L-band array element with integrated triplexer for GPS payloads

Patent metadata

Field	Value
Publication number	US-9972897-B1
Application number	US-201715672673-A
Country	US
Kind code	B1
Filing date	Aug 9, 2017
Priority date	Aug 9, 2017
Publication date	May 15, 2018
Grant date	May 15, 2018

Abstract

A phased array antenna including a plurality of antenna element units mounted to a panel having a first side and a second side. Each antenna unit includes a step aperture integrated radiating (STAIR) antenna element mounted to the first side of the panel and having an outer cylindrical waveguide, a septum polarizer including a plurality of steps and a septum feed structure, and a right hand circularly polarized (RHCP) feed structure electrically coupled to the septum feed structure. Each antenna unit further includes a triplexer module mounted to the second side of the panel and being responsive to a plurality of linearly polarized signals to be transmitted by the STAIR element, where the triplexer module operates to combine the plurality of linearly polarized signals and provide the combined signal to the RHCP feed structure to be converted by the septum polarizer to a circularly polarized signal for transmission.

First claim

What is claimed is:

1. A phased array antenna including a plurality of antenna element units mounted to a single panel having a first side and a second side, each antenna element unit comprising:
a step aperture integrated radiating (STAIR) antenna element mounted to the first side of the panel and including an outer cylindrical waveguide having a chamber and an aperture opening opposite to the panel, a septum polarizer including a plurality of steps and a septum feed structure configured within the chamber, and a right hand circularly polarized (RHCP) ridge feed structure mounted to the first side of the panel and being electrically coupled to the septum feed structure; and
a triplexer module mounted to the second side of the panel and being responsive to a plurality of linearly polarized signals to be transmitted by the STAIR element, said triplexer module operating to combine the plurality of linearly polarized signals and provide the combined signal to the RHCP feed structure, said septum polarizer converting the combined linearly polarized signal to a circularly polarized signal for transmission from the aperture opening.

2. The phased array antenna according to claim 1 wherein the plurality of linearly polarized signals include a first signal at the L1 frequency band, a second signal at the L2 frequency band and a third signal at the L5 frequency band.

3. The phased array antenna according to claim 1 wherein the triplexer module includes a notch filter for filtering the combined signal.

4. The phased array antenna according to claim 1 wherein the triplexer module includes a separate combline bandpass filter for each frequency band of the plurality of linearly polarized signals.

5. The phased array antenna according to claim 4 wherein each combline bandpass filter includes a plurality of filtering cavities.

6. The phased array antenna according to claim 1 wherein the triplexer module employs low passive inter-modulation (PIM) transverse electric and magnetic (TEM) line connections.

7. The phased array antenna according to claim 1 wherein the antenna is mounted to a global positioning system (GPS) satellite.

8. The phased array antenna according to claim 7 wherein the antenna provides earth coverage and spot beams from a medium earth orbit (MEO) with group-delay variations ranging from about 10 ns peak to peak to about 30 ns peak to peak and high power handling for the GPS satellite with improved location accuracies and a higher effective isotropic radiated power (EIRP) value.

9. The phased array antenna according to claim 1 wherein the panel is a hexagonal shaped panel.

10. The phased array antenna according to claim 1 wherein the panel is a honeycomb panel.

11. The phased array antenna according to claim 1 wherein the cylindrical waveguide has a diameter in the range of 7 to 10 inches and a height in the range of 13 to 17 inches.

12. The phased array antenna according to claim 1 wherein the plurality of steps is four steps.

13. The phased array antenna according to claim 1 wherein the cylindrical waveguide and the septum polarizer are configured to reduce the weight of the antenna element.

14. The phased array antenna according to claim 1 wherein the plurality of antenna elements is thirty-seven antenna elements.

15. The phased array antenna according to claim 1 wherein the STAIR antenna element includes a left hand circularly polarize (LHCP) feed structure mounted to the first side of the panel and configured within the chamber and being electrically coupled to an opposite side of the septum feed structure from the RHCP feed structure.

16. The phased array antenna according to claim 1 wherein each radiating element has an inner geometry designed to minimize a phase center variation to less than 0.2″ over the L1, L2 and L5 frequency bands resulting in improved location accuracy on ground and high aperture efficiency values of greater than 95%.

17. A phased array antenna for a GPS satellite, said phased array antenna including a plurality of antenna element units mounted to a single panel having a first side and a second side, each antenna element unit comprising:
a step aperture integrated radiating (STAIR) element mounted to the first side of the panel and including an outer cylindrical waveguide having a chamber and an aperture opening opposite to the panel, a septum polarizer including four steps configured within the chamber and a septum feed structure mounted to the first side of the panel and configured within the chamber, and a right hand circularly polarized (RHCP) feed structure mounted to the first side of the panel and being electrically coupled to the septum feed structure; and
a triplexer module mounted to the second side of the panel and being responsive to linearly polarized signals in the L1 frequency band, the L2 frequency band and the L5 frequency band to be transmitted by the STAIR element, said triplexer module including a separate bandpass filter for filtering each of the L1 frequency band signal, the L2 frequency band signal and the L5 frequency band signal, said triplexer module operating to combine the filtered L1, L2 and L5 frequency band signals and provide the combined signal to the RHCP feed structure, said septum polarizer converting the combined linearly polarized signal to a circularly polarized signal for transmission from the aperture opening.

18. The phased array antenna according to claim 17 wherein the triplexer module employs low passive inter-modulation (PIM) transverse electric and magnetic (TEM) line connections.

19. The phased array antenna according to claim 17 wherein the cylindrical waveguide has a diameter in the range of 7 to 10 inches and a height in the range of 13 to 17 inches.

20. The phased array antenna according to claim 17 wherein the plurality of antenna elements is thirty-seven antenna elements.

21. A phased array antenna comprising:
a step aperture integrated radiating (STAIR) antenna element configured to convert linearly polarized signals to circularly polarized signals, said STAIR antenna element including an outer cylindrical housing, an internal septum configured to divide the linearly polarized signals into two orthogonal components that are phase shifted by 90°, and a linear signal converter configured to convert transverse electric and magnetic signals into a linearly polarized waveguide signal; and
a triplexer module configured to combine a plurality of linearly polarized signals and provide the combined signals to the linear signal converter.

22. The phased array antenna according to claim 21 wherein the STAIR antenna element is one of a plurality of STAIR antenna elements mounted to a common panel.

23. The phased array antenna according to claim 21 wherein the STAIR antenna element is configured to provide a signal phase center variation less than about 0.2 inches over an L1, L2 and L5 frequency band.

Assignees

• Northrop Grumman Systems Corp
• Custom Microwave Inc

Inventors

• Rao Sudhakar K
• Lee-Yow Clency
• Venezia Philip E
• Scupin Jonathan R

Classifications

• H01Q21/0056

  Conically or cylindrically arrayed · CPC title

• G01S19/02

  Details of the space or ground control segments · CPC title

• H01Q3/2658

  Phased-array fed focussing structure · CPC title

• H01Q1/288 Primary

  Satellite antennas · CPC title

• H01Q3/2623

  composed of two antennas · CPC title