An E-field probe based near-field measurement system for on- and in-body antennas

For the characterization of the antennas for medical diagnostics or implanted devices, an E-field probe based antenna measurement system is presented here. Since the devices work in the near-field range of the antenna, the near-field measurement of the antennas is performed. A liquid phantom, a mixture from PEG and water, is chosen to emulate different tissues with regards to their dielectric properties. The system is characterized from 0.5 GHz to 5 GHz with pattern measurement both in E- and H-plane of the antennas. The short measured distance of 4-6 cm between two antennas in the liquid phantom is maintained. Benefiting from the positioning system with high accuracy motors and the small size of the probe for capturing the E-fields, the measurement system exhibits an extremely reliable results of the near-field pattern.