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Precipitation scatter interference on communication links with emphasis on the melting-snow layer Hulays, Rafeh Ahmad


A geometrical model has been developed to calculate hydrometeor interference between different microwave systems sharing the same frequency. The model is capable of calculating the interference for any combination of transmitter-receiver geometry and the program is flexible enough to allow for many assumptions related to the spatial and vertical structure of the rain cell. Furthermore, it can easily accommodate different attenuation and scattering models. The study also focuses on the melting-snow layer and it is found that this layer plays a significant role in the interference calculations. The melting layer significantly increases the interference in the 1-8 GHz range, and moderately in the 8-12 GHz. On the other hand, the melting layer results in a significant decrease in the interference level at higher frequencies, especially in the 30-40 GHz range. The study also examines the effect of the ice/snow region above the melting layer and it is concluded that this region plays an important role in the interference calculations, especially at higher frequencies. Three examples of interference geometries are examined in Chapter 4. The first deals with the interference from an up-link to terrestrial links in the near-forward direction, the second deals with the interference from an up-link to terrestrial links in the near-backward direction and the third deals with the interference from an up-link to a satellite in the forward direction. A comparison is made between two rain-cell models in Chapter 5. The COST 210 rain-cell model, which is adopted by the CCIR (International Radio Consultative Committee), is compared with the more physical Capsoni rain-cell model. A new empirical attenuation formula for rain and melting-snow has been developed, which, unlike previous formulae, has the frequency as a separate parameter. For detailed analysis, refer to Appendix D.

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