A new broadband method of characterisation of conductive polymers using discontinuities in microwave transmission lines

A new approach to measurement of the dielectric permittivity is proposed, using a discontinuity in a microstrip line or rectangular waveguide. A contour integral method is used in the first instance to calculate the S-parameters with knowledge of the permittivity (direct problem). Diagrams relating the dielectric constant to the S-parameter are obtained and a simple analytical expression is deduced for solution of the inverse problem.