Small-Size Dual-Antenna Implantable System for Biotelemetry Devices

A dual-element miniaturized implantable antenna is designed and experimentally demonstrated at Medical Device Radiocommunications Service (MedRadio) (401-406 MHz) band for wireless biomedical multiple-input-multiple-output (MIMO) applications. First, a single-fed planar monopole antenna is designed by embedding the spiral line as a radiator and helix line on the ground. The proposed antenna element can obtain effective size reduction and wide impedance characteristic at a fixed frequency operation. Second, two antenna elements were placed in close to study the coupling strength of the two elements. The proposed MIMO antenna has dimensions of 22 × 22 × 0.635 mm
³
. The simulated and measured impedance bandwidths are 35.9% and 61.7%, respectively. The measured maximum mutual coupling is below -26 dB at MedRadio Band.