Reflector antenna
A reflector antenna includes a feed configured to always point during operation in a direction that opposes ingress of water into the feed, and a reflector having a truncated spherical reflecting surface, wherein a relative orientation of the reflector and the feed is adjustable. Another reflector antenna includes a feed configured to always point during operation in a direction that opposes ingress of water into the feed, and a reflector spaced apart from the feed by a focal length at least as great as a diameter of the reflector. Another reflector antenna includes a feed and a reflector having a truncated spherical reflecting surface, wherein the reflector is spaced apart from the feed by a focal length at least as great as a diameter of the reflector.
1. An antenna comprising:
a) a feed configured to always point during operation in a direction that opposes ingress of water into the feed, wherein the direction is substantially vertically downward; and
b) a reflector having a truncated spherical reflecting surface;
wherein a relative orientation of said reflector and said feed is adjustable.
2. The antenna of claim 1 wherein the feed is configured to always point vertically downward.
3. The antenna of claim 1 wherein the feed is fixed in said direction that opposes ingress.
4. The method of claim 1 wherein the feed has a shape that repels rain when the feed is pointing in said direction that opposes ingress.
5. The antenna of claim 1 wherein the feed comprises a feedhorn.
6. The antenna of claim 5 wherein the feedhorn has a generally pyramidal shape.
7. The antenna of claim 5 wherein the feedhorn has a generally conical shape.
8. The antenna of claim 1 wherein the reflector is spaced apart from the feed by a focal length at least as great as a diameter of the reflector.
9. The antenna of claim 1 wherein the reflector is spaced apart from the feed by a focal length at least twice as great as a diameter of the reflector.
10. The antenna of claim 1 wherein the reflector is spaced apart from the feed by a focal length at least two-and-a-half times as great as a diameter of the reflector.
11. The antenna of claim 1 wherein said truncated spherical reflecting surface has a radius of curvature at least as great as a diameter of said reflector.
12. The antenna of claim 1 wherein said truncated spherical reflecting surface has a radius of curvature at least three times as great as a diameter of said reflector.
13. The antenna of claim 1 wherein said truncated spherical reflecting surface has a radius of curvature at least five times as great as a diameter of said reflector.
14. The antenna of claim 1 wherein the antenna excludes a radome.
15. The antenna of claim 1 wherein the reflecting surface of the reflector comprises a solid surface.
16. The antenna of claim 1 wherein the reflecting surface of the reflector comprises at least one aperture through the reflecting surface.
17. The antenna of claim 16 wherein the at least one aperture comprises a plurality of drainage apertures.
18. The antenna of claim 16 wherein the at least one aperture comprises a plurality of apertures and wherein each of the apertures has a diameter less than one-eighth of a wavelength intended to be reflected by said reflector.
19. The antenna of claim 16 wherein the at least one aperture comprises a plurality of apertures and wherein each of the apertures has a diameter less than one-twentieth of a wavelength intended to be reflected by said reflector.
20. The antenna of claim 1 wherein the reflector is rotatable about each of two perpendicular axes.
21. The antenna of claim 20 wherein one of said axes is a vertical axis for azimuthal rotation of said reflector thereabout and wherein the other one of said axes is a horizontal axis for elevational rotation of said reflector thereabout.
22. The antenna of claim 1 further comprising a waveguide in communication with said feed.
23. The antenna of claim 22 further comprising a transducer in communication with said feed via said waveguide.
24. The antenna of claim 23 wherein said transducer comprises a radio detector.
25. The antenna of claim 23 wherein said transducer comprises a radio transmitter.
26. The antenna of claim 23 wherein said transducer comprises a radio transceiver.
27. An antenna comprising:
a) a feed configured to always point during operation in a direction that opposes ingress of water into the feed, wherein the direction is substantially vertically downward; and
b) a reflector spaced apart from said feed by a focal length at least as great as a diameter of said reflector.
28. The antenna of claim 27 wherein the reflector is spaced apart from the feed by a focal length at least twice as great as the diameter of the reflector.
29. The antenna of claim 27 wherein the reflector is spaced apart from the feed by a focal length at least two-and-a-half times as great as the diameter of the reflector.
30. The antenna of claim 29 wherein a relative orientation of said reflector and said feed is adjustable.
31. The antenna of claim 27 wherein said reflector has a truncated spherical reflecting surface.
32. The antenna of claim 31 wherein the reflector is spaced apart from the feed by a focal length at least twice as great as the diameter of the reflector.
33. The antenna of claim 31 wherein the reflector is spaced apart from the feed by a focal length at least two-and-a-half times as great as the diameter of the reflector.
34. The antenna of claim 27 wherein a relative orientation of said reflector and said feed is adjustable.
35. A method comprising:
a) configuring a feed of an antenna to always point in a direction that opposes ingress of water into the feed, wherein the direction is substantially vertically downward; and
b) reflecting electromagnetic radiation to or from the feed using a reflector having a truncated spherical reflecting surface.
36. A method comprising:
a) configuring a feed of an antenna to always point in a direction that opposes ingress of water into the feed, wherein the direction is substantially vertically downward; and
b) reflecting electromagnetic radiation to or from the feed using a reflector spaced apart from the feed by a focal length at least as great as a diameter of the reflector.