Title :
Comparison of two multisheet transmission windows for millimeter-wave radiometers
Author :
Jacobson, M.D. ; Snider, J.B. ; Hogg, David C.
Author_Institution :
NOAA/Environ. Res. Lab., Boulder, CO, USA
fDate :
4/1/1988 12:00:00 AM
Abstract :
The design and performance of a triple-sheet Mylar window and a Teflon-and-foam window are studied theoretically and experimentally to determine which window produces the smaller brightness temperature variations and, therefore, leads to better accuracy of radiometers operating at frequencies of 20-90 GHz. Theoretical brightness temperatures due to emission and reflection by the windows are calculated and compared; experimental measurements obtained by using the clear atmosphere as a radiation source are also compared. Both theory and experiment indicate that the Teflon-and-foam window produces smaller brightness temperature variations at these operating frequencies. Effects of the windows on integrated water vapor and liquid measurements are also examined; errors are significant for the triple-sheet Mylar window but are negligible for the Teflon-and-foam window. It is observed that use of the Teflon-and-foam design results in acceptably small errors in radiometric measurements of water vapor and cloud liquid
Keywords :
measurement errors; microwave measurement; radiometry; spectral methods of temperature measurement; 20 to 90 GHz; EHF; SHF; Teflon-and-foam window; brightness temperature variations; clear atmosphere; cloud liquid; emission; errors; integrated water vapour measurements; millimeter-wave radiometers; multisheet transmission windows; radiation source; radiometric measurements; reflection; triple-sheet Mylar window; Atmosphere; Atmospheric measurements; Brightness temperature; Clouds; Dielectrics; Frequency; Instruments; Protection; Radiometers; Sea measurements;
Journal_Title :
Antennas and Propagation, IEEE Transactions on