Universal expression for the Poynting vector applicable for evanescent waves: inherent output from the method of single expression

An alternative expression for the Poynting vector valid for evanescent waves is presented. This expression is the natural variable in the method of single expression (MSE). The MSE does not exploit superposition principle, i.e. not representing solutions of Helmholtz's equation as the sum of counter-propagating waves, which permits to have alternative expression for the Poynting vector valid both in media with a positive product of permittivity and permeability, and at a negative product (relevant to evanescent waves) as well. The boundary problem solution by the MSE permits to observe spatial distributions in a confined medium not only for electric and magnetic field amplitudes, but also for the Poynting vector. The alternative expression for the Poynting vector is in perfect agreement with the traditional representation for propagating waves.