Planar Omnidirectional Detection of RFID/NFC Patches Inside a Cubic Structure

Abstract

Benefiting from advantages such as miniaturization, lightweight design, and cost-effectiveness, 13.56 MHz High Frequency Radio Frequency Identification (HF RFID) and Near Field Communication (NFC) tags have found increasing applications across various fields like biomedical, tracking, and logistics, bringing a lot of convenience to the industries and commercials, as well as decreasing the medical and employment pressure. Nevertheless, the smaller the tag, the less likely it is to be fixed in orientation. As the detection of such tags relies on magnetic coupling, the orientation sensitivity is high, and some nulls of detection are introduced inside the considered volume of interest in practical applications. It is essential to optimize the magnetic field vectorial distribution generated by the NFC reader. This paper uses a combination of two paralleled tuned coils (RLC resonator model) in series to be the RFID/NFC reader coils. In such a system, the currents feeding the coils are in quadrature. The system is made of two-phase coils. Additionally, each coil is composed of two sub-coils placed on opposite surfaces of a cube, for the prototype of this system presented in the paper. CST simulations have been analyzed and a 3D printed cube structure with copper tapes has been realized, to validate the idea experimentally. Detection tests were performed with a commercial HF RFID reader and an ISO15693 NFC tag.