Miniaturized and Differentially Fed Implantable Antenna for Biomedical Telemetry Applications

In this paper, a miniaturized patch antenna for biomedical telemetry application is proposed. The designed antenna operates in industrial-scientific-medical (ISM) band with a resonant frequency of 2.44 GHz. A slotted rectangular patch over the silicon substrate is used here and superstrate is employed for assuring biological safety. In this design, the dimension of the antenna is reduced significantly and differential feeding with coaxial cable is applied. The volume of the antenna is 20.24 cubic millimetre excluding superstrate. Antenna performance is evaluated in free space, skin phantom cube, and three-layer phantom model using the HFSS software. The value of the scattering parameter (S-11) and realized gain of the antenna in free space at the resonant frequency (2.6 GHz) are -48.2 dB and -27.1 dBi, whereas the scattering parameter (S-11) and realized gain of the antenna in skin phantom cube are -18.45 dB and -24.9 dBi at 2.44 GHz respectively. The simulated impedance bandwidth is 6.92% in free space and 6.55% in skin phantom cube. Because of its miniaturized structure, it has a great potential for the biomedical telemetry applications. Finally, the SAR of the antenna and link margin is calculated to limit the radiated power and make it perfectly biocompatible for practical use.