电磁盲区随波导内雷达发射角的变化特性

Characteristics of Radar Shadow Zone Changing with Transmitter Elevation Under Evaporation Duct

蒸发波导是一种出现概率最高的大气波导。利用蒸发波导可实现雷达的超视距探测,扩大探测距离,但是也会出现不同的电磁盲区,降低雷达性能。为了在雷达超视距探测中减小电磁盲区,需要掌握电磁盲区随雷达发射角的变化规律,以便在应用中对发射角进行调整。首先给出了抛物方程和射线描迹这两种描述大气波导中电磁波传播的方法,然后分别运用这两种方法对不同雷达发射角下的电磁盲区进行计算和仿真,获得了电磁盲区随雷达发射角变化的规律。同时也证明了尽管这两种方法的机理不同,但得到的电磁盲区的变化规律相同,它们都可以应用于电磁盲区计算。得到的结论为利用蒸发波导实现雷达超视距探测的工程实际应用奠定了基础。

Evaporation duct is a kind of atmospheric duct of the highest probability. Taking advantage of the evaporation duct can make the radar electromagnetic wave spread to a far fetch and increase the detection range, but it also appears different shadow zone of radar and reduces the radar ability. In order to reduce shadow zone of radar in the radar＇s over-the-horizon detection, we need to grasp the rule that shadow zone of radar changes with transmitter elevation to regulate the transmitter elevation in practical application. First, this paper gives the parabolic equation method and the ray tracing method which describe the electromagnetic wave propagation in the atmospheric duct. Next, the paper uses the two methods to calculate and stimulate the shadow zone of electromagnetic wave under the condition of different transmitter elevations and obtains the rule that shadow zone of radar changes with transmitter elevation. At the same time, it also demonstrates that even though the mechanisms of the two methods are different, the change rules of shadow zone are the same, which can be applied to the calculation of shadow zone of radar. The conclusion establishes the foundation for the engineering practical application of radar＇s over-the-horizon detection by using the evaporation duct.