Interaction of magnetic waves with drifting charges

The interaction between magnetic waves and drifting cerriers, with respect to the various possible configurations, is briefly considered. Discussion is then restricted to planar structures which appear to be the more promising. Some general properties of the interaction is analyzed on the basis of physical (energetic) considerations; the analysis shows that the surface-wave configuration is preferable to the volume wave although in the case of thin ferrite films considerable interaction can be expected in both cases. Thick and thin slabs are considered; in the first case the problem is reduced to that of the interface between two seminfinite media; in the second case (films) the solution implies the consideration of the whole sample. Approximate expressions are discussed for the gain (loss) of the system and the influence of the relevant parameters is discussed. In the case of thick samples positive interaction can be achieved in a very narrow bandwidth; the conductivity of the semiconductor and the losses in the Ferrite play an essential role in this phenomenon. In the case of thin films gain is predicted with bandwidths of several hundred Megahertz.