驅動海面型態以建立雷達海面雜波統計模型

Abstract

本論文提出一種方法，利用風速和風向資訊來預測雷達海面雜波的統計參數。先採用海浪頻譜的經驗式和蒙特卡羅法生成海面輪廓樣本，其為表面風速和風向的函數。再採用物理光學法計算每個海面輪廓樣本的雷達截面(RCS)，並考慮雷達偏振、掠射角和海水的電性。所得RCS的機率分佈符合KK分佈，其統計參數與風況和雷達參數有關。本方法模擬結果與文獻中Ingara系統的實驗數據進行比對，確認其可行性。比起傳統量測方法，本方法可以在更廣泛的海況、風況和雷達參數範圍內預測海面雜波的統計特性。

Statistical models of sea clutter were typically constructed from measurement data, which were contingent upon the sea state and radar parameters. In this work, we propose a systematic approach to predict the statistical parameters of radar sea-clutter by using the information of wind speed and wind direction relative to the radar beam. An ensemble of sea-surface profiles are generated with Monte-Carlo method based on empirical ocean-wave spectrum, which is a function of the surface wind speed and wind direction. The radar cross section (RCS) from each profile is computed with a physical-optics method, considering radar polarization, grazing angle and electrical properties of sea water. The distribution of RCS is fit with a KK distribution, of which the statistical parameters are related to the wind condition and radar parameters. The feasibility of this approach is validated by comparing with the experimental sea-clutter dataset of an Ingara system in the literature. By using the proposed approach, the statistical parameters of sea-clutter can be predicted over a much wider range of sea state, wind condition and radar parameters than conventional methods can provide.