Vertically-and horizontally-polarized antennas were investigated for on-body to on-body (OB2OB), in-body to in-body (IB2IB), and on-body to in-body (OB2IB) wireless propagations at frequencies of 915 MHz and 2.45 GHz. Theoretical formulations, simulations, and measurements were employed to study the effect of source antenna orientation on the attenuation of the radio frequency (RF) wave as it propagates around, inside, and through the body near the torso region. The results show that the vertical polarization is preferred for OB2OB communication, and the horizontal polarization is better for IB2IB communication. Furthermore, the dominant propagation mechanism and optimum antenna excitation for OB2IB communication are identified to be distance-dependent. The horizontallypolarized dipole is preferred at a shorter distance while the vertically-polarized dipole is preferred at a larger distance away from the source. The observed results were explained using the estimated attenuation rates of the different propagation mechanisms.