Ka‑Band Propagation Channel Study Based on In-Orbit NTN LEO Link Measurements

This thesis develops and applies a complete signal processing chain for the study of Ka-band propagation from a Low Earth Orbit (LEO) satellite, a geometry whose fast, continuously varying elevation sets it apart from the well studied geostationary case. A 19.2 GHz continuous wave beacon transmitted by the LIDE cubesat was recorded at the ESTEC site of the European Space Agency by two co-located terminals: a high-gain Cobham SeaTel 1500 on a building roof and a low-profile Kebni vehicular terminal on a van. The chain first compensates the predictable terms of the link budget, namely the satellite transmit-power variation, the free space path loss and the gaseous attenuation, each reconstructed from independent ancillary data. A dedicated segmentation step, robust to the deep multipath fades of the van terminal, then isolates the interval in which the beacon is genuinely received. On the conditioned signal the excess attenuation and the tropospheric scintillation are characterised and compared with predictions derived from radiosonde data through the Rytov model. The measured scintillation agrees with the prediction, in the median, above about 25 of elevation, whereas its temporal spectrum cannot be resolved on the short, noise-limited LEO records. By exploiting the co-location of the two antennas, the dominant residual impairments are shown to be instrumental rather than atmospheric: the periodic pointing cycle of the Cobham and the ground multipath of the Kebni are identified and separated from the propagation effects. A sun-outage screen confirms that the Sun only grazed the antenna beams, raising the noise floor by less than a decibel without ever blocking the link. The results, and an honest account of their limitations, motivate a set of improvements for future campaigns and the development of a machine learning model for the prediction of link outages.