Wireless body area networks are an increasingly important area of research and show great promise for monitoring and communication in diverse application areas such as healthcare, public safety and defence. The antenna is the crucial enabling component which allows communication between sensors, and with other off-body systems (e.g. GPS and GSM). But the antenna operates in a particularly challenging environment, in close proximity to the human body, and its performance may be affected by deformation, e.g. if integrated directly into clothing. The design of these antennas is thus challenging, and numerical simulation is an indispensable tool for the antenna engineer. This eSeminar will discuss the key challenges in the virtual prototyping of body worn antennas, describing how CST MICROWAVE STUDIO® can be used to construct realistic flexible and conformal geometries, and how these can be studied and optimized in the context of their body-centric environment.