Magnetic field shaping technique for HF-RFID and NFC systems

Abstract

In this paper, the magnetic field shaping technique using the magnetic field repeater for high frequency radio frequency identification (HF-RFID) system and nearfield communications (NFC) system is proposed. This technique aims to improve the communication area between HF-RFID or NFC reader and passive tag by changing the magnetic field distribution over the original HF-RFID or NFC reader antenna. The multiple rectangular loop resonators cooperating with low loss air variable capacitors are employed to construct the proposed magnetic field repeater. The proposed magnetic field repeater is installed on top of the original HF reader antenna without any direct connection to the original reader antenna. The HFRFID reader for laundry application is chosen as an example to prove the concept and verify the performance. We found that the communication area between the tag and off-the-shelf HF-RFID reader is improved. The proposed technique is useful for antenna improvement of off-the-shelf HF-RFID system in many applications such as laundry application, product tacking, etc. where a short range with wide communication area are required.