Contents I. Introduction
The inception of RFID (radio frequency identification) has enabled the contactless transfer of information without the requirement of line-of-sight association, specifically between a reader and transponders that reside on identified items. As the technology for RFID systems continuously improves and extends to structures of non-orthogonal shapes and to conformal sensors of wireless body-area networks (WBAN), there has been a need to design more “flexible” reader and tag systems. Namely, miniaturization of the transponder and ability to tune the system performance to accommodate EM (electromagnetic) absorption and interference from surrounding media, while compensating for fabrication tolerances has been one of the major priorities [1]. Three-dimensional transponder antennas that utilize wound coil inductors do make use of magnetic cores, but they are quite bulky and impractical. On the other side, magnetic materials for 2D embedded conformal planar antennas have not yet been successfully realized for standard use. This paper introduces for the first time a novel flexible magnetic composite for printed circuits and antennas, which can reap the same miniaturization and tuning benefits as the heavier and non-flexible 3D counterparts that use magnetic cores.
