A Miniaturized Dual-Band Circularly Polarized Implantable Antenna by Half-Cutting

In this paper, a miniaturized dual-band circularly polarized (CP) implantable antenna is proposed. The-10 dB impedance bandwidth of the antenna in Industrial Scientific Medical (ISM) band and the low frequency part of UWB can reach 30.3% (2:02 similar to 2:74 GHz) and 39.9% (3:73 similar to 5:59 GHz), respectively. The important features are its CP characteristic in two bands and a small volume. The miniaturization of the antenna is realized by half-cutting technique, which is to cut the original antenna meeting the symmetry of structure and electric field distribution into two halves to obtain a compact structure and wider impedance bandwidth, so that the final size is 5x 10:4x0:254mm(3). The CP wave performance of the Yantenna is achieved by exciting orthogonal polarization components on the radiation surface. The proposed antenna provides an axial ratio of less than 3 dB. CP axial ratio bandwidths in the two bands are 24.4% and 18.1%, respectively. In addition, the safety considerations and link margin are evaluated to analyze the performance of the proposed antenna. In order to verify the simulation results, the proposed antenna is fabricated. The measurements are carried out under the human muscle mimicking liquid circumstances. The measured data are in good agreement with the simulation results.