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Gurukulam International Journal of Innovation in Science and Engineering
Volume 2.Issue 1- Special Issue
ISSN: 2454-6631
Swathy S Nair, Suriyakala C.D
© Gurukulam International Journal of Innovations in Science and Engineering
Abstract— Electromagnetics has an important
role in power and energy industry. As the
demand for power increases, need for alternate
energy sources are essential. Radio frequency
(RF) energy transfer and harvesting techniques
becomes one of the solution. Basic RF
harvesting circuit consist of 3 elements. This can
be achieved by using a rectenna combination of
rectifier and antenna. The antenna is to receive
RF signal and rectifier to convert RF to DC
signal In between an impedance matching circuit
.This converted power is used by certain low
power devices. This paper presents an possible
sources applications and design configuration
and current scenerios .
RF energy is broadcasted from many reliable
electromagnetic resources and utilizing is very
meaningful to supply energy for a number of
devices like headsets, wearable medical sensors,
and battery free remote sensors. [1] The basic
block diagram of an RF harvesting system
consist of receiving antenna (rectenna) which
plays an important role in RF harvesting system.
The device used to harvest RF energy is called
‘Rectenna’. The concept of wireless power
transfer was introduced and demonstrated by
Tesla over 100 years ago. The methods for
transfer were prominent in recent years. Even
though Tesla could not implement his system for
commercial use but he successfully transmit
power from his oscillators to light two bulbs.
During World War II rectification of microwave
signals for supplying DC power through wireless power transmission was proposed W.C
Brown developed a device for efficient reception
and rectification for microwave power in 1960’s
.The rectifying antenna or rectenna developed by
Rytheon company consist of halfwave dipole
antenna with balanced bridge or single
semiconductor diode placed above a reflecting
plane. The resistive load was connected at
output port. 2.45 GHz is used as the transmitting frequency due to its advanced and efficient
technology base and location at the middle of
the ISM band[2]
Index Terms— Rectenna ,rectifying circuit , RF
Swathy S Nair: P.G Scholar, SNGCE, Kolenchery
Suriyakala C.D: Professor, SNGCE, Kolenchery
Energy is a basic necessity for sustaining human
life which prevades each and every one of our
activities. Communication is the fasest growing
segment of communication industry. There are
many ways by which energy can be extracted
from the nature. One of among sources is RF
energy. RF energy harvest home from the close
can have a crucial role within the future
electronic circuit. Energy harvesting from
different Environmental sources is important
aspect in order to enhance the quality and
simplicity of our daily life. Recently RF energy
harvesting has received a lot of attention since
The two advantages for rectennas are the
lifetime of rectenna is almost unlimited and it
doesnot need any replacement .also it is green
for the environment. .Sources of RF Energy area
unit FM radio systems ((88-108 megacycle,
transmitted power few tens of KW), TV Transmission (180-220 megacycle, transmitted power
few tens of KW), Cell Tower Trans-mission (10
to twenty W per carrier), Wi-Fi (2.45GHz,
5.8GHz), AM Transmission (540-1600 kHz,
Survey on Different Rectennas Used In RF Harvesting Systems
transmitted power few hundred KW) and mobile
phones (transmitted power 1W to 2W), etc. Cell
towers may be used as an eternal supply of
renewable energy as they transmit twenty four
hours. In Bharat cell towers transmit within the
frequency vary of 869- 890 mega-cycle in
CDMA, 935-960 megacycle in GSM 900 and
1810-1880MHz in GSM 1800 bands. It
transmits ten to 20W per carrier; there perhaps
three to four, carriers and three to four operators
on one tower or adjoin the roof high of buildings.[3]
can be integrated with integrated circuits, design
versatility and low mass production costs using
printed circuit technology[3].
The rectifier circuit in RF energy harvesting
system rectifies the alternating current signal
from receiving antenna. Output DC signal is
then stored in a capacitor. There are two rectification filtering in a RF harvesting system which
is prior to rectification and after rectification.
For both two low pass filters are used. LPF
usually suppresses the harmonics rejected by the
rectifying circuit and provides impedance
matching. Hence the filter plays a critical role in
determining the system’s ultimate performance.
The specifications of an RF scavenger depends
on several factors such as power handling
capability, Q factor, insertion loss, desired
operating frequency and size. High Q filters
such as cavity filters provide good interference
rejection and improved insertion loss but at the
cost of large dimensions. On the other hand,
printed filters are comparatively prone to losses
but can be compact, conformal and miniaturized.
This paper sectioned as follows Section I, Introduction describes the history of rectenna, section
II literature survey discusses the various design
configurations in RF harvesting system Conclusions are presented in section III.
Basically rectennas should have small dimensions. Thus low amount of power will be
received and hence used for low power applications. In rectenna, antenna one of the major
elements responsible for collecting the incoming RFE at various desirable frequencies.
Antennas with resonance at single or multiple
applicable frequencies are designed to meet
differrent specifications. Omnidirectional antennas are employed in scavenging systems so as
to enable reception from all directions. Hence
dipole antennas are conventionally preferred, but
the most commonly used antennas include the
dipole, loops, parabolic dish, horn, helical and
microstrip antennas. The main factors to be
considered in antenna design for RFE harvesting
systems are desired frequency of peration power
handling capability, radiation efficiency of the
antenna, polarization, bandwidth, weight and
size of the antenna [4][5].
A matching circuit is required between a filter
and a rectifier to have impedance matching
thereby leading to maximum power transfer. The
possible rectifier circuits that can be
implemented in a scavenging circuit are single
shunt full wave rectifier, a full wave bridge
rectifier or any other type of hybrid rectifier
employing Schottky diodes. At RF the input
power received is not enough to forward bias a
diode hence the other alternative preferred is to
use a Schottky diode. Compared to other diodes,
Schottky diodes have low forward voltage and
high switching speed [6]
Different rectifying circuits used in RF
harvesting systems The most commonly used
circuit is a series or parallel half wave rectifier
with single or multiple stage voltage doubler
structure to enhance output DC voltage or a dual
diode full wave rectifier to increase the alternating current to DC conversion efficiency. A
voltage doubler is designed using Dickson
Multiplier topology by Mahima et al [7]. The
RFE is converted into DC using a differential
reconfigurable configuration which improves the
With the growing demand for compact wireless
devices, the size of the antenna is also an
important design aspect. Hence printed miniaturized antennas are being worked on. Though
several types of antennas can be considered in a
rectenna, the most popularly used is the printed
microstrip patch antenna. The reason being they
are light weight, low profile, aligning any shape,
Vol 2.Issue 1-Special Issue 2017
sensitivity to -16dBm and efficiency to 60% at
840 MHz to 975 MHz is discussed in [8]. RFE
harvesting system with a single wideband 377Ω
E shaped patch antenna, a Pi matching network
and a 7 stage voltage doubler circuit designed at
the downlink radio frequency range of GSM900
band is discussed in [8]. A Grainacher voltage
doubler circuit, also known as single stage
Cockroft Walton voltage multiplier circuit, is
used in [9] to double the input voltage. A 10
stage Villard voltage multiplier circuit was
implemented using Manhattan Technique in [10]
to achieve an output voltage approximately ten
times the input voltage.
circuit consist of a microstrip line, a schottky
detector and a capacitor. The circuit can works
in 3 different bands .The frequency of operation
of this antenna is 2 to 6 GHz .The antenna has 2
stubs operating region changes as the length of
the stub changes. If the width changes the
resonant frequency changes. By changing stub
length the optimization of resonant frequency is
carried out. .Designing and simulation of the
structure is carried out in HFSS.
In order to harvest higher amount of ambint
energy from surroundings various rectenna
design approaches have been discussed. Various
sources of RF energy and their existing
frequencies and specifications were highlighted.
Microstrip patch antenna is widely used because
of low profile, and compact structure. In
addition modifications in matching and
rectifying circuit elements results into optimum
energy harvesting. Integrated and separated rf
harvesting systems were discussed.
In [13] a low power rectenna for low power
applications is presented the rectenna is
designed with the use of analytical models and
closed form analytical expression. In [14] a high
efficient 2.45 GHz rectenna which can harvest
low input RF power effectively. Here antenna
with a simple structure and high gain is directly
matched to rectifying circuit which eliminates
the low pass filter between the antenna and
rectifying circuit. In [15] a rectenna is designed
which consist of four printed dipoles located
perpendicular to one another to combine the
pattern and increase the gain. The rectifying
circuit is designed based on voltage diode with
stub matching circuit.
Mostly broadband
antennas used for rectenna . In [16] a compact
planar monopole antenna for multiband and
wideband operation is proposed. The proposed
antenna is of U shape and Tshaped stub
resonator. In [17] a broadband rectenna using
printed monopole antenna and a stub band pass
filter which is designed in the microstrip line
structure at 2.45 GHz for wireless transmission
of microwave power. The past several years,
rectennas are studied actively. Characteristics of
almost past rectennas are high power such as
over 100mW rectifying and the RF-DC
conversion efficiency is less than 10% at low
power such as 1mW microwave input [18]. In all
above papers the RF harvesting circuits are
incorporated within the rectenna , in this paper
an RF harvesting circuit is designed to find out
how much different the circuit’s efficiency from
above papers. In [19] a small planar wide band
antenna is used as the rectenna .The rectifying
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energy harvesting," Proceedings of the 2012 IEEE
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[2]N. Shinohara. "Wireless power transmission for
[3]IEEE 2015 International Conference on
Technologies for Sustainable Development (ICTSD)
Mumbai, India (2015.2.4-2015.2.6)] 2015 International Conference on Technologies for Sustainable
Development (ICTSD) - A review of RF energy
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[4] MahimaArrawatia, Maryam B, and Girish Kumar,
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900MHz Band,” National Conference on Communications, pp. 1-5, 2011.
[5] Lok Sabha Secretariat, “Norms for the Setting Up
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[13] H. C. Sun, Y. X. Guo and Z. Zhong, "A highsentivity 2.45 GHz rectenna for low input power
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[7]Cellular Operators Association of India, Annual
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[16]Novel broadband rectenna using printed
monopole antenna and harmonic suppressed stub
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Circuit for Rectenna,” International Conference on
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[11]W. C. Brown and J. F. Triner, "Experimental
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Dallas, TX, USA, 1982, pp. 185-187.
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Yoshitomi, “A highly compact dual-band
[19]Wireless power transmission circuit on a small
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