The Evaporation Duct and Its Implications for Low-Altitude Propagation at Kwajalein
Abstract
The principal intent is to provide a basis for understanding the influence of the evaporation duct, a low region of strong refraction existing nearly all the time on the open sea, with varying thickness. There is a survey of the literature, followed by application of published data to the task of estimating the effect of the evaporation duct on the performance of the radars at Kwajalein when the target height is only a few meters. It is concluded that this duct has negligible effect at VHF, UHF, and L band, that at times it causes a large extension of the coverage of the S-band radar, and that it very importantly extends the range of the C-band radar on targets at heights such as 5 meters. Attention is given to the effects of the duct on signal velocity, pulse compression, and polarization ratio. There is also a discussion of the effect of the atmosphere over tropical ocean on the location of the radio horizon for frequencies that are too low to be influenced by the evaporation duct.
Document Details
- Document Type
- Technical Report
- Publication Date
- May 11, 1978
- Accession Number
- ADA057117
Entities
People
- Jamin J. McCue
Organizations
- Massachusetts Institute of Technology