Attenuation of millimetre wave by spherical rain drops using rain parameters in yenagoa

In this paper, Mie theory was adopted to evaluate millimetre wave propagation in rain medium. This was to determine attenuation of propagating millimetre wave by rain drops in Yenagoa, Bayelsa State. We obtain Yenagoa climate weather averages for 2022 from weather.com and used these rain parameters to compute the effective permittivity of rain drops in Yenagoa by adopting Debye’s model. The shape of rain drops was assumed to be spherical as drop diameter in Yenagoa is smaller than about . Drop size distribution (DSD) was evaluated using Marshall-Palmer’s distribution and other distributions for different types of rain was studied. We observed that the all follow similar patterns. Finally, the specific attenuation by rain drops as a function of frequency and drop diameter was analysed and results obtained showed that the specific attenuation increases at smaller diameter rain drops and reduces for larger diameter rain drops. For smaller rain drops attenuation is due to absorption by water molecules with insignificant scattering by rain droplets while for larger rain drops there is significant scattering by rain drops with insignificant absorption of propagating millimetre waves by rain droplets. It was observed that the specific rain attenuation is constant at high frequencies. This is true for both day and night time as the maximum chord length of raindrop becomes comparable to the wavelength in the rain medium which causes the raindrop to reradiate energy.