Miniaturized wideband implantable slotted loop antenna for biotelemetry applications

Small size of the implantable antenna is the major concern in Implantable Medical Devices. A compact implantable wideband radiator working at the ISM band is proposed for biotelemetry applications. The overall dimension of the proposed radiator is 10 mm star 15 mm star 0.8 mm and the thickness includes substrate and super-strate thickness. The Coaxial feeding method is employed here. The inner and outer diameter of the coaxial feed is 1 and 1.5 mm respectively. The design process starts with a creation of rectangular patch of size 10 mm star 15 mm and the coaxial feed is located at (2.5, 7). Then slot like loops are introduced on a rectangular patch. This compact size is achieved by introducing small loops on a rectangular patch along with triangular cuts at the bottom right and top-left of the patch. The antenna is simulated with a tissue model (Skin, Fat, Muscle, Bone) and measured with a Body Equivalent Fluid (phantom). The -10 dB bandwidth is obtained over 1340 MHz (1.66-3 GHz) and the fractional bandwidth of 54.7% at the ISM band. The simulated gain and radiation efficiency of the radiator are -13.5 dBi and 3.15% respectively. The measured return loss of the proposed antenna is -30.53 dB and the SAR value averaged over 1 g tissue is 302.6 W/kg with 1 W input power. When compared to the previous works mentioned in the literature the proposed antenna displays wider bandwidth, high gain, low SAR and high radiation efficiency.