Wireless Body Area Networks (WBANs) are considered to be a new method for short range wireless communication. Channel characteristics of WBAN are different from those of other wireless channels; specifically, when the human body rotates, the WBAN channel between the body surface and the wireless access point is changed via body shadowing. This paper analyzes the characteristics of recently proposed off-body WBAN channels and bit error performances when the human body rotates. In order to avoid inadequate channels and to improve the bit error performances, the receive antenna is attached to the back side, additionally. And the performance for each diversity scheme is evaluated.