부산대학교 도서관

We have proposed a cavity resonance-enabled wireless power transfer (CR WPT) as a power feeding method to sensor nodes that construct a wireless sensor network. The challenge of CR WPT is that the power transmission efficiency $\eta $ between the power transmitter and the receiver is different for each receiving position because the electromagnetic-field distribution is not uniform inside the cavity. Consequently, the sensor node may not be driven on specific receiving positions. In this article, we propose a method to improve $\eta $ of each receiving position by utilizing probes [reflection probes (RPs)] terminated with a variable reactance circuit with the purpose of driving sensor nodes at all receiving positions. After explaining the principle of the proposed method, the effect of the combination of insertion positions and number of RPs on $\eta $ was confirmed. We used a combination that achieves the high $\eta $ at each receiving position to confirm the sensor node driving state and $\eta $ . As a result, the sensor node did not drive at the position where $\eta $ was the lowest before inserting RPs; however, after insertion, we succeeded in driving the sensor node at all receiving positions. We also confirmed that $\eta $ improved from 11.2% to 26.9% before and after inserting RPs at this position. From the earlier discussion, the usefulness of the RP was shown.