An impedance matching method for optical disc-based UHF-RFID tags

An impedance matching method applicable to UHF-RFID tags mounted on optical discs, where the main radiating element is the disc metallic layer (from now on optical disc-based tags) is presented in this paper. Such a method provides a very simple analytical approach and allows us to obtain any arbitrary matching level at the desired frequency, by using only one reactive element as a matching network. As a demonstration, the method is applied to the design of a DVD;R based tag, using the Alien Higgs 3 RFID ASIC, and forcing conjugate matching at 915 MHz. The tag design and synthesis process is explained and a bandwidth optimization analysis is also provided. The validity of the method is confirmed by EM simulations and experimental measurements. The measured read range of the fabricated tag reaches 8.3 m at 915 MHz and presents 50 MHz half-power bandwidth.