Patent ID: 7092840

Claim:
A position sensing system, comprising: a variable frequency signal source coupled to receive a frequency control signal and operable, in response thereto, to supply a sensor drive signal at a frequency; an embedded stripline resonant transmission line sensor having one or more resonant frequencies, the transmission line sensor including first and second conductive substrates, a fixed dielectric substrate having at least a first surface and a second surface, a sensor conductor coupled to at least one of the first and second surfaces, and a moveable dielectric at least partially surrounding the sensor conductor, the moveable dielectric including a first moveable dielectric substrate disposed between the first conductive substrate and the fixed dielectric substrate first surface, a second moveable dielectric substrate disposed between the second conductive substrate and the fixed dielectric substrate second surface, the sensor conductor having a driven end coupled to receive the sensor drive signal and a terminal end configured to reflect the sensor drive signal to thereby supply a reflected signal to the driven end, the moveable dielectric configured to receive a drive force and, upon receipt thereat to move the dielectric to a position and thereby vary the one or more resonant frequencies of the transmission sensor; a summing circuit coupled to receive the sensor drive signal and the reflected signal and operable, in response thereto, to supply a standing wave signal having an amplitude that varies with the one or more resonant frequencies of the transmission line sensor; a control circuit coupled to receive the standing wave signal and operable, in response thereto, to (i) determine the sensor drive signal frequency relative to at least one of the transmission line sensor resonant frequencies and (ii) supply the frequency control signal to the variable frequency source, to thereby adjust the sensor drive signal frequency to substantially match at least one of the transmission line sensor resonant frequencies; and a position determination circuit coupled to receive the adjusted sensor drive signal and operable, in response thereto, to determine the position of the moveable dielectric relative to the sensor conductor.