海面低飞情况下机载航管二次雷达覆盖研究

二次雷达较之一次雷达有许多优点，使其在军用和民用领域得到广泛应用。但当装有航管二次雷达的飞机在海面低飞时，会出现常见的多径效应现象。文章详细分析了飞机机体和海面对航管二次雷达方向图的影响，并利用HFSS软件对飞机在海面低飞时航管二次雷达方向图进行仿真。结果表明，海面影响航管二次雷达的方向图并导致根据其分叉变形，根据平面对天线方向图的影响及其计算公式，对不同飞行高度的方向图进行了计算，得出了在海面低飞时的最佳飞行高度。

Research of SSR Coverage while Aircraft Crossing the Sea at a Low Altitude

The secondary radar is widely used in the military realm and civilian areas because it has more advantages than primary radar. Unfortunately, when the aircraft with secondary surveillance radar （SSR） flying at a low altitude, tile most common muhipath effect will appear across the sea. The paper details the effect of the airframe and the sea surface on the antenna pattern, and antenna pattern the simulation gots frous when the aircraft flying at a low altitude by HFSS. The simulations reveal that the sea surface changes the antenna pattern. According to the formula of the effect of a plane on the antenna pattern, the antenna pattems of SSR at different heights are also drawn, and the best altitude of the aircraft is reached in the end.