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#### APPENDIX B

LUNAR SSPS POWER

Geosynchronous orbit is 35,400 km above the Earth, while Ll (the
location of SSPSs used for lunar power) is 64,400 km above the near side
of the Moon. Thus, if lunar SSPSs are identical to terrestrial SSPSs, the
microwave beam covers about twice as much area on the surface of the Moon
as compared to Earth. Changing the wavelength can reduce beam spread but
results in a loss in the (dc-to-dc) efficiency of the system. Terrestrial
SSPSs are assumed to transmit at a 10 cm wavelength with 67 percent
efficiency. Using information provided by Glaser et.al.
(ref. 4), the relationship between microwave efficiency and
beamwidth leads to a lunar
system with a wavelength of 3 cm, a 30 percent efficiency, and using a
rectenna area of 27 km^2

For the lunar system the rectenna is made up of 3,000 dipoles/m^2 and
weighs 5 kg/m^2. All is produced on the Moon except gallium arsenide for
the diodes and possibly some dielectric materials and glues which need to
be brought up from Earth, amounting to about 0.6 kg/m^2.

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