PT symmetry in non-Hermitian electronic models has drawn much attention over
the past decade mainly because it guarantees that the band structures
calculated under open boundary conditions be the same as those calculated under
periodic boundary conditions. PT symmetry in electromagnetic (EM) models, which
are usually borrowed from electronic models, has also been of immense interest
mainly because it leads to 'exceptional' parameter values below which
non-Hermitian operators have real eigenvalues, although PT symmetry is not the
sole symmetry which allows such exceptional parameter values. In this article,
we examine 1-dimensional PT-symmetric non-Hermitian EM models to introduce
novel concepts and phenomena. We introduce the band-structure concept of 'fixed
points', which leads to 'bidirectional' reflection zeros in the corresponding
finite structures, contrary to a common belief about the EM structures with PT
symmetry (and without P and T symmetries). Some of the fixed points manifest
themselves as what we name 'extended states in the bandgap' on the band
structure while some other fixed points are the 'turning points' of the band
structure. The extended states in the band gap are in fact the dual of the
well-known 'bound stated in the continuum' while the turning points allow us to
observe 'ideal' superluminal tunneling in the corresponding finite structures.
By 'ideal' superluminal tunneling we mean the case where not only the
transmission coefficient has an almost uniform phase over a broad bandwidth but
also the magnitudes of the transmission and reflection coefficients are almost
equal to unity and zero, respectively, over the bandwidth