雷达导引头在下视探测超低空目标时,集中在第一菲涅尔区的多径能量会影响雷达的探测能力。针对菲涅尔区的特性,定义了电磁波传输的空间菲涅尔区和超低空探测下的地面菲涅尔区。根据惠更斯菲涅尔定理,建立了空间和地面菲涅尔区的数学模型。通过仿真分析了馈源与接收天线距离和工作波长对第一空间菲涅尔区的影响,得到了第一地面菲涅尔区随弹目投影间距离和投射余角的变化规律。研究结果为处理多径信号、对反射面进行有限截断提供了理论依据。

When radar seeker detected ultra-low altitude targets in downward-looking, the energy of multipath signal which primarily concentrates on the first Fresnel zone would have impacts on the detection capability of radar. According to the characteristics of the Fresnel zone, the Space Fresnel zone of electromagnetic wave transmission and the ground Fresnel zone under ultra-low altitude detection were defined. According to Huygens-Fresnel theorem, the mathematic models of the space and ground Fresnel zone. The influences of the distance between the feed source and receiving antenna and operating wavelength on the first dimensional Fresnel zone was analyzed by simulation. The change regulation of the first Fresnel zone along with complement angle of the radar seeker and distance between projection of radar seeker and target was obtained. The research results provided the theoretical foundation for multipath signal processing and finite truncation of reflector.