A radio frequency identification (RFID) tag is provided including a lower antenna, an upper antenna, a RFID chip, and a spacer. The lower antenna has a coupling projection at one end. The upper antenna has a coupling groove at one end. The RFID chip contains information of an object which can be communicated with a reader device. One end of the RFID chip is coupled with the projection of the lower antenna and the other end is coupled with the groove of the upper antenna. The spacer is between the antennas to isolate the antennas electrically. The antennas are combined on both sides of the spacer in parallel. The RFID chip is connected with the antennas and fitted on a top side or a bottom side of the spacer so that active signals are transmitted through the antennas to send the information in the RFID chip to the reader device.