Methods and systems for mitigating interference with a nearby satellite
In one embodiment, an antenna system is described. The antenna system includes a primary antenna on an aircraft. The primary antenna is mechanically steerable and has an asymmetric antenna beam pattern with a narrow beamwidth axis and a wide beamwidth axis at boresight. The antenna system also includes a secondary antenna on the aircraft, the secondary antenna including an array of antenna elements. The antenna system also includes an antenna selection system to control communication of a signal between the aircraft and a target satellite via the primary antenna and the secondary antenna. The antenna selection system switches communication of the signal from the primary antenna to the secondary antenna when an amount of interference with an adjacent satellite reaches a threshold due to the wide beamwidth axis of the asymmetric antenna beam pattern.
1. An antenna system for mounting on an aircraft, the antenna system comprising:
a primary antenna on the aircraft, wherein the primary antenna has a first acceptable service area for transmission of an uplink signal from the aircraft to a target satellite while satisfying an uplink interference requirement with a non-target satellite;
a secondary antenna on the aircraft, wherein the secondary antenna has a second acceptable service area for transmission of the uplink signal from the aircraft to the target satellite while satisfying the uplink interference requirement with the non-target satellite, and wherein the second acceptable service area is different than the first acceptable service area; and
an antenna selection system to control communication of the uplink signal from the aircraft to the target satellite via the primary antenna and the secondary antenna, wherein the antenna selection system switches transmission of the uplink signal between the primary antenna and the secondary antenna based on a geographic location of the aircraft and the first and second acceptable service areas.
2. The antenna system of claim 1 , wherein the antenna selection system selects the primary antenna to transmit the uplink signal when the geographic location of the aircraft is within the first acceptable service area, and the antenna selection system selects the secondary antenna to transmit the uplink signal when the geographic location of the aircraft is outside the first acceptable service area and is within the second acceptable service area.
3. The antenna system of claim 1 , wherein the first acceptable service area and the second acceptable service area define a composite acceptable service area of the antenna system, the composite acceptable service area larger than each of the first acceptable service area and the second acceptable service area.
4. The antenna system of claim 1 , wherein the antenna selection system further selectively changes one or more transmission parameters of the uplink signal.
5. The antenna system of claim 4 , wherein the antenna selection system selectively changes the one or more transmission parameters of the uplink signal to adjust power spectral density of the uplink signal in a direction of the non-target satellite.
6. The antenna system of claim 4 , wherein the one or more transmission parameters includes one or more of a power level of the uplink signal and a bandwidth spreading of the uplink signal.
7. The antenna system of claim 1 , wherein the first acceptable service area and the second acceptable service area have an overlap.
8. The antenna system of claim 7 , wherein the antenna selection system selects the primary antenna to transmit the uplink signal when the geographic location of the aircraft is within the overlap.
9. The antenna system of claim 7 , wherein the antenna selection system switches transmission of the uplink signal between the primary antenna and the secondary antenna when the geographic location of the aircraft is moving from the overlap to one of the first acceptable service area and the second acceptable service area.
10. The antenna system of claim 9 , wherein the antenna selection system only switches transmission of the uplink signal between the primary antenna and the secondary antenna when the geographic location of the aircraft is moving from the overlap to one of the first acceptable service area and the second acceptable service area.
11. The antenna system of claim 1 , wherein the antenna selection system switches transmission of the uplink signal between the primary antenna and the secondary antenna at boundaries of the first and second acceptable service areas.
12. The antenna system of claim 11 , wherein the antenna selection system selects the primary antenna to transmit the uplink signal when the geographic location of the aircraft is within the first acceptable service area.
13. The antenna system of claim 1 , wherein the antenna selection system further controls communication of a downlink signal from the target satellite to the aircraft via the primary antenna and the secondary antenna.
14. The antenna system of claim 13 , wherein the antenna selection system switches reception of the downlink signal between the primary antenna and the secondary antenna upon switching transmission of the uplink signal between the primary antenna and the secondary antenna.
15. The antenna system of claim 13 , wherein the antenna selection system maintains reception of the downlink signal via the primary antenna upon switching transmission of the uplink signal to the secondary antenna.
16. The antenna system of claim 1 , wherein the antenna selection system maintains a return link operating point of the uplink signal upon switching transmission of the uplink signal between the primary antenna and the secondary antenna.
17. The antenna system of claim 16 , wherein the antenna selection system maintains the return link operating point of the uplink signal by changing transmit power of the uplink signal.
18. The antenna system of claim 1 , wherein the primary antenna has at least one performance characteristic for communicating the uplink signal that is different than that of the secondary antenna.
19. The antenna system of claim 18 , wherein the primary antenna has at least one of higher gain, lower sidelobes and lower cross-polarization than that of the secondary antenna.
20. The antenna system of claim 1 , wherein differences between the first and second acceptable service areas are due to differences between the primary antenna and the secondary antenna.