Specific Absorption Rate (SAR) safety assessment for Wireless Network after Next (WNaN) radio antennas

Our primary objective is to provide a safety assessment for the two antennas that are recently developed by the Defense Advanced Research Projects Agency (DARPA) under the Wireless Network after Next (WNaN) program. Of these two antennas, one is a standard mast or "whip" structure while the other is a Body Wearable Antenna (BWA) that will be mounted on the body armor vest of the soldier. These antennas are part of an experimental radio technology which provides U.S. warfighters with an integrated radio system that has the capability to access voice, data and video communications simultaneously. It is designed to allow the soldier to communicate in real time through voice and data networks, providing seamless radio communications among team members, team leaders and squad leaders. The key concept is to develop a low-cost radio that is capable of selecting a vacant frequency and forming small networks within a larger battlefield congested network. The requirements for testing compliance of WNaN radios are to include the electromagnetic safety limits evaluation of soldier exposure to maximum strength of the radiation under normal operation conditions. Specific Absorption Rate (SAR) testing is recognized to provide data on how much electromagnetic energy is being absorbed by the human body. Traditionally, SAR measurements have been done by measuring the heating of the body tissue due to RF transmission. CERDEC system uses electric field (E-field) probe, which are part of an autonomous system that can move the probe at various location within a flat phantom containing simulating liquid. The two antennas are investigated and tested over a frequency range from 900 6000MHz to study the effects of SAR distribution over the soldier\´s body tissue. The method presented in this paper has been adopted from the FCC guidelines for human exposure to radio frequency electromagnetic fields, IEEE 1528-2003 and lEC 62209-2 ED.1 standards.