Experiences with special Ka- and Q-band receivers for alphasat signal monitoring in prague, CZ

This paper describes special Ka- and Q-band receiver for the Alphasat signal developed for the Institute of Atmospheric Physics (IAP) Prague and first operational experiences with it. The signal level monitoring enables us to derive the atmospheric attenuation which is object of our research (its statistics and relation to relevant meteorological parameters like rain, liquid water content (LWC) and water vapor density. The LNB is located in the focus of 1.8 m parabolic offset antenna and signal is twice converted down. The resolution is 0.5 dB and sampling rate 20 Hz. Signal record is burdened by satellite space motion. Therefore a new detector was added later to enable the autonomous antenna tracking in elevation and the daily peak to peak variation due to satellite motion was significantly reduced. Recently merged splitter on second IF 1.7 GHz provides signal for 39 GHz radiometer. Examples of recorded signal with and without atmospheric attenuation are added. The satellite frequency changes are discussed, too.