Characterization of chip-size electrically-small antennas for smart wireless biomedical devices

The new requirements for smarter and smaller biomedical microsystems demand for new integration technologies, including antenna integration. This can be solved with the use of microfabrication technologies, allowing the fabrication of chip-size antennas that may be placed on top of silicon wafers. However, due to their ultra-small physical dimensions and special operating conditions (e.g., covered with body tissue phantoms), antenna characterization requires the use of auxiliary custom-made transitions between antenna and test equipment, which are much larger than the antennas under test. Since electrically small antennas show also very small gain, the use of test boards may carry a significant impact on the antenna´s characteristics. This paper presents a methodology used to investigate the performance of chip-size 3D antennas (500×500×500 μm³) designed to operate inside the human body in the frequency band 1-8 GHz.