Description

It has been investigated and found that extreme climatic conditions disturb propagation of electromagnetic signals at higher frequencies. In most of practical channels when the signal propagates through the atmosphere affect of many factors on the signal has to consider along with the free space propagation channel assumption. Because the other factors in the atmosphere causes absorption, refraction and scattering. Signal attenuation through the atmosphere is mainly due to molecular absorption by oxygen due to water vapours. Rain and fog has the most significant impact since the size of the rain drops is on the order of the wavelength of the transmitted signal. It results in energy absorption by the rain drops themselves, and as a secondary effect, energy is scattered by the drops. The frequency selective absorption characteristics of the atmosphere can be approximated by a transfer function.