  We theoretically study negative refraction of inhomogeneous waves at the
interface of lossy isotropic media. We obtain explicit (up to the sign)
expressions for the parameters of a wave transmitted through the interface
between two lossy media characterized by complex permittivity and permeability.
We show that the criterion of negative refraction that requires negative
permittivity and permeability can be used only in the case of a homogeneous
incident wave at the interface between a lossless and lossy media. In a more
general situation, when the incident wave is inhomogeneous, or both media are
lossy, the criterion of negative refraction becomes dependent on an incident
angle. Most interestingly, we show that negative refraction can be realized in
conventional lossy materials (such as metals) if their interfaces are properly
oriented.
