High efficiency synthetic aperture radar satellite
Systems and methods in accordance with various embodiments of the present disclosure provide high efficiency synthetic aperture radar satellite designs that achieve higher power efficiency and higher antenna aperture size to satellite mass ratios than the current state of the art. In various embodiments, a high efficiency synthetic aperture radar satellite includes a satellite bus and a parabolic reflector antenna coupled to the satellite bus. The satellite system may further include a traveling wave tube amplifier configured to drive the parabolic reflector antenna, and a body-mounted steering system configured to mechanically steer the satellite system to direct the parabolic reflector antenna. The satellite system may further include a processor configured to combine the pulse reflections and generate image data representing the region of interest, in which the image data is effectively obtained with a synthetic aperture greater than the actual antenna aperture.
1. A radar satellite system, comprising:
a satellite bus;
a parabolic reflector antenna coupled to the satellite bus, the parabolic reflector antenna comprising a central hub and a plurality of antenna ribs movable from a stowed position to an operational position, the antenna ribs foldable around the central hub in the stowed position and expandable into a parabolic reflector configuration in the operational position, wherein the antenna is configured to transmit a series of pulses from different positions over a region of interest and receive a corresponding series of pulse reflections, and wherein the parabolic reflector antenna has a power aperture factor to mass ratio of at least 600 kilowatts-meter squared per kilogram;
a traveling wave tube amplifier configured to drive the parabolic reflector antenna;
a body-mounted steering system configured to mechanically steer the satellite system to direct the parabolic reflector antenna; and
a processor configured to combine the pulse reflections and generate image data representing the region of interest, the image data associated with a synthetic aperture greater than the antenna aperture.
2. The radar satellite system of claim 1 , wherein the parabolic reflector antenna further comprises a feed source from which radio-frequency signals are transmitted and received, the feed source including a center feed at positioned at the center of the reflector antenna and a Cassegrain hyperbolic reflector positioned at the focal point of the parabolic reflector antenna.
3. The radar satellite system of claim 1 , wherein the body-mounted steering system comprises an actuation system comprising a control moment gyroscope.
4. The radar satellite system of claim 1 , wherein the satellite bus has a mass less than 150 kilograms.
5. The radar satellite system of claim 4 , wherein the parabolic reflector antenna has an antenna aperture size to satellite mass ratio of at least 0.10 square meters per kilogram.
6. A radar satellite system, comprising:
a satellite having a satellite mass, the satellite comprising:
a satellite bus; and
an antenna expandable from a stowed position into an operational position, the antenna having an antenna aperture size, the antenna aperture size and the satellite mass having a ratio of at least 0.03 meters squared per kilogram, wherein the antenna is configured to transmit a series of pulses from different positions over a region of interest and receive a corresponding series of pulse reflections, wherein the antenna has a power aperture factor to mass ratio of at least 600 kilowatts-meter squared per kilogram; and
a processor configured to combine the pulse reflections and generate image data representing the region of interest, the image data associated with a synthetic aperture greater than the antenna aperture.
7. The radar satellite system of claim 6 , wherein the satellite mass is less than 150 kilograms.
8. The radar satellite system of claim 6 , wherein the antenna is a parabolic reflector antenna or a phased array antenna.
9. The radar satellite system of claim 6 , wherein the antenna comprises a central hub and a plurality of antenna ribs, the antenna ribs foldable around the central hub in the stowed position and expandable into a parabolic reflector configuration in the operational position.
10. The radar satellite system of claim 6 , wherein the antenna comprises at least one of: a plurality of antenna ribs configured to wrap around each other in the stowed positioned, truss structures stowable in a cylinder formation, flexible phased arrays stowable in a rolled configuration, phased arrays stowable in a hinged position, or foldable phased arrays.
11. The radar satellite system of claim 6 , wherein the antenna comprises a main reflector and a feed source, the feed source including at least one of an offset fed reflector facing off-center from main reflector's focal point, a direct and center fed reflector aligned with the main reflector's center point and at the main reflector's focal point, or a center feed at positioned at the main reflectors center with a Cassegrain hyperbolic reflector positioned at the main reflector's focal point.
12. The radar satellite system of claim 6 , further comprising:
an amplifier configured to drive the antenna, the amplifier comprising a traveling wave tube amplifier or a solid state power amplifier.
13. The radar satellite system of claim 6 , further comprising:
a body-mounted steering system configured to direct the antenna by moving the satellite through mechanical steering.
14. The radar satellite system of claim 13 , wherein the body-mounted steering system comprises an actuator system, the actuator system comprising a control moment gyroscope.
15. A satellite imaging method, comprising:
powering a parabolic reflector antenna of a synthetic aperture radar satellite using a traveling wave tube amplifier, wherein the parabolic reflector antenna has a power aperture factor to mass ratio of at least 600 kilowatts-meter squared per kilogram;
mechanically steering a body-mounted steering system to move the antenna relative to a region of interest;
transmitting a series of radio-frequency pulses via the antenna at different positions relative to a region of interest;
receiving pulse reflections corresponding to the series of transmitted radio-frequency pulses; and
processing the pulse reflections and generate image data representing the region of interest.
16. The radar satellite system of claim 15 , further comprising:
expanding the antenna from a stowed position into an operational position, wherein the antenna comprises a plurality of antenna ribs foldable around a central hub in the stowed position.
17. The radar satellite system of claim 15 , further comprising:
generating low power complex waveforms for transmission by the antenna.
18. The radar satellite system of claim 15 , wherein the synthetic aperture radar satellite has a mass less than 150 kilograms.
19. The radar satellite system of claim 18 , wherein the synthetic aperture radar satellite has an antenna aperture size to satellite mass ratio of at least 0.03 meters squared per kilogram.
20. The radar satellite system of claim 15 , wherein the parabolic reflector antenna further comprises a feed source from which radio-frequency signals are transmitted and received, the feed source including a center feed at positioned at the center of the reflector antenna and a Cassegrain hyperbolic reflector positioned at the focal point of the parabolic reflector antenna.