30-05-2012, 02:12 PM
5.8-GHz Circularly Polarized Dual-Diode Rectenna and Rectenna Array for
Microwave Power Transmission
5.8GHz Circularly Polarized DualDiode Rectenna.pdf (Size: 476.23 KB / Downloads: 50)
Abstract
—This paper reports a new circularly polarized
rectenna whose rectifying circuit includes two diodes. The
rectenna consists of a coplanar stripline (CPS) truncated patch
antenna and CPS bandpass filter, which can block harmonic
signals up to the third order reradiating from the rectifying
circuit. The rectenna is printed on Rogers Duroid 5880 substrate
with = 22 and a thickness of 20 mil. The new dual-diode
rectenna can provide at least twice the dc output voltage than the
traditional rectenna with only a single diode, which has the same
layout dimension as the single-diode rectenna. The dual-diode
rectenna achieves an RF-to-dc conversion efficiency of 76% at
5.8 GHz. The proposed rectennas can be interconnected to form
the rectenna arrays by series, parallel.
INTRODUCTION
OVER THE last century, space solar power transmission
(SPT) and microwave wireless power transmission (WPT)
have become an interesting topic for an energy transmission in
the future. The rectenna, i.e., rectifying antenna, is one of the
most important components in the application of SPT and WPT.
The rectenna has been used for ground-to-ground, ground-tospace,
and space-to-space power transmission, and its development
has been reviewed in [1]–[3]. A new dual-frequency
rectenna was reported in [4] where a circularly polarized ringslot
antenna was used, which has been shown to have a useful
application for portable wireless devices. A rectenna with a harmonic-
rejecting circular-sector antennawas presented in [5] and
the rectenna can avoid the use of the low-pass filter connecting
the antenna and rectifying diode. A new patch antenna with a
high gain of 9 dB was designed for the finite-ground coplanarwaveguide
rectenna [6]. The patch antenna has characteristics
comparable to that of a two-element antenna array and, hence,
it can allow the rectenna not only to receive more power.
RECTENNA DESIGN
Rectenna Components
The newly developed dual-diode rectenna is shown in Fig. 1.
It consists of a pair of CP truncated patch antennas (TPAs), a harmonic-
rejecting BPF to suppress harmonic signals, two detector
diodes for RF-to-dc conversion, and a dc pass filter (capacitor).
The resistive load will affect the output voltage and rectenna efficiency.
The CP TPA fed by the CPS has a high gain and high
radiation efficiency. The circuit and antenna can be duplicated
and extended to form a traveling-wave antenna array.
CPS Parameters
The CPS is shown in the inset of Fig. 1. The CPS gap is
0.2 mm and width is varied on each section including the
antenna feed line, BPF, and transmission line for the purpose of
impedance matching. The substrate thickness is 0.508 mm
(20 mil) and the dielectric constant is 2.2. The conductor
thickness is 1-oz copper whose metal thickness is 0.036 mm
(1.4 mil). At 5.8 GHz, the effective dielectric constant
of the transmission-line section (the CPS from the diode to the
load resistance) is 1.84, is 38.06 mm, and its characteristic
impedance is 120 . This is chosen to match the impedances
of the antenna with the BPF and the diode [10]–[12]
to reduce the signals reflections between these components.
CONCLUSIONS
In this paper, a 5.8-GHz dual-diode rectenna and its arrays
have been developed. A truncated dual-patch antenna achieves
a CP gain of 6.38 dB and an AR of 0.42 dB. A CPS BPF is
used to suppress the harmonic signals generated from the diodes
by over 32 dB, which can block the second- and third-order
harmonics. The dual-diode rectenna can provide a maximum
efficiency of 76% with at least twice as much output voltage as
compared to the single-shunt diode rectenna, while their circuit
layout dimensions are the same.