Metamaterial Self-oscillating Active Antennas for Extending Readable Range of RFID

In this paper, we briefly review the recent progress on self-oscillating active integrated antenna (AIA) designs using metamaterial resonators, as it presents an important breakthrough in improving the antenna performance in terms of dc-to-RF conversion efficiency, phase noise, etc. To be specific, it solves the long-term paradox in selecting the quality (Q) factor of the frequency selective element in an oscillating AIA by decoupling the radiating and oscillating parts. The design philosophy is briefly reviewed and some new idea on reconfigurability is proposed.