Semi-active 866 MHz RFID implantable tag fed by 6.78 MHz inductive wireless power transfer

The paper presents a compact battery-less semi-active UHF RFID tag powered by an inductive wireless power transfer designed to be implanted into the human body. Communication runs at frequency of 866 MHz whereas powering is performed at frequency of 6.78 MHz to reduce losses. Tag sensitivity for communication was increased by about 21 dB with the help of inductive wireless powering when compared to a tag which did not employ this powering. Communication and powering circuits were integrated within compact structures on the sides of the reader and the tag. The reader side consists of a center-excised Archimedes spiral antenna for communication and a circular loop for powering. The tag side consists of a folded dipole antenna for communication and a rectangular loop for powering.