  Transformation-media designed by standard transformation-optics (TO)
approaches, based on real-valued coordinate-mapping, cannot exhibit
single-negative (SNG) character unless such character is already possessed by
the domain that is being transformed. In this paper, we show that, for a given
field polarisation, pseudo-SNG transformation media can be obtained by
transforming a domain featuring double positive (or double-negative) character,
via complex analytic continuation of the coordinate transformation rules.
Moreover, we apply this concept to the TO-based interpretation of phenomena
analogous to the tunnelling effects observable in bi-layers made of
complementary epsilon-negative (ENG) and mu-negative (MNG) media, and explore
their possible TO-inspired extensions and generalizations.
