Implantable Ultra Wideband (UWB) Antenna for Wireless Body Centric Network Based Medical Applications

A unique axe-shaped ultra-wideband (UWB) antenna for implantable medical applications has been proposed in this research paper. The antenna has been designed with a defected ground plane and an FR-4 substrate with a relative permittivity of 3.0. The size of the antenna is $0.21 \lambda \times 0.13 \lambda \times 0.017 \lambda$. A quasi-self-complementary design with delicate multiple slots on the ground plane assisted in miniaturization of the design. In free space simulations, the antenna shows prominent results in terms of bandwidth, return loss, VSWR, gain, and efficiency, while the s11 curve entirely remained operational within the ultra-wideband range by staying under 10 dB with multiple resonant points. Primarily, four different frequencies within the UWB range have been monitored to analyze the antenna parameter, where 4 GHz and 8 GHz produced more optimized results with around 20 and 40 dB return loss, respectively, with a peak gain over 2 dBi. Later, the antenna has been tested by implanting into the muscle layer of an artificially created torso phantom consisting of multiple layers and frequency dispersive features. Though the antenna perfectly sustained its operability within the UWB range, its primary resonance remained close to 4 GHz with around 30 dB return loss and optimum gain close to -11.9 dBi. The design shows promise to perform in implantable wireless body-centric network-based medical applications, while keeping the primary frequency of operation at 4 GHz.