A Circularly Polarized Implantable Antenna for 2.4-GHz ISM Band Biomedical Applications

In this study, a single-fed broadband circularly polarized implantable patch antenna that operates at the 2.4-GHz Industrial, Scientific, and Medical band is designed for biomedical applications. The simulated impedance, axial ratio, and radiation patterns are studied in a cubic skin phantom. The influence of three other tissue models is also discussed. An impedance bandwidth of 6.2% with a 3-dB axial-ratio bandwidth of 8.13% is simulated in a one-layered-skin model. The experiments are carried out in both skin-mimicking gel and pork. The measured impedance bandwidths are 5.45% and 5.69%, respectively. Moreover, by setting the designed antenna in pork, an axial-ratio bandwidth as wide as 10% can be achieved. To the best of our knowledge, the proposed implantable patch antenna has the widest axial-ratio bandwidth at 2.4 GHz among all the reported ones.