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

Abstract

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 ∼ 2.74 GHz) and 39.9% (3.73 ∼ 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 5 × 10.4 × 0.254 mm 3 . The CP wave performance of the antenna 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.

A Dual-Band Ultra-Wideband Conformal Antenna for Wce

“…To reach the IEEE-specified human safety level limit of 1.6 W/kg, the maximum allowable input powers for small intestine model and four-layer model are 2.12 mW and 2.05 mW. The maximum allowable input power is much higher than the output power of actual commercial transmitters [20]. The link margin of the WCE antenna is analyzed to evaluate the communication capability.…”

Design and Analysis of Compact Dual-band Antenna System for Scalp and Skin Implantation

“…The communication ability range of the proposed implantable antenna with the external receiver antenna at a distance of 'd' is investigated by evaluating the link margin (LM). The LM, according to Friis Transmission Formula, as mentioned in [11,35], is calculated as:…”

“…L f is the path loss, N 0 the noise power, and B r the bit rate. Other than the transmitter gain G t and resonance frequency, the parameters for LM calculation are considered from [35]. For reliable communication, the 20 dB LM is considered.…”