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Dual band microstrip implantable antenna design for biomedical applications

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2015
Alptekin, Damla
In this study, numerical and experimental analysis of a dual band (Medical Implant Communications Service-MICS; 402 − 405 MHz, Industrial, Scienti c and Medical-ISM; 2.4 − 2.48 GHz) implantable antenna design for biomedical applications are presented. The proposed antenna is in the type of Planar Inverted-F Antenna (PIFA) covered with a superstrate. For miniaturization, the metallic patch of the antenna is meandered and shorting-pin is used between the patch and ground plane. In addition, stacking patch structure is used to lengthen the current fl ow path. Numerical analysis of the implant antenna is carried out using commercially available Finite Element Method (FEM)-based High Frequency Structure Simulator (HFSS) software. As a tissue model a generic dispersive skin model is used. Two antenna designs are presented: an initial antenna operating in MICS band and a miniaturized optimized antenna operating in dual band (MICS and ISM). For both antennas, a parametric antenna model is presented and each antenna design step is explained. For experimental studies, skin mimicking phantoms are developed in MICS and ISM bands. The proposed antenna is fabricated and in vitro tested. It is shown that the antenna resonates at 403.5 MHz with a refl ection coeffi cient of −23 dB, and a 10-dB bandwidth of 56 MHz, which covers the MICS band, moreover, it resonates at 2.45 GHz with a re flection coeffi cient of −22 dB, and a 10-dB bandwidth of 200 MHz, which covers the ISM band. The maximum simulated gain is found as -33 dBi. Communication link measurements are performed using commercially available Microsemi-Zarlink Application Development Kit for Medical Telemetry (ZLE70102) in order to check the functioning of the proposed antenna. Designed antenna is inserted into MICS band phantom and it is achieved to wake-up base station module at ISM band and to send data at MICS band in 4 meter range. Moreover, patient safety issues, comparative analysis of radiation performance for di fferent phantom models, eff ect of coaxial cable, far fi eld properties of implantable antennas, and gain measurement of the electrically small antennas are discussed.