nasa technical paper 1804

8/6/2019 Nasa Technical Paper 1804

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NASA Technical Paper 1804

Solar Power SatelliteSystem Sizing Tradeoffs

G. D. Arndt and L. G. Monford

FEBRUARY 198

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TECH LIBRARY KAFB, NM

NASA Technical Paper 1804

Solar Power SatelliteSystem Sizing Tradeoffs

G. D. Arndt and L. G. MonfordLyudon B . Johtzsou Space CelzterHouston, Texas

National Aeronauticsand Space AdministrationScientific and TechnicalInformation Branch1981


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CONTENTS

Section PageI NTR ODUC TI ON . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1BACKGROUND . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1OP TI M I ZED M I C R OW AVEYSTEMS- . 450 MHz AND 5800 MHz . . . . . . . . . 2MAXIMUM ANTENNA SIZEO N S I D E R A T I O N S . . . . . . . . . . . . . . . . . 7S YS TEMOS TR ADEOF F S . . . . . . . . . . . . . . . . . . . . . . . . 9.I O N O S P H E R I C ,TM OS P HER I C . ANDHER M AL LI M I TATI ONS . . . . . . . . . . 14

I O N O S P H E R I CI M I T A T I O N S . . . . . . . . . . . . . . . . . . . . . . 16A T M O S P H E R I CI M I T A T I O N S . . . . . . . . . . . . . . . . . . . . . . 16THER M AL LI M I TATI ONS . . . . . . . . . . . . . . . . . . . . . . . . 17

MULTIPLENTENNAS . . . . . . . . . . . . . . . . . . . . . . . . . . 18CONCLUSIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19R E F E R E N C E S . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22A P P E N D I XA . NTENNAAPERS . . . . . . . . . . . . . . . . . . . . . A- 1A P P E N D I X B . XAMPLEALCULATIONS . . . . . . . . . . . . . . . . . . B-1

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TABLES

Table1 MICROWAVE SYSTEM CHARACTERISTICS AT 2.45 GHz . . . . . . . . .2 MICROWAVE SYSTEM CHARACTERISTICS AT 5.8 GHz . . . . . . . . .3 SPS SUMMARY COSTS FOR 2.45 GHz OPERATION

(a) Physical parameters . . . . . . . . . . . . . . . . . . .(b) Costs . . . . . . . . . . . . . . . . . . . . . . . . . .4 SPS SUMMARY COSTS FOR 5.8 GHz OPERATION

(a) Physical parameters . . . . . . . . . . . . . . . . . . .( b ) Costs . . . . . . . . . . . . . . . . . . . . . . . . . .B- 1 STUDY SSUMPTIONS . . . . . . . . . . . . . . . . . . . . . .B-2 COST AND MASS FACTOR DEFINITIONS . . . . . . . . . . . . . . .B-3 PREDEFINED COST AND MASS FACTORS FOR ANTENNA/RECTENNACONFIGURATIONS . . . . . . . . . . . . . . . . . . . . . . .B-4 COST AND MASS STATEMENTS FOR 5.8 GHz SYSTEMS

(a) PS . . . . . . . . . . . . . . . . . . . . . . . . . . .(b) Rectenna . . . . . . . . . . . . . . . . . . . . . . . .B-5 COST AND MASS STATEMENTS FOR 2.45 GHz SYSTEMS

(a) SPS . . . . . . . . . . . . . . . . . . . . . . . . . . .( b ) Rectenna . . . . . . . . . . . . . . . . . . . . . . . .

B-6 COST UMMARY(a) Physical parameters . . . . . . . . . . . . . . . . . . .( b ) Costs . . . . . . . . . . . . . . . . . . . . . . . . . . .

Page56

1 111

1212B-3B-5

B-7

B-8B-10

B -11B - 1 3

B-14B-14

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FIGURES

Figure Page1 Microwave transmission efficiency for the 2.45 GHzreference PS onfiguration . . . . . . . . . . . . . . . . 32 Antenna nd rectenna izing ummary . . . . . . . . . . . . . 83 Rectenna collection efficiency for various phase errorbudgets . . . . . . . . . . . . . . . . . . . . . . . . . . 84 Electricity osts or 2 . 4 5 GHz ystems . . . . . . . . . . . 1 35 Electricity costs for 5 .8 GHz systems . . . . . . . . . . . . 156 Antenna patterns for three SPS configurations . . . . . . . . 1 57 Relative sizes for several antennalrectennaconfigurations . . . . . . . . . . . . . . . . . . . . . . 2 0

A-1 Rectenna collection efficiency vs . array taper . . . . . . . A-2

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INTRODUCTION

The i n i t i a l s i z i n g f o r t h e s o l a r power s a t e l l i t e (SPS) was o p t i m i z e d oa 1-km t r a n s m i t t i n ga n t e n n a p r o d u c i n g 5 GW of DC power from a r e c e i v i n g a n -t e n n a r e c t e n n a )a p p r o x i m a t e l y 10 km i nd i a m e t e r .T h e r e a re a d v a n t a g e s o alower power out put nd a smal ler rectenna.C o mm e rc ia l u t i l i t y c om pa ni espre-f e r o n t e g r a t e o w e r power l e v e l s n t o h e i rg r i d s .R e c t e n n a s smal ler t h a nth e 10-km d i a m e t e r n h e r e f e r e n c e c o n f i g u r a t i o n w ou ld make m ore r e c t e n n as i t e s a v a i l a b l e .

The purposeo f t h i sp a p e r i s t o n v e s t i g a t e h e r a d e o f f s of smaller SPSsy s te m s . The nd r e s u l t i s a compar i sonbe tween hecostso f smal ler sys temsand thoseo f h e 5 GW, 10 km dia me ter ect enn a efe ren ce yst em . The micro-wave system i s r e o p t i m i z e d o re a c ha n t e n n a / r e c t e n n ac o n f i g u r a t i o n .B o t h h e2.45 GHz ref er en ce re qu en cyand a h igher 5 .8 GHz) f r e q u e n c ya r eu s e d n h ec a n d i d a t es y s t e m s .

Inc o m p l i a n c ew i t h h e NA S A ' s p u b l i c a t i o np o l i c y , h e o r i g i n a lu n i t s o fmeasurehavebeenconver t ed to h e e q u i v a l e n t v a l u e n h e S y st sm e n te r-n a t i o n a ld ' U n i t & S I ) . A s an a i d o h e e a d e r , h e S I u n i t sa r ew r i t t e nf i r s t and t h e o r i g i n a lu n i t s a r e w r i t t e n p a r e n t h e t i c a l l y h e r e a f t e r .

BACKGROUND

The SPS s i z i n g w i t h a 1-km t r a n s m i t t i n gan t enn a and 5 GW of DC o u t p u tpower from a re c te n n a was base don1. A t he rm al im i t a t io n o f 3 kW/m2 in he r a ns m i t t i nga n t e n n a2. A peak power d en s i t y of 23 mW/cm2 in he o n o s p h e re3 .C o s te f f e c t i v e n e s s t h e a r g e r h e power sy s t e m h e m ore c o s t

e f f e c t i v e )The t h e r m a l i m i t a t i o na t h ec e n t e r of t h ea n t e n n a i s a f u n c t i o n of t h eamountof heatg e n e r a t e d by t h ekl ys t r on s (DC-to-RF co nv er te rs ) andof he e f -f e c t i v e a d i a t o ra r e a . The r e f e r e n c ec o n f i g u r a t i o nh a s 7 2 kW k l y s t r o n u b e so p e r a t i n g a t 8 5 - p e r c e n tc o n v e r s i o ne f f i c i e n c ya n dcoo le d by pas s iv eh e a tp i p er a d i a t o r s . From t h e r m a l o n s i d e r a t i o n s , a r g e r r a n s m i t t i n g n t e n n a s a re de-

s i r a b l e . However, a s h e n t e n n a i z e n c r e a s e s , h e power d e n s i t y n h ei o n o s p h e r e n c r e a s e s nd i r e c tp r o p o r t i o n . A t some t h r e sh o l d power d e n s i t yl e v e l , w h i c h i s d e p e n d e n tu p o n h eo p e r a t i n g r e q u e n c y ,n o n l i n e a r n t e r a c -t ionsb e t w e e n h e o n o sp h e r ean d he power beam co ul db e g i n oo c c u r .T h e s en o n l i n e a rh e a t i n ge f f e c t s a re o fconcernb e c a u seofposs ib led i s rup t ionspro -duced i n low f r equencyc o m m u n i c a t i o n san dnav iga t ionsy s t e m sby ad io r e -q u e n c y n t e r f e r e n c e W I ) n d by m u l t i p a t he f f e c t s .T h e o r e t i c a l t u d i e s oft h e o n o sp h e r ec o m p l e t e dd u r i n g h ee a r l yp h a se s of t h e SPS e v a l u a t i o n p r o -gram in d i ca te d he power de ns i ty sh ou ld be l i m i t e d o 23 mW/cm2 in o r d e r op r e v e n t u c hn o n l i n e a rh e a t i n ge f f e c t s .T h i s h e o r e t i c a lv a l u e was t a k e n


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as the SPS design guideline. Subsequent ionospheric heating tests have indi-cated that this 3 mW/cm2 threshold maye too low, as will be discussedlater. From ionospheric considerations, smaller antennas are desirable.Therefore, from the two opposing requirements, the reference system was sizeto produce 5 GW of power with an antenna lan in diameter.The 2.45 GHz downlink power beam frequency is in the center of100 MHzwide IMS (Industrial, Medical,nd Scientific) band in which users may inter-fere with other users ofhat band. This 2400-2500 MHz band is not particu-larly affected by weather conditions and an SPS system usingt should notsuffer weather outages. Another IMS band (5800 f 75 MHz) is also availablefor possible SPS usage. However, an SPS system operating in this frequencyregion might have o be shut down under very poor weather conditions, as wibe discussed later. Smaller rectennas are more amenable to the higher 5.8 Hzoperating frequency as a result of greater antenna focusing.

OPTIMIZED MICROWAVE SYSTEMS~ - 2450 MHz ND 5800 MHzTo use a smaller rectenna, the antenna must be enlarged and the trans-mitted power decreased in order to avoid exceeding the 23 mW/cm2 ionosphericlimit. In reoptimizing the microwave sys,tem to decrease the rectenna sizeand reduce the transmitted power, two operating requencies, 2.45 GHz and5.8 GHz, were considered. The reference SPS microwave system has an effi-ciency budget shown in figure1 (ref. 1).The rectenna collection efficiency88 percent) is the percentage ftransmitted power from the satellite antenna incident upon the ground rec-

tenna. One of the ground rules for this study was that the rectenna for eachconfiguration be sized to receive 88 percent of the transmitted power. It wasassumed that the antenna performance parameters would be the same as those ithe present SPS reference configuration. These include l oo root mean squared(rms) phase error, fO.l dB amplitude error, 2-percent tube failure rate,0.63 cm (0.25 in.) mechanical spacing between subarrays,l arc min antennatilt, and +3 arc min subarray tilt. A 10-dB Gaussian taper is used for anten-na illumination, since his taper maximizes rectenna collection efficiencywhile minimizing sidelobe peaks (see appendix ) . The only constraint onsidelobes is that the first sidelobe peak should have power density of lessthan 0.1 mW/cm2. A buffer strip extends around the rectenna to exclude thegeneral public from .1 mW/cm2 or higher microwave radiation levels.The procedure to optimize the microwave system for maximum efficiencywith different antenna/rectenna configurationss first to use closed-formequations (1) and (2) to obtain the general microwave system characteristics.These characteristics, together with the antenna error parameters listed pre-viously, are then used in microwave simulation programso obtain the antennapatterns and collection efficiencies.

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63% overall efficiency(from D C / R F input to RF/DC output)

0.98 mechanicalpointingand subarray/waveguide tolerances

b b ) GWw 0.88 0.89.97(10 km rectenna diameter;

a=lO0,& 0.1 dB, 2% toleranceson transmitting antenna)

Figure 1.- Microwave transmission efficiency for the 2.45 GHz referenceSPS configuration.


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'D-GR - 'D-ARRAY rl - 10 dB/201'A2R2 L 0.115dB J

where'D-GR'D-ARRAY

= peak power density at rectenna boresight= peak power density at center of transmitting antenna

AT = transmitting antenna areax = power beam wavelength (0.1225 m)R = nominal range from satelliteo rectenna ( 3 6 000 km)dB = amount of dB taper for Gaussian antenna illumination10)'TRANS = total power radiated from transmitting antennaFor a 2.45 GHz operating frequency, two operating constraints were

considered:1. Retaining the 23 mW/cm2 ionospheric limit y reducing transmittedpower as the size of the atellite antenna increased.2. Allowing the ionospheric power density limit to increase yretaining the same transmitted power as the size of the antenna increased,

The microwave system characteristics for.45 GHz operation may be summarizedas shown in table .

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TABLE 1.- MICROWAVE SYSTEMCHARACTERISTICS AT 2.45 GH z

C h a r a c t e r i s t i c I o n o s p h e r i c l i m i t No i o n o sp h e r i cof23 mW/cm2 1 m i t

T r a n s m i t t i n ga n t e n n ad iamete r , km . . . . . . . .Transmitted microwavepower, GW . . . . . . . . . .Power de ns i ty n on o-sp h e r e , mW/ cm2 . . . . . . .Output DC power fromr e c t e n n a , GW . . . . . . . .Rectennadiameter ocap-t u r e 8 8 %fnergy, km . . .R e c t e n n a a r e a r e l a t i v e o

r e f e r e n c e . . . . . . . . . .. .

1 1.36.53 2 1.36.53 2

6.5.53.78.64.5.5.5

23333 424 91

5 2 . 7 2 2.14.2 5 5.05.0 5

10.6.8 5 7.6.8 5

1.0.56.46.25.56.46.25

The hermal l i m i t of23 kW/m2 i s not a c o n s t r a i n t o r h e a r g e ra n t e n n a /s m a l l e r e c t e n n a y s t e m so p e r a t i n ga t 2.45 GHz. The io no sp he ri c l i m i t i s t h ec r i t i c a lp a r a m e t e r ns y s t e m s i z i n g f o r 2.45 GHz.

F o rop er a t io n n he 5 .8 GHzMS fre qu en cyband, a d i f f e r e n t s e t of on-s t r a i n t s m us tbecons idered .S ince hegain of anantenna i s p r o p o r t i o n a l othe r equencysquared ,an tennassmal l e r han 1 km ind i a m e t e rcan be usedwithr e c t e n n a s smal ler t h a n h e1 0 km d iam ete r e f e re nce ec te nnas . The an tennat h e r m a l i m i t a t i o n i s t h ec r i t i c a lp a r a m e t e r o rs y s t e ms i z i n g a t 5.8 GHz.The ionospher ic l i m i t of23 mW/cm2 i s no onger a f a c t o rb e c a u s e h i s h r e s h -o l d i s a l sop r o p o r t i o na l o r e q u e n c y q u a r e d .T h a t i s , t he d jus t ed ono-s p h e r i c l i m i t f o r5 . 8 GHz i s

25 ' 8 0 = 23 [5 .6] = 129 mW/cm 2'D-5.8 GHz 'D-2.45 GH z[GIS i n c e h e 5.8 GHz an tenna w i l l be smal ler , o r a t l e a s t no l a r g e r , h a n

1 km i nd i a m e t e r , h ea d j u s t e d o n o s p h e r i c l i m i t of129 mW/cm2 w i l l notbee x c e e d e d .O t h e r a c t o r s n f lu e n c i n g y s t e m i z i n g n c lu d e o w e re f f i c i e n c i e s

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i n s e v e r a l o f t h emicrowavesubsys temsopera t ing a t thehigher5 .8 GHz f r e -quency.T h e o p e r a t i n gc o n s t r a i n t s a t 5.8 GHz a re1. Re ta in in g he 23 kW/m2 ante nna herm al l i m i t by r e d u c i n g r a n sm i t t e dpower as t h e s i z e of t h e s a t e l l i t e a n t e n n ad e c r e a se s .2. Al lowing he n tenna hermal l i m i t t o nc re as e somewhat as t h ea n t e n n as i z ed e c r e a s e s by r e d e s i g n i n g h e h e r m a l r a d i a t i o ns y s t e m .3 .Reduc ing ubsys tem f f i c i enc ies as fo l lows:

8 0 - p e r c e n t , a t h e r h a n85 -p er ce nt , DC-RF kl ys tr onc o n v e r s i o ne f f i c i e n c y9 7 - p e r c e n t , a t h e r h a n9 8 - p e r c e n t ,e f f i c i e n c y o rn o r m a la t m o sp h e r i c r a n sm i s s i o n8 7 - p e r c e n t 9 a t h e r h a n8 9 - p e r c e n ta v e r a g e RF-DC conver s ione f f i c i e n c y n h e g ro un d e c te nn a

Themicrowavesys tem ch a ra c t e r i s t i c s fo r 5 .8 GHz op er a t io n may besummarizeda s shown i n t a b l e 2.

TABLE 2.- MICROWAVE SYSTEMCHARACTERISTICS AT 5.8 GHz

C h a r a c t e r i s t i cr e s e n th e r m a ll i m i t of23 kW/m2

Tr a n sm i t t i n ga n t e n n ad iamete r , km . . . . . . . . 0.75.5Transmitted microwave

power, GW . . . . . . . . . . 2.84.68Power d e n s i t y n o n o s p h e r e ,

mw/ cm2 . . . . . . . . . . . 30.87Output DC power fromr e c t e n n a , GW . . . . . . . . 2 1 . 1 7R e c t e n n ad i a m e t e r oc a p t u r e88% o f r a n sm i ten erg y, km . . . . . . . . . 5.8.75Rectenna area r e l a t i v e t or e f e r e n c e . . . . . . . . . . 0.336.765

Thermal 1 m i twith mproved

des ign

0.75 1

3.78.5

4022

2.72.8

5.8.3

0.336.185

~~ ~

1.5

2.88

12 9

2.12

2.8

0.078

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The candidate configurations have two thermal limits;.e., the present2 3 kW/m2 limit and that of an improved design, whichill be discussed later.

MAXIMUM ANTENNA SIZE CONSIDERATIONS

The relative antenna nd rectenna sizes for . 4 5 GHz and 5 . 8 GHz opera-tion are shown in figure . Let us now consider the mechanical and elec-tronic constraints on the maximum size for the satellite antenna as a func-tion of frequency.One limitation on antenna size is the phase control system. An activeretrodirective phase control technique is usedo point and focus the down-link power beam. In the reference system, a pilot beam signal is transmittedfrom the ground to the satellite, where it is received and processed at eachof the 101 000 power modules (tubes). A phase reference is distributedthroughout the antenna to each of the power modulesia a Master Slave Re-turnable Timing System (MSRTS) developed by the LinCom Corporation (ref.) .If the antenna is enlarged, additional power modules are needed. Thepower output from each tube would be reduced, but the number would increaseeven if the overall transmitted power were lower. The reason is that the an-tenna mechanical pointing requirement for the attitude control system is de-termined by grating lobe levels which are dependentn the area of the antennadriven by one tube. Thus, given as an average antenna area associated withone tube as constrained by the antenna attitude control system, a larger an-tenna requires more power modules.If the antenna size increases, he phase reference has to be distributed

over a larger area, thereby increasing the phase error buildup. The presentSPS system has a l oo rms phase error budget, which consists of errors in thephase distribution system, ionosphere-induced perturbations of the uplinkpilot beam signal, errors in the@ receiver and processing electronics ineach power module, etc. Larger antennas must still adhere to the10' phaseerror budget in order to achieve the expected transmission efficiencies.Rectenna collection efficiencies for a.5 km diameter antenna with varyingamounts of phase error are shown in figure. The data indicate that an in-crease in phase error could easily negate the advantage of a larger antenna;i.e., a smaller rectenna.Operating at the 5 . 8 GHz frequency imposes a further constraintn the

phase reference distribution system within the antenna. This reference sig-nal is distributed at an intermediate frequency and is then multipliedp tothe power frequency, either . 4 5 GHz or 5 . 8 GHz, in the F receiver elec-tronics in order to perform the phase conjugation of the uplink pilot signal.Because of this multiplication process, the allowable phase error within thereference distribution system is inversely proportionalo the output fre-quency. Thus, operating at 5 . 8 GHz requires an improvement (reduction) of5 . 8 1 2 . 4 5 or 2.37 in the phase distribution system error.A smaller antennaat 5 . 8 GHz would probably help the phase control system achieve the requireperformance. In summary, when considering the present reference system phase7


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ee

100

80

60

40

20

0

Transmitting antenna diameter (km)Figure 2.- Antenna and rectenna sizing summary.

- 8%collection ...*..............." " rms phase error10" rms phase error20" rms phase error-.....

Conditions:1.53 km antenna diameter(7 = 2% failures, 0.1 dB amplitude error+ 3 4 5 6 7 8

Rectenna diameter (km)3.- Rectenna collection efficiency for varioushase error budgets.

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c o n t r o l and a t t i t u d e c o n t r o l e q u i r e m e n t s , e a so n a b l ea n t e n n a i z e smigh t bea 1.5-km diameter a t 2.45 GHz and a 0.75-km d iamete r a t 5.8 GHz.

SYSTEM COSTTWDEOFFS

A d e t a i l e d a n a l y s i s ofsubsystemcostsand masses f o r h e r e f e r e n c e 5 GWso la r power s a t e l l i t e w i t hs i l i c o ns o l a rc e l l s i s g i v e n n e f e r e n c e 3. Thesev a l u e s a re used as a b a s e l i n e fo r computing co s t s f o r h ed i f f e r e n ta n t e n n a /r e c t e n n ac o n f i g u r a t i o n s .S i n c e h ep u r p o s e of t h i s e p o r t i s t od e t e r m i n e h er e l a t i v e o rd i f f e r e n t i a l c o s t s f o r h e v a r i o u s c o n S i g u r a t i o n s , any f u t u r echanges i n hea b s o l u t ec o s t s o r h e e f e r e n c es y s t e ms h o u l dn o th a v e a g r e a ti m p a c to n h ec o n c l u s i o n ss t a t e dh e r e i n .The p r inc ipa le l e m e n t s n h e SPS r e c u r r i n gc o s t s a re1. S a t e l l i t e a r d w a r e2 . T r a n sp o r t a t i o n sp ace and round)3 . Space ons t ruc t ion nd uppor t4 . Rect nna5 . Programmanagementn d i n t e g r a t i o n6 . C o s t l l o w a n c e o r mass growthSome generalc o s t i n ga s su m p t i o n s n c l u d e1.2.3 .4.5.

6.7.

3 0 - y e a ro p e r a t i n g i f e t i m e0 . 9 2p l a n t a c t o r o r 2.45 GHz o p e r a t i o n0 . 9 0p l a n t a c t o r o r 5.8 GHz o p e r a t i o n1 5 - p e r c e n t a t e of r e t u r no n n v e s t m e n tc a p i t a l22-percent mass g r o w t h a c t o r oc o v e rp o t e n t i a l i s k s ns o l a ra r r a y a n dmicrowavesystemperformance es t imates17-percent of n et SPS ha rd wa rec o s t a c t o r oa c c o u n t o r m assgrowth10 GW p e ry e a radd i t io na l power gen era t io nc a p a c i t y

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T h e t o t a l mass and co s t o r he e f e r en ce SPS sys tem a re 599 8 4 m e t r i cton s and 12 32 m i l l i on . The cos tan d mass s t a t e m e n t s o r h e n d i v i d u a ls a t e l l i t e subsystem a re d i v i d e d n t o h e o l l o w i n gc a t e g o r i e s :1. Power c o l l e c t i o n : t r u c t u r e , o l a r c e l l s , p o w e r d i s t r i b u t i o n , a n d

maintenance2 . R o t a r yo i n t3. Power t r a n s m i s s i o n : t r u c t u r e , l y s t r o n s a n dher ma l ont rol , wave-g u i d e s , u b a r r a y t r u c t u r e , power d i s t r i b u t i o n c o n d u c t o r s , w i t c h -g e a r s , DC-DC c o n v e r t e r s , h e r m a l o n t r o l ) , n e r g y t o r a g e ,p h a s econ t ro l ,ma in t enancesys t ems , and an t enn am e c h a n i c a lp o i n t i n g4 .nformation managementnd a t t i t u d e o n t r o l : a r d w a r e n d r o p e l l a n t5.ommunications6 . T r a n s p o r t a t i o n : l e c t r i c r b i t r a ns fe r eh i c l e (EOTV), pe r sonne ll a u n c hveh i c l e (PLV), pe r s on ne lo r b i t r a n s f e rv eh ic le (POTV), andheavy l i f t l a un c hvehicle (HLLV)7 . C o n s t r u c t i o n p e r a t i o n s : o wE ar th rb it (LEO) and eosynchronous

o r b i t (GEO)The cos t andmass romeach of th esesubsys t ems w i l l v a r ya c c o r d i n g o

t o t a l po wer, a n t e n n a i z e , r e q u e n c y , t c . of t h e a n d i d a t e n t e n n a / r e c t e n n as y s t e m s .S i n c e h ec a l c u l a t i o n s a re q u i t e e n g t h y ,o n l y h e end r e s u l t s o r2.45 GHz and5.8 GHz o p e r a ti o n a re shown in a b l e s 3 and4 . The d e t a i l s a r eg i v e n na p p e n d i x B , t o g e t h e rw i t h a c o m p l e t es a m p l ec a l c u l a t i o n o rone con-f i g u r a t i o n . n a b l e 3 ( 2 .4 5 GHz), t h emicrowave ys temhasbeen ized oconformwi th he23 mW/cm2 io n o s p h e r ic l i m i t f o r h e f i r s t f o u r a n t e n n a /r e c t e n n a o n f i g u r a t i o n s .T h i s o n o s p h e r i c o n s t r a i n th a sbe en removed f o rt h e a s t h r e e c o n f i g u r a t i o n s ,r e s u l t i n g n a maximum of 91 mW/cm2 f o r h e5 GW, 2 km d ia m et erantennasys tem.

The e l e c t r i c i t y c o s t s n m i l l s pe r kwh and th e d i f f e r e n t i a l c o s t n c r e a s eas compared to h e 5 GW, 1-km a n t e n n a e f e r e n c es y s t e ma r e shown i n f i g u r e 4f o r 2.45 GHz op er at io n . The to pc u r v e ,c o n s t r a i n e d oa n o n o s p h e r i c l i m i tof23 mW/cm2, shows a s i g n i f i c a n t n c r e a s e n e l e c t r i c i t yc o s t as th ean t ennas i z e n c r e a s e s . M icrow av e power d e n s i t y n h e o n o s p h e r e i s d i r e c t l yp r o p o r -t i o n a l o r a n s m i t t i n ga n t e n n a area and t o t a l r a n s m i t t e d power; t h e r e f o r e , ft h ea n t e n n a area i s do ub led, he power mustbe educedbyo ne-h alf i n o r d e r t om a i n t a i n h e same power de ns i t y . The e l ec t r i c i t yc o s t a t e s m i l l s / k W h )a r ed e te r m in e d by t h e o t a ls a t e l l i t ec o s t sd i v i d e d by t h ede l i ve red power . A st h eco s t summary i n a b l e 3 show s , he o t a l s a t e l l i t e c o s t sd e c r e a s ea t amuch slo we r ate ha nd o e s h ede l ivered power as t h ea n t e n n as i z e n c r e a s e s .The costd i s a d v a n t a g ew i t h a r g e ra n t e n n a s i s removed i f h e o t a l r a n s m i t t e dpower rem ains ons tan t as t he n t enn a i ze hang es . However, t h e on os ph e r i cpower de ns i t y nc rea se sa c c o r d i n g l y .

10


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TABLE 3.- SP S SLTMMARY COSTS FOR 2.45 GHz OPERATION

( a )h y s i c a la r a m e t e r s

23 mWlcm2 i on os ph er ic I n c r e a s e d o n o s o h e r i cp e c i f i c a t i o n1 m i t l i m i t

~ - _ _1.53 2 1.36 1 .53 22 .78 1.64 6 . 5 6 . 5 6 . 5

A n t e n n ad i a m e t e r , km . . . . . . .S a t e l l i t e power o u t p u t , GW . . . .Power dens i tya t e c t e n n a ,

mw/ cm2 . . . . . . . . . . . . .R e c t e n n ai a m e t e r , km . . . . . .P o w e r d e l i v e r e d , GW . . . . . . .

16 .5

23105

1.363.53

237. 62.7

23 23 42 54 916.8 5 7 .6 6 .8 52 .1 1.26 5 5.05 5 .05

. ~ . .""C o s t c a t e g o r y I n c r e a s e d o n o s p h e r i c1 i m i t23 mW/cm2 i on os ph er icl i m i t

SP S h a r d w a r e ,m i l l i o nd o l l a r s . . . . . . . . . . . .

L e s s m o r t i z a t i o n ofi n v e s t m e n t ,m i l l i o nd o l l a r s . . . . . . . . . . . . .

T o t a l ,m i l l i o nd o l l a r s . . . . .M i s s i o n o n t r o l ,m i l l i o n

d o l l a r s . . . . . . . . . . .T r a n s p o r t a t i o n ,m i l l i o nd o l l a r s . . . . . . . . . . . .C o n s t r u c t i o no p e r a t i o n s ,

m i l l i o no l l a r s . . . . . . . .R e c t e n n a ,m i l l i o no l l a r s . . . .Programmanagement ndi n t e g r a t i o n ,m i l l i o n

d o l l a r s . . . . . . . . . . . .C o s ta l l o w a n c e o rm a s sg r o w t h ,m i l l i o no l l a r s . . . .T o t a l ,m i l l i o nd o l l a r s . . . . . .Mil l s per kwh . . . . . . . . . .C e n t sp e r MJ . . . . . . . . . . .% i n c r e a s e n e l e c t r i c i t y

c o s t s o m p a r e d o o s to f1 . 3 ~ 1 M . J 4 7m i l l s / k W h ) o rt h e e f e r e n c e SP S s y s t e m . . . .

4946 4072 412006 989 845 511 2

4 7 34473

257381 5

20 2 11 9 473 473 4733918 4950 5425 5982 7639

1 00 10 10 10

2721 31 8663 991 884 9

1170 1615 1233 1395 19331293 835 1852 1646 1283

10 10

31 20 2700

96 12578

10661561

495 407 41 2 50 7 904 5 81 1

76 012432

471.3

64 910243

71.62 . 0

66 6 84 1 922 1017 12991019 0 11 944 13 671 14613 17 24

90.6 180.1 52 55 67.12 .5 5 .0 1 .4 1 .5 1 .9

52.4 92.783 10.6 172 .7

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17/45

TABLE 4 . - SPS SUMMARY COSTS FOR 5 . 8 GHzOPERATION

( a )P h y s i c a lp a r a m e t e r s

S p e c i f i c a t i o n

A n t e n n adia met er , km . . . . . . .S a t e l l i t e power o u t p ut , GW . . . .Power dens i tya t e c t e n n a ,

mW/ cm2 . . . . . . . . . . . . .R e c t e n n aiam ete r , km . . . . . .Power de l ivered , GW . . . . . . .

P r e s e n tt h e r m a ld e s i g n

0 . 7 52 . 8 4

305 .a

2

.C o s t a t e g o r y

-~ .SPS hardware,m i l l i o n

d o l l a r s . . . . . . . . .L e s sa m o r t i z a t i o n o f

inves tment, m i 11 ond o l l a r s . . . . . . . . .T o t a l ,m i l l i o nd o l l a r s . . .M i s s i o n o n t r o l ,m i l l i o n

d o l l a r s . . . . . . . . .T r a n s p o r t a t i o n ,m i l l i o n

d o l l a r s . . . . . . . . .C o n s t r u c t i o no p e r a t i o n s ,

m i l l i o no l l a r s . . . . .R e c t e n n a ,m i l l i o no l l a r s .Programmanagement nd

i n t e g r a t i o n ,m i l l i o nd o l l a r s . . . . . . . . .

Cos t l lowance f o r massg r o w t h ,m i l l i o no l l a r s .

T o t a l ,m i l l i o nd o l l a r s . . .Mil l s per kwh . . . . . . .C e n t sp e r M J . . . . . . . .% i n c r e a s e in e l e c t r i c i t y

c o s t s o m p a r e d o o s t of1.3clM.l ( 4 7 m i l l s / k W h ) o rt h e e f e r e n c e SPS s y s t e ma t 2 . 4 5 GHz . . . . . . .

( b ) C o s t s

.~

. . .

. . .

. . .

. . .

. . .

. . .

. . .

. . .

. . .

. . .. . .

. . .

. . .

Improved hermald e s i g n

0 . 5. 7 5 1 .0 1. 51 . 6 8. 7 8. 5 2.88

7 . 87 4 0 1 2 2 1 2 98 . 7 5 5 .a 4 . 3 2 . 81 . 1 7 2 . 7 2 4 . 8 2 . 1 2

Presen tmprovedhermalt h e r m a le s i g nd e s i g n

...

1 4 5 2

1 2 21 3 3 0

1 01 2 a a

4 4 44 9 2 5

1 4 5

226a 3 6 8

1 3 83.8

1 9 3

1 2

2 7 57 30 90 62 7 6 38 9 35 6 82 a a

10 1 0 10 1 02 0 7 01 2 07 2 07 9 4

7 3 40 5 72 7 06 32 6 7 20 0 30 6 35 7 8

3 0 33 67 74 9

4 7 0 a 3 2 7 7 78 99 0 2 225 10 aa5 7 9 6 9

6 40 . 396 . 1I . a 1 . 4. 7. 1

36 7 1112


18/45

5.O4.43.9

2 3.3\t4- 2.8cncn0)r0

0

+0 2.2+.-.= 1.72 1.3w 1.1+

180160140

3> 120x--E- 100cncn0.c,

0 80.-h 60

280+-ncn240

23mW/cm2ionospheric /limit . I .-...-*' Increasing..-* ionosphericReference .**

120 $a,cu

1 .O 1.25.5.75.0Transmitting antenna diameter (km)

80 '0C.-+40 2a,a0

Figure 4 . - E l e c t r i c i t y c o s t sf o r 2 . 4 5 GHz systems.

13


19/45

The 5.8 GHz s y s t e m sd e s c r i b e d n a b l e 4 h a v e h e r m a l i m i t a t i o n s nt h e r a n s m i t t i n g a n t e n n a r a t h e r h a n o n o s p h e r i c i m i t a t i o n s as t he dominan tc o n s t r a i n t . The 5.8 GHz syste ms a re i n h e r e n t l y smal ler ( a n t e n n a , r a n s m i t t e dpower, nd re ct en na ) as compared t o h e 2.45 GHz co nf ig ur at io ns as a r e s u l to f h e n c r e a se da n t e n n ag a i n a t h i g h e r r e q u e n c i e s .

The e l e c t r i c i t y c o s t s f o r h e 5 . 8 GHz sy s te m s are c om pa red t o h e r e f e r -ence 2.45 GHz sys tem in i g u r e 5 . The da ta nd ic a t e ha t a s i g n i f i c a n t e d u c -t i o n nc o s t sc a nb ea c h i e v e dw i t h a modest mprovement i n the rm al r a d i a t o rd e s i g n .S i n c e h e n c r e a s e nd i f f e r e n t i a lc o s t i s reduced rom 64 pe rc en tt o 36 p e r c e n t o r h e0 . 7 5 km d iamete ran tenna by us ing a new t herm al adi a-t o rco nf ig ur a t io n , improvement s in he rm ald e s i g n a re consideredmandatory .D e t a i l s of t h e h e r m a ld e s i g ne s t i m a t e sa r eg i v e n n a l a t e r s e c t i o n .

I n s u m m a r i zi n g h ec o s t i n g e su l t s and t h em i c r o w a v esys tem radeof f s ,s e v e r a lo p t i o n ss h o u l db ec o n s i d e r e d u r t h e r :

2.45 GHz

' I n c r e a s ei o n o sp h e r i c l i m i t -- 1.53-km an te nn a; 6.8-km re c te n n at o 54 mW/cm2 wi th 5 GW g r i d power; d i f f e r e n t i a lc o s t n c r e a s e i s 1 7 p e r c e n t t o1.5c/MJ 55mills/kWh))

R e t a i n 23 mW/cm2 -- 1.36-km an te nn a; 7.6-km r e c t e n n aas i o n o sp h e r i c w i t h 2 .7 GW g r i d power; d i f f e r e n t i a l1 m i c o s t n c r e a s e i s 5 0 .2p e r c e n t t o2.Oc/M.J (70.6mills/kWh))

5. 8 GHz In c r e a s en t e n n a -- 0.75-km a nt en na ; 5.8-km r e c t e n n athermal l i m i t by with 2.72 GW g r i d power; d i f f e r e n t i a l33percen t c o s t n c r e a s e i s 36 p e r c e n t t o1.8c/MJ (64mills/kWh))

Themicrowave r ad ia t ion p a t t e r n s f o r h e 1.53-km an te nn ao p e r a t i n g a t 2.45 GHzand the 0.75-km a n te n n a o p e r a t i n gat 5 .8 GHz a r e compared i n f i g u r e 6 wi th hel-km an tenna , 5 GW re fe re nc e SPS system.

IONOS P HER IC , ATMOSPHERIC,- AND THERMAL. . LIMITATIONS.The r e l a t i v e e l e c t r i c i t y c o s t s f ro m h ev a r i o u sa n t e n n a / r e c t e n n ac o n f i g u -

r a t i o n s a re heav i lydependen tupon he onospher i c ,a tmospher i c ,a n d h e r m a lc o n s t r a i n t s i m p o se don themicrowave ys t ems . The v a l i d i t y of the se con-s t r a i n t s i s under eviewand may be re v is e dp e n d i n g h e e s u l t s of a numbero f s t u d i e s .

14


20/45

3.9

3.3

2.8I\ev* 2.2ncn00

c.>r'0- 1 . 7YL$ 1 . 3

1 . 1-

100;

L10

hNE

1 ool80

60

40Transmitting antenna diameter (km)

F i g u r e 5.- E l e c t r i c i t y c o s t s for 5.8 GHz systems.

1.53-km antenna, 2.4 5 GHz, rectenna outputpower= 5.05 GWantenna, 5.8 GHz, rectenna output2.72 GW

- -km antenna, 2.45 GHz, rectenna outputpower=5 GW-- Power density evel at edge of rectenna

3Radius from rectenna boresight (km)n1

ool Costssingresentantenna thermal limit80

ReferenceI o.75 1 .o 1.25.5

Costs using presentantenna thermal limit

Referencesystem costsP- I o.575 1 .o 1.25.5 a

1 5F i g u r e 6 . - A n t e n n ap a t t e r n s for t h r e e SPS c o n f i g u r a t i o n s .

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IONOSPHERICLIMITATIONS

R e s i s t i v e( o h m i c )h e a t i n ge ff ec ts by t h e power beam may pro du cenonl in-ear i n s t a b i l i t i e s s u c h as e n h a n c e de l e c t r o nh e a t i n g n h e o w e r o n o s p h e r e(D and E r e g i o n s )a n d h e r m a ls e l f - f o c u s i n ge f f e c t s n h eu p p e r o n o s p h e r e(F re gio n) . The Department of Energy (DOE) h a s e c e n t l y p o n s o r e d a numberof i onosp he r i c t ud i e sw h i c h n c l u d e ( 1 ) t h e o r e t i c a l a ndexper imenta lana l -y s e s o f t h e e f f e c t s of u n d er d e ns ehea t ingupon onosphe r i cphys ics ,performedi n p a r t a t t h eA r e c i b b ,P u e r t oR i c o ,o b s e r v a t o r y ; 2 )e x p e r i m e n t a ls t u d i e s b yt h e n s t i t u t e o rT e l e c o m m u n i c a t i o nS c i e n c e s I T S ) n t oh e a t e d o n o s p h e r i ce f f e c t s u p on o w re qu e nc yconnnunica t ionandnaviga t ionsys tems loran, OMEGA,WWV and AM b r o a d c a s t i n gs t a t i o n s ) .Th i s ITSwork i s beingperformedundert h ed i r e c t i o n o fC h a r l e s Rush u s i n g h e P l a t t e v i l l e , C o l o r a d o , h e a t i n gf a c i l i t y .

The r e s u l t s o f t h e e s t sp e r f o r m e d od a t e a t A r e c i b o a n d P l a t t e v i l l eshow o ev id en ce o up po rt 23 mW/cm2 as anupper l i m i t . T h e e l e c t r o n t e m -p e r a t u r e n c r e a s e sd u e ou n d e r d e n s eh e a t i n g are a f a c t o r of 2 o r3 , a t h e rt h a n h eo r d e r of m a g n i t u d ep r e d i c t e d n h ee a r l ya n a l y s e s r e f .4) . Thet h e o r y i s now beingr e vi se d and i n i t i a l r e s u l t s p r e d i c t a l / f 3 h e a t i n g r a t h e rt h a n / f 2 . The l / f 3h e a t i n g w ou ld i n c r e a s e h e power d e n s i t y l i m i t . I n addi-t i o n , h e r e a re no i n d i c a t i o n s of i r r e g u l a r i t i e s b e i n g fo rm ed i n h e o w e ri o n o s p h e r ed u r i n gu n d e r d e n s eh e a t i n g .E f f e c t sprod uced by s imula t e d SP Sh e a t i n g are many times l e s s t h a nn a t u r a l o n o s p h e r i cd i s t u r b a n c e sc r e a t e dby s o l a r l a r e s p r i v a t e c om m un ic ati on r om C . Rush, Dec. 197 9).

An iono spher e power de ns i t y ev e l of50-60 mW/cm2may be a r e a s o n a b l el i m i t andwou ld ccom mod ate t h e 54 mW/cm2 leve lpr od uc ed by th e 1.5-km an ten -na , 5 GW s a t e l l i t e sys tem. More i on os ph e r i c t ud i e sw i t hu p g r a d e d a c i l i t i e sa t A r e c i b oa n dP l a t t e v i l l e op ro d uc e 50-60 mW/cm2 e q u iv al en th e a t i n g e v e l si n h eu p p e r o n o s p h e r e (F r e g i o n )a r en e e d e d o v e r i f y h eh i g h e r l i m i t s .

ATMOSPHERIC L I M I T A T I O N S

T h e e f f i c i e n c y b u d g e t fo r h e 2.45 GHz re fe re n ce c o n f i g u r a t i o nh a s98-pe rcen t ransmiss ion 2 -pe rcen t loss) throughhe tmosphere .This ig-n a la t t e n u a t i o n i s p r i m a r i l ydu e o a i n and tmosphe r ic bsorp t ion .The2 - p e r c e n ta t t e n u a t i o n ,or 130 MW loss, r e p r e s e n t s a badcase butnot hew o r s tp o s s i b l ec o n d i t i o n ) o r h e2 .4 5 GHz fr eq ue nc y. The 5.8 GHz fr eq ue nc yh asapprox ima te ly he same t r a n s m i s s i o ne f f i c i e n c ya sh a s h e2 . 4 5 GHzthrough a nonra inya tmosphe re ,bu t he5. 8 GHz fr eq ue nc y i s s e v e r e l yd e g r a d e du n d e r a i n yc o n d i t i o n s . The l o s s e s o r two s y s t em sprov id ing 5 GW of groundg r i d power may b e um mar izedas ol low s re fs . 5 and 6) :

1 6


22/45

MediumIonosphereN e u t r a la tm o s p h e r ea tm id - U n i t e dS ta t e sl a t i ude(watervaporandoxygena b s o r p t i o n )Ra inHeavy ( 1 5 mmlhr over 15-km p a t h )C e n t r a l /E a s t e r n U.S. - 9 h r / y rSo uth ern U.S. - 3 h r / y rWestern U.S. - 3 h r / y r

Moderate ( 5 mmlhr over 10-km path)C e n t r a l lEa s t e r n U . S . - 4 5 h r / y rSouthern U.S. - 8 5 h r / y rWestern U . S . - 1 0 h r / y r

A t t e n u a t i o n o s s e s2 .4 5 GHz 5.8 GHz0 . 2 5 kW 1 kW90 Mw 1 0 0 Mw

1 4 8 MW

34 Mw

1.8 GW

4 0 5 MW

Wet h a i l 2.6 GW 4 .9 9 GW

The 2 .4 5 GHz f r e q u e n c yh a sv e r ymin i ma l o sses due ton o n id e a lw e a t h e rc o n d i -t i o n s ; h e 5.8 GHz f r e q u e n c yo p e r a t e ss a t i s f a c t o r i l y n h ed r yc l i m a t e so ft h es o u t h w e s t e r nU n i t e dS t a t e sbu t would su f fe ro u t a g e s nw e t t e r r e g i o n s .The impact on a c om mer cia l u t i l i t y g r i d of a 5 .8 GHz m ic ro wa ve ys temt h a t may ha v e o be sh ut down onan unscheduledbas i sbecau se of weatheref-f e c t s i s no t known. I f a 5 .8 GHz mic ro wa ve ys te m i s t ob es e r i o u s l y c o n -s i d e r e da sa na l t e r n a t i v e o a 2 .4 5 GHz sy st em , h ena n n d e p th t u d yo f h i sq u e s t i o n i s r e q u i r e d .

THERMAL LIMITATIONS

S i n c ea n t e n n a h e r m a l a d i a t i o n i s a m a j o r c o n s t r a i n t f o r a 5 .8 GHz s ys -t e m , a n n v e s t i g a t i o n n t o h eu p p e r h e r m a l l i m i t was under taken . The in i-t i a l d e s i g n f o r h e h e r m a l r a d i a t o r s n h e r e f e r e n c e SPS s y s t e m g i v e n nr e f e r e n c e 7 ) was found t o be qu i t ec o n s e r v a t i v e a nd m pro ve me nt s ( i n c r e a s e s )i n h e amountof waste h e a t e j e c t i o n a re p o s s i b l e . T h emajor mprovement i sdue to u s i n g g r a p h i t e c o m p o s i t e m a t e r i a l s w i t h a h i g h e m i s s i v i t y c o a t i n g f o rt h e r a d i a t o r , as w a s proposedseve ra lyea rsa go by Grumman i n h e s y s t e m d e -s i g n f o r c r o s s f i e l d a m p l i f i e r s .

It i s f i r s t n e c e s s a r y o est imate t h e RF l o s s e s a n ddeterminewhere heyo c c u r n a 5 .8 GHz k ly st ro n ub e. A p r e l i m i n a r y es t imate , asprovided by

17


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24/45

of in cr ea se d demands forg e o sy n c h r o n o u ss lo t s by o t he ru s e r s , i t may becomenec ess a ry o edu ce he numberof SPS s a t e l l i t e s . M u l t i p l ea n t e n n a so no n eSPS s a t e l l i t e a re recommended. I t hasbeen shown t h a t SPS anten nas anoper-a t e i nc l o s ep r o x i m i t yw i t hn e g l i g i b l e n t e r f e re n c e r o me a c h0 th er . l Anexampleof a m u l t i p l ea n t e n n asystem wouldbe a 5 km by 20 km s o l a r a r r a y( t w i c e h e s i z e of t h ep r e s e n ts o l a ra r r a y o ro n ean te nna ) eed ing two 5 GWan tennas ,one a t each nd. I t may be dvantageous t o have ouror more anten -nas on a s i n g l e s a t e l l i t e e s p e c i a l l y f a l a r g e ra n t e n n a / s m a l I e rr ec tenna con-f i g u r a t i o no r a hig her req uen cy 5.8 GHz) system i s chosen. The r e l a t i v es i z e s f o r a numbero f a n t e n n a / r e c t e n n ac o n f i g u r a t i o n s a re shown i n f i g u r e 7 .

CONCLUSIONS

The s a t e l l i t e and as so c i a t ed mic rowavesystemhavebeen eoptimizedwithla rg er n t en na s a t 2 .45 GHz), reducedoutput power and sm al le r ec te nna s.F o u r o n s t r a i n t s were cons idered : 1 ) he23 mW/cml io n o s p h er ic l i m i t ,(2 ) a hig her 54 mW/cm2) io n o s p h e ri c l i m i t , ( 3 ) the 23 kW/m2 thermal l i m i ti n h ea n t e n n a , and ( 4 )an mproved hermaldes ign o r he5 .8 GHz sy s te m sa l lowing 33 p e r c e n t d d i t i o n a lw a s t eh e a t . The d i f f e r e n t i a lc o s t s ne l e c -t r i c i t y o rs e v e na n t e n n a / r e c t e n n ac o n f i g u r a t i o n s o p e r a t i n ga t2 . 4 5 GHz andf i v e a t e l l i t e y s t e m so p e r a t i n ga t 5.8 GHz h avebee n alc ulat ed. The con-c l u s i o n sa r e

1. La r g e r n t e n n a / sm a I l e r e c t e n n a o n f i g u r a t i o n s r e c o n o m i c a l l y e a -s i b l eu n d e rc e r t a i nc o n d i t i o n s .2 . Tr a n sm i t t i n g n t e n n ad i a m e t e r s h o u l dpro bab ly be l i m i t e d o 1-1 .5 kmf o r 2.45 GHz ope ra t i on and0.7 5-1 .0 km fo r5. 8 GHz be ca us e of p h a s ec o n t r o l ,

c o n s t r u c t i o nc o s t s , and a t t i t u d ec o n t r o l .

1 G . D . Arndt nd J . W. Sey l : RF I n t e r f e r e n c e / O r b i t a lS p a c i n gA n a l y s i sf o rSo la r Power S a t e l l i t e s . Lyndon B . JohnsonSpaceCenter Houston,Tex.) ,t o b epubl ished.

19


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Single antenna configurations

5 km 2.45 GHz 5.8 GHz

Relativesatellitesize nlom0

Transmitting 1 km 1.36 km 1.53 kmantennadiameter

Relativerectennasize 0 0lOx l3km 7 .6x9 .9km.8x8.8kmGroundpower 5 GW 2.7 GW 5.05 GWoutput

Multiple antenna configurations

Two - 5 GW , 1 kmdia. systems a t2.45 GHz

0

Four - 5.05 GW,1,53 km dia. systemsa t 2.45 GHz

0.75 km 1 km 1.5 km

1 l o x 13 km I 6.8 x 8.8 km

5 . 8 ~.5 km 4.3 x 5.6 km 2.8 x 3.6 km2.72 GW 4.78 GW 2.12 GW

Four - 272 GW, .75 kmdia. systems a t5.8 GHz

I15.8 x 7.5 kmFigure 7.- Relative sizes for several antenna/rectenna configurations.

2 0


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3. Two 2.45 GHz configurations are selected, dependent upon he iono-spheric power density limit.23 mW/cm2 54 mW/cm21 mi 1 mi

Antenna diameter, m . . . . . . . . . . 1.36 1.53Rectenna DC grid power, W . . . . . . . 2.76.05Rectenna diameter, km . . . . . . . . . 7.6 6.8Relative rectenna area, % . . . . . . . 56 46Electricity cost increase, . . . . . . 50.2 17Electricity cost, mills/kWh . . . . . . 70.6 55Electricity cost, c/MJ . . . . . . . . 2.0.5Note: The rectenna areas and electricity costs arein comparisonto those for the reference SPS system.4. The present ionospheric limit of 23 mW/cm2 is too low and should be

raised after the ionospheric heating tests and studies are completed. Be-cause of SPS cost considerations, it is very important to ascertain the trueupper limit5. The 5.8 GHz configurations are constrained by antenna thermal limita-tions rather than ionospheric limits. A reasonable configuration based on a33-percent improvement in waste heat rejection is

Antenna diameter, km . . . . . . . . . . 0.75Rectenna rid, km . . . . . . . . . . . 5.8Relative ectenna rea, % . . . . . . . 33Rectenna DC grid power, GW . . . . . . . 2.72Electricity ost ncrease, % . . . . . . 36Electricityost,ills/kWh . . . . . . 64Electricity cost, c/MJ . . . . . . . . . 1.86. The impact on commercial utility grids of5.8 GHz system that hasto be shut down on an unscheduled basis due to localized weather conditionsshould be investigated.7. Multiple (two to four) antennas on a single solar satellite are def-initely recommended regardless ofhe particular antenna/rectenna configura-tion chosen. This is a means of maintaining he same amount of power suppliedto the ground while reducing the number of geosynchronous slots (spacings)

required for the satellites.Lyndon B. Johnson Space CenterNational Aeronautics nd Space AdministrationHouston, Texas, December , 1980986-15-89-00-72

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REFERENCES

1 . S a t e l l i t e PowerSystem:ConceptDevelopment ndEvaluationProgram,Ref-erenceSystemR eport . NASA TM-79762, 19 79 .

2. Li n d se y , W. C .: A S o l a r P ow er S a t e l l i t eT r a n s m i s s i o nS y s t e m n c o r p o r a t i n gAutomaticBeamforming, St ee rin g ndP h a s eControl . Rep.TR-7806-0977,LinCom C or p. C on tr ac t NAS 9-152371, Ju ne1978.3. S o l a r Power S a t e l l i t e S y s te mD e f i n i t i o nS t u d y - P h a se 11. Volume I1 -ReferenceSys temDescr ip t ion .B o e i n gAerospace Co. (Co n t r a c t

NAS 9-15 63 6) . NASA CR-160443, 19 79 .4.Duncan, L e w i s M . ; andGordon,Will iam E . : Ionospher i c Power B e a m S t u d i e s .

P a p e rp resen ted a t SPS Workshop onMicrowavePower Transmissiona ndRecept ion Houston,Tex.) , an . 5-18, 980.5.Gordon, William E . ; andDuncan, L e w i s M .: Ionosphere/Microwave Beam In-

t e r a c t i o nS t u d y ,F i n a lR e p o r t .R i c eU ni ve rs i t y C on tr ac t NAS 9-15212).NASA CR-151821, 1978.

6 .P a r k , K. Y. : A t t e n u a t i o no f S-Band, X-Band, and Ku-Band S i g n a l s n aOne-way an d Two-way E a rt h -t o -S a te ll i teL i n k . Rep. ASAO-PR20079-9,Magnavox Governmenta n d I n d u s t r i a l E l e c t r o n i c s C o . ,Feb.1979.

7 . S o l a r Power S a t e l l i t e S y s t e mD e f i n i t i o nS t u d y - P a r t 11. Volume I V -MicrowavePower TransmissionSys tems .Boe ingAerospace Co. (C on tra ctNA S 9-15196). NASA (33-151668, 1977.

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APPENDIX A

ANTENNA TAPERS

The antenna illumination taper for the reference SPS system was optimizedto provide maximum rectenna collection efficiency while minimizing sidelobelevels. Previous simulation results for a 1-km antenna indicated that a 10-dBGaussian taper maximized the rectenna collection efficiency in the5-90 per-cent range while satisfying the antenna thermal constraints. These data,taken for an antenna operating with the specified error parametersi.e.,(5 = loo phase error, kO.1 dB amplitude error, and percent tube failures)yield an 88-percent collection efficiency over approximately a 10m diameterrectenna. This appendix addresses the question of whether other tapers wouldbe more efficient with larger antennas.

The results are given in figure A-1 for a 1-km antenna operating with nerrors and a 2-km antenna transmitting with the specified error parameters.As the amount of taper increases, the main beam peak intensity decreases andthe beam width increases. There is more power in the main beam and less powerin the near sidelobes. This condition increases the rectenna collection ef-ficiency. Both systems achieve good performance, with rectenna collectionefficiency in the 85-90 percent range using a 10-dB taper. ll the SPS con-figurations in this report have a 10-dB taper.

A-1


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APPENDIX B

EXAMPLE CALCULATIONS

The purpose of this appendix iso review the assumptions, methods,ndsteps by which cost and mass were calculated for variousPS configurations.The rationale is explained n the body of the text. The Boeing-JSC referencedesign cost and mass numbers were used as the basis for all comparative calations in this study. Where applicable, these numbers are included as case.Study assumptions are defined n table B-1, and cost and mass (C/M) factorsare included in table B-2. The factors referred to n table B-1 are definedin table B-2. They were used to estimate new costs and masses for the varioualternative configurations.

Factor values are presented in table-3. In case A , the satellite RFpower output is 1.68 GW. Factor 1 is calculated by dividing this number by6.5 GW, as explained in table B-2. The resulting value of factor 1 is 0.258.The antenna diameter in case is 0.5 km. Therefore, factor 2 is calculated( 0 . 5 ) 2 / ( 1 ) 2 = 0.25. The reference rectenna diameter (case) excluding thebuffer zone is 10 km. In case A , the rectenna diameter is 8.75 km. Factor 3is then given by 8.75)2/ (1012 = 0.76. Factor 4 is the relative land areaincluding the buffer zone out to 0 .1 mW/cmZ. For case A , major and minor di-ameters are found in table -4 (12.9 km and 9.2 km). Factor 4 is thus calcu-lated 71 (12 .9 ) 9 .2 ) i (158.3) = 0.589. The buffer zone area for the refer-ence configuration is given in table B-5. Before factor can be calculated,the total mass of the transmitting antenna in question must be estimated.Factor 6 is required for maintenance system mass. It is determined by ex-tracting the s uare root of factor 2. In this case factor 2 was 0.25, sofactor 6 is P-.25 = 0.5.

Factors 7 , 8 , 9 , and 10 are simple calculations based on factors, 2 ,and 3 . Factor 11 is used for calculating LLV costs as a portion of factor 13.In the reference case,208 launches are required 94 for solar power systems,46 for the transmitting antenna, and 8 for other purposes. Factors 1 and 2are used in scaling factor11 for HLLV costs, as is shown in table B-2. Be-cause of the simplicity of factors2-16, a detailed explanation of their cal-culation is not necessary (see table- 2 ) .In table B-5, the values for reference system mass and cost are listedin the last two columns. The first two columns (case F) are derived by mul-tiplying the last two columns, respectively, by the appropriate factor valuefrom table B-3. The mass of the power collection structure, for example, isfound by multiplying 654 X 0.543 = 2527. In this manner, values are foundfor all costs and masses until antenna mechanical pointing is reached. Thisrequires the use of factor , which has not been determined. o overcomethis obstacle, the mass for mechanical pointing is assumed to be the sameas the reference. Using this value, an interim total power transmission massis found. Factor 5 is determined using this mass, and new mechanical point-ing value is calculated using the factorvalue. Then a more accurate powertransmission mass is totaled.

B- 1


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A s can be calculated from the firstass column in table B-5, the sub-total of all power ransmission masses except that for mechanical pointingis 12 679 t. Adding 134 t to this from the Last mass column (reference case)results in 12 813 t for the interim total. The power transmission mass totalfor the reference case is 3 628 t. From the definitionin table B-2, fac-tor 5 (for case F) turns out to be

(12 813) x (1.36)2/(13 628)(1)2 = 1.74

This value of factor is then used to determine new value for the mechani-cal pointing mass: 134 x 1.74 = 233 t. The power transmission mass may thenbe retotaled to provide 12 12 t for the 1.36-km case.The equations presented as factor 17 are used to determine the cost electricity in mills per wh. For a 15-percent rate of return R ) over a30-year period (y), the equation

produces 152.3 as a constant multiplying factor. In the denominator of theequation for 2.45 GHz, the hours per year of operation with92-percentplant factor were 8050. Because of brownout during rainstorms at 5.8Hz,the plant factor was reduced to0 percent, resulting in 7875 annual hoursof operation. Using these constants, system cost, and plant capacity for2.45 and 5.8 GHz cases, the cost of electricity was calculated for eachscenario. Results are presented in table B-6. For case A , in which powerdelivered is 1.17 GW and total system ost is $8368 million, factor 7 resultsin a cost of

(152*3) 8368) = 138 mills/kWh = 3.8c/MJ(7875) (1.17)

In each instance, factors are usedo determine the amount of variationfrom the reference case. Tables B-4 and B-5 present the results obtainedafter applying the equations and factors as described above. Totals for thevarious satellite configurations are listed in table-6.

B- 2


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TABLE B-1.- STUDY ASSUMPTIONS

1. Each scenario will have the same total electrical capacity10 GW)installed per year.2. For the following subsystems of the solar power collection system, costand mass (C/M) vary linearly ith power (factor ).

a StructureSolar cellsa Power distributionMaintenance

3 . The cost and mass of the rotary joint are related to antenna mass anddiameter squared (factor ).4 . Cost and mass of the following subsystems of the microwave power

transmission system vary as indicated.Structure - C/M vary linearly with area (factor)Klystrons and thermal control C/M vary linearly with power

a Waveguides - C/M vary linearly with area (factor)Subarray structure C/M vary linearly with area (factor)(factor 1 )

a Power distribution- Conductors - C/M vary linearly with area and power (factor)- Switchgears, DC-DC converters, thermal control C/M vary

linearly with power (factor )a Energy storage - remains constantPhase control - C/M vary linearly with area (factor)a Maintenance systems - C/M vary with square rootf antenna areaa Antenna mechanical pointing C/M vary linearly with factor(factor 6 )

5 . The information management and control systems have cost and mass varia-tions as follows.a Mass varies with antenna area (factor) .a Cost varies with square root of antenna area (factor) .

6. The cost and mass of the attitude control system vary linearly withfactor 5.7. Communication systems remain constant.8. The mass growth allowance forhe satellite remains constant at2 per-cent of the total satellite mass.

B- 3


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9,

10.

11.

12.

1 3 .

TABLE B-1.- Concluded

The cost of the rectenna is dependent upon the following items:Buffer zone out to 0.1 mW/cm2 - factor 4Structure and installation varies with rectenna area (factor)Ground plane and RF assemblies - vary with rectenna area(factor 3); RF assemblies also vary with frequency squaredDistribution buses vary with rectenna area and power accordingto factor 8Command and control center remains constantPower processing and grid interface varies with square root ofpower (factor 7 )

The amortization of satellite investment costs varies with power(factor 1 ) .The costs of the transportation system for personnel and materials aredivided into four categories:

EOTV - varies with power (factor )PLV - varies with power (factor 1) and antenna diameter0 POTV - varies with power (factor ) and antenna diameterHLLV - varies with power nd antenna area according o factor 11

Program management nd integration requires10 percent of the hardwarecosts.The construction operation costs for the satellite are divided into lEarth orbit staging costs and geosynchronous orbit construction costs.

LEO - varies with square root of power (factor )GEO - varies with square root f power and the transmitter areaaccording to factor 10

B-4


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TABLE B-2.- COST AND MASS FACTOR DEFINITIONS

1. Power/reference power

2. Antenna area/reference area3. Rectenna area/reference area4. Rectenna buffex area outo 0.1 mW/cm2/reference buffer area5. Antenna mass X diameter2/reference antenna diameter26. Square root of antenna area (factor )7. Square root of power (factor 1)8. Rectenna area (factor 3) X power (factor 1)9. Antenna area (factor2) X power (factor 1)10. Construction operation costs 0.5 x square root of factor 1+ 0.5 X factor 2

12. End-to-end microwave power transmission efficiency at 5.8Hz13. Satellite material and personnel transportation costs ( $ 1

0 EOTV = $652 million X factor 10 PLV = $286 million X factor 1 X antenna diameter0 POTV = $14 million X factor 1 X antenna diameter0 HLLV = $2167 million factor 11

14. Amortization of investment = $473 million X factor 115. Program management and integration expenses 10% of hardware costs16. Construction costs ($1, for 2.45 GHz operating frequency

0 LEO = $313 million factor 70 GEO = $648 million x factor 10

For 5.8 GHz operating frequency0 LEO = $344 million X factor 70 GEO = $713 million factor 10

B- 5


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1 7 . E l e c t r i c i t yc o s t s n m i l l s p e r kwh

152.3 X s y s t e m c o s t ($10 )7875 X p l a n tc a p a c i t y (GW)

F~~ 5.8 GHz = ..........................

B-6


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.TABLE B -3 . - PREDEFINED COST AND ASS FACTOHS FOR ANTENNA/HECTENNA CONFIGUKA'I'IONS

Microwave characteristic Satellite configurationE G HB C D I J K L

...__2.45 2.45

26. 5.5

Transmitting frequency. GHz . . .Antenna diameter. km . . . . .Satell ite power output. GW . . . .Power density at rectenna.mWlcm2 . . . . . . . . . . . . .Rectenna diameter. km . .Power delivered. GW . . . . . . .Power delivered per ! a 2 ofland. kW/kmZ . . . . . . . . . .Factor

1 . . . . . . . . . . . . . . .2 . . . . . . . . . . . . . . .3 . . . . . . . . . . . . . . .4 . . . . . . . . . . . . . . .5 . . . . . . . . . . . . . . .6 . . . . . . . . . . . . . . .7 . . . . . . . . . . . . . . .8 . . . . . . . . . . . . . . .9 . . . . . . . . . . . . . . .

10 . . . . . . . . . . . . . . .11 . . . . . . . . . . . . . . .12 . . . . . . . . . . . . . . .

5.80 .5

1.68

5.80.753.78

5.81.06. 5

5. 81.5

2.88

5.8 2.45 2.45 2.450.75 1.36 1.53 22.84 3.53 2.78 1 .64

2.451.366.5

2.451.535.5

7 .878.751.17

4 05. 8

2.72

12 24 .34 .8

1292.8

2.12

30 23 23 235.8 7.6 6. 8 5

2 2.7 2 . 1 1.26

4 27. 6

5

546. 8

5.05

91350

5.05 5

12.5 53.6 67.9 65.8 39.8 30.3 29.9 30.9 53.6 67.5 110.6 31.6

0 .2580.250 .76

0 .5890.07

0. 50 .5080.196

0 .06450 .378

0 .50 .698

0 . 5 8 10.5620.3360 .320

0 . 3 30 .75

0 .7620 .1950 .3260 .662

0 . 7 20 .720

11

0 .1850.445

I1I

0 .185II1

0 . 7 3 5

0 .4432.25

0.0780 .203

2.361.5

0.6660 . 0 3 4

11.461.03

0.735

0.4360 .5620.3360 . 3 2 00.278

0.750 .6600.1460 . 2 4 50.611

0 .650 .713

0 .5431.850 .58

0 .562I . 41.36

0.7360 .314

1I . 90 .98

-_

0.4272.34

0 .4620 .445

2 .341.53

0 . 6 5 30 .197

11.49

1.037"

0 .2524. 0

0 .250.258

5.42. 0

0 .500 .063

12.25

1.325"

11.850.58

0 .5892.321.36

I

0.581.851.421.19"

I 14. 0 1

0 .25 10.286 1

7. 7 12. 0 1

1 10 .25 1

4 .0 12. 5 1

1.66 1" "

12.34

0 .4620 .468

3 . 31.53

10 .462

2.341.671 .30"

B- 7


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TABLE B-4.- COST AND MASS STATEMENTS FOR 5. 8 G H ~ YSTEMS

Component A B C(0.5 km, D(0.75 km, E1 . 6 8 GW) 3 . 7 8 GW ) ( 1 km, (1. 5 km, (0. 75 km,6. 5 G W ) 2.88 GW)Mass, t C o s t , $ Mass, t C o s t , $ Mass, t C o s t , $ Mass, t C o s t , $ c o s t , $2.84 GW)

P o w e r c o l l e c t i o n( 1 )S t r u c t u r e( 1 )S o l a r e l l s( 1 ) Po wer d i s t r i b u t i o n(1 )M a in t e n a n c e

T o t a l 7 13 778 36741762 2 7 66 630322561343 a1321( 5 )o t a r y 1 7 7 78 3436025741 28Power ransmiss ion( 2 ) S t r u c t u r e1 7( 1 )l y s t r o n sn dh e r m a lo n t r o l 1 80 8 12 3( 2 ) Waveguides01( 2 ) S u b a r r a yt r u c tu r e 3 1 40

P o w e r d i s t r i b u t i o n( 9 )o n d u c to r s 1( 1 )w i t c h g e a r s , DC-DC c o n v e r t e r s , 4 8 28E n e r g y t o r a g e 31 3( 2 ) P h a s e o n t r o l 5 23

(6 )M a in t e n a n c e y s t e m s 11552( 5 )A n te n n am e c h a n i c a lp o in t i n g 14 1

t h e r m a l o n t r o l

182 154 071 2 7 71 57620

70 558116 6

1 08675313 5

10166 717 378

324 267 00 7772 80 4131 25481

31 3 523 0 504200 21

180

7293 104 21 15 96 309792 8 22 63 2

35 6 1882 8 13 331 3 534 5 756

41 20 347 1 50

1 512 020 815 8

476

551

637 8

Informat ionmanagementan dcontrolComputers - ( 2 ) Mass (6)ost 1 15 3 23.50. 707C a b l i n g - ( 2 ) Mass (6)o s t3 9 51 131. 17. 3056 1 731

A t t i t u d e o n t r o l(5 ) 1 7 5 20440( 5 )P r o p e l l a n t 48 1668 670 3 0 11 4 0 25 9 0 0

a T h e s ec o s t o t a l sh a v eb e e nadjus ted by 0 .85/0 .80 = 1 . 0 6 oa c c o u n t o r e d u c e dk l y s t r o n DC-RF c o n v e r s i o ne f f i c i e n c y .


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TABLE H-4.- Continued

(a) Concluded

Canponent~ ~~

A B C D( 0 . 5 km, (0.75 km,1.68 GW) 3.78 GW) 6.5 GW)E( 1 km, (1.5 km, (0.75 km,2.8 8 GW 2.84 GW)Mass,ost, $ Mass,ost, $ Mass, t Cost, $ Mass, tost, $ c o s t , $

CamnunicationsMass growth (22% of t o t a l

s a t e l l i t e m a ss )S a t e l l i t e o t a l

Transportation(13) EOTV

PLVPOTVHLLV

TotalConstruction operations

(16) LE OGEO

0.2 x lo 62435 -

13 506452

16 837210811288

17 5269

0. 2 8 x 1065 93 -

2905038

379125615602070

262472

0. 2 8 x 106940 -

5195366

6522861421673120

344713

0.2 8 x lo 6601 -

3597171

289190923322720

8 x lo 6-2494

28494514091794

229 22 7104136Total 444 734 105727063

Missioncontrol 10 1 0 1000


39/45

TABLEB-4 .- Concluded(b )e c t e n n a

Canponent A B C D E(0 .5 km, (0 .75 km, ( 1 km, (1 .5 km,1.68 GW ) 3.78 GW) (0.75 km,6.5 GW) 2.88 GW) 2.84 GW)

C o s t ,m i l l i o nd o l l a r s( 4 )L a n d . . . . . . . . . . . . . . . . . . . . .( 3 )S t r u c t u r e n d n s t a l l a t i o n . . . . . . . . . .( 8 )D i s t r i b u t i o nb u s e s . . . . . . . . . . . . . .Ccmunand and ontrol enter . . . . . . . . . . . .( 7 ) o w e r r o c e s s i n g n d r i d n t e r f a c e . . . . .

T o t a l . . . . . . . . . . . . . . .(3)Gro u n dplane nd RF asse mbl i es . . . . . . . .

L a n d e q u i r e do u t o0 .1 mW/cm2,m2 . . . . . . . .w R e c t e n n ai a m e t e r , km . . . . . . . . . . . . . . .I B u f fe ri a m e t e ru to. 1 mW/cm2I"L0 ( m i n o r x i s ) , km . . . . . . . . . . . . . . . . .B u f f e rd i a m e t e ro u t o0 . 1 mW/cm2

( m a j o rx i s ) , km . . . . . . . . . . . . . . . . .

5726 340816070394

492593.28.75

9 . 212.9

3111 61804607059 1267250.75. 8

6 . 89 . 5

446499 3577077 5

200370.44 . 3

811.2

202741 9117051 6

106332.22.8

5 .47.6

3111 618044570

512257850.75. 8

6. 89. 5


40/45

TABLE 8 -5 . - COST AND MASS STATEMENTS FO R 2 .45 GHz SYSTEMS

(a) SPS

Canponent F G H I J K L( 1 . 3 6 km, ( 1 . 5 3 km, ( 2 km, ( 1 . 3 6 km, ( 1 . 5 3 km, ( 2 km,

3 . 5 3 C W ) 2 . 7 8 GW) 1 .64 C W ) 6 . 5 G W ) 6. 5 G W ) 6 . 5 G W ) 6 . 5 G W )( 1 km,

Mass,os t , Mass,ost,ass,ost,ass,ost,ass,ost,ass,ost, Mass, Cost ,t $Ma t SM t SM t SM t SM t SM t SM

Power co l lect ion(1) S t r u c t u r e(1) S o l a rc e l l s(1 ) Power d i s t r ibu t ion( 1 ) Maintenance

T o t a l( 5 ) R o t a ry o i n tPower transmission

( 2 ) S t r u c t u r e(1) Klys t rons nd hermal( 2 ) Waveguides

c o n t r o l( 2 ) S u b ar r ay t r u c t u r e

Power d i s t r ibu t ion( 9 ) Conductors(1 )Swi tchgears ,

tdIPP

DC-DC co n v e r t e r s ,thermal ont ro l

Energy torage( 2 ) Phase ont ro l( 6 ) Maintenance ystems( 5 ) Antennamechanical

p o i n t i n gT o t a l

Information management ndc o n t r o l s

Computers - ( 2 ) Mass( 6 ) Cost

Cabl ing - ( 2 ) Mass( 6 ) Cost

11 4 8 12 5276 1 733 7

1 5 0 2 34 2 0

60 03 8054 3231 93 3

35 61 0 1 4

31 331 323 3

12 912

22 .2

816 9

24 31079

8114 9

1 5 5 318 1

4 825 932 94 3 3

1816 3

56 85

22 .224

1986

4 224

9 0291 98 7

53 226 511 813

55 3

7 582 9925 4 6 92 4 4 5

35 679 8

31 335 2

2831 4

13 25

1021 3

19 284 9

641 1 7

1 2 2 123 8

6120 441 754 8

1812 9

57 7 1

2833

2214

4726

1 17 35 329

31 415 6

6 9721 27 3

1 2961 76 69 3484 180

35 64 7 1

31 34 6 0

4 87 2 2

18 96 0

1836 4

11 350 1

3869

7 2 15 50

10 412 07 1 293 6

1876

548

100875

3102

6135

4 6542 1 14 51 24 6

62 127 666

547

60 07 00 74 323I 93 3

1 86 955 9

31 322

31 031 3

17 250

816 9

4 4 81988

15 02 742860

23 7

4 847 732 94 3 3

3330 1

56 8 5

2232

2364

4224

4 65421 1451 24 6

62 121 666

7 78

15 87 0 075 4 6 92 445

83 31 86 9

31 335 2

2044 2

1 9 51 6

1021 3

4 4 8I 9 8 8

15 021 4

286033 6

6 14 1 741 754 8

30 14 2

57 7128

462658

4 126

4 654 4 4 821 14 5 19881 24 6 15 06 2 1 2 1 4

21 66 28601 81 785

1 29 6047 00 1 4 1 19 348124 180361 42 421 86 901

313 54 6 0 1 0 0 8

4 8 4 81 0 3 2 1 0 8

2 1 3 8 3 7 7 1

18136 45

4 65421 145I 24 6

62 121 66

23 6

7 00132 4

2 3311 0 4 5

35 61 86 9

31 323 0

1213 4

1 3 2 8

4 4 81988

15 027 4

286010 2

41 726

17 823 4

30 118

550 4

1214

1769

4. 5 3 0 . 191 .1 1 7 . 3

-a$M = m i l l i o n d o l l a r s .


41/45

TABLE 8-5.-Continued

(a )oncluded

Component F G H I J K L(1 .36 km,3. 53 GW) (1 . 5 3 km, ( 2 km, (1.36 km, (1 . 5 3 km, (2 km,2.78W).64 GW) 6.5 GW) 6.5 GW) 6.5 G W ) ( 1 km,6.5 GW)

Mass,ost ,ass,ost ,ass,ost ,ass,ost ,ass,ost ,ass,ost ,ass,ost ,t SM t SM t S M t SM t SM t SM t SM

A t t i t u d e o n t r o l(5 )Hardware( 5 )P ro p e l l a n t 236781874340015714928 13 5 0 177 - 411 177 - 25 1 - 586 76.1 0-Camnunications . 2 8 . 2 a . 2 a . 2 a . 2 a . 2 8 .2 8Massrowth22% of t o t a l 658 - 52021s a t e l l i t e m a s s ) 104905427846 -

w S a t e l l i t eo t a lIPh) Tra n s p o r t a t i o n(13) EOTVPLVPOTV

HLLVTo t a lC o n s t ru c t i o n o p e ra t i o n s

(16) LEOG E OTo t a l

3478 164522187 14410 192125247871 25792700

6525252 42872 2861421673120

389 21 282721186639918 3597817

2300457 a366620 1458 313 3131066170615233 648

M i s s i o n 0 10 10000


42/45


( b ) Rectenna

Canponent F G H I J K L(1.36 km, (1.53 km, (2m, (1.36 km, (1.53 km, (2 km,3.53W).78W).64W) 6.5 GW) (1 km,6.5W).5W).5W)

Cost, million dollars

. . . . . . . . . . . . .(3) Structure and(4) Land(3) Ground plane andinstallation

(8) Distribution busesRF assembliesCommand and control center . . .(7) Power processing and gridinterface . . . . . . . . . . .

. . . . . . . . . .. . . . . . . . .. . . . . .. . . . . . . . . . .w

P

TotalI Land equired ut o .1 W/cm2,w km2 . . . . . . . . . . . . . . .

Rectenna diameter, km . . . . . . .Buffer diameter out to 0.1 mW/cm2(minor axis), km . . . . . . . . .Buffer diameter out to .1 mW/cm2(major axis), km . . . . . . . . .

61205567097

53 30 71 56 120346959

3486.560 86.5 201 160

4461705061293

2402070388835

556179707151852

443142707751646

24077707751283

30870775

25785701561

89.017.6

70.336.8

40.885

93.27.6

74.066.8

45.25

158.310

128 6.1 9.2 8.2 6.4

12.6 11.2 8.54 12.9 11.5 9.0 16.8


43/45

TABLE 8-6.- COST SUMMARY

(a) Physical parameters

MicrowaveharacteristicA B C D E F G H I J K L

Frequency,GHz . . . . . . . . . . . . . 5.8 5.8.8.8.8.45.45.45.45.45.45.45Antenna diameter,km . . . . . . . . . . 0.5 0.75 I o 1.5.75.36.53 2 1.36.53 2 1Satellite power output,GW . . . . . . 1.68.78.5.88.84.53.78.64.5 6.5.5.5

( b ) Costs

CostategoryA B D E F G H I J K L

SPS ardware, illion ollars . . . . . 1452 038Less amortizationof invest-ment (see factor 14), milli ondollars . . . . . . . . . . . . . . . 122 75Total, million o11ars . . . . . . . . . 1330 2763Mission ontrol, illion ollars . . . . 10 10Transportation, million ollars . . . . 1288 070Construction operations,million ollars . . . . . . . . . . . 444 734Rectenna, million ollars . . . . . . . 4925 672Progra m management and in-

tegration (see fact or15),million dollars . . . . . . . . . . . 145 03Cost allowance or massgrowth, million ollars . . . . . , . 226 470Total, million ollars . . . . . . . . . 8368 022Mills per kwh (see factor 17 ) . . . . . 138 64Cents per J . . . . . . . . . . . . . . 3.8 1.8Z increase in electricity costscompared to c ost of 1.3c/MJ(47 mills/kWh) for thereference PS ystem . . . . . . . . . 193 36

5366 4777 2494072 4120 5069 5898 6455 8112 4946

47348910

3120

209456810

2720

206 2572288 381510 10

1794 2700

2023918

102721

473542510

3639

1194950

103186

4735982

103918

473763910

4849

474473

103120

10572003

12701063

663 10662578 1561

11701293

1615835

12331852

13951646

19331283

9612578

536 477 24 407 41 2 507 590 645 811 495

83212 45150.3

I .4

77710 885

992.7

389 6497969 10 24376.1 71.62.1 2.0

66610 19090.62.5

84I1 944180.15.0

92213 671

521.4

101714 613

551.5

129917 82467.11.9

76012 432

471.3

7 11 1 62 52.4 92.7 283 10.6 17 42.7


44/45

~~

1. 2. Government Accession No. 3. Recipient's Catalog No.~.

I SOLAR POWER SATELLITE SYSTEM SIZING TRADEOFFS 1 ~~ ~~8. Performing Organization Report No ."G. D. Arndt and L. . Monford

9. Performing Organization Na me and AddressLyndon E. Johnson Space CenterHouston, Texas 7 7 0 5 8

12. Sponsoring Agency Name and AddressNational Aeronautics and Space AdministrationWashington, D.C. 20546

10. Work Unit No.

13. Type of Report and Period CoveredTechnical PaDer

14. Sponsoring Ag mcy code

15. Supplementary Notes

16. AbstractThe present reference configuration for a solar power satellite system providof electrical power at the ground using akm diameter antenna transmitting at 2.45 GHzand a 10 km diameter receiving antenna (rectenna). This paper considers technical andeconomic tradeoffs of smaller solar power satellite systems configured with larger antereduced output power, and smaller rectennas. These systems are reoptimized by changing tguidelines of the sizing studies; that is, the ionospheric power density limit, thefrequency, and the antenna thermal limit.The differential costs in electricity for seven antennalrectenna configurations operaat 2.45 GHz and five satellite systems operating at 5.8 GHz are calculated. Two 2.45 configurations dependent upon the ionospheric power density limit are chosen as exIf the ionospheric limit could he increased to 54 mW/cm2 from the present 23 mWa 1.53 km antenna satellite operating at 2.45 GHz would provide 5.05 GW of output pfrom a6.8 km diameter rectenna. This system gives a 54-percent reduction in rectenna relative to the reference solar power satellite system at a modest 17-percent increaelectricity costs. At 5 .8 GHz, a .75-km antenna providing 2.72 GW of power from a.8 kmdiameter rectenna is selected for analysis. This configuration would have a 67-percenduction in rectenna area at a 36-percent increase in electricity costs. Ionospheric,mospheric, and thermal limitations are discussed. Antenna patterns for three configuratito show the relative main beam and sidelobe characteristics are included. Multiple asatellites can effectively reduce the number of geosynchronous slots (spacings) requfor the solar power satellites.

17.Ke y Words Suggested byAuthor(s) ) 18 . DistributionStatement ISolarowerenerationicrowave Unclassified - UnlimitedEnergy conversion transmissionefficiency Phase errorAntenna design Cost analysisIonospheric heating Subject Category 4419. Security Cla nif. (of this report )

A034nclassifiednclassified22.Rice '21.O. of Pages0. Security Classif. (o f this page)

'For sale by the Nation al Technical In for ma tion Service, Springfield, Virginia 22 16 1 NASA-Langl ey , 1981


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