micropulsations from a finite source

In this paper the polarization and the spatial and frequency dependence of the magnetic field at the ground resulting from a specified Pc 1 disturbance of finite extent are obtained. At small lateral distances from the center of the incoming disturbance, the ground signal can be identified as a directly transmitted signal having the spatial properties of the incoming disturbance. The polarization and frequency characteristics of the direct signal are related to the corresponding properties of the incoming wave. At lateral distances that are large when compared to the size of the incoming disturbance, the signal can be identified as a ducted signal with properties that can be quite different.