Abstract
In this paper, the diffraction of an electromagnetic wave within perfectly conducting parallel-plates embedded in a homogeneous biisotropic medium is examined. The vector diffraction problem is reduced to the scattering of a single scalar field, the latter being the normal component of either a left-handed or a right-handed Beltrami field. The scattering of the left-handed field component is explicitly analyzed, with that of the other scalar field being analogously tractable.