Modelling attenuation on an earth-space path using dual-polarisation radar

Dual polarization radar operated at 10 cm was employed to examine the errors in estimating radar-data predicted microwave attenuation due to rain interposed between ground and GEO radio links. Alternate vertical and horizontal polarizations were transmitted at 610 Hz from a 25 m antenna issuing a 0.25 deg beamwidth. The transmission path considered is used by the OTS satellite. Specific attenuation was calculated for various volume drop densities and drop diameters by integrating the forward scattering amplitudes over the drop-size distribution, which was analytically defined. The dual-polarization radar was found to yield data for the melting layer region and improve evaluation of drop sizes. The sources of random and systematic errors are discussed.