The analysis of advection fog attenuation algorithms in Terahertz wave band

Terahertz wave propagation property, which contains the voltage fluctuation, the reflection effect, the dispersion effect, multipath effect, attenuation effect, etc., in random medium such as the atmosphere is one of the most essential problems to consider in the application of Terahertz wave. The absorption due to the molecules in atmosphere of the Terahertz wave is significant in the absorption peaks and relatively small in the absorption valleys and those are the wavelengths where communication applications will be operated on. The scattering of the particles in the atmosphere such as rain drop, fog, and aerosol can also affect the propagation of Terahertz wave. Attenuation of advection fog is studied because in it is the most common fog in the seaside area. Two methods for the calculation of advection fog attenuation are presented in this paper: the efficiency Rayleigh approximation and the accurate Mie theory method. Rayleigh approximation is widely used in the calculation of fog attenuation in the low frequencies, but in high frequencies such as Terahertz wave band, Rayleigh approximation could only be valid in the lower frequencies. The application regions of Rayleigh approximation under tolerant relative error are given, and this is a simple method to also simplify the process and ensure the accuracy. The specific attenuations of advection fog with different visibilities through the whole Terahertz wave band are shown in the end of this paper, and the results increase with the frequency below 3.5THz and after experiencing a slight fall down and then tend to become invariable.