A Miniaturized Dual Band Antenna for Harmonic RFID Tag

A miniaturized antenna is required for a small form factor RFID tag. For harmonic RFID tag, the tag should be capable of receiving and transmitting at two different frequencies (fundamental and harmonic). Implementation of two different antennas for the operation would increase the footprint of the antenna. Hence, an optimized antenna structure is proposed, which will have a small form factor while maintaining a considerable gain. The dual band antenna would be capable of receiving at fundamental frequency and transmit information at harmonic frequency while maintaining small tag size. The dual band antenna has a miniaturized rectangular board dimension of 96.5 mm and 81 mm with resonance at 434 MHz at low frequency and 860 MHz to 1000 MHz at high frequency. The harmonic tag was designed with nonlinear transmission line and the dual band antenna. The harmonic RF tag would be useful for numerous RF applications where the single frequency tags will not be a good option such as underground object tagging, tag detection in an industrial set up with strong reflectors such a metal in the vicinity. In this paper, the design, fabrication and characterization of dual band harmonic RFID tag antenna is presented.