Abstract: A receiver designed to pick up an electromagnetic signal, comprises: a passive receiving antenna; a resonant circuit connected to the antenna, formed of passive components and replying, by transmitting an electric signal, to the electromagnetic signal picked up, and an electric signal processing circuit. This receiver also comprises a threshold comparator circuit defining a reference threshold and connected directly to the terminals of the resonant circuit to compare the electric signal, not amplified, with the reference threshold and to activate said processing circuit only when the amplitude of the electric signal exceeds the threshold. An object tracking system making use of the receiver described above is also disclosed.