Absorption of 30 and 20 GHz Microwave Communication Signal as a Function of Rain Rate

The attenuation of Microwave communication signals operating at 30 GHz and 20 GHz has been measured as a function of rain rate. The line of sight distance between the transmitters and receivers was 2.3 km. It is experimentally observed that as the rain starts falling the signal received by the receivers at both the frequencies starts decreasing and as the rain rate starts increasing, the signals received by both the receivers starts decreasing and reaches to a minimum value when the rain rate is highest and as the rain rate starts decreasing the signal received at both the frequencies starts increasing and reaches the previous maximum value when the rain stops. This shows that microwave signal is absorbed by water contents of rain and we must transmit more power during rain to get the same power at the receiver. However, the increase in power at the transmitter end will depend on the rain rate. It is observed that the attenuation of microwave signal operating at 30 GHz and 20 GHz follow the same pattern. Line of sight path attenuation as a function of rain rate has also been experimentally measured at these frequencies. It is observed that the rain induced attenuation increases at both the frequencies as the rainfall rate increases. It is observed that the rain induced attenuation at 30 GHz is higher than at 20 GHz for the same rainfall rate. Specific rain induced attenuation has also been calculated using Medhurst technique and compared with Marshal and Palmer and International Telecommunication Union Models. Rain attenuation parameters as a function of rainfall rate obtained in this experimental study can be used for designing efficient and reliable terrestrial and satellite communication systems.