Synchrotron Radiation at Radio Frequencies from Cosmic Ray Air Showers
  We review some of the properties of extensive cosmic ray air showers and describe a simple model of the radio-frequency radiation generated by shower electrons and positrons as they bend in the Earth's magnetic field. We perform simulations by calculating the trajectory and radiation of a few thousand charged shower particles. The results are then transformed to predict the strength and polarization of the electromagnetic radiation emitted by the whole shower. 
Denis A. Suprun, Peter W. Gorham and Jonathan L. Rosner