  Left-handed materials are studied numerically using an improved version of
the transfer-matrix method. The transmission, reflection, the phase of the
reflection and the absorption are calculated and compared with experiments for
both single split-ring resonators (SRR) with negative permeability and
left-handed materials (LHMs) which have both the permittivity and permeability
negative. Our results suggest ways of positively identifying materials that
have both permittivity and permeability negative, from materials that have
either permeability or permittivity negative.
