  This paper extends current knowledge on electromagnetic wave scattering from
bounded moving media in several regards. First, it complements the usual
dispersion relation of moving media, $\omega(\theta_\mathbf{k})$
($\theta_\mathbf{k}$: phase velocity direction, associated with the wave
vector, $\mathbf{k}$), with the equally important impedance relation,
$\eta(\theta_\mathbf{S})$ ($\theta_\mathbf{S}$: group velocity direction,
associated with the Poynting vector, $\mathbf{S}$). Second, it explains the
interluminal-regime phenomenon of double-downstream wave transmission across a
stationary interface between a regular medium and the moving medium, assuming
motion perpendicular to the interface, and shows that the related waves are
symmetric in terms of the energy refraction angle, while being asymmetric in
terms of the phase refraction angle, with one of the waves subject to negative
refraction, and shows that the wave impedances of the two transmitted waves are
equal. Third, it generalizes the problem to the case where the medium moves
obliquely with respect to the interface. Finally, it highlights the connection
between this problem and a spacetime modulated medium.
