System for transmitting power from a solar satellite to earth and subsequent conversion to a 60 Hertz three phase signal

• US 4,408,206 A
• Filed: 12/21/1979
• Issued: 10/04/1983
• Est. Priority Date: 12/21/1979
• Status: Expired due to Term

• Current Assignee: The Boeing Co.
• Original Assignee: The Boeing Co.
• Inventors: Spencer, Donald B., Fitch, John L.
• Primary Examiner(s): Blum, Theodore M.
• Application Number:
  US06/106,099
• Time in Patent Office: 1,383 Days
• Field of Search: 343/100 PE, 343/DIG. 2, 343/100 ST, 136/292
• US Class Current: 342/352
• CPC Class Codes: H02J 50/27 characterised by the type of receiving antennas, e.g. rectennas
• CPC Class Codes: H04B 7/185 Space-based or airborne stations; Stations for satellite systemsH04B7/204 takes precedence
• CPC Class Codes: Y10S 136/292 Space - satellite

Abstract

Electrical power at microwave frequencies produced by solar cells or similar devices on satellite stations in space is phase modulated prior to its being beamed to earth. At the receiving station on earth, the power in the beamed signal is recovered at the modulation frequency. In the first embodiment, the microwave signal from the power originating device drives a circularly polarized antenna; the modulation is achieved by reversing the phase of the drive signals so that the polarization of the propagated wave alternates between right hand and left hand polarization at a 360 Hertz rate. On earth, the detected outputs of the receiving antennas are combined in such a manner to produce a 60 Hertz three phase power signal. In the second embodiment, the microwave signal drives two orthogonal, linearly polarized antennas; the modulation is achieved by gradually changing the phase of the microwave drive signals so that the polarization of the propagated wave rotates at a 60 Hertz rate. On earth, the detected outputs of three linear antennas, spaced at 120° angular intervals, are summed to produce a 60 Hertz three phase power signal.

Claims

1. A system for transmission of power which is in the form of continuous-wave microwave-frequency electrical signal energy, comprising:

first antenna means configured and arranged to transmit the microwave signal with a given polarization;

means for driving said first antenna means with a microwave signal in such a manner that the polarization of the transmitted microwave signal changes regularly with time throughout the transmission of the microwave signal, in a predetermined manner, at a selected rate which is substantially less than the frequency of the microwave signal;

second antenna means for receiving the transmitted microwave signal;

means associated with said second antenna means for recovering the power in the transmitted microwave signal received by said second antenna means; and

means responsive to said recovering means for converting the recovered microwave signal into a three phase signal at a power frequency, the resulting signal being suitable for use as a power signal.

3. The system of claim 1, wherein the power frequency is 60 Hertz.

4. The system of claim 1, wherein said generating means, said first antenna means, and said driving means are located on a satellite in space, and said second antenna means and said recovering means are located on earth.

5. The system of claim 1, wherein the transmitted signal wave is a continuous wave.

6. The system of claim 1, wherein said first antenna means comprises two orthogonal dipoles capable of circular polarization.

7. The system of claim 6, wherein the first antenna means is circularly polarized, so that the polarization of the transmitted signal wave rotates at the frequency of the microwave power signal, and wherein said driving means includes means for alternating the polarization of the transmitted signal wave between left hand and right hand circular polarization.

8. The system of claim 7, wherein said first antenna means includes left hand and right hand ports and wherein said means for alternating includes two circuit branches, each responsive to the mircowave signal, one circuit branch including a 180°

phase shifter and switching means for switching said phase shifter into and out of said first circuit branch, and means for applying the output signals from said first and second circuit branches alternately to said left hand and right hand ports of said first antenna means.

9. The system of claim 8, wherein said second antenna means includes two orthogonal dipoles, and wherein said recovering means includes detector means associated with each dipole, and a summing and switching means responsive to the outputs of said detector means for producing three alternating current waveforms at the power frequency, each waveform being separated in phase by 120°

.

10. The system of claim 9, wherein the selected frequency is 360 Hertz and the power frequency is 60 Hertz.

11. The system of claim 6, wherein said first antenna means comprises two orthogonal radiating elements, each of which is linearly polarized, and wherein said driving means includes means for changing the phase of the signal provided to each radiating element in such a manner that the polarization of the transmitted signal wave rotates at the selected frequency.

12. The system of claim 11, wherein said driving means includes two circuit branches, each responsive to the microwave power signal, each branch including a phase shifter, the phase shifter in one circuit branch gradually changing the phase of the signal in that circuit branch in one direction and the phase shifter in the other branch gradually changing the phase of the signal in that branch in the other direction, said driving means including means for applying the outputs of the first and second circuit branches to said two radiating elements of said first antenna means.

13. A system of claim 12, wherein said second antenna means includes three dipoles spaced at equal angular intervals relative to each other, and said converting means includes diode means associated with each dipole and a switch connected to each diode means, each diode means including a parallel connection of two diodes in opposite polarity, the switch connecting each diode in the diode means alternately to an output line, wherein the signal produced on the output line is an alternating current waveform at the power frequency, with the waveforms from the three diode means being at 120°

angular intervals.

2. The system of FIG. 1, wherein said first and second antenna means move related to each other in operation of the system.

14. A method for transmitting power which is in the form of continuous-wave microwave-frequency electrical signal energy, comprising the steps of:

transmitting the microwave signal with a polarization that changes regularly with time throughout the transmission of the microwave signal, in a predetermined manner, at a selected rate which is substantially less than the frequency of the microwave signal;

receiving the transmitted microwave signal;

recovering the power from the received microwave signal; and

converting the recovered microwave signal into a three phase signal at a power frequency, the resulting signal being suitable for use as a power signal.

15. The method of claim 14, wherein the source of the transmitted electrical signal is a converter which produces microwave signal energy from solar energy, and wherein the microwave signal is transmitted from a satellite in space to earth.

16. The method of claim 14, wherein the transmitted microwave signal is circularly polarized, and wherein the method includes the steps of alternating the polarization of the transmitted microwave signal between left hand and right hand polarization.

17. The method of claim 14, wherein the transmitted microwave signal is linearly polarized, and wherein the method includes the steps of continuously changing the phase of the polarization of the transmitted microwave signal at the selected rate.

18. The method of claim 16 or 17, wherein the selected rate of change of the polarization is a multiple of sixty hertz.