1

Seminar Report

“WIRELESS POWER SYSTEM TRANSMISSION FOR SOLAR POWERED

SATELLITE”

Submitted in Partial Fulfillment of the requirements

For the degree of

Bachelor of Technology

in

Instrumentation &Control Engineering

Department of Instrumentation and Control Engineering

Amity School of Engineering and Technology

GGS Indraprastha University, New Delhi

Guide: Submitted By:

Mr. Vineet Dahiya Akanksha Trikha

ECE/ICE Department 0410403010

ICE – 4th

Year

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CERTIFICATE

This is to certify that Mr. Akanksha Trikha student of B.Tech. (Instrumentation & Control), has

successfully completed his report entitled “WIRELESS POWER SYSTEM

TRANSMISSION FOR SOLAR POWERED SAELLITE” comprehends the authentic

work of his individual.

This report fulfills his Bachelor of Technology course requirement at 7th

semester at the Amity

School of Engineering and Technology, an institution affiliated to Guru Gobind Singh Indraprastha

University, New Delhi.

Date: Mr Vineet Dahiya

Place: New Delhi ECE/ICE Department

3

ACKNOWLEDGEMENT

First and foremost, I would like to thank Professor(Dr.) Rekha Agarwal, Director for the education.

Under her guidance that has provided strong fundamentals, positive competition and unmatched

learning experience.

I express my gratitude to our esteemed Ms. Pinki Nayak, (Head, Department of ECE & ICE) and

my guide Ms. Rachana Nagal. Their inspiration, motivation, suggestion and invaluable guidance

enabled me to study. Their careful observations and precise ideas were an immense help in refining

our content.

Akanksha Trikha

[04010403010]

4

ABSTRACT

Wireless Power transmission (WPT) is a useful and convenient technology that can be employed to

collect solar energy and concentrate on earth surface without the need for a wire connection called as

solar power satellites (SPS). Solar Power Satellite is an energy system which collects solar energy in

space and transmits it to the ground. It has been believed as a promising infrastructure to resolve

global environmental and energy problems for human beings. One of the most important

technologies for the SPS is the wireless power transmission from the geostationary orbit to the

ground. Microwave power transmission has been investigated and demonstrated for more than 40

years, but still requires further research regarding high-efficiency power conversion and high-

accuracy beam control for SPS application. 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 system.

It may be their combination. The third segment is a gigantic antenna array.

5

Table of Contents

Certificate 2

Acknowledgement 3

Abstract 4

1. Introduction 7

1.1 wireless power transmission 8

1.2 solar power satellites 9

1.2.1 Background 9

1.2.2 Basic concept 10

1.2.3 Importance 10

1.2.4 Advantages 10

1.3 Transmission

1.3.1 Microwave transmission 11

1.3.2 Laser transmission 11

2. system design-basic components 14

3. wireless powering of solar power satellite 16

6

4. Recent Technologies and trends of Wireless Power 19

Transmission Antennas and Transmitters

4.1 Antennas for Microwave Power Transmission 19

4.2 Recent Technologies for Transmitters 19

4.3 magnetron 20

5. Environmental issues 21

6. Advantages 24

Conclusion 25

Bibliography 26

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LIST OF FIGURES

1. Chapter 1

Fig1: wireless power transmission block diagram

Fig2: solar power satellite-basic concept

2. chapter 2

Fig3: functioning of a rectenna

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Chapter 1

INTRODUCTION

A Major problem Planet Earth is facing is provision of an adequate supply of clean energy. We face

three simultaneous challenges -- population growth, resource consumption, and environmental

degradation -- all converging particularly in the matter of sustainable energy supply. It is widely

agreed that our current energy practices will not provide for all the world's peoples in an adequate

way and still leave our Earth with a livable environment. Hence, a major task for the new century

will be to develop sustainable and environmentally friendly sources of energy. An approach to

exploiting solar power is to capture it in space and convey it to the Earth by wireless means. As with

terrestrial capture, Space Solar Power (SSP) provides a source that is virtually carbon-free and

sustainable. As will be described later, the power-collecting platforms would most likely operate in

geosynchronous orbit where they would be illuminated 24 hours a day (except for short eclipse

periods around the equinoxes). Thus, unlike systems for the terrestrial capture of solar, a space-based

system would not be limited by the vagaries of the day-night cycle. Furthermore, if the transmission

frequency is properly chosen, delivery of power can be carried out essentially independent of

weather conditions. Thus Space Solar Power could provide base load electricity.

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1.1 WIRELESS POWER TRANSMISSION (WPT)

BACKGROUND

The vision of achieving WPT on a global scale was proposed over 100 years ago when Nikola Tesla

first started experiments with WPT, culminating with the construction of a tower for WPT Tesla's

objective was to develop the technology for transmitting electricity to anywhere in the world without

wires. Wireless communication is the transmission of the energy over a distance without, the usage

wires or cables, where in distances involved may be short or long. Wireless operations permits

services, such as long-range communications, that are merely unfeasible using wires. Wireless

energy transfer or wireless power transmission is the transmittance of electrical energy from a power

source to an electrical load without interconnecting wires. Wireless transmission is useful in cases

where interconnecting wires are inconvenient, hazardous, or impossible. The problem of wireless

power transmission differs from that of wireless telecommunications, such as radio. In the latter, the

proportion of energy received becomes critical only if it is too low for the signal to be distinguished

from the background noise. With wireless power, efficiency is the more significant parameter. A

large part of the energy sent out by the generating plant must arrive at the receiver or receivers to

make the system economical. The most common form of wireless power transmission is carried out

using direct induction followed by resonant magnetic induction. Other methods under consideration

include electromagnetic radiation in the form of microwaves or laser beam technology.

Two types of WPT:

1) Ground based power transmission

2) Space based power transmission

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Fig 1

1.2 SOLAR POWERED SATELLITES

1.2.1 BACKGROUND

Fig 2

11

Since 1967, Solar Power Satellites (SPS) have proposed to collect solar energy in space and

beam it down to the Earth. With the energy crisis of the early 1970's, SPS was seriously

considered as an alternative to producing electric power from fossil fuels.

1.2.2 SOLAR POWER SATELLITE: BASIC CONCEPT

Basic idea of SPS is to collect the solar energy in orbit and send it to ground by microwave, laser

beam or some other way. The concept of the Solar Power Satellite energy system is to place giant

satellites, covered with vast arrays of solar cells, in geosynchronous orbit 22,300 miles above the

Earth's equator. Each satellite will be illuminated by sunlight 24 hours a day for most of the year.

Because of the 23" tilt of the Earth’s axis, the satellites pass either above or below the Earth’s

shadow. It is only during the equinox period in the spring and fall that they will pass through the

shadow. They will be shadowed for less than 1% of the time during the year.The solar cells will

convert sunlight to electricity, which will then be changed to radio-frequency energy by a

transmitting antenna on the satellite and beamed to a receiver site on Earth. It will be reconverted to

electricity by the receiving antenna, and the power would then be routed into our normal electric

distribution network for use here on the Earth. Figure 1 illustrates the concept. The great advantage

of placing the solar cells in space instead of on the ground is that the energy is available 24 hours a

day, and the total solar energy available to the satellite is between four and five times more than is

available anywhere on Earth and 15 times more than the average location. Testing has demonstrated

that wireless energy transmission to the Earth can be accomplished at very high efficiencies. Tests

have also shown that the energy density in the radio-frequency beam can be limited to safe levels for

all life forms. The concept is simple; the technology exists.

1.2.3 Importance:

Realization of external supplying power to satellite moving on its orbit can lead to weight reduction

and miniaturization of power

system. It can also reduce difficulties in launching satellite like launching cost. Standardization of

wireless power transmission module has the effects of being on market faster and improvement of

usability’s effects. Thus, building of the Flexibility Power Supply Network which uses wireless

power transmission technology expands potential of nano-satellites in space

1.2.4 Advantages

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There are several advantages to SPS. Solar radiation can be more efficiently collected in space,

where it is roughly three times stronger than on the surface of the Earth and it can be collected 24

hours per day (since there are no clouds or night in high Earth orbit). SPS does not use up valuable

surface area on the Earth and can be beamed to areas with the highest demand at any particular time.

Most of these systems would utilize photovoltaic (PV) cells similar to those on Earth-based systems

Others would utilize reflectors and mechanical collectors similar to those used in special large-scale

solar facilities in France and the California desert (Barstow). Some PV systems would also use

reflective concentrators. Most of these systems collect solar energy in space and transmit it via a

microwave energy beam to an Earth-based rectenna which converts the beam into electricity for use

on Earth. Microwave beams have a fairly low wavelength (lower than visible light) and do not

appear to pose any danger to the Earth's atmosphere.

energy in space and transmit it via a microwave energy beam to an Earth-based rectenna which

converts the beam into electricity for use on Earth.

1.3 TRANSMISSION

Various methods of wireless energy transfer are being studied that may allow us to

transmit large amounts of power over long distances without the need for a

conducting connection. Additionally, wireless transmission presents the possibility of

sending and receiving power from space, which can have useful applications.

Microwave Power Transmission

One of the earliest demonstrations of wireless energy transfer was the use of microwave radiation to

power a small helicopter in 1964. This experiment contained the basic elements of microwave power

transmission: a source of electromagnetic radiation, and a microwave receiver with a DC rectifier to

transform the microwave energy into DC electrical power. Since then, efforts have been made to

increase the efficiency, power, and range of microwave transmission. The highest microwave-to-DC

electrical energy conversion achieved was 84% in an experiment in 1975. However, more practical

systems with higher power output have had lower efficiencies. A team in Japan built a system

consisting of a set of solar panels attached to a microwave transmitter, and a receiver which converts

13

microwaves to a DC voltage. The transmitter was designed to track the receiver and automatically

direct its microwave output toward the receiver. This system was able to achieve a conversion

efficiency of over 75% with an output of 300 watts. A next desired goal would be to achieve high

efficiency energy transfer over long distances.

Laser Transmission

The laser method of energy transfer involves shining a laser beam onto a photovoltaic receiver. This

requires the ability to precisely track the position of the receiver relative to the laser transmitter. The

advantage of a laser is that its monochromaticity allows better control of the beam over long ranges,

as well as a possibility to tune the photovoltaic receiver to the laser beam. Recent experiments using

commercially obtainable laser sources have generated over 7.2 watts of photovoltaic output from a

70 watt laser beam (from which only 25 watts reached the receiver). This corresponds to a power

density of 13.6 watts per square centimeter of receiver area, as well as a 28% optical-to-electrical

conversion efficiency, which is promising for real applications if the experimental result can be

scaled to larger systems.

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CHAPTER 2

SYSTEM DESIGN -BASIC COMPONENTS

SPACETENNA: (THE ANTENNA ON SATELLITE)

Spacetenna is a triangular prism with a length of 800 m and sides of 100 m. The main axis lies in the

north-south direction, perpendicular to the direction of orbital motion. The transmitting antenna on

the horizontal under-surface faces the Earth, and the other two sides of the prism carry solar arrays. The faces of the prism are embedded with photovoltaic cells. These Photovoltaic cells would convert

sunlight into electrical current, which would, in turn, power an onboard microwave generator. The

Microwave thus produced Travels through Atmosphere & is collected by RECTENNAS on Earth.

The Spacetenna has a square shape whose dimension is 132 meters by 132 meters and which is

regularly filled with 1936 segments of sub array. The sub array is considered to be a unit of phase

control and also a square shape whose edges are 3 meters. It contains 1320 units of cavity-backed

slot antenna element and DC-RF circuit. Therefore, there will be about 2.6 million antenna elements

in the spacetenna. The spacetenna is composed of pilot signal receiving antennas followed by

detectors finding out the location of the rectenna on the earth, power transmission antenna elements

and phase control systems. Moreover, the pilot signal frequency and a frequency for the energy

transmission are different from each other. Using two kinds of frequency for the power transmission

and the pilot signal prevents each other from interfering and makes it possible to find out the

accurate direction of a specified rectenna.

RECTENNNA :(RECTIFYING ANTENNA)

A Rectenna can be considered as a base station for a geo-stationary satellite. Microwaves of 2.45

GHz frequency are used to transmit power from the satellite to the rectenna. It consists of a mesh of

an array of dipole antennas connected to diodes to convert the radio frequency energy to DC voltage,

15

which is then converted to regular AC electricity and wired to homes, factories, etc. A simple

reflector plane could be added to the mesh to improve the efficiency to 50%.

Fig 3

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Chapter 3

Wireless powering of solar power satellite

Solar power from the satellite is sent to Earth using a microwave transmitter. This transmission is

transmitted to the relevant position via an antenna. The transmission is transmitted through space

and atmosphere and received on earth by an antenna called the rectenna. Recent developments

suggest using laser by using recently developed solid state lasers allow efficient transfer of

power. A range of 10% to 20% efficiency within a few years can be attained, but further

experimentation still required taking into consideration the possible hazards that it could cause to

the eyes. In comparison to laser transmission microwave transmission is more developed, has

high efficiency up to 85%, beams is far below the lethal levels of concentration even for a

prolonged exposure. The microwave transmission designed has the power level well below the

international safety standard (Frequency 2.45 GHz microwave beam). The electric current

generated from the photovoltaic cells is passed through a magnetron which converts the electric

current to electromagnetic waves. This electromagnetic wave is passed through a waveguide

which shapes the characteristics of the electromagnetic wave.

Effectiveness of Wireless Power Transmission (WPT) depends on many parameters. Only a part

of WPT system is discussed below, which includes radiating and receiving antennas and the

environment between them. The wave beam is expanded proportionately to the propagation

distance and a flow power density is increased inversely proportional to the square of this

distance. However the WPT has some peculiarities, which will be mentioned here. WPT systems

require transmitting almost whole power that is radiated by the transmitting side. So, the useful

result is the power quantity at the receiving antenna, but not the value of field amplitude as it is

usually required. Efficiency of WPT systems is the ratio of energy flow, which is intercepted by

receiving antenna to the whole radiating energy.

Field distribution on the receiving antenna usually is uniform because its size is small

comparatively to the width of the beam. For WPT systems this distribution IS NOT uniform. It

has a taper form and it depends on the field distribution on the transmitting antenna.

17

For increasing of the energy concentration on the receiving antenna the phase distribution on the

radiating antenna has usually a spherical form with the center in the point on crossing of the

receiving plate and the radiating axis. Radiating antenna of the WPT systems usually has a taper

distribution of the field. This distribution allows to increase the efficiency and to decrease the

field out of the receiving antenna.

The efficiency of energy transmission is expressed by the functional 2. To increase the field

distribution on radiating aperture is made as a tapered distribution. High value of is supposed to

be in the majority of known projects of the WPT systems.

However, the effectiveness of the WPT system is defined not only by the value of . It is also

determined by the rectangularity of the field distribution on the radiating aperture, the rectangular

distribution factor in the theory of antennas is usually called the surface utilization factor. The

meaning of these two parameters and is discrepant because to increase 2 it is necessary to have

the field falling down to edges, but to increase it is necessary to have a uniform field.

To increase the effectiveness of WPT system it is necessary to increase the product 2, though the

requirements for each of both multipliers are opposite. This product is named a generalize

criterion! It is possible to find the way out of this contradiction if the antenna is discontinuous

(discrete) one. Let us produce the field distribution in the radiating discrete antenna falling to its

edges not by means of creation of non-uniform distribution of the field but with the help of

irregular situation of identical sub apertures, each of them having the uniform field distribution. It

is supposed that the number of these apertures is sufficiently high in order to admit the

approximation of the integral optimum monotonous Gauss distribution by means of step

function. The places of sub aperture disposition can be found by the differentiation of this step

function. Discrete distribution of sub apertures presents non-equadistant antennaarray consisting

of the similar elements. Such optimization is optimal in Chebyshevâ„¢s sense since the

maximum error tends to zero while the number of sub apertures is tended to infinity. So the field

in the place of observerâ„¢s disposition would be similar to step and the monotonous signal

source. The falling to the edge field distribution is typical for the WPT problems. For the

discrete-step distributions that means the concentration of sub apertures in the center and their

gradual discharge on the edges. Thus all sub apertures are similar and have the uniform

distribution of the field with the equal amplitude, which may reach the maximum admissible

value.

The dismemberment of continuous apertures and slight moving of them apart in the space when

all of apertures are equal and uniformly feed increases their effectiveness (the generalized

18

criterion is increased). The generalized criterion determines the quality of the WPT Systems

better than usual criterion. The optimal distribution form may be reached for the large radiating

apertures where dismemberment at many parts is easily realized by disposition of sub aperture

clots in places, which correspond to high field intensity (first of all it concerns the center of the

radiator) and relieving sub aperture density at edges of antenna. This construction allows to

approach to unit the value both of coefficients 2 and As a result the effectiveness of the WPT

system will be essentially increased. For receiving these transmitted waves rectennas are set up at

the Earth. An antenna comprising a mesh of dipoles and diodes for absorbing microwave energy

from a transmitter and converting it into electric power. Microwaves are received with about

85% efficiency and 95% of the beam will fall on the rectenna but the rectenna is around 5km

across (3.1 miles). Currently there are two different design types being looked at- Wire mesh

reflector and Magic carpet. Wire mesh reflector type rectennas are built on a rigid frame above

the ground and are visually transparent so that it would not interfere with plant life whereas in the

magic carpet type material pegged to the ground.

19

Chapter 4

Recent Technologies and trends of Wireless Power Transmission

Antennas and Transmitters:

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 in ground-

to-ground MPT experiment in 1994-95 in Japan (See Fig.2.2 and Fig.2.6). 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.

Recent Technologies for Transmitters

However, we have to use a phased array antenna for the MPT from/to moving transmitter/receiver

which include the SPS because we hav The technology employed for the generation of microwave

radiation is an extremely important Phased Array Used in Japanese Field MPT Experiment ( for

MILAX in 1992, for SPRITZ in 2000) e to control a microwave beam direction accurately and

speedy. The phased array is a directive antenna which generate a beam form whose shape

anddirection 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, slot

antennas, or any other type of antenna, even parabolic antennas.In some MPT experiments in Japan,

20

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.

Magnetron

Magnetron is a crossed field tube in which E B r r × 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 in

1921. 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

proposed the divided anode-type magnetron The magnetrons main were advanced and manufactured

for the microwave ovens. As a result, the magnetron of 500 – 1,000 W is widely used in microwave

ovens in 2.45 GHz, and is a relatively inexpensive oscillator (below $5). There is a net global

capacity of 45.5GW/year for all magnetrons used in microwave ovens whose production is 50– 55

millions. A history of the magnetron is a history of a microwave oven. The first microwave oven

with a magnetron sold shortly in U. S. A. after the World War II ended for more than $2,000, the

equivalent of about $20,000 today. In 1960’s, Japan played a important role to reduce the cost of the

microwave oven. Compared that American tube’s cost was $300 and they planned to sell for $500 in

1960’s, Japanese tube cost was less than $25. In 1970, U.S. manufacturers sold 40,000 ovens at $300

to $400 apiece, but by 1971 the Japanese had begun exporting low-cost models priced $100 to $200

less. Sales increased rapidly over the next 15 years, rising to a million by 1975 and 10 million by

1985, nearly all of them Japanese[5]. But history repeats itself. Instead of Japanese microwave oven,

Korean and Chinese more reduce the cost of the microwave oven now. Therefore, the magnetron is

suitable device for the MPT because of high efficiency and low cost unsuitable device because of its

unstable frequency and uncontrollable phase. If we do not make a phased array to control beam

direction electrically, the magnetron can be applied for the MPT system. However, the cooker-type

magnetron itself cannot be applied for the phased array-type MPT because it is only a generator and

we cannot control/stabilize the phase and the amplitude. The cooker-type magnetron was considered

as noisy device. It is however confirmed that spurious emissions from the cooker-type magnetron

with a stable DC power supply is low enough and this can be applied to the MPT system[6]. Peak

21

levels of higher harmonics are below -60 dBc and other spurious is below -100 dBc..

22

Chapter 5

ENVIRONMENTAL ISSUES

Interferences to Existent Wireless System

There is no allowed frequency band for the MPT ,therefore, we used the ISM band. The bandwidth

of the microwave for the MPT do not need wideband and it is enough quite narrow since an

essentially monochromatic wave is used without modulation because we use only carrier of the

microwave as energy. Power density for the MPT is a few orders higher than that for the wireless

communication. We have to consider and dissolve interferences between the MPT to the wireless

communication systems. One calculation of the interferences between the MPT of the SPS, mainly

2.45 GHz, to the wireless communication systems was done in Japan[20]. If the harmonics of the

MPT frequencies are, however regulated by the ITU (International Telecommunication Union)

power flux density (PFD) limits, some modulation might be necessary. Carrier noises, harmonics,

and spurious emissions of the MPT signal should be quite small to avoid interference to other radio

services in operation around the world. Grating lobes and sidelobes of the MPT beam should be low

enough in order to make the affect region as small as possible. Also, grating lobes should be

mitigated because they are a direct loss of transmitter power. The other interference assessment on

2.45 GHz and 5.8 GHz MPT of the SPS was published inJapan.

Safety on Ground

One of the characteristics of the MPT is to use more intense microwave than that in wireless

communication systems. Therefore, we have to consider MPT safety for human. In recent years there

24have been considerable discussions and concerns about the possible effect for human health by RF

and MW radiation. Especially, there have been many research and discussions about effects at 50/60

Hz and over GHz (microwave). These two effects are different. There is long history concerning the

safety of the microwave[24]. Contemporary RF/microwave standards are based on the results of

critical evaluations and interpretations of the relevant scientific literature. The SAR (specific

23

absorption rate) threshold for the most sensitive effect considered potentially harmful to humans,

regardless of the nature of the interaction mechanism, is used as the basis of the standard. The SAR

is only heating problem. The scientific research results have indicated that the microwave effect to

human health is only heating problem. This is different from the EMF research. Famous guideline,

the ICNIRP (International Commission on Non-Ionizing Radiation Protection) guidelines, are 50 or

10 W/m2 for occupationally exposed vs. the general public, at either frequency[25]. The

corresponding limits for IEEE standards for maximum permissible human exposure to microwave

radiation, at 2.45 or 5.8 GHz, are 81.6 or 100 W/mas averaged over six min, and 16.3 or 38.7 W/m2

as averaged over 30 min, respectively, for controlled and uncontrolled environments[26]. The

controlled and uncontrolled situations are distinguished by whether the exposure takes place with or

without knowledge of the exposed individual, and is normally interpreted to mean individuals who

are occupationally exposed to the microwave radiation, as contrasted with the general public. In

future MPT system, we have to keep the safety guideline outside of a rectenna site. Inside the

rectenna site, there remains discussion concerning the keep out area, controlled or uncontrolled area.

Interaction with Atmosphere

In general, effect of atmosphere to microwave is quite small. There are absorption and scatter by air,

rain, and irregularity of air refraction ratio. In 2.45 GHz and 5.8 GHz, the absorption by water vapor

and oxygen dominate the effect in the air. Especially, it is enough to consider only absorption by the

oxygen in the microwave frequency. It is approximately 0.007 dB/km[27]. In the SPS case, the

amount of total absorption through the air from space is approximately 0.035 dB[28]. When

elevation is 47 degree in the middle latitude, for example, in Japan, the total absorption is

approximately 0.05 dB.

24

Chapter 6

Advantages

It is Unaffected by day-night cycle, weather or seasons. Optimized advances may enable 21 hour

power supply per day .This is an eco-friendly, renewable and maintenance free energy resource

unlike the conventional fuels .As the equipment is positioned in space, it is occupies no land area

and remains unaffected by harsh weather conditions. Rectennas can share land with farms. The

spacetenna could direct energy to any rectenna on earth within the range of its steering angle,

which could satisfy the energy requirements of all the equatorial countries. Waste heat is re-

radiated back into space, instead of warming the biosphere.

25

CONCLUSION

Electrical energy can be economically transmitted without wires to any terrestrial distance. The

economic transmission of power without wires is of crucial importance to man. It will enable him to

dispense with innumerable causes of sinful waste. This technology opened up the possibility of

constructing power stations on the moon. These power stations will be capable of transmitting power

to earth using microwave energy. Such microwave energy would then be converted into electricity

using a vast array of rectenna receivers on the earth. Nevertheless with all the challenges that face

wide-scale deployment of this new technology wireless power transmission for solar power satellite

is still considered as a next-generation power transmission system.

26

BIBLIOGRAPHY

• “Wireless Power Transmission Technologies for Solar Power Satellite” Susumu Sasaki, Koji

Tanaka. International communication conference IEEE 2011.

• S.Sasaki, K.Tanaka and Advanced Mission Research Group, “SSPS Technologies

Demonstration in Space” , IAC-10.C3.4.1, 61st International Astronautical Congress, Prague,

Sep.-Oct. 2010.

• “Wireless Power Transmission – A Next Generation Power Transmission System”. S. Sheik

Mohammed, K. Ramasamy, T. Shanmuganantham. IEEE 2010 International Journal of

Computer Applications.

• P.E.Glaser, “Power from the Sun: Its Future”, Science, vol.162,pp.867-886, 1968.

• Yamamoto, S., N. Shinohara, and H. Matsumoto, “Study of Phase Array with Phase

Controlled Magnetrons (in Japanese)”, Proc. of IEICE, 2003, p.C-2-105