In order to investigate the attenuation effect of clear atmosphere on millimeter wave signals

the gases contributing the most to millimeter wave absorption in the atmosphere were analyzed based on HITRAN 2008 database of atmospheric molecular absorption spectroscopy parameters. A fine calculation model of the absorption of molecular spectral lines in the far wing was obtained by utilizing the Gross dynamic line. Based on this model

the physical property parameters and absorption spectrum of 6 primary absorbing gases including H2O

O2

and O3 were calculated using the Line by Line method. Then

attenuation effects of atmosphere on millimeter wave were analyzed in both homogeneous and inhomogeneous path

respectively. Results calculated by the Line-by-Line method agreed well with the results calculated by the Liebe model method. In addition

compared with 94 GHz test system measurement data

the relative deviation was 3.7%. H2O and O2 strongly attenuated the millimeter wave signal in the 75-110 GHz millimeter wave band

accounting for more than 95% of the total gas attenuation. When the millimeter wave signal was transmitted horizontally at about 20 km

the attenuated effect of O3 on the signal should be considered

and the attenuated effect of CH4

CO

N2O was negligible. The research results can provide reference for the engineering application of millimeter wave radar parameter design.