Patent ID: 7216054

Claim:
A method for monitoring a position of an object, or related parameters, including a measurement of the position of the object as a distance between the object and a sensing element, motion of the object along the distance defining a motion axis, the method comprising: placing at least one electromagnetic sensing element in proximity to the monitored object; exciting an alternating electromagnetic field in the sensing element at a frequency and in a form at which the electromagnetic field extends to the object; measuring a variation of at least one electromagnetic parameter of the sensing element, the variation caused by a variation in the position of the object; converting results of the measurements into a representation of the position of the object along the motion axis, wherein at least one electrically conductive surface is formed on, or coupled to, the monitored object, the surface facing the sensing element, the alternating electromagnetic field exited as an opposite-phase slowed-wave in a coupled slow wave structure, the electromagnetic field having a spatial distribution, the distribution depending on the position of the conductive surface; and providing an indication of the position of the object.