Study of gaseous attenuation at tropical locations

Oxygen and Water Vapour are the principal absorbers of transmitted radio signals in the troposphere. This paper evaluates the specific gaseous attenuation due to Oxygen and Water Vapour at four tropical sites in the frequency range of 10-350 GHz using Liebe model. The isolated resonant absorption line of Oxygen was found to be at 118 GHz, together with series of absorption spectra lines between 54-66GHz, the peak being at 60 GHz. The spectra lines of Water Vapour appear at 22, 184 and 326GHz. The specific attenuation exhibits both seasonal and geographical variations. It is generally higher during wet season than dry season; Kano (3.12oN, 8.32oE), an inland site, has the least specific attenuation, while Lagos (6.32oN, 3.21oE), a coastal station, has the highest values. The implications of the results for microwaves communication links are also discussed. Keywords: Oxgyen, water vapour, specific attenuation, microwaves absorption Nigerian Journal of Physics Vol. 18 (1) 2006: pp. 111-11