多径效应对航向信标系统电磁环境影响分析

着陆导航是飞行安全中的重要一环,随着机场周边建筑物的密集化,由机场跑道周围地形地物产生的多径效应将影响导航信息的准确性。从天线辐射场型的角度,基于二元天线阵对航向信标天线建模,得到理想天线辐射场型;以建筑物反射为例,结合天线镜像原理得到多径效应下的天线辐射场型。仿真对比结果表明建筑物多径效应造成了航向信号方向性变差,幅值发生剧烈跳变。基于航向信标系统高级仿真(advanced trainer on localizer, ATOLL)分别进行进近飞行与圆弧飞行的信号校验仿真,分析多径效应对航道调制深度差值及航道信号覆盖范围的影响,找出某新建机场存在航向信号不稳的原因。

Analysis of influence of multipath effect on electromagnetic environment of localizer

Landing navigation is an important part of flight safety. With the incredibly intense construction around the airport, the multipath reflection caused by buildings surrounded has a serious influence on the accuracy of navigation information. From the perspective of the antenna radiation pattern, the ideal antenna radiation pattern is possessed by the model of localizer antenna which is based on the binary antenna array. Taking the reflection of buildings as an example, the antenna radiation pattern under multipath effect is obtained according to the principle of antenna mirroring. The simulation comparison results show that the multipath effect of the building causes the directionality of the heading signal to deteriorate and the amplitude to jump sharply. Based on the advanced trainer on localizer, the major cause of the poor navigation information of the new airport is found out through carrying out the signal verification simulation of approach flight and arc flight respectively and analyzing the influence of multipath affection on the channel difference in depth of modulation value and navigation signal range.