Ferromagnetic Resonance Identification (FMR-ID) under Low Magnetic Field for microwave RFID

A method for ferromagnetic resonance identification (FMR-ID), using magnetic nanowires (MNWs) made from cobalt-iron, is presented for sub-mmWave RFID applications. For use in a tag, a circuit comprised of a MNW chip with copper back placed above a grounded coplanar waveguide (GCPW) line is evaluated. According to simulation, minimal mismatch in the GCPW line and maximum FMR absorption in the MNW chip occurs when it is centered over the gap of the GCPW line. Five unique DC magnetic field strengths, between 0 and 0.2 T, have been applied perpendicular to the MNW chip. The detected FMR absorption is observed at five sub-mmWave frequencies between 20 and 30 GHz. This approach lays the foundation for five-bit tag identification addressing.