The robustness of S-parameter methods for measuring the intrinsic properties of microwave materials

S-parameter data are often used to retrieve the intrinsic properties of a disparate range of microwave materials; the permittivity of low loss dielectrics and the permittivity, permeability and chirality of lossy chiral composites may all be measured using broadly similar techniques. The robustness of three S-parameter methods for measuring the intrinsic properties of arbitrary materials is investigated. Using simulated error data the performance of each method is analyzed and conclusions drawn as to its effectiveness. The amplitude-only method exhibited highly fluctuating error data. Significantly, the importance of error in S-parameter amplitude data does not necessarily remain constant when two phase values are swapped for two amplitude values. When adopting optimized amplitude parameter measurement schemes for four parameter measurements, one must not assume that the effects of amplitude error remain unaffected