Phased Array Antenna System with Two Dimensional Scanning

• US 20090167605A1
• Filed: 05/29/2007
• Published: 07/02/2009
• Est. Priority Date: 06/09/2006
• Status: Active Grant

• Current Assignee: Flir Belgium BVBA (Teledyne Technologies Incorporated)
• Original Assignee: Qinetiq Limited (QinetiQ Group PLC)
• Inventors: Haskell, Philip Edward
• Granted Patent: US 7,911,383 B2
• Time in Patent Office: Days
• US Class Current: 342/372
• CPC Class Codes: H01Q 21/0006 Particular feeding systems
• CPC Class Codes: H01Q 21/061 Two dimensional planar arrays
• CPC Class Codes: H01Q 3/36 with variable phase-shifters

Abstract

A phased array antenna system with two dimensional scanning includes a two dimensional array A of antenna elements A_1,1 to A_12,12 arranged in lines; each line is associated with a respective first rank corporate feed network 16₁ to 16₁₂ having outputs 17_1,1 to 17_12,12 connected to respective antenna elements A_1,1 to A_12,12 and inputs for variable relative phase input signals. These corporate feed networks each have first and second inputs A1/B1 to A12/B12 connected respectively to outputs 17_{1 CD}/17_12CD to 17_1EF/17_12EF of different second rank corporate feed networks 16_CD and 16_EF. The corporate feed networks 16₁ to 16_EF convert input signals of variable relative phase into relatively greater numbers of output signals for a phased array. The system (30) includes a phase varying circuit 40 for varying phase differences between input signals to each second rank corporate feed network 16_CD or 16_EF and between input signals to different second rank corporate feed networks 16_CD and 16_EF to provide control of antenna beam direction in two dimensions.

Claims

1. A phased array antenna system having a two dimensional array of antenna elements and a plurality of corporate feed networks, and wherein:

a) the corporate feed networks are grouped in first and second ranks and are arranged to convert network input signals of variable phase relative to one another into network output signals phased appropriately for antenna elements of a phased array, the network output signals being in relatively greater numbers than the network input signals for corporate feed networks in at least one of the first and second ranks;

b) first rank corporate feed networks are arranged to provide network output signals as input signals to respective lines of antenna elements; and

c) second rank corporate feed networks are arranged to provide network output signals as input signals to respective lines of inputs of first rank corporate feed networks; and

d) the system includes phase difference control means for varying network input signal phasing for second rank corporate feed networks to provide control of antenna beam direction in two dimensions.

2. A phased array antenna system according to claim 1 wherein the phase difference control means is arranged to:

a) vary the phase difference between each input signal to one second rank corporate feed network and input signals to another second rank corporate feed network to provide control of antenna beam direction in a first dimension; and

b) vary both the phase difference between input signals to one second rank corporate feed network and the phase difference between input signals to another second rank corporate feed network to provide control of antenna beam direction in a second dimension.

3. A phased array antenna system according to claim 2 wherein the phase difference control means is arranged to maintain:

a) the phase difference between input signals to one second rank corporate feed network to be equal to the phase difference between input signals to another second rank corporate feed network; and

b) the phase differences between each input signal to one second rank corporate feed network and both input signals to another second rank corporate feed network to be equal.

4. A phased array antenna system including a two dimensional array of antenna elements arranged in lines, and wherein:

a) each line of antenna elements is associated with a respective first rank corporate feed network having outputs for providing signals to respective antenna elements and inputs for receiving signals of variable phase relative to one another;

b) the first rank corporate feed networks have;

i) first inputs connected to outputs of one second rank corporate feed network;

ii) second inputs connected to outputs of another second rank corporate feed network;

c) the corporate feed networks provide a means for converting input signals of variable phase relative to one another into multiple output signals for phased array antenna elements, the number of output signals being relatively greater than the number of input signals; and

d) the system includes phase difference varying means for;

i) varying the phase difference between each input signal to one second rank corporate feed network and input signals to another second rank corporate feed network to provide control of antenna beam direction in a first dimension; and

ii) varying both the phase difference between input signals to one second rank corporate feed network and the phase difference between input signals to another second rank corporate feed network to provide control of antenna beam direction in a second dimension.

5. A phased array antenna system according to claim 4 wherein each corporate feed network provides a means for converting input signals expressed by vectors A and B into other signal vectors given by expressions of the form p_iA+q_iB, where p_i and q_i are numerical factors in the range −

1 to 1.

6. A phased array antenna system according to claim 4 wherein the phase difference varying means comprises:

a) a first variable phase shifter connected via a splitter to a second variable phase shifter and a first fixed phase shifter each connected to respective inputs of one second rank corporate feed network;

b) a second fixed phase shifter connected via a splitter to a third variable phase shifter and a third fixed phase shifter each connected to respective inputs of another second rank corporate feed network; and

c) means for ganging together operation of the second and third variable phase shifters.

7. A phased array antenna system according to claim 4 wherein antenna elements are positioned to define a curved surface such as a cylindrical, spherical or toroidal surface.

15. A phased array antenna system according to claim 5 wherein antenna elements are positioned to define a curved surface such as a cylindrical, spherical or toroidal surface.

16. A phased array antenna system according to claim 6 wherein antenna elements are positioned to define a curved surface such as a cylindrical, spherical or toroidal surface.

8. A method of scanning a phased array antenna system having a two dimensional array of antenna elements and a plurality of corporate feed networks, and wherein:

a) the corporate feed networks are grouped in first and second ranks and are arranged to convert network input signals of variable phase relative to one another into network output signals phased appropriately for antenna elements of a phased array, the network output signals being in relatively greater numbers than the network input signals for corporate feed networks in at least one of the first and second ranks;

b) first rank corporate feed networks are arranged to provide network output signals as input signals to respective lines of antenna elements; and

c) second rank corporate feed networks are arranged to provide network output signals as input signals to respective lines of inputs of first rank corporate feed networks; and

d) the method includes varying network input signal phasing for second rank corporate feed networks to provide control of antenna beam direction in two dimensions.

9. A method according to claim 8 wherein the step of varying network input signal phasing comprises:

a) varying the phase difference between each input signal to one second rank corporate feed network and input signals to another second rank corporate feed network to provide control of antenna beam direction in a first dimension; and

b) varying both the phase difference between input signals to one second rank corporate feed network and the phase difference between input signals to another second rank corporate feed network to provide control of antenna beam direction in a second dimension.

10. A method according to claim 9 including maintaining equal:

a) the phase difference between input signals to one second rank corporate feed network and the phase difference between input signals to another second rank corporate feed network; and

b) the phase differences between each input signal to one second rank corporate feed network and both input signals to another second rank corporate feed network.

11. A method of scanning a phased array antenna system having a two dimensional array of antenna elements arranged in lines, and wherein:

a) each line of antenna elements is associated with a respective first rank corporate feed network having outputs for providing signals to respective antenna elements and inputs for receiving signals of variable phase relative to one another;

b) the first rank corporate feed networks have;

i) first inputs connected to outputs of one second rank corporate feed network;

ii) second inputs connected to outputs of another second rank corporate feed network;

c) the corporate feed networks provide a means for converting input signals of variable phase relative to one another into multiple output signals for phased array antenna elements the output signals being in relatively greater in number compared to the input signals; and

the method includes;

d) varying the phase difference between each input signal to one second rank corporate feed network and input signals to another second rank corporate feed network to provide control of antenna beam direction in a first dimension; and

e) varying both the phase difference between input signals to one second rank corporate feed network and the phase difference between input signals to another second rank corporate feed network to provide control of antenna beam direction in a second dimension.

12. A method according to claim 11 wherein each corporate feed network provides a means for converting input signals expressed by vectors A and B into other signal vectors given by expressions of the form p_iA+q_iB, where p_i and q_i are numerical factors in the range −

1 to 1.

13. A method according to claim 11 wherein the steps of varying phase difference comprise:

a) applying a first variable phase shift via a splitter to a second variable phase shifter and a first fixed phase shifter each connected to respective inputs of one second rank corporate feed network;

b) applying a second fixed phase shift via a splitter to a third variable phase shifter and a third fixed phase shifter each connected to respective inputs of another second rank corporate feed network; and

c) ganging together operation of the second and third variable phase shifters.

14. A method according to claim 11, including positioning the antenna elements to define a curved surface such as a cylindrical, spherical or toroidal surface.

17. A method according to claim 12 wherein the steps of varying phase difference comprise:

a) applying a first variable phase shift via a splitter to a second variable phase shifter and a first fixed phase shifter each connected to respective inputs of one second rank corporate feed network;

b) applying a second fixed phase shift via a splitter to a third variable phase shifter and a third fixed phase shifter each connected to respective inputs of another second rank corporate feed network; and

c) ganging together operation of the second and third variable phase shifters.

18. A method according to claim 12 including positioning the antenna elements to define a curved surface such as a cylindrical, spherical or toroidal surface.

19. A method according to claim 13 including positioning the antenna elements to define a curved surface such as a cylindrical, spherical or toroidal surface.