Preliminary analysis to design a 77 GHz weather radar

The European Telecommunications Standards Institute (ETSI) defines the frequency band around 77 GHz as the one dedicated to automatic cruise control long-range radars. This work presents the preliminary analysis for the design of a mini weather radar and/or a microwave rain gauge operating at such a frequency. Firstly, the Mie scattering formulation applied to a weather radar working in the W-band is briefly introduced, then the operative conditions are described in order to define the system functional requirements. Atmospheric attenuation, including the contribution due to water vapor, is estimated taking into account the ITU-T recommendations. The technical specifications are evaluated in order to meet the functional requirements, paying particular attention to the use of already developed components for radars installed on cars. A sensitivity analysis of the system is also given considering the proper relationship between the radar reflectivity factor Z and the rain rate R determined for a 77 GHz radar. Results provide the basis for the design and realization of a 77 GHz weather radar.