On the measurement errors in SAR supervision introduced by directional couplers

Motivation: The literature does not present a framework for quantifying the error in SAR introduced by directional couplers, which are used for online SAR supervision. Goal(s): The goal of this work is to find a framework for quantifying the error introduced by directional couplers in online SAR supervision. Approach: Through reformulation of the mathematical problem, we show that the measurement errors can be translated into a new set of SAR matrices that can then be compared to the original SAR matrices to calculate the relative error. Results: The results show that the coupling within transmit arrays has a large impact on the measurement error. Impact: This work provides a framework for calculating the measurement error in SAR calculations introduced by the directivity of the directional couplers used to measure the forward power in parallel transmit systems.