Abstract: In order to understand the long-term and short-term changing trend in time and space of electromagnetic environment, three studies were carried out by vehicle survey. Firstly, in 2022 and 2023, frequency selective monitoring of electromagnetic environment ranging from 30 MHz-6 GHz were conducted on four ring roads in Beijing, including the Second Ring Road, the Third Ring Road, the Fourth Ring Road, and the Fifth Ring Road, respectively, which collected 200,000 values. Through temporal and spatial variation analysis on different ring roads and base stations of different generation, it reveals that the general electric field rising from (1.34±0.85) V/m to (1.64±1.00) V/m, and all the values show that: the Third Ring Road > the Second Ring Road > the Fourth Ring Road > the Fifth Ring Road; also the electromagnetic field from 5G BS in 2023 exceeds that of 4G BS. In terms of spatial distribution, the total number of hotspots in 2023 is significantly higher than that in 2022, and the number of hotspots in the Fifth Ring Road is less than that in other ring roads. The electromagnetic environment level in the eastern and western parts of each ring road is relatively high. Secondly, in 2024, vehicle surveys of electromagnetic environment ranging from 0.1 MHz-6 GHz both in the daytime and nighttime were implemented on the Beijing Ring Roads, extracting spectral data and analyzing the proportion of major electromagnetic radiation sources,and found that the base station had the highest proportion. Third, in 2023 and 2024, the same 5G base station was continuously monitored for 24 hours, and it is found that the average hourly values in 2024 are basically higher than those in 2023, and due to the adjustment of the night working modes, the values in the 4-7 o’clock period change from the background value in 2023 to the normal working state in 2024.

Key words: vehicle survey, ring roads of Beijing, ambient electromagnetic radiation, continuously monitoring, spectrum analysis, temporal and spatial variation trend