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28 Dr. S.G. Srivani , Gagana P
International Journal of Electronics, Electrical and Computational System
IJEECS
ISSN 2348-117X
Volume 6, Issue 6
June 2017
Solar Power Satellite for Wireless Transmission
Dr. S.G. Srivani
Associate professor Gagana P
RV College of Engineering, Bangalore RV College of Engineering, Bangalore
(Autonomous Institution Affiliated to VTU, Belgaum) (Autonomous Institution Affiliated to VTU, Belgaum)
Abstract— The paper presents a review of recent
researches in the field of wireless power transmission
and also about the solar energy conversion technology
by satellite to microwaves using an externally device
called magnetron. The methods applied for wireless
power transmission are also discussed. The solar power
wireless transmission of energy is completely based on
solar energy resources widely available through the
outer environment. Satellites in the earth’s atmosphere
receive the ultraviolet rays from the sun in the form of
photons and then transmit them to the broadcast center
in the form of converted microwaves. These microwaves
travel a long area to reach the device in the receiving
station on earth called rectenna. These rectenna will
convert those microwaves into required energy source
and distributes them to all available places. This
technology overcomes the power loss prevailing in the
present society
Keywords: Rectenna, Magnetron, Microwave, Energy
source wireless transmission, WiTricity, solar power
I. INTRODUCTION
Electricity is the most versatile and widely
used form of energy. The global demand for
electricity is continuously growing. Of the total
generation worldwide, more than 60 percent of
energy is generated using coal-fired station
resulting in carbon dioxide emission threatening the
global warming. To mitigate the consequence of the
climate change, the generation systems need to
undergo significant changes [3].
One of the major issues in power system is
the losses occurring during the transmission and
distribution of electrical power. The percentage of
loss of power during transmission and distribution
is approximated as 26%. The main reason for power
loss during transmission and distribution is the
resistance of wires used in grid. According to the
World Resources Institute (WRI), India’s electricity
grid has the highest transmission and distribution
losses in the world – a whopping 27-40%. Tesla had
proposed methods of transmission of electricity
using electromagnetic induction.
Tesla had always tried to introduce worldwide
wireless power distribution system. But due to lack
of funding and technology of that time, he was not
able to complete the task. Research is being going
on and recent developments have been observed in
this field. Despite advances wireless power
transmission has not been adopted for commercial
use.
Highlight of a wireless transmission in 1891 in
Tesla’s “experimental station” at Colorado is shown
in figure 1.
Fig.1. Tesla’s experimental lamp.
In 1899 Sir Nicolas Tesla and Heinrich
Hertz powered a fluorescent lamp keeping it 25
miles away from source. Wireless power
transmission experiments were conducted at
Warden Clyffe tower. High frequency current, of a
Tesla coil, could light lamps filled with gas (like
neon). In this method, a closed circuit is made using
transmitter, ionized path between upper atmosphere
and transmitter, second ionized path connecting
receiver. The circuit back to the transmitter is
completed through the earth. High potential is
maintained at transmitter and receiver end as well.
A high potential transmitter transmits an
electromotive impulse” through the ionized path to
29 Dr. S.G. Srivani , Gagana P
International Journal of Electronics, Electrical and Computational System
IJEECS
ISSN 2348-117X
Volume 6, Issue 6
June 2017
the upper atmosphere where it ionizes the air, and
this air between the transmitter and receiver would
conduct like a neon tube.
Fig. 2. Neon tube
Warden clyffe tower was designed by Tesla
for trans-Atlantic wireless telephony and also for
demonstrating wireless electrical power
transmission today. [4]
Fig. 3. Warden clyffe tower also known as tesla’s
tower (187 foot) at long Island, New York.
II. METHODS OF WIRELESS
TRANSMISSION OF ELECTRICAL POWER:
1. Induction
The principle of mutual induction between
two coils can be used for the transfer of electrical
power without any physical contact in between. The
simplest example of how mutual induction works is
the transformer, where there is no physical contact
between the primary and the secondary coils. The
transfer of energy takes place due to
electromagnetic coupling between the two coils. [7]
2. Electromagnetic Transmission
Electromagnetic waves can also be used to
transfer power without wires. By converting
electricity into light, such as a laser beam, then
firing this beam at a receiving target, such as a solar
cell on a small aircraft, power can be beamed to a
single target. This is generally known as “power
beaming”.
3. Evanescent Wave Coupling
Researchers at MIT believe they have
discovered a new way to wirelessly transfer power
using non-radiative electromagnetic energy
resonant tunneling. Since the electromagnetic
waves would tunnel, they would not propagate
through the air to be absorbed or wasted, and would
not disrupt electronic devices or cause physical
injury like microwave or radio transmission.
Researchers anticipate up to 5 meters of range. [2]
4. Electrodynamic Induction
Also, known as "resonant inductive coupling"
resolves the main problem associated with non-
resonant inductive coupling for wireless energy
transfer; specifically, the dependence of efficiency
on transmission distance. When resonant coupling
is used the transmitter and receiver inductors are
tuned to a mutual frequency and the drive current is
modified from a sinusoidal to a non-sinusoidal
transient waveform. Pulse power transfer occurs
over multiple cycles. In this way, significant power
may be transmitted over a distance of up to a few
times the size of the transmitter. [4][6]
5. Radio and Microwave
Power transmission through radio waves can
be made more directional, allowing longer distance
power beaming, with shorter wavelengths of
electromagnetic radiation, typically in the
microwave range. A rectenna may be used to
convert the microwave energy back into electricity.
Rectenna conversion efficiencies exceeding 95%
have been realized. Power beaming using
microwaves has been proposed for the transmission
of energy from orbiting solar power satellites to
Earth and the beaming of power to spacecraft
leaving orbit has been considered.
6. Electrostatic Induction
Also, known as "capacitive coupling" is an
electric field gradient or differential capacitance
between two elevated electrodes over a conducting
ground plane for wireless energy transmission
involving high frequency alternating current
potential differences transmitted between two plates
or nodes. [4]
30 Dr. S.G. Srivani , Gagana P
International Journal of Electronics, Electrical and Computational System
IJEECS
ISSN 2348-117X
Volume 6, Issue 6
June 2017
III. CURRENT TECHNOLOGY IN THE
FIELD OF WIRELESS POWER
TRANSMISSION
1. Microwave Transmitter
The most current research and proposals use
microwaves as the frequency range of choice for
transmission. At present an efficiency of 76% is
possible using current technology for microwave
power transmission. For transmission efficiency, the
waves must be focused so that all the energy
transmitted by the source is incident on the wave
collection device. Higher frequencies are also
impractical because of the high cost of transmitters
and the relative low efficiency of current optical and
infrared devices. [5]
Fig. 4. Microwave transmitter
The most common transmitters for microwaves are
the travelling wave tube (TWT), klystron and
magnetron. The TWT is far too expensive and
power restrictive making it impractical for the task
of power transmission. The klystron has been the
DC to microwave converter of choice however it is
also somewhat expensive. [1]
Fig. 5. Klystron
Many researchers are looking to use magnetrons
instead because they are cheap and efficient.
Magnetron frequency output is not as precisely
controllable as the klystron or TWT but power
transmission is more lenient to frequency
fluctuations than communication systems are. One
of the more common proposals would be for an
array of magnetrons to be used as the transmitter.
One of the main advantages to using many smaller
magnetrons as opposed to a few klystrons is that
300 W to 1kW magnetrons are already mass
produced for microwave ovens. The efficiency of
magnetrons is inconsistently reported.
2. Use of Microwave Power Transmission in Solar
Power Satellites (SPS)
Solar power generating satellites launched
into space and transmitting power to Earth stations.
This idea was first proposed in 1968 and all of the
experiments have only been carried out in terrestrial
laboratories. The SPS satellites would be put in high
earth orbit at geosynchronous location. This would
allow them to receive light 99% of the year. A large
rectenna array facility will be built on the Earth to
collect the incoming microwaves. To maintain a
good lock on the rectenna the satellite will need to
be built with a retro directive transmitter which
locks on to a pilot beam emanated from the ground
station.
Fig. 6. Solar power satellite.
Since most of the research is done in the 2.4
GHz to 5.8 GHz range there are some spectrum
regulatory issues to deal with. Also since the retro
directive antenna system is unproven. There is the
health concern that the microwave beam could veer
off target and microwave some unsuspecting
family. However, a Japanese government agency is
31 Dr. S.G. Srivani , Gagana P
International Journal of Electronics, Electrical and Computational System
IJEECS
ISSN 2348-117X
Volume 6, Issue 6
June 2017
planning to send up 10 to 100 kW low earth orbit
satellite to prove its feasibility. [2]
IV. LATEST INVENTION AND
EXPERIMENTS
1. WiTricity
The new technology called WiTricity is
based on using coupled resonant objects [10]. Two
resonant objects of the same resonant frequency
tend to exchange energy efficiently, while
interacting weakly with extraneous off-resonant
objects. After Nicolas Tesla, there was rebirth of
this in 2007 by the team from Massachusetts
Institute of Technology, who call their invention
‘WiTricity’. In the first successful trial of its kind,
the team was able to illuminate a 60-watt light bulb
7ft away.
Fig.7.Overall picture of Wireless transmission
They simulated a transfer of 60W across two
identical loops similar in dimension. The coils had a
radius of 30 cm, with a cross section of 3cm and
distance between the coils was 200m. Basic
principle is Two resonant objects of the same
resonant frequency tend to exchange energy
efficiently, while interacting weakly with
extraneous off-resonant object
Fig.8.Experiment at MIT for WPT
The investigated design consists of two
copper coils, each a self-resonant system. One of
the coils, attached to the power source, is the
sending unit. The resonant nature of the process
ensures the strong interaction between the sending
unit and the receiving unit, while the interaction
with the rest of the environment is weak. [4]
Fig.9.Transmission of electricity is occurring
inspite of the obstruction in between them.
Fig.10. An alternate view of the previous picture.
V. SOLAR POWER SATELLITE
Future suitable and largest application of the WPT
via microwave is a Space Solar Power Satellite
(SPS). The SPS is a gigantic satellite designed as an
electric power plant orbiting in the Geostationary
Earth Orbit (GEO). It consists of mainly three
segments; solar energy collector to convert the solar
energy into DC (direct current) electricity, DC-to-
microwave converter, and large antenna array to
beam down the microwave power to the ground.
The first solar collector can be either photovoltaic
cells or solar thermal turbine. The second DC-to-
microwave converter of the SPS can be either
microwave tube system and/or semiconductor
32 Dr. S.G. Srivani , Gagana P
International Journal of Electronics, Electrical and Computational System
IJEECS
ISSN 2348-117X
Volume 6, Issue 6
June 2017
system. It may be their combination. The third
segment is a gigantic antenna array. Table 1.1
shows some typical parameters of the transmitting
antenna of the SPS. [5][2]
Table 1: Typical parameters of the
transmitting antenna of the SPS [5]
Old JAXA1 JAXA2 NASA
Model JAXA model model /DOE
Model MODEL
Frequency 5.8 GHz 5.8 GHz 5.8 GHz 2.45 GHz
Diameter of 2.6 kmφ 1 kmφ 1.93 kmφ 1 kmφ
Transmitting
antenna
Amplitude 10 dB 10 dB 10 dB 10 Db
Taper Gaussian Gaussian Gaussian Gaussian
Output power 1.3 GW 1.3 GW 1.3 GW 6.72 GW
(beamed to
earth)
Minimum 6.3 mW/ 42 mW/ 11.4 0.22 W/
power cm^2 cm^2 mW/cm^2 cm^2
Density at
center
Antenna
spacing 0.75 λ 0.75 λ 0.75 λ 0.75 λ
Powerper Max. 0.95 Max. Max. 1.7 Max. 185
antenna W 6.1W W W
(3.54 (540 (1,950 (97
billion) million) million) million)
Rectenna
diameter 2.0 kmφ 3.4 kmφ 2.45 kmφ 1 kmφ
180 26 100 23
Maximum mW/cm^ Mw/cm^ mW/cm^ mW/cm^
power 2 2 2 2
Density
Efficiency 96.5 % 86 % 87 % 89 %
JAXA: Japan Aerospace Exploration Agency, NASA:
National Aeronautics and Space Administration, DOE:
Department of Energy.
An amplitude taper on the transmitting antenna is
adopted in order to increase the beam collection
efficiency and to decrease sidelobe level in almost
all SPS design. Atypical amplitude taper is called
10 dB Gaussian in which the power density in the
center of the transmitting antenna is ten times larger
than that on the edge of the transmitting antenna.
The SPS is expected to realize around 2030. Before
the realization of the SPS, we can consider the other
application of the WPT. In recent years, mobile
devices advance quickly and require decreasing
power consumption. It means that we can use the
diffused weak microwave power as a power source
of the mobile devices with low power consumption
such as RF-ID. The RF-ID is a radio IC-tug with
wireless power transmission and wireless
information. This is a new WPT application like
broadcasting. [1][2]
Fig.11 Recent Technologies and Researches of
Wireless Power Transmission – Antennas And
Transmitters [1]
VI. ANTENNAS FOR MICROWAVE POWER
TRANSMISSION
All antennas can be applied for both the MPT
system and communication system, for example,
Yagi-Uda antenna, horn antenna, parabolic antenna,
microstrip antenna, phased array antenna or any
other type of antenna. To fixed target of the MPT
system, we usually select a large parabolic antenna,
for example, in MPT demonstration in 1975 at the
Venus Site of JPL Goldstone Facility and inground-
33 Dr. S.G. Srivani , Gagana P
International Journal of Electronics, Electrical and Computational System
IJEECS
ISSN 2348-117X
Volume 6, Issue 6
June 2017
to-ground MPT experiment in 1994-95 in Japan. In
the fuel-free airship light experiment with MPT in
1995 in Japan, they changed a direction of the
parabolic antenna to chase the moving airship.
However, we have to use a phased array antenna for
the MPT from/to moving transmitter/receiver which
include the SPS because we have to control a
microwave beam direction accurately and speedy.
Power distribution at the transmitting antenna is
given by (1-r²), where r is the radius of antenna. [5]
The phased array is a directive antenna which
generate a beam form whose shape and direction by
the relative phases and amplitudes of the waves at
the individual antenna elements. It is possible to
steer the direction of the microwave beam. The
antenna elements might be dipoles [8], slot
antennas, or any other type of antenna, even
parabolic antennas [9]. In some MPT experiments
in Japan, the phased array antenna was adopted to
steer a direction of the microwave beam All SPS is
designed with the phased array antenna. We
consider the phased array antenna for all following
MPT system.
Japan wants to power up three million
houses with wireless energy from space. They have
serious plans to send a solar-panel-equipped
satellite into space that
could wirelessly beam a giga watt-strong stream of
power down to earth. A small test model is
scheduled for launch in
2015. To iron out all the kinks and get a fully
functional system set up is estimated to take three
decades. A major kink, presumably, is coping with
the possible dangers when a 1-gigawatt microwave
beam aimed at a small spot on Earth misses its
target. The $21 billion project just received major
backing from Mitsubishi and designer IHI (in
addition to research teams from 14 other countries).
[4] [8]
Fig. 12. Japan’s wireless, power-generating, solar satellite
in habitat
VII.WIRELESS POWER TRANSMISSION
Fig.13 Schematic diagram of wireless power
transmission via solar power satellite
Components of WPT system: The Primary
components of Wireless Power Transmission are
Microwave Generator, transmitting antenna and
Receiving antenna (Rectenna) [5]
OPERATION
Fig.14 Functional Block Diagram of Wireless
Power Transmission System [5]
In the transmission side, the microwave power
source generates microwave power and the output
power is controlled by electronic control circuits.
34 Dr. S.G. Srivani , Gagana P
International Journal of Electronics, Electrical and Computational System
IJEECS
ISSN 2348-117X
Volume 6, Issue 6
June 2017
The waveguide 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
transmitting antenna radiates the power uniformly
through free space to the rectenna impedance
matching is the practice of designing the input
impedance electrical load output impedance to
maximize the power transfer or minimize
reflections from the load. [1]
VIII. MAGNETRON
Magnetron is a crossed field tube which
forces electrons emitted from the cathode to take
cyclonical path to the anode. The magnetron is self-
oscillatory device in which the anode contains a
resonant RF structure. The magnetron has long
history from invention by A. W. Hull in1921. The
practical and efficient magnetron tube gathered
world interest only after K. Okabe Average RF
output power versus frequency for various
electronic Devices And semiconductors [2] [6] [9]
Fig.15.A cross sectional view of Magnetron
IX. RECENT TECHNOLOGIES AND
RESEARCHES OF WIRELESS POWER
TRANSMISSION - BEAM CONTROL,
TARGET DETECTION, PROPAGATION,
RECENT TECHNOLOGIES OF
RETRODIRECTIVE BEAM CONTROL
A microwave power transmission is suitable for a
power transmission from/to moving
transmitters/targets. Therefore, accurate target
detection and high efficient beam forming are
important. Retro directive system is always used for
SPS.
A corner reflector is most basic retro directive
system [8]. The corner reflectors consist of
perpendicular metal sheets, which meet at an apex.
Incoming signals are reflected back in the direction
of arrival through multiple reflections off the wall
of the reflector. Van Atta array is also a basic
technique of the retro directive system [9]. This
array is made up of pairs of antennas spaced
equidistant from the center of the array, and
connected with equal length transmission lines. The
signal received by an antenna is re-radiated by its
pair, thus the order of re-radiating elements is
inverted with respect to the center of the array,
achieving the proper phasing for retro directivity.
Usual retro directive system has phase conjugate
circuits in each receiving/transmitting antenna,
which play a same role as pairs of antennas spaced
equidistant from the center of the array in Van Atta
array. A signal transmitted from the target is
received and re-radiated through the phase
conjugate circuit to the direction of target. The
signal is called a pilot signal. We do not need any
phase shifters for beam forming. The retro directive
system is usually used for satellite communication,
wireless LAN, military, etc. There are many
researches of the retro directive system for these
applications [11] - [17]. They use the almost same
frequency for the pilot signal and returned signal
with a local oscillator (LO) signal at a frequency
twice as high as the pilot signal frequency in the
typical retro directive systems. Accuracy depends
on stability of the frequency of the pilot signal and
the LO signal. Prof. Itoh’s group proposed the pilot
signal instead of the LO signal [18].
There are other kinds of the phase conjugate circuits
for the MPT applications. Kyoto University’s group
have developed a retro directive system with
asymmetric two pilot signals, ωt+Δω and ωt+2Δω,
and the LO signal of 2ωt [19].ωt indicate a
frequency of a transmitter. Other retro directive
system with 1/3 ωt pilot signal and without LO
signal. The LO signal is generated from the pilot
signals. The latter system solves a fluctuation
problem of the LO and the pilot signal which cause
phase errors because the fluctuations of the LO and
the pilot signals are synchronous. They have used
2.45 GHz for ωt. Mitsubishi Electric Corporation in
Japan have developed PLL-heterodyne type retro
directive system in which different frequencies for
the pilot signal and the microwave power beam,
3.85 GHz and 5.77 GHz, respectively, have been
used [20]. The retro directive system unifies target
35 Dr. S.G. Srivani , Gagana P
International Journal of Electronics, Electrical and Computational System
IJEECS
ISSN 2348-117X
Volume 6, Issue 6
June 2017
detection with beam forming by the phase conjugate
circuits. There are some methods for target
detecting with pilot signal which is separated to
beamforming. We call the method “software retro
directive”.
Computer is usually used for the software recto
directive with the phase data from a pilot signal and
for the beam forming with calculation of the
optimum phase and amplitude distribution on the
array. In the software recto directive, we conform
microwave beam freely, for example, multi-beams.
On contrary, we need phase shifters in all antennas.
(a) (b)
(c) (d)
Fig. 16. Various retro directive array with phase
conjugate circuits Developed in (a) Kyoto University
and kobe university in 1987 (2.45GHz),
(b) Kyoto university in 1996 (2.45GHz), (c) queen’s
university (62-66GHz) (d) Jet propulsion laboratory
and university of michigan in 2001 (5.9GHz) [3]
X. RECENT TECHNOLOGIES OF
RECTENNA
The word “rectenna” is composed of “rectifying
circuit” and “antenna”. The rectenna and its word
were invented by W. C. Brown in 1960’s [8][9]
[11]. A typical rectenna site is 4 km in diameter f or
a transmitting antenna diameter of 1km operating at
5.8 GHz. Under these conditions, 93% of the
transmitted power is collected. The peak microwave
power density at the rectenna site is 27 mW/cm2 if
a Gaussian power profile is assumed f or the
transmitter. The beam intensity pattern has a non-
uniform distribution with a higher intensity in the
center of the rectenna and a lower intensity at its
periphery as shown in Fig. 2. The safety
requirement f or the microwave power density f or
humans is set to 1mW/cm2 in most countries, which
is satisfied at the periphery.
Fig. 16 gives the Typical power density at a
rectenna site (1kmφ TX antenna with 10dB
Gaussian power distribution) [5]
Fig.17. Graph of Intensity Verses Range [5]
Fig.18. Block Diagram of the Rectenna Element [9]
In well-matched rectenna arrays, the diode is the
most critical component to achieve high efficiencies
because it is the main source of loss. Schottky
barrier diodes utilizing Si and GaAs have been
employed with rectification efficiencies greater than
80%.Although the electron mobility of GaAs is
over six times greater over Si for high efficiency, Si
has a higher thermal conductivity for better
reliability Proper diode selection for a WPT
application is dependent on input power levels, and
the diode parameters should be chosen carefully for
an efficient rectifier at a specified operating
frequency. The breakdown voltage (Vbr) limits the
diode’s power handling capability and is directly
related to the series resistance and junction
capacitance through the intrinsic properties of the
diode’s material and structure. For instance,
increasing the breakdown voltage increases either
the series resistance or junction capacitance.
Decreasing the series resistance will decrease the
power dissipated in the diode; however, the
breakdown voltage will decrease or the junction
36 Dr. S.G. Srivani , Gagana P
International Journal of Electronics, Electrical and Computational System
IJEECS
ISSN 2348-117X
Volume 6, Issue 6
June 2017
capacitance will increase. Increasing the junction
capacitance will lower its cut off 1frequency. These
parameters must be traded in selecting the proper
diode for high- power applications. [7] [22]
XI. RECENT TECHNOLOGIES OF
CYCLOTRON WAVE CONVERTER
If we would like to use a parabolic antenna as a
MPT receiver, we have to use Cyclotron Wave
Converter (CWC) instead of the rectenna. The
CWC is a microwave tube to rectify high power
microwave directly into DC. The most studied
cyclotron wave converter (CWC) comprises an
electron gun, a microwave cavity with uniform
transverse electric field in the gap of interaction, a
region with symmetrically reversed (or decreasing
to zero) static magnetic field and a collector with
depressed potential as shown in Fig.16. Microwave
power of an external source is converted by this
coupler into the energy of the electron beam
rotation, the latter is transformed into additional
energy of the longitudinal motion of the electron
beam by reversed static magnetic field; then
extracted by decelerating electric field of the
collector and appeared at the load-resistance of this
collector.
Fig.19 Schematic picture of cyclotron wave
converter [2]
Efficiency
We classify the MPT efficiency roughly into three
stages; DC-RF conversion efficiency which
includes losses caused by beam forming, beam
collection efficiency which means ratio of all
radiated power to collected power on a receiving
antenna, and RF-DC conversion efficiency.
RF-DC Conversion Efficiency
The RF-DC conversion efficiency of the rectenna or
the CWC is over 80 % of experimental results as
shown in Fig.16. Decline of the efficiency is caused
by array connection loss, change of optimum
operation point of the rectenna array caused by
change of connected load, trouble of the rectenna,
and any losses on the systems, for example, DC/AC
conversion, cables, etc. However, it is easier to keep
high efficiency than that on the other two stages.
Beam Collection Efficiency
The beam collection efficiency depends on the
transmitter and receiver aperture areas, the
wavelength, and the separation distance between the
two antennas as shown in the section 1. For
example, it was calculated approximately 89% in
the SPS reference system with the parameters as
follows; the transmitter aperture is 1 km φ, the
rectenna aperture is 10x13 km, the wavelength
is12.24 cm (2.45GHz), and the distance between the
SPS and the rectenna 36,000 km [3]. They
assume10dB Gaussian power taper on the
transmitting antenna. Decline of the efficiency is
caused by phase/frequency/amplitude error on a
phased array. [1]
DC-RF Conversion Efficiency
If we do not have to steer a microwave beam
electrically in a MPT, we can use a microwave
transmitter with high DC-RF conversion efficiency
over 70-80 % like microwave tubes. However, if we
need to steer a microwave beam electrically without
any grating lobes, we have to use phase shifters
with high loss. Especially in the SPS system, the
optimum and economical size of the transmitting
phased array and microwave power are calculated
as around a few km and over a few GW,
respectively. It also means that phase shifter has to
be installed after the microwave
generation/amplification (Fig.16) if microwave
beam will be steered to directions of larger than 5
degrees without grating lobes. In present, the power
loss of the phase shifter is over 4-6 dB. It means
that DC-RF conversion efficiency in the MPT
system in Fig16.is below 20% if we use over 70%
efficiency
37 Dr. S.G. Srivani , Gagana P
International Journal of Electronics, Electrical and Computational System
IJEECS
ISSN 2348-117X
Volume 6, Issue 6
June 2017
Nasa’s first practical solar power satellite:
Fig.20. SPS-ALPHA: The First Practical Solar
Power Satellite via Arbitrarily Large Phased
Array
SPS-ALPHA (Solar Power Satellite via Arbitrarily
Large Phased Array) is a novel, bio-mimetic
approach to the challenge of space solar power. If
successful, this project will make possible the
construction of huge platforms from tens of
thousands of small elements that can deliver
remotely and affordably ten to thousands of
megawatts using wireless power transmission to
markets on Earth and missions in space. The
selected NIAC project will enlist the support of a
world-class international team to determine the
conceptual feasibility of the SPS-ALPHA by means
of integrated systems analyses, supported by
selected "proof-of-concept" technology
experiments. [22]
XII. CONCLUSION
Wireless power transmission of electrical power can
be considered as a large scope in future prospects of
power generation and transfer. Solar power
satellites are the future for supplying non-
conventional energy. The various methods and
aspects regarding wireless transmission of electrical
power and the details of design of solar power
satellite has been discussed. The evolution of the
technology from the time of Tesla has been
overviewed.
XIII. REFERENCES [1] Wireless Power Transmission For Solar Power
Satellite (SPS) by R.Gautham, G.Elavarasan,
Mr.kamalakannan, International Journal of Power
Control Signal and Computation (IJPCSC) Vol. 4
No. 2 April- June -2012
©gopalaxjournals,singapore ISSN:0976-268X
[2] G. E. Maryniak, “Status of international
experimentation in wireless power Transmission,”
Sunset energy counsel, Solar energy, vol. 56,1996.
[3] “Wireless Power Transmission Using Satellite Based
Solar Power System”, Hemant m. dighade1,
Akhilesh A. Nimje2 Volume 2, Issue 10, October
2013 ISSN 2319 –4847 International Journal of
Application or Innovation in Engineering &
Management (IJAIEM)
[4] Wireless Transmission of Electrical Power Overview
of Recent Research & Development by Sagolsem
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[5] Wireless Power Transmission Via Solar Power
Satellite by M.Muthupriya,B.E(EEE), S.Vinothini,
B.E(EEE), vivekanandha college of technology,
Namakkal for women, Namakkal, Tamil nadu,India.
International Journal of Scientific & Engineering
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[21] solar satellite power generation Shariq mohammed
Ansari1, Alam afzal2, Dilshad ahmad Ansari3, Noor
mohammed4, Gulrez Bodhle5, International Journal
of Research in Science & Engineering e-ISSN:
2394-8299 Volume: 3 Issue: 2 March-April 2017 p-
ISSN: 2394-8280
[22] SPS-ALPHA: The First Practical Solar Power
Satellite via Arbitrarily Large Phased Array By John
Mankins Artemis Innovation Management Solutions
updated on October 11,2011.