Radiation From an Oscillating Source Moving Through a Dispersive Medium With Particular Reference to the Complex Doppler Effect

The complex Doppler effect is analyzed from the time behavior of the radiation field of an oscillating source traversing a dispersive medium. The effect is calculated for the case where an oscillating electric dipole is moving uniformly through an ionized gas permeated by an infinitely large magnetostatic field. It is found that the radiation field can be split into a number of waves, each having characteristics of its own, and that the number of waves changes with time. The group velocity of each individual wave is shown to play an important role in the physical mechanism of the effect.