Design of Low-profile ultrawideband Antennas for Body-Centric Communications using the FDTD method

Low-profile coplanar waveguide antennas are successfully designed considering body-centric communications requirements. A finite difference in time-domain-based programme, which considers dispersion in human tissues and antenna dielectric substrates, is developed for this purpose. Parametric simulations and visualisation helped to acquire a greater understanding of radiation mechanisms. Consequently, two approaches are investigated. In the first approach, the antenna bandwidth is optimised regardless of its size and travelling wave antennas with characteristics suitable for on-body communications are obtained. In the second approach, restricting the bandwidth to ultrawideband (UWB) frequencies, while minimising the antenna size, leads to low-profile antennas useful for on-body as well as for off-body applications. For each approach, several prototypes are built to validate the proposed designs and check the repeatability of the results. Measured and simulated return loss and radiation patterns are coherent. Based on the consulted bibliography, the smallest low-cost and low-profile omnidirectional wearable antenna is made, which covers the entire UWB frequencies with no special coaxial connectors or expensive dielectric substrates.