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目的研究地下电磁信号对机场导航台站的干扰机理,并进行仿真计算。方法建立导航台天线的电流分布模型,研究外部电磁干扰对导航台天线上电流分布形式的影响。基于导航台的工作原理,研究外部电磁干扰对导航台辐射方向图的影响,并进行仿真计算。计算航线下滑线空间点上的场强值受外部电磁信号干扰的影响。结果地下电磁信号传播至导航台天线所在区域,造成T型天线的左右顶负载的电流不再满足镜像反对称的状态,导致T型天线覆盖区域中的场强值变化,水平面的无方向性方向图产生波瓣分裂,进而导致航线下滑线上空间点接收到的场强值幅度产生波动,仿真结果显示波动值高达32.7%。结论地下电磁信号对无方向性信标台造成干扰,导致原来的无方向性方向图产生波瓣分裂,航线下滑线上的场强值产生波动,影响了飞行安全,需要加以抑制屏蔽。
Aim To study the interference mechanism of underground electromagnetic signals to airport navigation stations and to simulate them. Methods The current distribution model of the navigation antenna was established and the influence of external electromagnetic interference on the current distribution on the navigation antenna was studied. Based on the working principle of the navigation station, the influence of external electromagnetic interference on the radiation pattern of the navigation station is studied and simulated. The calculation of the field strength value at the point of the gliding line of the route is affected by the interference of the external electromagnetic signal. As a result, the underground electromagnetic signal propagates to the area where the antenna of the navigation platform is located, resulting in that the currents of the left and right top loads of the T antenna cease to satisfy the mirror antisymmetric state, resulting in the change of the field strength in the coverage area of the T antenna. The result is that the amplitude of the field strength received at the space point on the glide line is fluctuating, and the simulation result shows that the flutter value is as high as 32.7%. Conclusion The underground electromagnetic signal may cause interference to the non-directional beacon station. As a result, the original non-directional directional pattern produces lobed splinter and the field strength value fluctuates on the glide line, affecting the flight safety and shielding needs to be suppressed.