Rain clutter measurements with c.w. radar systems operating in the 8-mm wavelength band

摘要

The objects of this work were to investigate the extent of rain clutter using 8-mm continuous-wave radar systems with both a single aerial (common transmission and reception) and dual aerials (separate transmission and reception) and to investigate the reduction of this clutter by orthogonal polarization techniques. In the common transmission and reception case using polarization duplexing, the amplitude of the rain clutter was measured in terms of decibels below the valve power level by a direct comparison method and plotted against the rainfall rate in millimetres per hour. This was also done for the separate transmission and reception case, which did not employ a duplexer. The results showed that the rain clutter amplitude in the common transmission and reception case was some 60 db below valve power level for a moderate rainfall of 3 mm/h. In the separate transmission and reception case rain clutter decreased with increasing aerial spacing and was some 95 db below valve power for a rainfall rate of 3 mm/h with 2-ft diameter aerials spaced 3 ft centre to centre. Details of the methods of measurements, the equipment used and the experimental observations are given.