This paper presents the design of a novel multiband antenna operating at 1.5, 2.4, and 4.3 GHz. The compact size of the antenna also makes it applicable for biomedical applications when implanted, as it covers the ISM band at 2.4 GHz. The antenna’s multiband capabilities were evaluated in both free space and in-body environments. The paper demonstrates the design of a compact, low-cost, high-performance antenna with a unique concentric interlocked shaped patch and a FR-4 substrate. With multi resonant been achieved using a partial ground plane and superstrate, the aggregate dimensions of the antenna are 16 × 16 × 1.4 mm3. Furthermore, the device is powered by a 50 Ω coaxial feed. A three-dimensional torso phantom is created to test the antenna’s performance inside the human body. These results are compared against the gain results of the antenna, along with its radiation properties, showing that the antenna is suitable for implantation within the human body. The overall design was carried out and tested using the Computer Simulation Technology (CST) Studio Suite software.