Fine-Tuning Impedance Matching Circuit for a Triple-Band Meandered PIFA in Brain-Implantable Bio-telemetric Systems

This article presents a study of the tunable impedance matching to our recently reported compact self-matched triple-band brain-implantable planar-inverted-F antenna (PIFA). It operates at Medical Device Radiocommunication Service (MedRadio) band (401–406 MHz) and Industrial, Scientific, and Medical (ISM) bands (902–928 MHz and 2400–2483.5 MHz). To achieve this, we investigated the optimal reflection coefficient characteristics of PIFA at desired frequencies by employing four
$\pi$
- and T-type matching circuits. Our results show that a T-type circuit selected for further assessment provides suitable fine-tuning possibilities for all combinations of desired upwards and downwards frequency-tuning of the three operating frequencies to ensure reliable wireless implant communications.