2018, 40(1): 181-188.
doi: 10.11999/JEIT170253
Abstract:
To describe the effect of atmospheric conditions on the microwave propagations precisely, establish the theoretical foundation for the new applications of the atmospheric inversion by microwave links, the propagation attenuation by the absorptive gas and various atmospheric particles are investigated systematically in this paper. The absorption of main gas component in atmosphere are calculated by ITU-R model, and then based on the physical characteristics and dielectric model of different types of precipitation particles, cloud and fog particles, and sand particles, the scattering characteristics of atmospheric particles cluster at the microwave band are calculated, the effect of particle size distribution, intensity, phase, and temperature on the microwave propagation at different waveband are discussed systematically. The numerical simulation results show that there are absorption band at 60 GHz, 180 GHz, and 320 GHz due to oxygen and vapor, and the attenuation is positively related to both the vapor content and air pressure, while it is negatively related to the temperature. The microwave propagation attenuation by precipitation are mainly influenced by the precipitation intensity, particles size distribution, phase and its component rate, the water content and phase of cloud and fog are the main factors that affect the microwave attenuation, the number density, size distribution and water content of dust are the main factors that affect the microwave attenuation, while the temperature is the least factor. In sum, in order of the attenuation coefficient, it goes: blast dust, precipitation, gas absorption, water fog, ice fog, and atmospheric dust.