Currently, many researchers have been concerning with body-centric wireless communications systems (BWCS) since their numerous medical applications including in combination with low rate wireless personal area (LR-WPAN) technology for human physiological monitoring system. This paper proposes a novel wearable antenna that operates at 2.45 GHz for off-/on-body communication application. The proposed antenna is a printed inverted-F antenna, which is fed by a coplanar waveguide (CPW) in order to get a small and compact structure with relatively wide bandwidth, possible for integrated-circuit, easy for impedance matching and resonant frequency tuning. This paper investigates the characteristics of the wearable antenna in the proximity to the human body by using two numerical phantom models (3-layer and muscle-equivalent) in numerical simulation. Measurement is conducted with real human body and muscle equivalent physical phantom. The results show that the simulated and measured antenna performances are in good matched, wide bandwidth and acceptable radiation pattern when the antenna is installed in the vicinity of the human phantom. Moreover, the antenna has an acceptable gain within about 30m of communication range.