paper presentation on wireless power transmission

1. National Conference on Recent Trends in Generation and Application of
Microwave in Industries and Service sector
Wireless Power Transmission using Microwave: A
Gen-next Approach
Hina Saxena, Jyoti Agrawal, Anusha Srivastava
B.tech 3rd year(ECE), Raj Kumar Goel Institute Of Technology
Abstract: In this paper, we have discussed
about the transmission of power without
using wires in order to abate the cost and
losses in power transmission. This is called
Microwave power Transmission. We have
described an innovative idea to obliterate
the perilous usage of electric wires that are
onerous to organize. We also discussed the
technological developments in Wireless
Power Transmission (WPT) which are
required for the improvement. A technique
including transfer of power through
microwaves using rectennas is also
presented. This is particularly suitable for
long range distances ranging kilometers.
The applications, advantages and major
concerns of WPT are also mentioned here.
Introduction
Since conventional energy transfer is made
possible using wires, hence losses that
occur during the transmission and
distribution of electrical power are one of
the major issues in power transmission.
Most of the energy is lost in transmission,
on an average 30% and in India it exceeds
to 40%. The main reason for power loss
during transmission and distribution is the
resistance of wires used for grid. By using
high strength composite over-head
conductors and underground cables that
use high temperature super conductor we
can improve the power transmission up to
a certain level. But still it remains
inefficient.
This problem can be solved by choosing an
alternative for power transmission that
could avoid power theft, reduce
transmission cost and provide much
efficient power transmission. Wireless
Power transmission using Microwave is one
of the promising technologies and may be
the righteous alternative for efficient power
transmission.
Wireless Power Transmission
‘Nikola Tesla’ he is who invented radio and
shown us that he is indeed the “Father of
Wireless”. Nikola Tesla is the one who first
conceived the idea of Wireless Power
Transmission and demonstrated “the
transmission of electrical energy without
wires" that depends upon electrical
conductivity as early as 1891. In 1893, Tesla
demonstrated the illumination of vacuum
bulbs without using wires for power
transmission at the World Columbian
Exposition in Chicago.
Wireless Power Transmission using
Microwave: William C. Brown, the pioneer
in wireless power transmission technology,
has designed, developed a unit and
demonstrated to show how power can be
transferred through free space by
microwaves. In the transmission side, the
microwave power source generates

2. National Conference on Recent Trends in Generation and Application of
Microwave in Industries and Service sector
microwave power and the output power is
controlled by electronic control circuits. The
wave guide ferrite circulator which protects
the microwave source from reflected power
is connected with the microwave power
source through the Coax – Waveguide
Adaptor. The tuner matches the impedance
between the transmitting antenna and the
microwave source. The attenuated signals
will be then separated based on the
direction of signal propagation by
Directional Coupler. The transmitting
antenna radiates the power uniformly
through free space to the rectenna. In the
receiving side, a rectenna receives the
transmitted power and converts the
microwave power into DC power. The
impedance matching circuit and filter is
provided to setting the output impedance
of a signal source equal to the rectifying
circuit. The rectifying circuit consists of
Schottky barrier diodes converts the
received microwave power into DC power.
Key Components of Wireless Power
Transmission
The key components of WPT are:
 Microwave Generator
 Transmitting Antenna
 Receiving Antenna or Rectenna
The details of these are described below:
Microwave Generator: Microwave
generator systems are designed to provide
stable and controllable microwave power
required by many heating processes and
industrial applications. Complete microwave
generator systems are available as an
integrated unit or with a remote magnetron
head. Magnetron is widely used for
experimentation of WPT. The integrated
microwave generator houses all of the
generator subcomponents in a single cabinet,
while the remote head separates the power
supply and magnetron head by a cable
assembly. All complete microwave generator
systems are supplied with a power supply,
magnetron head, cable assembly, and
isolator.

3. National Conference on Recent Trends in Generation and Application of
Microwave in Industries and Service sector
Transmitting Antenna: The slotted wave
guide antenna, microstrip patch antenna, and
parabolic dish antenna are the most popular
type of transmitting antenna. The slotted
waveguide antenna is ideal for power
transmission because of its high aperture
efficiency (> 95%) and high power handling
capability.
Rectenna: The rectenna was invented in
1964 and patented in 1969 by US electrical
engineer William C. Brown, who
demonstrated it with a model helicopter
powered by microwaves transmitted from
the ground, received by an attached
rectenna.
A rectenna is a rectifying antenna, a special
type of antenna that is used to
convert microwave energy into direct
current electricity. A simple rectenna
element consists of a dipole antenna with an
RF diode connected across the dipole
elements. The diode rectifies the AC current
induced in the antenna by the microwaves,
to produce DC power, which powers a load
connected across the diode. Schottky
diodes are usually used because they have
the lowest voltage drop and highest speed
and therefore have the lowest power losses
due to conduction and switching. Large
rectennas consist of an array of many such
dipole elements.
Types and Technologies of WPT
 Near Field Techniques:
 Inductive Coupling
 Resonant Inductive Coupling

4. National Conference on Recent Trends in Generation and Application of
Microwave in Industries and Service sector
 Air Ionization
 Far Field Techniques:
 Microwave Power
Transmission
 LASER Power Transmission
Microwave Power Transfer (MPT)
In MPT high power from one place to another
is transferred, two places being in line of
sight usually. There are the basic steps
below:
1. Converting Electrical energy to
Microwave energy.
2. Capturing Microwaves using
rectennas.
3. Converting Microwave energy to
Electrical energy.
Since AC can not be directly converted to
microwave energy so it is converted into DC
first.
DC is converted in microwave energy using
Magnetron. Transmitted waves are received
at rectenna which rectifies and gives DC as
output. Again DC is converted back to AC.
Applications of WPT
Wireless power transfer has the ability to
change the world with all the different
applications it has to offer. As simple as
charging a cell phone to supplying the Earth
with all the energy it needs. The first
application that consumers are most likely to
see would be a charging station that will
range from about one to five meters. This is a
small box-like object that will be able to
charge compatible electronics within the
range of the system. Wireless power transfer
charging systems are proven to have
efficiencies near that of conventional
charging devices. For example, a household
would need about one transmitter per room
and allow the house be completely wireless.
Once wireless power transfer becomes more
advanced, the scale of applications can begin
to grow. The range of the electromagnetic
waves will begin to increase. Once the range
reaches around twenty meters, entire homes
will be able to be charged by a single
transmitter located close to the home. As
the range expands entire blocks and streets
will be powered by a single transmitter. Once
this point emerges, consumers can notice
cars converting to completely electric with
the capability of being wireless
charged. Roads will adapt to have wireless
chargers spaced so far apart so a car will be
able to run endlessly.
The final step in this phase involves outer
space solar panels. Using the outer space
solar panels to collect the Sun’s energy, solar

5. National Conference on Recent Trends in Generation and Application of
Microwave in Industries and Service sector
powered satellites will beam it back to Earth.
This will severely reduce our dependence on
conventional fuels.
Advantages of WPT
This mode of wireless power transfer is highly
efficient over distances ranging from
centimeters to several meters.
 Wireless Power Transmission system
would completely eliminates the
existing high-tension power
transmission line cables, towers and
sub stations between the generating
station and consumers and facilitates
the interconnection of electrical
generation plants on a global scale.
 It has more freedom of choice of
both receiver and transmitters. The
cost of transmission and distribution
become less and the cost of electrical
energy for the consumer also would
be reduced.
 The power could be transmitted to
the places where the wired
transmission is not possible.
 The power failure due to short circuit
and fault on cables would never exist
in the transmission and power theft
would be not possible at all.
Major Concerns with WPT
Wireless power transfer is possible, but when
trying to sustain a constant power level,
some problems can occur with the efficiency
of the transmission. This occurs most
noticeably in the electromagnetic wave
system.
 The problem with radio waves is that
they scatter the energy in different
directions through free space
propagation. This causes the
efficiency to be much lower than if
they could be transmitted directly to
the receiving antennas.
 If a world-wide electromagnetic wave
WPT system was used, then free
space propagation would cause
numerous problems. The free space
energy would either go unused or
would be received by antenna that
the transmission was not intended
for. This would pose the most direct
problem to consumers within the
WPT grid.
 Individual consumers would either
not be receiving their required
energy, or would be receiving too
much and paying a much high
electricity bill. These are some
problems that are trying to be
corrected through multiple antennae
arrays, but high efficiencies have yet
to be accomplished.
 Another concern consumers have is
the safety of free flowing energy and
its effects on the human body.
Microwave beams are the main
concern of wireless power transfer.
The safety issues are closely related
to those that involve cell phones,
radar, and wireless internet. Unlike
what many consumers think, cancer
is not the main concern.
 Typically other problems such as
severe headaches, sleep

6. National Conference on Recent Trends in Generation and Application of
Microwave in Industries and Service sector
disturbances, memory loss, learning
disabilities, attention deficit disorder,
and infertility affect a person before
cancer. So far there has not been any
reported major health issues related
directly to microwaves but any
extended period of EM exposure can
cause serious health risks.
Conclusion
Wireless power transfer has the
potential to change this planet on so
many different levels. Whether it is
charging a handheld device, to
changing the effect of global
warming on this planet, wireless
power transfer has an answer. The
most commercially viable application
arising to counter the effects of
global warming and the increasing
demand for electricity is WPT
through microwave transmission
from space. This application will
supply limitless power to earth and
also open up many new
opportunities for space
exploration. With WPT through
resonance and inductive coupling,
emerging tech companies are able to
broaden the capabilities of most
small electronics including cell
phones, PDAs, and mp3 players.
With global warming having
significant impact on this earth by
2050, alternatives to high polluting
fossil fuel plants need to be
created. Earth’s future could be
dependent entirely on wireless
power transfer. Even though the
actual process does not produce any
energy, the improvements it can
make to this earth are staggering.
Only a few examples include
pollutant free electricity, reduction of
fossil fuel demand, a solution to the
oil crisis, increased safety for medical
procedures, and the mobility of
having power anywhere at any time.
Currently wireless power transfer is
the most marketable and sustainable
alternative to fossil fuel power
plants. With advancements in the
field happening all the time, a
worldwide wireless power transfer
system is a possibility in the near
future.
References  Peter Vaessen, “Wireless Power
Transmission”, Leonardo energy,
September 2009.

7. National Conference on Recent Trends in Generation and Application of
Microwave in Industries and Service sector
 David Schneider, “Electrons
Unplugged”, IEEE spectrum, May
2010.
 M.Venkateswra Reddy, K.Sai
Hemnath, “Microwave Power
Transmission”, Jan-Feb 2013.
 Nikola Tesla, “The Transmission of
Electrical Energy Without Wires as a
Means for Furthering Peace,”
Electrical World and Engineer, Jan
1905.
 http://www.engineersgarage.com/c
ontribution/wireless-power-transmission
Wireless Power
Transmission.