A wireless body area network (WBAN) consists of a wireless network with devices placed close to, attached on, or implanted into the human body. Wireless communication within human body experiences loss in the form of attenuation and absorption. A path loss (PL) model is thus necessary to identify these losses in homogeneous medium which is proposed in this paper. The model is based on 3-D electromagnetic simulations and is validated with measurements. Simulations are further extended for different relative permittivity er and conductivity σ combinations spanning a range of human tissues at 2.45 GHz, and the influence of the dielectric properties on PL is investigated and modeled. This model is valid for insulated dipole antennas separated by a distance up to 8 cm. Furthermore, PL in homogeneous medium is also compared with the path loss in heterogeneous tissues. The path loss model for homogeneous medium is the first in-body model as a function of er, σ, and separation between antennas and can be used to design an in-body communication system.