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°, and three years are of simultaneous measurements at Ka and X band with an elevation angle of 4.2°. 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.