A highly miniaturized antenna with wider band for biomedical applications

A highly miniaturized planar monopole antenna is presented for biomedical applications. The proposed antenna utilizes polydimethylsiloxane (PDMS) with dielectric constant 2.7 and loss tangent 0.0314 with thickness 0.3 mm as substrate and with thickness 0.2 mm as superstrate. A copper foil of 0.03 mm thickness is used for radiating elements. The proposed structure contains a unique structure, made of loop-based structure with three rectangular-shaped stubs are added to tune the operating frequency to 5.8 GHz and to improve the reflection coefficient. The incorporation of stubs achieved the intended frequency of operation, utilization of the loop-based structure for designing the antenna achieved high miniaturization. The proposed antenna is analyzed under various conditions like under skin, muscle, stomach, small intestine,, colon etc., and comparative analysis is presented with the help of reflection coefficient, radiation patterns and specific absorption rate (SAR). SAR is evaluated over a volume of 1 g tissue as per the standards of Federal Communications Commission (FCC). SAR value of the antenna is below 1.6 W/kg for input power 1.9 mW. The simulated analysis showed that the designed antenna is suitable for both implantable and endoscopic applications. Moreover the simulated and measured analysis for reflection coefficient of the proposed antenna showed good agreement.