| Wireless power transmission (WPT) is a new technology in energy supply methods in the past ten years. Being applied in the bioengineering area, this technology provides a more suitable way for implantable instrument. The development of the technology will improve the treatment condition and has far-reaching applications. This paper presents a WPT system with enhanced power transmission efficiency (PTE) for powering implantable devices in the radiative near-field. The gain of the implantable receiving antenna is improved by 8 dB through utilizing a parasitic patch. The system is further optimized by maximizing the PTE between the transmitting antenna array and the implantable receiving antenna, yielding an optimal excitation distribution for the transmitting antenna array.Compared to a reference WPT system with the transmitting array fed by the uniform amplitudes and phases, the PTE of the optimized system is about 1.3 times higher than that of the reference one.The improvement of the quality of human life promotes the application of body-centric wireless network technology. In order to achieve multi-function,reconfigurable antenna is an important part of this technology. Two pattern reconfigurable antenna with low profile for wireless body centric communications are presented. They are composed of a shorted annular ring and a circular patch. Two types of radiation patterns with omni-direction in azimuth plane for on-body communications and uni-direction in elevation plane for off-body communications at 2.45GHz are obtained simultaneously. |
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