In this article, a novel dual-band multi-port compact rectenna design for RF energy harvesting is proposed. An E-shaped coaxial fed microstrip antenna combined with an inverted L-shaped structure is used to achieve a dual-band operation at 0.9 GHz (GSM900) and 2.4 GHz (WiFi) frequency bands with gains of 0.8 dBi and 4.4 dBi, respectively. A shorting post is incorporated in the design, which restricts the antenna size to 50 mm x 47 mm, making the overall rectenna compatible with any sensor nodes. Further, a compact rectifier circuit covering both the frequency bands is designed to obtain a conversion efficiency up to 50% for an input power as low as -20 dBm. The matching circuit ensures that the nonlinear impedance of the rectifier matches with that of the antenna under varying operating conditions. Finally, the rectennas designed are combined and arranged together to form a cubical structure to produce an output voltage as large as 0.5 V for an input power of -20 dBm. With 360˚ coverage and orthogonal polarization reception, the cubical antenna arrangement ensures improved harvesting efficiency making the proposed design suitable for powering low power IoT devices.
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