Characteristics of atmospheric ducts and its impacts on FM broadcasting in Wuhan

The atmospheric ducts affect the broadcasting quality and service reliability of the broadcasting system seriously. However, the research on the appearance of the inland atmospheric duct is not paid enough attention, and there is no domestic research present about its influence on the broadcasting system. In this paper, the characteristics of atmospheric duct environment in Wuhan, which is a typical subtropical monsoon climate region, and its impacts on broadcasting frequency are studied. Based on the principle of radio meteorology, the results of duct environmental characteristics from 2017 to 2019 are given, including the occurrence probability, structural characteristics, and the radio frequency trapped. The results show that the occurrence probability of atmospheric duct is over 28%, and the impact probability on the FM frequency band can reach more than 13%. This work numerically simulated the propagation ch- aracteristics of 92.7 MHz radio waves along the Wuhan-Xinyang path and the power distribution from Wuhan transmitting station to Xinyang under standard atmosphere and atmospheric condition of typical ducting event using the parabolic equation method. The numerical results of selected atmospheric duct events show that the signal power of 0-100 m above the surface can be increased by more than 6.12 dBm at a location 85 km away from Wuhan and in Xinyang about 172 km away from Wuhan. The results and its corresponding phenomenological events show that the inland atmospheric ducts have serious impacts on the radio broadcasting system. It provides reliable reference for the relevant researches.