中文摘要：

提出了利用地面非合作辐射源如FM广播的外辐射源机载预警雷达系统的概念。为了分析影响其性能的关键因素——信杂比的变化范围和状况，分析、仿真了典型FM广播电台的辐射方向图尤其是垂直方向图，结合FM台站、AEW接收系统和目标的空间位置关系，利用双基地雷达的信号模型，得到了信杂比-60～-110dB的分布范围及其类似于信噪比变化的卡西尼卵形线的变化规律。

英文摘要：

The concept of PCL （passive coherent location） AEW （airborne early warning） radar system utilizing illuminators of opportunity such as FM broadcast is proposed firstly, and then its description and characteristics analysis are performed. To analyze the key factor of SCR（signal-clutter ratio） for passive radar, the vertical radiation pattern for FM broadcast station and the corresponding elevation angle for target or AEW are established. With the aid of bistatic radar equation, the SCR for this novel passive radar system is got and simulated. Finally, the conclusion is obtained that a reasonable SCR lies in the range of -- 60 ～ -- 110 dB and constant SCR holds Cassini ovals as SNR for bistatic radar.