太赫兹波段信号在雾中的传输特性研究

Transmission characteristics of terahertz signal in fog

太赫兹(THz)波提供的通信带宽和容量远大于毫米波。与可见光和红外光相比,THz脉冲的波长较长,在随机介质中传播时,不但会发生时域和空域的形变,介质中的粒子还会对入射波发生散射,这些都会使得脉冲信号发生衰减。根据Mie理论与随机离散分布粒子的波传播与散射理论,计算了THz波信号入射下雾滴粒子的消光系数,分析了不同THz波波长下,雾滴粒子消光系数随粒子尺寸的变化。结合雾滴粒子谱分布,考虑粒子群的平均体系散射特性,得到了不同波长下的平均反照率与相函数。最后分析了THz波段信号在不同能见度雾中的传输特性。结果表明:大气环境中,雾对THz波产生的吸收和衰减不容忽视,不同THz信号的水的折射率虚部的变化严重影响了THz信号在雾中的传输。

The terahertz wave provided greater communication bandwidth and capacity than millimeter. Compared with the visible light and the infrared light, THz pulses had longer wavelength propagating in the random medium, not only caused the temporal and spatial deformation, but also affected on the incident particle scattering, then the pulse signal attenuation occurred. Based on the Mie theory, using the discrete distribution of particles with the random wave transmission and scattering theory, the extinction coefficient of fog droplet in the terahertz wave was calculated. And the extinction coefficients of different wavelengths of terahertz wave change with the particle size were analyzed. Considered the droplet particle size distribution, the average albedo and phase function were obtained under different wavelengths. Finally, propagation characteristics of terahertz signals in fog particles by different visibilities were analyzed. The result shows that in the atmospheric environment, the absorption and attenuation of fog in terahertz wavelength can not be ignored, the imaginary part of the refractive index changes greatly with different wavelengths, and the transmission of the THz wavelength in fog is seriously impacted.