Method and apparatus for tri-band feed with pseudo-monopulse tracking
Methods and apparatus for a feed assembly for a reflector antenna including an aperture common to low, mid, and high frequency bands, a polyrod design to launch signals in the mid and high frequency bands, a horn to launch signals in the low frequency band, a co-located phase center for launching signals in the low, mid, and high frequency bands, and a low-band monopulse array located on a surface about the aperture to track a satellite.
1. A feed assembly for a reflector antenna, comprising:
an antenna aperture common to low, mid, and high frequency bands;
a polyrod to launch signals from the aperture in the mid and high frequency bands while supporting the low band;
a horn to launch signals from the aperture in the low frequency band;
a co-located phase center for launching signals in the low, mid, and high frequency bands; and
a low-band monopulse array located on a surface about a perimeter of the aperture to track a satellite.
2. The feed assembly according to claim 1 , wherein respective beamwidths for the low, mid, and high frequency bands is approximately equal.
3. The feed assembly according to claim 2 , wherein the respective beamwidths are about 10 dB.
4. The feed assembly according to claim 1 , wherein the monopulse array includes a four patch antenna array.
5. The feed assembly according to claim 1 , wherein a waveguide network for the low frequency band is elongated to minimize blockage of the reflector antenna.
6. The feed assembly according to claim 1 , wherein a length of a polarizer for the mid and high frequency bands is reduced to minimize blockage of the reflector antenna.
7. The feed assembly according to claim 1 , wherein a length of a feed is less than six inches.
8. The feed assembly according to claim 1 , wherein a diameter of the aperture is less than 2.5 inches.
9. The feed assembly according to claim 1 , wherein the monopulse array is implemented in a single stripline layer.
10. The feed assembly according to claim 1 , wherein the monopulse array provides sum, delta azimuth, and delta elevation beams in a downlink band and a single beam in an uplink band.
11. The feed assembly according to claim 1 , further including a turnstile junction coupled to the horn for coupling low-band energy to four symmetric waveguide channels.
12. A method, comprising:
receiving and transmitting signals using a feed assembly for a reflector antenna having an antenna aperture common to low, mid, and high frequency bands;
employing a polyrod to launch signals from the aperture in the mid and high frequency bands while supporting the low band and employing a compact horn to launch signals from the aperture in the low frequency band, wherein a phase center for launching signals in the low, mid, and high frequency bands is co-located; and
employing a low-band monopulse array located on a surface about a perimeter of the aperture to track a satellite.
13. The method according to claim 12 , further including employing respective beamwidths for the low, mid, and high frequency bands that are approximately equal.
14. The method according to claim 13 , wherein the respective beamwidths are about 10 dB.
15. The method according to claim 13 , wherein the monopulse array includes a four patch antenna array.
16. The method according to claim 13 , further including elongating a waveguide network for the low frequency band to minimize blockage of the reflector antenna.
17. The method according to claim 13 , further including reducing a length of a polarizer for the mid and high frequency bands to minimize blockage of the reflector antenna.
18. The method according to claim 13 , wherein a length of a feed is less than six inches.
19. The method according to claim 13 , wherein a diameter of the aperture is less than 2.5 inches.
20. The method according to claim 13 , further including implementing the monopulse array in a single stripline layer.