A Simple Ranging System Based on Mutually Coupled Resonating Circuits

In this paper, a ranging technique based on inductive coupling between resonating coils is presented. By exploiting resonance, both a high range and high signal-to-noise ratio at the receiver are achieved. The theoretical background is discussed; a theoretical model is presented; and a practical implementation is illustrated and experimentally validated. It is shown that the proposed technique, implemented using off-the-shelf components, is only moderately sensitive to the effect of conductive objects placed close to the receiver, whereas it proves its effectiveness in an ordinary laboratory setup, achieving a maximum error of <;3 cm over a 5.8-m range. It is thus suitable for indoor positioning applications.