Characteristics of meander coil impedance with opened scale coil for linear sensor

A meander coil type linear sensor(MLS) can detect the position of a linear pulse motor's (LPM) mover. This sensor uses a LPM's stator as the scale, so it is possible to be combined with the LPM, in addition, because the excitation frequency of this sensor is several mega hertz, a high-speed response can be expected. We are studying the MLS that uses a meander coil as the scale, with the scale coil open for optimum performance. In our study, we measured the impedance change characteristics while the scale coil was open. While a resonance capacitor was connected to the detection coil and adjusted from 10 nF to 660 pF, the impedance change was 17.51 times. Furthermore, by adjusting the scale coil line width from 0.5 to 1.1 mm, the impedance change was 2.67 times.