A Novel Rectenna With Class-F Harmonic Structure for Wireless Power Transfer

The concept of wireless power transfer for powering a low-power electronic circuit is demonstrated in this brief using a novel rectifying-antenna (rectenna). The proposed rectenna is consisted of by a wide-band antenna and a modified rectifier. The antenna bandwidth has been optimized to cover both the
$f _{1}\,\,=$
868 MHz and
$f _{2}\,\,=$
915 MHz UHF-RFID bands. A dual-band Class-F harmonic structure is employed to maximize the power conversion efficiency (PCE) at both the
$f _{1}$
and
$f _{2}$
at low levels of radio frequency (RF) input power (–30 dBm
$ < {P} \mathrm {_{IN}} < 10$
dBm) compared to conventional designs. The dual-band class-F harmonic load compensates for the capacitive reactance of the rectifier diodes at the fundamental frequencies
$(f _{1}$
and
$f _{2}$
) and controls the rectifier output harmonics at
$2f _{1}$
,
$2f _{2}$
,
$3f _{1}$
and
$3f _{2}$
. The proposed modified rectifier depicts a measured maximum PCE of 71% (at
$f _{1}$
) and 64% (at
$f _{2}$
) for an RF input power
${P} \mathrm {_{IN}}\,\,=$
0 dBm with an optimum load resistance
$({R} \mathrm {_{L}}$
) of 7
$\text{k}\Omega $
. To demonstrate the proof of concept of wireless powering and validate of the rectenna performance, a DC-DC boost converter, a supercapacitor
$(C \mathrm {_{OUT}}\,\,=\,\,370\,\,\mu \text{F}$
), and a low-power electronic circuit is connected to the presented rectenna. According to measured results, the proposed rectenna demonstrates wireless powering of an LED at different distances and various
$P \mathrm {_{IN}}$
levels (at both the
$f _{1}$
and
$f _{2}$
). The proposed circuit can be used in wireless power transfer and battery-less wireless sensing systems.