Reduced-size Biocompatible Implantable Planar Inverted F- Antenna

Abstract

The existence of implantable antennas presents intrinsic challenges as the performance of the antenna degrades due to the high losses of body tissues. In this study, a reduced-size Planar Inverted F- Antenna (PIFA) operating at Industrial, Scientific Medical (ISM) band (2.4 GHz) is designed and optimized. The design of PIFA is modeled to study and analyze the effect on the implantable antenna by placing it within the human body model, particularly in the arm. Copper is used as the patch material and the ground layer of the proposed antenna with Rogers RO3210 as its substrates.  The simulation was carried within the human fat layer which is sandwich between the skin dan muscle layer. The design optimization of the antenna  for operation  in a human fat layer with optimal performance was achieved by reducing the size of the antenna.  The antenna exhibits good stability with the reflection coefficient, S11 ≤ -10 dB at 2.4 GHz suitable for WBAN application in the environment of the human fat layer for near field communication. Analysis performance of the antenna was conducted by the transient movement of the antenna position due to the antenna being prone to movement when it is implanted within the body. The transient movement analysis is done when the implantable antenna is moving toward the skin layer and toward the muscle layer from the initial position within the fat layer. Additionally, 1 mm, 2 mm, interface of the layer and when the antenna within another tissue layer has been set to examine the performance of the implantable antenna. Correspondingly, simulation results indicate the impact of the human body layer due to the electrical properties of the human body in terms of conductivities, permittivity, and thicknesses of the layers. This has shown the design optimization of the antenna satisfies all requirements for an implantable antenna, such as small size of 5.08 × 4.00 × 0.66 (), biocompatible, low reflection coefficient of -42 dB at 2.4 GHz, realized gain of -18 dBi suitable for near field communication, and acceptable performance in fat layer. Future work will expand on conducting Specific Absorption Rate (SAR) to study the high attenuation of the radiated power of the human body on implanted antennas for the safety reason to bring in real life where it is being performed and examined.