Analysis and Measurement of Electrically Small Surface Mount Inductor as Radiating Element for WBAN Communication in MedRadio Band

Wireless body area network (WBAN) communications in 400 MHz Medical Device Radio-communication (MedRadio) band seek wearable and implantable sensor nodes with extremely small antennas for reduced form factor. However, it is very challenging to shrink the 400 MHz antenna dimensions to sub-cm region for the conventional 50 Ω transmitters (TX) due to large wavelength. Thus there is a strong need to investigate extremely small, unconventional radiating elements with alternate TX topologies. In this work, we utilize extremely small surface mount inductors (SML) as a radiating element in non-50 Ω MedRadio band TX and present detailed fundamental analysis and models for its radiating-zone boundaries and corresponding path losses. To validate the proposed theory, simulation and measurement results of path loss of a cylindrical SML (1.2mm× 8.5mm) have been also presented, which show congruence with analytical models within ≤3 dB.