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/sub s/ due to EMI (electromagnetic interference) from rain drops. This extra term T/sub 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.