A Compact Wideband Biocompatible Circularly Polarized Implantable Flexible Antenna for Biomedical Applications

In this article, the design of a compact, wideband, biocompatible, implantable circularly polarized (CP) open-ended slot antenna on the flexible substrate for biomedical applications is presented. The antenna is designed to operate in the industrial, Scientific, and medical (ISM) frequency band of 920 MHz. To attain biocompatibility with human tissue and reduce the antenna profile, a biocompatible coating layer of alumina (Al2O3) is considered all around the implantable CP antenna. Also, the antenna is constructed by utilizing a thin (0.2 mm) dielectric substrate to attain flexibility characteristics. The overall dimensions of the proposed compact antenna with coating is 0.03 lambda(0)x 0.03 lambda(0) x 0.0007 lambda(0), where lambda(0) is the free-space wavelength at 920 MHz frequency. Also, the implant CP antenna provides a high axial ratio bandwidth (ARBW) of 21.87 % covering the 902-928 MHz ISM band. Moreover, a peak gain of -23.35 dBi and co-cross pol discrimination of 22 dB at the bore sight direction is obtained at 920 MHz.