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近年来,用安装在直升飞机上的机载毫米波雷达来检测非运动目标在技术上己受到极大的注意。这些非运动目标可以是地面的静止目标,例如坦克和卡车,或悬浮的直升飞机。检测是在地杂波中和恶劣的气候如雾和雨等条件下进行的。由于检测距离不是很远（大约为5公里左右）,毫米波雷达能很好地适合于这种应用,其主要原因是由于这种雷达具有较高的工作频率（即窄的波束宽度）,在设置有目标的地面上对应着较小的地杂波区,这就能提供较好的目标-杂波信号比。同样,由于它的较窄波束宽度对着较小的雨滴空间,从而降低了因雨的后向散射而引起的噪声影响。在本文中,给出了在无杂波环境里检测目标的基本雷达搜索方程,计算了地杂波引入的噪声以及大气环境诸如雨滴等所产生的噪声。另外还概述了大气衰减的计算方法和应用实例。在检测非运动目标时,利用了两种毫米波（35GHZ_和95GHZ）雷达,指出了在检测非运动目标时,对于给定的天线尺寸,使用较高的工作频率比利用较低的工作频率能获得更远的检测距离。这主要是由于较窄的波束宽度减小了地杂波区和穿越雨滴的空间。
In recent years, the use of airborne millimeter-wave radars mounted on helicopters to detect non-moving targets has received great technical attention. These non-moving targets can be stationary targets on the ground, such as tanks and trucks, or suspended helicopters. Detection is carried out in clutter and in adverse weather conditions such as fog and rain. Due to the fact that the detection range is not very far (about 5 km), millimeter-wave radar is well suited for this application, mainly due to its high operating frequency (ie narrow beamwidth) The setting of the target ground corresponds to a smaller ground clutter region, which provides a better target-clutter signal ratio. Also, the noise impact caused by the backscattering of rain is reduced due to its narrower beam width facing a smaller raindrop space. In this paper, the basic radar search equation for detecting targets in a clutter-free environment is given and the noise introduced by ground clutter and the noise generated by atmospheric environment such as raindrops are calculated. In addition, the calculation methods and application examples of atmospheric attenuation are also summarized. In detecting non-moving targets, two types of millimeter-wave (35GHZ_ and 95GHZ) radars are used, and it is pointed out that when detecting a non-moving target, using a higher operating frequency for a given antenna size than using a lower operating frequency Can get farther detection distance. This is mainly due to the narrower beam width reducing the clutter area and the space through the raindrops.