Long-Term Measurements of Tropospheric Scintillation at Very Low Elevation Angles - Initial Analysis

Four years of scintillation measurements at very low elevation angles at Kjeller, Norway are analyzed and compared with the ITU-R model. One year is at Ka band with an elevation angle of 3 degrees, and three years are of simultaneous measurements at Ka and X band with an elevation angle of 4.2 degrees. The measured scintillation is highly asymmetrical with more than 40 dB fades recorded at Ka band. In agreement with previous results, the scintillation spectra for low elevation angles have a low corner frequency. Compared with the ITU-R model, the measurements highlight issues with uncertainty of input parameters, as well as accuracy of the deep-fading part of the model. The model predicts the measured scintillation well for high percentages of the time, but poorly for low percentages of the time. The deep-fading part of the model significantly overestimates fades at X band, highlighting a previously observed issue with frequency scaling.