defined as the measuring range m the remaining length of the coil of 15 of the length l for instance forms an overhang which is also essential in the function of the pair of coils a b as presented in fig1 and enlarged in fig2 the overlapping can be achieved by positioning the coils a b either next to each other having a relatively wide damping part covering both coil tracks or by having a pair of coils positioned below each other on the top and bottom part of the coil carrier and by having a respective smaller damping part both variations of overlapping will end up with the array of characteristic curves as shown in fig1 shown here as function of the position s of the damping part is the resonant frequency f of both coils a b of an oscillator each particular coil is a part of it one can see from fig1 that for the mentioned rectangular shaped coil configurations the correlation between the resonant frequency f a s and f b s and the damping part position s is linear in each case because coil b is offset by 15 of the coil length l for example.