  We investigate the twofold functionality of a cylindrical shell consisting of
a negatively refracting heterogeneous bianisotropic (NRHB) medium deduced from
geometric transforms. The numerical simulations indicate that the shell
enhances their scattering by a perfect electric conducting (PEC) core, whereas
it considerably reduces the scattering of electromagnetic waves by closely
located dipoles when the shell surrounds a bianisotropic core. The former can
be attributed to a homeopathic effect, whereby a small PEC object scatters like
a large one as confirmed by numerics, while the latter can be attributed to
space cancelation of complementary bianisotropic media underpinning anomalous
resonances counteracting the field emitted by small objects (external
cloaking). Space cancellation is further used to cloak a NRHB finite size
object located nearby a slab of NRHB with a hole of same shape and opposite
refracting index. Such a finite frequency external cloaking is also achieved
with a NRHB cylindrical lens. Finally, we investigate an ostrich effect whereby
the scattering of NRHB slab and cylindrical lenses with simplified parameters
hide the presence of dipoles in the quasi-static limit.
