ELEVATED DUCT PROPAGATION IN THE TRADE WINDS
Abstract
All of the maximum propagation ranges (at 220 mc) observed in an elevated duct region varied from 500 to 1200 miles, compared to less than 400 miles observed with the same equipment outside the duct. The measurements were made at the optimum season (November) in a trade-wind region between Brazil and Ascension Island (8 degree S latitude). The field strengths above 400 ft are as much as 40 db larger than those at lower ALTITUDES. From the level at average duct height (6000 ft) the field decreases slowly to 10,000 ft, the maximum altitude investigated. The slow fading rate usually associated with duct propagation is not always observed, even on the very long range runs. An extrapolation to propagation conditions in the month of March via refractive index measurements indicates minimal ducting conditions 10 to 20% of the time. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 01, 1961
- Accession Number
- AD0262042
Entities
People
- F.c. Macdonald
Organizations
- United States Naval Research Laboratory