Feature in antenna pattern for pointing and orientation determination
Systems and methods for antenna pointing are disclosed. A transmit antenna system having an adjustable boresight transmits a signal exhibiting a far-field pattern including a feature (e.g. a V-Notch) in a polarization of the signal disposed at a fixed position off a beam peak of the far-field pattern of the signal. A receive antenna system scans across the far-field pattern of the signal in the polarization to locate the feature and determine a pointing error of the adjustable boresight therefrom. The system may be applied to a cross-polarization of the signal where a co-polarization of the signal is simultaneously used for telecommunication.
1. An apparatus for determining antenna pointing, comprising:
a transmit antenna system for transmitting a signal having an adjustable boresight and exhibiting a far-field pattern including a feature in a polarization component of the far-field pattern disposed at a fixed position off a beam peak of the far-field pattern; and
a receive antenna system for scanning across the far-field pattern in the polarization component to locate the feature and determine a pointing error of the adjustable boresight therefrom;
wherein the feature of the far-field pattern comprises a notch having a depth relative to a main lobe of the far-field pattern varying with an angle of the fixed position off the boresight.
2. The apparatus of claim 1 , wherein the feature disposed at the fixed position off the beam peak of the far-field pattern is mapped with the transmit antenna system installed to include any multipath effects.
3. The apparatus of claim 1 , wherein the pointing error is transmitted to the transmit antenna system and the boresight is adjusted to correct the pointing error.
4. The apparatus of claim 1 , wherein the transmit antenna system is installed on a spacecraft and the receive antenna is disposed at a ground station.
5. The apparatus of claim 1 , wherein the polarization component having the feature in the far-field pattern is a cross-polarization component and a co-polarization component is simultaneously used to communicate while the receive antenna system determines the pointing error.
6. The apparatus of claim 5 , wherein the co-polarization component comprises a right circular polarization (RCP) and the cross-polarization component comprises a left circular polarization (LCP).
7. The apparatus of claim 1 , wherein the feature in the far-field pattern of the polarization component is switchably activated.
8. The apparatus of claim 7 , wherein the polarization component having the feature in the far-field pattern is a co-polarization component and the feature is only temporarily activated for the receive antenna system to determine the pointing error.
9. A method for determining antenna pointing, comprising:
transmitting a signal with a transmit antenna system having an adjustable boresight and exhibiting a far-field pattern including a feature in a polarization component of the far-field pattern disposed at a fixed position off a beam peak of the far-field pattern; and
scanning across the far-field pattern in the polarization component with a receive antenna system to locate the feature and determine a pointing error of the adjustable boresight therefrom;
wherein the feature of the far-field pattern comprises a notch having a depth relative to a main lobe of the far-field pattern varying with an angle of the fixed position off the boresight.
10. The method of claim 9 , further comprising mapping the feature disposed at the fixed position off the beam peak of the far-field pattern with the transmit antenna system installed to include any multipath effects.
11. The method of claim 9 , further comprising transmitting the pointing error to the transmit antenna system and adjusting the boresight to correct the pointing error.
12. The method of claim 9 , wherein the transmit antenna system is installed on a spacecraft and the receive antenna is disposed at a ground station.
13. The method of claim 9 , wherein the polarization component having the feature in the far-field pattern is a cross-polarization component and a co-polarization component is simultaneously used to communicate while the receive antenna system determines the pointing error.
14. The method of claim 13 , wherein the co-polarization component comprises a right circular polarization (RCP) and the cross-polarization component comprises a left circular polarization (LCP).
15. The method of claim 9 , wherein the feature in the far-field pattern of the polarization component is switchably activated.
16. The method of claim 15 , wherein the polarization component having the feature in the far-field pattern is a co-polarization component and the feature is only temporarily activated for the receive antenna system to determine the pointing error.
17. An apparatus for determining antenna pointing, comprising:
a transmit antenna system means for transmitting a signal having an adjustable boresight and exhibiting a far-field pattern including a feature in a polarization component disposed at a fixed position off a beam peak of the far-field pattern; and
a receive antenna system means for determining a pointing error of the adjustable boresight from scanning across the far-field pattern in the polarization component to locate the feature;
wherein the feature of the far-field pattern comprises a notch having a depth relative to a main lobe of the far-field pattern varying with an angle of the fixed position off the boresight.
18. The apparatus of claim 17 , wherein the feature of the far-field pattern is mapped with the transmit antenna system means installed to include any multipath effects.