隧道横截面对电磁波传播特性的影响

利用解析方法与数值分析方法重点研究了电磁波在圆形隧道、矩形隧道和拱形隧道中的传播特性，得出了当隧道横截面积越大衰减率越小，及隧道横截面形状对衰减率影响。当频率较高时，圆形隧道、矩形隧道和拱形隧道的衰减率表达式是一致的；当隧道半径或长边长的一半大于波长10倍以上时，电磁波的衰减率很小，几乎与横截面形状无关，仅仅与隧道横截面积的大小有微弱的关系。

Using analytical method and numerical method, the paper emphatically researches propagation characteristics of electromagnetic waves in circular tunnel, rectangular tunnel and arched tunnel. A conclusion is made that the larger area of cross sections is, the lower attenuation rate is, and shape of cross sections affects on attenuation rate too. When frequency is comparatively high, circular tunnel, rectangular tunnel and arched tunnel have same formulation of attenuation rate. When the radius or half of larger side is ten times larger than the free-space wavelength, attenuation rate is very low and hardly related to the shape of cross sections, and only related slightly to the area of cross section of tunnel.