This study presents a 2 × 2 sequentially rotated patch antenna array designed for a body area network (BAN) biotelemetry system operating in the unlicensed 5.8 GHz band. Circular polarization is achieved by truncating two diagonally opposite corners of the square patches, which excites two orthogonal modes within the antenna. This design enables the generation of circularly polarized radiation with enhanced characteristics in terms of bandwidth and gain. A prototype of the antenna array was manufactured and experimentally validated, demonstrating strong agreement between the simulated and measured results in terms of impedance bandwidth, axial ratio, gain, and radiation characteristics. The measured results show that the antenna operates from 5.65 to 5.91 GHz with a peak gain of 9.8 dBic. With its compact and low-profile design, the proposed antenna is well-suited for low-profile devices operating in the ISM band for biomedical applications.