REFLECTIONLESS TRANSIT OF ELECTROMAGNETIC WAVES AT THE NORMAL INCIDENCE ON THE SYMMETRIC THREE-LAYERED STRUCTURE CONTAINING A NEGATIVE-PERMITTIVITY LAYER

The effect of reflectionless normal transit of electromagnetic waves through symmetric three-layered structures containing negative-permittivity layers excites considerable interest. It is stipulated by both an unusual nature of the effect and its unique technical applications. Moreover the electromagnetic-wave reflectionless transit effect has been investigated not enough and not all the peculiarities of the effect have been found and described yet. By now the reflectionless transit effect has been considered only for some concrete values of the permittivity and thickness of a symmetric three-layered structure. In this paper a more general approach based on entering dimentionless values of the thickness of the structure layers is used. This approach makes it possible to study the reflectionless transit effect irrelatively to some concrete wave band. It is shown that the presence of a negative-permittivity layer in a three-layered structure leads to a considerable change in the reflection spectrum of electromagnetic waves. It has been found that in the reflection spectrum of the electromagnetic waves there are wide regions of a weak reflection. The width of these regions can be controlled efficiently by matching a value of the negative permittivity of the middle layer in the three-layered structure. The influence of the energy losses in the middle layer of the three-layered structure on the reflection spectrum of the electromagnetic waves is studied. The obtained results are of great practical importance for developing new devices of electronics, photonics, and photovoltaics.