A generalised material characterisation technique for partially-filled waveguides

A generalisation of the well-known Nicholson-Ross-Weir algorithm, applicable to a sample partially filling a section of rectangular waveguide, is derived. The technique is validated by comparison with a finite element solution and applied to retrieve the permittivity and permeability of the sample. The scheme finds application at high temperatures and in circumstances where a sample cannot be cut to fit standard waveguide.