Ka-Band Cloud Radar Comparison of Vertical and Slanted Polarization on Transmit

In two successive winters RHI-Scans have been made at the Munich Airport. In the first winter signal was transmitted with slanted polarization, in the second winter the antenna was rotated by 45 deg around the beam axis so that the signal was transmitted with vertical polarization. In both cases co- and cross polarized signals where received simultaneously. In both configurations LDR and and the correlation between co and cross receiving signal RHO_LDR was calculated. A significant difference between both configurations was observed. The conclusion is that the configuration with vertical polarization on transmit is more useful for distinguishing melting layer and insects, and it also allows to distinguish between randomly shaped snow flakes and systematically shaped ice crystals. The configuration with slanted polarization on transmit is more sensitive to differences in the shape and size of ice flakes and crystals and flattening of droplets. LDR and RHO_LDR show a large variety of elevation dependence for different targets but their interpretation is difficult.