A novel method for predicting site dependent specific rain attenuation of millimeter radio waves

The use of millimeter radio communication systems has seen a remarkable increase in recent years. However, there remains a need for validation and improvement of millimeter propagation prediction methods tot safe design and operation of the systems. At this high frequency range, propagation related degradation is primarily caused by rainfall. The goal is an improved method for predicting specific attenuation due to rainfall. A general method for establishing the relationship between rainfall rate and specific attenuation is developed. Drop size distributions (DSDs) measured by a Joss distrometer are analyzed, and the three climate classification parameters rain rate, DSD median, and DSD mode are used in the development of these new methods. These parameters are investigated as candidate classes to categorize drop size distributions. Categories of the classes are then established to improve the long-term DSD estimate. The typical long-term DSD is used to derive new prediction methods that are compared with observed attenuation. The influence of wind on the rainfall measurements is studied, and a corresponding correction is suggested, reducing the prediction error significantly. Testing of the three new methods using measurements at 40 and 60 GHz shows noticeable improvement over the method recommended by the International Telecommunication Union (ITU) using measurements at 60 GHz at deep attenuation. Index Terms--Drop size distributions (DSDs), millimeter wave attenuation, propagation prediction methods, rainfall rate.