A design of a self-complementary dual-band fifth-generation (5G) antenna for a wireless body area network (WBAN) has been presented in this paper. Like many other advantages, dual-band antennas have the benefit of being able to establish a reliable wireless connection in places that are frequently out of reach. The antenna operates at two popular 5G NR, FR-2 frequency bands: n257, or 28 GHz, and n260, or 39 GHz. FR-2 bands are prominent for high-speed data transactions within a limited range, which is perfect for WBAN applications. The proposed self-complementary single element design has a physical size of
6
mm
×
8
mm
×
1.59
mm
and is designed with a Rogers RT6002 substrate with a dielectric constant of 2.94. In free space simulations, the antenna performed satisfactorily, achieving around 90% efficiency and having return losses of 16.32 dB and 20.47 dB at the lower and upper frequency bands sequentially. The antenna generated almost omnidirectional patterns at both frequencies with a peak gain of 4.74 dB. By placing the antenna next to a 3D human torso phantom that had been digitally created with accurate human body features, the design’s onbody performance was assessed. Onbody simulations produced favorable performance with a small dispersion from their peak values in some parameters, i.e., efficiency and reflection coefficients but produced more gains: 4.34 dBi at 28 GHz and 6.19 dBi at 39 GHz. For further distance-based investigation, the antenna was placed in five different positions relative to the torso. The test yields 67% efficiency with the minimum gap and 71% at the highest distance from the human body for the lowest band. Though the lower-frequency band produces better results with more gaps, the higher-frequency band performs consistently better in even the closest placement to the human body model by reaching more than 6 dB of gain with above 81% efficiency and wider than 10 GHz of bandwidth. The overall performance indicates this design can be a good solution to complex WBAN scenarios.