Long-term over-the-horizon microwave channel measurements and statistical analysis in evaporation ducts over the Yellow Sea

Abstract

Maritime high-speed over-the-horizon wireless communication is realizable through evaporation ducts. Detailed measurement, analysis, and modeling of duct channels are essential for application of this communication technique. In this paper, X-band electromagnetic (EM) wave propagation systems were developed and deployed for a 133-km over-the-horizon microwave link in coastal areas of the Yellow Sea. The propagation length was 7.7 times the line-of-sight length. Measurement results including the path loss (PL) and meteorological data were obtained during a 54-day period in autumn 2021. The long-term channel results were analyzed on the basis of statistical analysis and model simulations. Results showed that our measurement system, with a maximum measurable power loss of 200 dB, had connected with a probability of 56.2% during the measurement period. Model simulation showed that evaporation duct environments are not ideal in autumn, with an average evaporation duct height (EDH) of 10.6 m. The land breeze in autumn introduced dry and cold air to the link, which could promote evaporation of seawater and reduce PL by approximately 40 dB. Annual spatiotemporal characteristics of EDH showed that evaporation ducts are most suitable for over-the-horizon communication in spring, especially May.

Atmospheric Ducts and Their Electromagnetic Propagation Characteristics in the Northwestern South China Sea

“…In coastal areas, atmospheric ducts display noticeable horizontal non-uniformity [6,20,37,38]. NCEP CFSv2 and ERA5 data, with their superior spatial resolution, offer a more accurate representation of the distribution features of horizontal non-uniformity in atmospheric ducts along the sea-land boundary region, as compared with other data sources (e.g., MERRA, JRA, and NCEP2, etc.).…”

“…In the northwest region of the SCS, a variety of mesoscale and sub-mesoscale marine processes occur, including fronts and upwelling, etc. [36,37]. The atmospheric duct environment in this area is complex.…”

Investigating the spatio–temporal characteristics of lower atmospheric ducts across the China seas by performing a long–term simulation using the WRF model

“…When the atmospheric duct occurs, electromagnetic waves can be easily trapped within a specific height level due to dramatic changes in atmospheric refractivity, resembling the motion within a duct (Turton et al, 1988;Shi et al, 2023). These atmospheric duct events can induce severe interference during the processes of radio communication and radar detection (Hitney et al, 1985;Craig and Levy, 1991;Anderson, 1995;Wang S. et al, 2023). For instance, atmospheric ducts can lead to widespread interference in mobile signals, extension in radar detection range, and appearance of radar blind areas (Patterson et al, 1994;Babin and Dockery, 2002;Dinc and Akan, 2014;Ma et al, 2022;Kang et al, 2023).…”