| Summary: | Body-Centric Wireless Communication (BCWC) is a central topic in the development of healthcare and biomedical technologies. Increasing healthcare quality, in addition to the continuous miniaturisation of sensors and the advancement in wearable electronics, embedded software, digital signal processing and biomedical technologies, has led to a new era of biomedical devices and increases possibility of continuous monitoring, diagnostic and/or treatment of many diseases. However, the major difference between BCWC, particularly implantable devices, and conventional wireless systems is the radio channel over which the communication takes place. The human body is a hostile environment from a radio propagation perspective. This environment is a highly lossy and has a high effect on the antenna elements, the radio channel parameters and, hence a dramatic drop in the implanted antenna performance. This thesis focuses on how to improve the gain of implanted antennas. In order to improve the gain and performance of implanted antennas, this thesis uses a combination of experimental and electromagnetic numerical investigations. Extensive simulation and experimental investigations are carried out to study the effects of various external elements on the performance improvement of implanted antennas. The thesis also shows the design, characterisation, simulation and measurements of four different antennas to work at ISM band and seventeen different scenarios for body wireless communication. A 3- layer (skin, fat and muscle) and a liquid homogenise phantom were used for human body modelling in both simulation and measurements. The results shows that a length of printed line and a grid can be used on top of the human skin in order enhance the performance of the implanted antennas. Moreover, a ring and a hemispherical lens can be used externally in order to enhance the performance of the implanted antenna. This approach yields a significant improvement in the antenna gain and reduces the specific absorption rate (SAR) in most cases and the obtained gain varies between 2 dB and 8 dB.
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