  This paper explores the time-modulated waveguide setups for unique and
accurate permittivity and permeability extraction of lossy dispersive samples
with phase-less measurements. We theoretically demonstrate that when the
position of the short-circuit termination is dynamically modulated in a
predefined way, the phase information of the reflection S-parameter manifests
itself into the amplitude level of the emerging harmonics. Being insensitive to
the calibration plane shifts and phase uncertainties in reflection measurements
while bypassing a priori knowledge about the material under test (MUT) and also
the transmission coefficient, can be enumerated as the main advantages of the
proposed time-modulated retrieval scheme. Moreover, the presented
reconstruction algorithm offers a simple post-processing step to facilitate
fast computations of $\varepsilon_r$ and $\mu_r$. Several illustrative examples
at X-band frequencies have been presented to numerically verify the validity of
the proposed approach for some applicable and practical types of homogeneous
materials. Two possible realization and measurement configurations are
suggested and discussed based on mechanical actuation and electrical phase
control. We have also performed an uncertainty analysis to examine how the
realization tolerances can affect the accuracy of results. By involving the
temporal dimension, the proposed strategy takes a great step forwards in
phase-less reconstruction of the electromagnetic parameters.
