The miniature design is achieved by inserting a conductive layer into the antenna structure to increase the capacitive reactance of the antenna, which lowers the self-resonant frequency of the antenna and allows high reactance impedance to be obtained with a small-size RFID tag antenna. The experimental test shows that the maximum read range of the prototype placed on a metallic object is about 1.5 m with 4 W EIRP radiation power of the RFID reader. In order to achieve the low cost and easy mass production, the miniature RFID metal tag design by using a single-layer substrate is currently under investigation.