Wide-Beam Rectenna Design Using Multi-port Metasurface-Based Antenna

The design of a wide beamwidth rectenna utilizing a multi-port metasurface (MTS) antenna for energy harvesting (EH) is described in this paper. In order to extend the narrow beam of a conventional rectenna to successfully convert enough low power in the circuit stage of harvesters, a three-port wide-beamwidth nonuniform MTS antenna is presented. In this antenna, two modes are excited through the middle and the side apertures. The first one is the fundamental MTS mode, with inphase current distribution and a directional radiation pattern. The second one is the higher MTS mode, with opposite current distributions and a directional tilted-angle radiation pattern. The key advantage of this MTS antenna is that the effective MTS area is reused by the three ports for three different radiation modes with different radiation patterns simultaneously. Incident radio frequency waves from different directions can be collected by the metasurface and fed to one of the three ports depending on the incident angle. Then, the direct current (DC) power after rectification at the three ports is combined to achieve a wide beam effectively. The measured main beamwidth of the combined rectenna is 114°. The main beam angles of the three ports are −35°, 0° and +35° respectively. An RF-to-DC conversion efficiency of 6%–67% was achieved at 2.45 GHz when the input power ranged from −30 to 0 dBm.