Line of sight link degradation at millimeterwaves due to EMI from rain drops

The utilization of the Ka band (35 GHz) with a bandwidth of 2500 MHz seems to represent the largest significant achievement in LOS link application. The performance of a transceiver system in this band is determined largely by the ratio of wanted power to the unwanted power in the receiver. The unwanted power contributions are coming from two factors: (1) internal thermal noise generated by random atomic motions within the elements of the receiver and (2) the contribution in the sky noise temperature T_s due to EMI (electromagnetic interference) from rain drops. This extra term T_s has so far been ignored. Therefore, in view of propagation and noise study in the Ka band, both rain attenuation and receiver noise floor variations with rain are estimated over a tropical station, Calcutta, India. This is concluded with a special discussion of receiving systems utilising LNBCs (low noise block down converters) at the front end which are typically at 30 K or less where rain EMI effects are severe.