Meaning
Wireless transmitter designed to operate in close proximity to human tissue for extended periods. A body worn radio includes smartphones, tablets, wearable sensors and medical implants that maintain an active RF link while held against or strapped to a user. These devices must comply with specific absorption rate limits to ensure that the energy deposited into biological tissue remains within safety boundaries.
Thermal Interface
Heat dissipation occurs through the device enclosure directly into the skin or clothing of the operator. Thermal control is necessary. Careful management of the body worn radio ensures that surface temperatures do not exceed comfort or safety levels during high-duty cycle transmissions.
Designers often use graphite sheets or thermal spreaders to move heat away from the contact surface.
Compliance Testing
Assessment of electromagnetic exposure requires specialized phantoms and liquid stimulants to model human electrical properties. The body worn radio undergoes testing in various orientations to identify the maximum energy absorption peak. Such evaluations typically occur during the final qualification phase before market entry.
These results determine the minimum separation distance required for safe operation. Technicians measure the field strength at multiple points to build a complete map of the energy distribution across the device surface.
Signal Attenuation
Signal strength decreases when the human body absorbs a portion of the radiated energy. Obstruction by the user affects the body worn radio by creating shadowed regions where the link budget may fail. Engineers compensate for this loss by employing antenna diversity or beamforming techniques to maintain connectivity.
