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Attenuation of Weather Radar Signals Due to Wetting of the Radome by Rainwater or Incomplete Filling of the Beam VolumeA search of scientific literature, both printed and electronic, was undertaken to provide quantitative estimates of attenuation effects of rainfall on weather radar radomes. The emphasis was on C-band (5 cm) and S-Band (10 cm) wavelengths. An empirical model was developed to estimate two-way wet radome losses as a function of frequency and rainfall rate for both standard and hydrophobic radomes. The model fits most of the published data within +/- 1 dB at both target wavelengths for rain rates from less than ten to more than 200 mm/hr. Rainfall attenuation effects remain under 1 dB at both frequencies regardless of radome type for rainfall rates up to 10 mm/hr. S-Band losses with a hydrophobic radome such as that on the WSR-88D remain under 1 dB up to 100 mm/hr. C-Band losses on standard radomes such as that on the Patrick AFB (Air Force Base) WSR-74C can reach as much as 5 dB at 50 mm/hr. In addition, calculations were performed to determine the reduction in effective reflectivity, Z, when a radar target is smaller than the sampling volume of the radar. Results are presented for both the Patrick Air Force Base WSR-74C and the WSR-88D as a function of target size and range.
Document ID
Acquisition Source
Kennedy Space Center
Document Type
Technical Memorandum (TM)
Merceret, Francis J.
(NASA Kennedy Space Center Cocoa Beach, FL United States)
Ward, Jennifer G.
(NASA Kennedy Space Center Cocoa Beach, FL United States)
Date Acquired
September 7, 2013
Publication Date
April 9, 2000
Subject Category
Communications And Radar
Report/Patent Number
NAS 1.15:211171
Distribution Limits
Work of the US Gov. Public Use Permitted.
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