Design of long-range, powerless RFID sensor at 10 GHz

The design of a radio frequency identifier (RFID) tag sensor based on the modulated scattering technique (MST) is presented. The tag works in the X band at 10 GHz and achieves an operative range of about 10 m with a limited amount of power. The power supply required by the transponder is obtained from the interogating electromagnetic field with a customised rectifying Chockcroft-Walton multiplier circuit. The communication between the reader and the tag is obtained using the standard EM4102 RFID protocol, the information is carried on by modulating the load of the tag antenna with a suitable switch circuit. The antenna tag, the rectifying circuit and the switch have been optimised to reach the maximum operative range. A tag prototype has been designed, fabricated and experimentally assessed. The obtained experimental results are quite good.