Apparatus and method for metal detection using radio frequency reflection

摘要

A radio frequency (RF) metal detector and an electronic article surveillance (EAS) system are disclosed. The RF metal detector in example embodiments transmits an RF signal. A receiver measures the power and phase of the signal as reflected from metallic objects in an interrogation zone. The RF metal detector can be deployed in a combined system that performs multiple functions. For example, the RF metal detector can be integrated with an EAS system that also sends RFID commands and receives RFID responses. In some embodiments the metal detector can discriminate between moving metal objects and stationary metal objects, and/or discriminate between objects in the interrogation zone and objects outside the interrogation zone. An antenna or antennas can be connected in a mono-static or bi-static configuration and the phase and power signals can be either DC-coupled or AC-coupled into the system through a mixer.

主权项

1. A system comprising: a receiver to receive a returned RF signal including a carrier signal reflected from a metal object; a transmitter to transmit an incident radio frequency (RF) signal modulated with radio frequency identification (RFID) commands; and a processor connected to the transmitter and the receiver to extract modulated RFID responses from the returned RF signal to detect an RFID tag, and detect metal objects by measuring at least one parameter of the carrier signal in the returned RF signal.