The Wireless Body Area Network (WBAN) has become an important part of the wireless communication world in the past decade leading to the need for efficient antennas for In-, On- and Off-Body links. The design of such antennas depends critically on the understanding of their interaction with the host body, and thus on the propagation of waves in inhomogeneous lossy media of finite dimensions. To this aim, we propose a simplified spherical multishell model of the lossy body, and study its interaction with elementary sources placed within or on the latter.