This work addresses the design and implementation of a broadband differential rectifier\n(DR) combined with an Archimedean spiral dipole antenna (ASDA) for wireless power harvesting\nat low incident power densities below 200 micro W/cm2. The proposed design exhibits an improved\nRF-DC conversion efficiency over a wide frequency range from 1.2 to 5 GHz. This frequency band is\nassociated with several wireless communication services, for instance, ISM, WLAN, 5G, LTE, and\nGPS applications. The receiving planar ASDA exhibits circular polarization and has an average\nmeasured gain of 4.5 dBi from 1.2 to 5 GHz. To enable a wide operating bandwidth, the rectifier\ncircuit is constituted by two architectures, designated A and B. Each scheme is designed to harvest\npower efficiently across a specific bandwidth. The optimal performance of both rectifiers are obtained\nusing the nonlinear harmonic-balance simulations. The antennaâ??rectifier integration yields a compact\nrectenna with a high-efficiency performance over the intended bandwidth from 1.2 to 5 GHz for an\ninput power of 9 dBm and terminal load resistance of 1 kilo Ohms. The total measured RF-DC conversion\nefficiency is maintained above 30% across the entire frequency range with a peak value of 61%\nachieved at 1.2 GHz. In comparison with similar architectures, the proposed rectenna maintains a\nstable output efficiency despite the wide fluctuations in the input frequency and also has a minimum\nfootprint size (58 * 55 mm2).
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