Multipath Propagation over Snow at Millimeter Wavelengths,
Abstract
A series of multipath measurements over snow were conducted at Hanscom AFB during the winter 1978/1979. Data were obtained over a path-length of 179.5 m at frequencies of 35, 98, and 140 GHz. The gently rolling grass-covered terrain showed maximum height differences of 0.8 m. Snow covers included freshly fallen snow, old metamorphic snow, and sleet. The equipment consisted of CW transmitters at 2-m height and receivers mounted on a vertical positioner to measure the height-gain pattern of the received signal between 0.2- and 4-m height. Grazing angles for this geometry range between 0.5 and 2 degrees. Measured interference patterns between direct and terrain-reflected rays were generally coherent in appearance and exhibited cancellation depths of 20 dB and lower, depending on the type of snow cover. A computer program was developed in order to model the reflection as a specular process, with the underlying terrain represented by a series of linear sloping segments, derived from actual terrain height measurements. With appropriate transitions between the linear segments and reflection coefficients calculated from relevant snow parameters, calculated and measured height-gain patterns display quite similar qualities. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Feb 01, 1980
- Accession Number
- ADA087747
Entities
People
- Dallas T. Hayes
- Uve H. W. Lammers
Organizations
- Rome Laboratory