  We describe a method of extrapolation based on a "truncated" Kramers-Kronig
relation for the complex permittivity ($\epsilon$) and permeability ($\mu$)
parameters of a material, based on finite frequency data. Considering a few
assumptions, such as the behavior of the loss tangent and the overall nature of
corrections, the method is robust within a small relative error, if the assumed
hypotheses hold at the extrapolated frequency range.
