A comparison of microwave propagation models and evaporation duct height estimation techniques with actual near water atmospheric and radio data taken in North Queensland, Australia in May 2001

For a number of years, RSRG, together with DSTO and JCU, has been taking measurements of radio propagation inside the evaporation duct using large arrays together with near ocean measurements of atmospheric refractivity. This paper presents results from such experiments carried out in May 2001. The authors collected a vertical profile of received signal strength from a transmitter 18 km away, propagating on an over water path inside the tropical evaporation duct. This data was compared to a simulated field using the TERPEM parabolic equation based propagation software (see Levy, M., "Parabolic Equation Methods for Electromagnetic Wave Propagation", IEE Press). In addition, a number of measurements of near ocean atmospheric measurements were taken and, from these, the height of the evaporation duct inferred. These measurements were compared to duct height calculations using TERPEM which are based on the 'bulk parameter' method of calculating duct height.