Abstract
The paper deals with electromagnetic problem of the radiation generated due to the excitation of a periodic interface of an artificial material with dispersive constitutive parameters by an electron beam moving over this interface. It is demonstrated that the possibility of excitation of eigen waves of periodic surface has the principal influence on the radiation characteristics, which show anomalously high levels of the secondary filed. It is also shown that an accurate solution to the spectral problem, allowing numerical modeling of eigen regimes, provides the profound description and physical explanation of the complicated electromagnetic phenomenon.