Claims
- 1. A method for shaping reflectors, comprising:
selecting a desired analytical aperture field distribution and a feed pattern from a feed; defining parameters of the main and sub reflectors; mapping energy from the feed pattern to the aperture field distribution; incrementally defining surface normals for each point of the main and sub reflectors; determining the shape of the main and sub reflectors to provide an aperture field distribution that generates optimal sidelobes under a predetermined sidelobe envelope for maximizing aperture illumination efficiency.
- 2. The method according to claim 1, further including incrementally determining wavefront parameters of energy from the feed to points on the sub reflector.
- 3. The method according to claim 2, further including determining wavefront parameters from the points on the sub reflector to corresponding points on the main reflector.
- 4. The method according to claim 3, further including determining surface normals for the points on the main reflector.
- 5. The method according to claim 1, further including synthesizing the reflector shapes about a feed angle with respect to a feed axis.
- 6. The method according to claim 5, further including synthesizing the reflector shapes about a rotation angle about the feed axis for each feed angle.
- 7. The method according to claim 1, further including adjusting the main reflector shape and/or the sub reflector shape to make equal path lengths from the feed to the sub reflector to the main reflector.
- 8. The method according to claim 1, further including capturing more than 95 percent of the feed pattern energy.
- 9. The method according to claim 1, further including capturing from about 95 percent to about 98 percent of the feed pattern energy.
- 10. The method according to claim 1, further including utilizing a feed angle in the range from about ±45-50 degrees.
- 11. The method according to claim 1, further including adjusting a synthesis interval based upon the linearity of the analytical aperture field distribution.
- 12. The method according to claim 1, further including shaping the main reflector and the main reflector to achieve an overall antenna efficiency of greater than about 75 percent while meeting a sidelobe requirement of about 29-25 log10θ, wherein θ is the pattern angle measured from antenna boresight.
- 13. The method according to claim 12, wherein the main reflector corresponds to about a 95 cm Ka-band antenna.
- 14. The method according to claim 1, further including providing a −15 dB sub reflector edge taper.
- 15. The method according to claim 1, further including selecting the desired analytical aperture field distribution from the group consisting of truncated Gaussian, cosine, higher order cosines, and quadratic functions.
- 16. A dual reflector antenna, comprising:
a shaped sub reflector for reflecting a feed pattern from a feed; a shaped main reflector for reflecting energy from the sub reflector to generate an actual aperture field distribution modified from an analytical aperture field distribution for allowing maximum sidelobes under a predetermined sidelobe envelope.
- 17. The antenna according to claim 16, wherein a feed angle ranges from about 45-50 degrees.
- 18. The antenna according to claim 16, wherein an edge taper is up to about −20 dB.
- 19. The antenna according to claim 16, wherein an edge taper is up to about −15 dB.
- 20. The antenna according to claim 16, wherein the sub reflector captures from about 95-98 percent of energy in the feed pattern.
- 21. The antenna according to claim 16, wherein the analytical aperture distribution is selected from the group consisting of truncated Gaussian, cosine, higher order cosine, and quadratic function.
- 22. The antenna according to claim 16, wherein the main reflector has a diameter selected from the group consisting of about 95 cm, 75 cm, and 65 cm.
- 23. The antenna according to claim 16, wherein the main reflector has a diameter of about 95 cm, the sub reflector captures from about 95-98 percent of the feed energy, the sub reflector edge taper is about −15 dB, and the antenna has an illumination efficiency of over 91 percent.
- 24. A dual reflector antenna, comprising:
a feed; a shaped sub reflector for reflecting a feed pattern from the feed; a shaped main reflector for reflecting energy from the sub reflector to generate an actual aperture field distribution modified from an analytical aperture field distribution for allowing maximum sidelobes under a predetermined sidelobe envelope.
- 25. The antenna according to claim 24, wherein the subreflector captures more than about 95 percent of the feed pattern energy.
- 26. The antenna according to claim 24, wherein the antenna utilizes a feed angle in a range from about ±45-50 degrees.
- 27. The antenna according to claim 24, wherein the antenna is greater than 70 percent efficient for a sidelobe requirement of about 29-25log10(θ) dBi, where θ is the angle from antenna boresight.
- 28. The antenna according to claim 24, wherein the subreflector has an edge taper of about −15 dB.
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. Provisional Patent Application No. 60/268,354, filed on Feb. 13, 2001, which is incorporated herein by reference.
Provisional Applications (1)
|
Number |
Date |
Country |
|
60268354 |
Feb 2001 |
US |