Triplexer-Based Multiband Rectenna for RF Energy Harvesting From 3G/4G and Wi-Fi

In this letter, we propose a solution to improve efficiency and selectivity of triplexers, which operate as filters (or matching circuits) for triple-band energy harvesting. The triplexer consists of multiple higher-order open stubs of (2n+1)λ/4 length ( n is an integer, n ≥ 1), which is proven to yield high selectivity. With the high selectivity of the filters, the proposed triplexer achieves the efficiencies of 92%, 86%, and 83% at 1.85, 2.1, and 2.45 GHz, respectively. The triplexer is incorporated in a rectenna, yielding a final efficiency of 60% at 5 dBm input power.