Numerical analysis of bodyworn UHF antenna systems

Bodyworn antennas are found in a wide range of medical, military and person al communication applications, yet reliable communication from the surface of the human body still presents a range of engineering challenges. At UHF and microwave frequencies, bodyworn antennas can suffer from reduced effici ency due to electromagnetic absorption in tissue, radiation pattern fragmen tation and variations in feed-point impedance. The significance and nature of these effects are system specific and depend on the operating frequency, propagation environment and physical constraints on the antenna itself. Th is paper describes how numerical electromagnetic modelling techniques such as FDTD (finite-difference time-domain) can be used in the design of bodywo rn antennas. Examples are presented for 418 MHz, 916 .5 MHz and 2 . 45 GHz, in the context of both biomedical signalling and wireless personal-area ne tworking applications such as the Bluetooth(TM)* wireless technology.