Development of duststorm attenuation model for microwave links

Abstract

Duststorms are significant meteorological phenomena which occur in arid and semi arid areas, especially in African Sahara and Middle East deserts. However, only a limited amount of research was carried out and the available data is very scarce. A mathematical model has been developed using Mie solution of Maxwell`s equations for the scattering of electromagnetic waves. The scattering centers are assumed to be spherically shaped dielectric particles. In the proposed model the term visibility denotes the degree of the duststorm density instead of the total number of dust particles per unit volume. The proposed model shows that the microwave signal attenuation depends on; visibility, frequency, radius of dust particles and dielectric constant. The predicted attenuation by the proposed model is compared with the values measured in Saudi Arabia and Sudan. The predicted attenuation using proposed model varies 7% from the measurement done in Saudi Arabia while the differences are more than 50% by using existing models. The proposed model showed 17% variation with the measurement done in Sudan, while the prediction by existing models are more than 60%. The visibilities are less than 1 km in both cases. It shows very close agreement, than current models. Fade margins were investigated, based on long term data collected during duststorms in arid and semi arid areas of Sudan and Saudi Arabia. It is found that 2.5 dB/km and 4 dB/km margins for dust attenuation are required to achieve 99.99% reliability for microwave links operating at Ku and Kabands respectively. At frequencies above 10 GHz, it is recommended that duststorms attenuation needs to be considered in radio planning and link budget analysis. A regional propagation map should be developed to consider duststorms characteristics. The proposed model will be useful method to predict the attenuation in microwave signal due to duststorm.