A Miniature RFID Tag Antenna Design for Metallic Objects Application

This letter proposes a miniature radio frequency identification (RFID) tag antenna design for metallic objects application. The antenna structure consists of two rectangular patches electrically connected through vias to the ground plane and a nonconnected interconductive layer to form an RFID tag antenna that is suitable for mounting on metallic objects. The miniature design is achieved by inserting a conductive layer into the antenna structure to increase the capacitive reactance of the antenna. This causes the self-resonant frequency of the proposed antenna to approach low frequency; therefore, the high imaginary part of the antenna impedance can be obtained with a small-size RFID tag antenna. The experimental tests show that the maximum read range of RFID tag placed on a metallic object is about 1.5 m, and the overall size is 32 times 18 times 3.2 mm³. Simulation and measurement results of the proposed RFID tag antenna are also presented in this letter.