Evaporation Duct Effects at Millimeter Wavelengths
NAVAL COMMAND CONTROL AND OCEAN SURVEILLANCE CENTER RDT AND E DIV SAN DIEGO CA
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The evaporation duct strongly influences low-altitude over-the- horizon propagation at millimeter wavelengths. Results from more than 2000 hours of propagation and meteorological measurements made at 94 GHz on a 40.6 km over- horizon, over-water path along the southern California coast show that that average received power was 63 dB greater than d for propagation in a nonducting, or standard, atmosphere 90 percent of the measurements were at least 55 dB greater than diffraction. A numerical model of transmission loss based on the observed surface meteorology is discussed and results are compared to measured transmission loss. On average, modeling results underestimate observations by only 10 dB. In addition, results from modelling based on an independent climatology of evaporation duct heights for the area are shown to be adequate for most propagation assessment purposes. The reliability and reasonable accuracy of the numerical model provides a strong justification for utilizing the technique to assess millimeter wave communication and radar systems operating in many, if not all, ocean regions. electromagnetic, propagation, electro-optics, atmosphere.
- Radiofrequency Wave Propagation