Design of 3.6 GHz Rectenna with Broad Power Range for Efficient Energy Harvesting

In this paper, a rectenna (antenna + rectifier) is proposed for ambient RF energy harvesting. A modified rectangular microstrip patch antenna with inset feed is designed at 3.6 GHz with a gain of 4.3 dB. The antenna is compact in size with a layout area of
$0.36\lambda \mathrm{x}\ 0.36\lambda$
where
$\lambda$
is free space wavelength corresponding to resonating frequency. The antenna resonates at 3.6 GHz with impedance bandwidth (IBW)
$(\mathbf{lS}_{11} < -20\ \mathbf{dB})$
of 4.53% and a radiation efficiency of 68.5% is noted. To hoard the available RF energy, a simple RF-DC rectifier is designed using equal ripple Low Pass Filter (LPF) on FR4 substrate with height of 1.6mm. To improve the efficiency of the rectifier and to achieve broad range power conversion efficiency (PCE), additional radial stubs are incorporated on the rectifier design. Maximum PCE of 60.7 % is achieved with a load of
$2\mathbf{K}\Omega$
at 7dBm. The novelty of RF- DC rectifier is PCE of above 30% is achieved for broad range of input power (−10 dBm to 10 dBm).