A ground slot for harmonic suppression

In ultra low power RF energy harvesting circuits, it is required that incident power is handled efficiently. One such requirement is to avoid re-radiation of higher order harmonics generated in the single or two diode rectenna. In this paper, a ground slot is proposed to eliminate the higher order harmonic resonance, while ensuring a fixed fundamental resonance at 2.1 GHz, and circular polarization at 3 dBi gain in the broadside. The proposed antenna is suitable for cellular energy harvesting in the W-CDMA down link band (2110 - 2170 MHz).