A position sensing system uses a resonant transmission line having a
moveable dielectric as a position sensor. The system includes circuitry
that supplies a drive signal to the resonant transmission line, which
reflects the drive signal. Based on a standing wave signal, which is
generated from the drive signal and the reflected drive signal, the
circuitry determines the frequency of the sensor drive signal relative to
a resonant frequency of the resonant transmission line, and adjusts the
sensor drive signal frequency to match a resonant frequency of the
transmission line. The circuitry determines the relative position of the
moveable dielectric based on the adjusted sensor drive signal frequency.