Magneto-Inductive HF RFID System

Efforts to increase read range in passive HF RFID systems are hampered by the poor scaling law of inductive coupling. An alternative approach enlarging capture volume-increasing lateral extent antenna-is proposed, using a magneto-inductive (MI) travelling wave arrangement allow larger antenna sizes. A theory load modulation MI is first presented, together with field simulations volume. 2.3 metre-long then constructed, and an active tag emulator used demonstrate modulation. demonstrated, both reflection transmission modes, custom reader constructed from laboratory equipment. transverse 0.5 m obtained commercial off-the-shelf cards 10 W RF power, high uniformity along length antenna.