  We report the realization of coupling-independent, robust wireless sensing of
fully-passive resistive sensors. PT-symmetric operation obviates sweeping,
permitting real-time, single-point sensing. Self-oscillation is achieved
through a fast-settling nonlinearity whose voltage amplitude is proportional to
the sensor's resistance. These advances markedly simplify the reader. A dual
time-scale theoretical framework generalizes system analysis to arbitrary
operating conditions and a correction strategy reduces errors due to detuning
from PT-symmetric conditions by an order of magnitude.
