A monitoring circuit for monitoring the position of a target, comprising: an inductive system; wherein the inductive system comprises a multitude of air core inductors (28, 30); and wherein the inductive system comprises a multitude of capacitors (24, 26); wherein the multitude of air core inductors (28, 30) and the multitude of capacitors (24, 26) form at least two resonant circuits, which are magnetically coupled; wherein the inductive system is adapted such that depending on the distance between the target and the inductive system a frequency response (34, 26) of the inductive system is changed, such that when the target is close to the inductive system the bandwidth of the frequency response of the inductive system is increased; further comprising an evaluation unit; wherein the evaluation unit is adapted to differentiate between at least two frequencies (38, 40), wherein the evaluation unit comprises: at least two band filters (8, 10); wherein the centre frequency of a first band filter is close to a first frequency; wherein the first frequency is a lower cut-off frequency of the frequency response of the inductive system when the target is close to the inductive system; wherein the first band filter is adapted to allow a first signal with the first frequency to pass; wherein the centre frequency of a second band filter is a second frequency; wherein the second frequency is a resonance frequency of the inductive system when the target is remote to the inductive system; wherein the second band filter is adapted to allow a second signal with the second frequency to pass. an inductive system; wherein the inductive system comprises a multitude of air core inductors (28, 30); and wherein the inductive system comprises a multitude of capacitors (24, 26); wherein the multitude of air core inductors (28, 30) and the multitude of capacitors (24, 26) form at least two resonant circuits, which are magnetically coupled; wherein the inductive system is adapted such that depending on the distance between the target and the inductive system a frequency response (34, 26) of the inductive system is changed, such that when the target is close to the inductive system the bandwidth of the frequency response of the inductive system is increased; further comprising an evaluation unit; wherein the evaluation unit is adapted to differentiate between at least two frequencies (38, 40), wherein the evaluation unit comprises: at least two band filters (8, 10); wherein the centre frequency of a first band filter is close to a first frequency; wherein the first frequency is a lower cut-off frequency of the frequency response of the inductive system when the target is close to the inductive system; wherein the first band filter is adapted to allow a first signal with the first frequency to pass; wherein the centre frequency of a second band filter is a second frequency; wherein the second frequency is a resonance frequency of the inductive system when the target is remote to the inductive system; wherein the second band filter is adapted to allow a second signal with the second frequency to pass. at least two band filters (8, 10); wherein the centre frequency of a first band filter is close to a first frequency; wherein the first frequency is a lower cut-off frequency of the frequency response of the inductive system when the target is close to the inductive system; wherein the first band filter is adapted to allow a first signal with the first frequency to pass; wherein the centre frequency of a second band filter is a second frequency; wherein the second frequency is a resonance frequency of the inductive system when the target is remote to the inductive system; wherein the second band filter is adapted to allow a second signal with the second frequency to pass.