Regional Modeling of Atmospheric Attenuation for Ku- and Ka-Band Satellite Links over Iraq

Abstract

A satellite propagation model has been developed for Ku- and Ka-band propagation over three regions in Iraq: Erbil, Baghdad and Amarah, and this propagation model is presented in this paper. The model is a generalized GEO reference link with region-specific environmental inputs from NASA POWER and MERRA-2 aerosol reanalysis from January 2023 to December 2025. The free space loss is determined according to ITU-R P.525, the rain attenuation is determined according to ITU-R P.838 with clearly defined wettest-day mean-intensity proxy and the gaseous attenuation is determined according to ITU-R P.676-13, using pressure, temperature and water-vapour density. The dust attenuation is obtained from a Rayleigh extinction formula, published dielectric properties, and the five-official dust-bin radii and densities in MERRA-2. The monthly bulk DUSMASS product does not include mass fractions per bin, so the highest mass-extinction coefficient for the month in the five bins is selected as the conservative upper limit. Across the four operating cases, mean atmospheric attenuation ranges from 0.095 to 0.101 dB at 12 GHz, 0.122 to 0.131 dB at 14 GHz, 0.418 to 0.456 dB at 20 GHz, and 0.491 to 0.544 dB at 30 GHz. Most of the mean loss is due to gaseous absorption, the second source of loss is rain and direct dust attenuation is less than 4.8×10⁻⁴ dB for the present monthly concentration and path assumptions. The received power for Mean (30-GHz) is around -84.1dBm for all three cities and the percentages vary quickly when the reference level is close to the received-power range during the month. The study demonstrates that the regional aerosol loading can be simulated in the satellite-link without directly considering the optical or surface mass variables as microwave loss. This results in a framework which is transparent, repeatable and can be used for comparative planning studies and the limitations are clearly defined, allowing distinction between simulated link behaviour and measured operational availability.