Site Diversity is one of techniques to compensate rain attenuation in milimeter-wave. However, to implement appropriate site diversity techniques have to involve base knowledge about rain cell dimension. In this paper, Vector AR (VAR) Model with Granger Causality Test is implemented to rainrate at 3 raingauge sites. Granger Causality test is used to check whether one site “granger-cause” to another site and vice versa. The result show that site C “granger-cause” to site B and site B “granger-cause” to site A. It mean that rain cell have < 1 km diamate
