Radiation from a charged particle in uniform straight motion through a particular stratified medium

The stratified medium here considered is constituted by a set ofN equispaced metallic films imbedded in a homogeneous isotropic dielectric. The films are assumed to be infinitely thin and to have a reflection coefficient ϱ0<1. The general expression of the radiated electromagnetic field is found for particle velocities below the Cerenkov threshold for the dielectric considered. Numerical evaluations have been performed in the particular casesN=1,N=2,N=∞; the results show that the gain over the case of a single film with infinite conductivity presents rather steep peaks revealing the existence of sharp cones of radiation. It seems that the structure may be employed for measuring the particle velocity as well as for generating millimetric and submillimetric power.