RESOLVING PHASE AMBIGUITY IN THE INVERSE PROBLEM OF REFLECTION-ONLY MEASUREMENT METHODS

Abstract

We have applied the phase unwrapping technique to resolve the phase ambiguity problem arising from complex expressions of scattering parameters, for re∞ection-only measurement conflgurations, since, at some instances, only one side of the sample under test is accessible for electromagnetic measurements. We considered two difierent measurement conflgurations for testing the applicability of the phase unwrapping technique as: 1) two identical samples with difierent lengths ∞ushed by a short-circuit termination and 2) one sample shorted by a varying short-circuit termination. For each measurement conflguration, the underlying expressions for the re∞ection scattering parameters are derived. For both cases, we evaluated the suitability of the phase unwrapping technique by considering a highly-dispersive medium (distilled water) as our test sample. We note that continuity of the real part of the complex wavelength is a key issue in the unwrapping technique for (one-port) re∞ection-only measurements.