Beam steering in sub-arrayed antennae

• US 20020180639A1
• Filed: 02/15/2002
• Published: 12/05/2002
• Est. Priority Date: 02/15/2001
• Status: Active Grant

• Current Assignee: ROKE Manor Research Limited (Chemring Group PLC)
• Original Assignee: ROKE Manor Research Limited (Chemring Group PLC)
• Inventors: Rickett, Bryan Stephen, Wright, Peter John, Carter, Nicholas Alfred
• Granted Patent: US 6,661,375 B2
• Time in Patent Office: Days
• US Class Current: 342/372
• CPC Class Codes: G01S 13/4463 using phased arrays
• CPC Class Codes: G01S 3/42 the desired condition being maintained automatically
• CPC Class Codes: H01Q 21/061 Two dimensional planar arrays
• CPC Class Codes: H01Q 21/22 Antenna units of the array energised non-uniformly in amplitude or phase, e.g. tapered array or binomial array
• CPC Class Codes: H01Q 25/002 providing at least two patterns of different beamwidth; Variable beamwidth antennas
• CPC Class Codes: H01Q 3/22 varying the orientation in accordance with variation of frequency of radiated wave
• CPC Class Codes: H01Q 3/36 with variable phase-shifters

Abstract

A method is presented for operating a phased array antenna comprising a number of sub-arrays. The method comprises the steps of introducing phase offsets into signals received from/transmitted to each element in the antenna, to provide directional transmit or receive sensitivity in a first direction; summing signals received from each element in each sub-array to provide respective sub-array signals; introducing respective phase offsets into the respective sub-array signals to adjust the direction of maximum sensitivity within a sensitivity envelope defined by the phase offsets applied to each element of the antenna as a whole. The method further comprises the step of adjusting the phase offset of each element of each respective sub-array by a respective amount, thereby to alter the directional sensitivity of each respective sub-array, respective sub-arrays having the phase offset of their elements adjusted by differing amounts thereby providing the sub-arrays with a variety of directional sensitivities diverging from the first direction.

Claims

1. A method for operating a phased array antenna (10), itself comprising a number of sub-arrays (36), comprising the steps of:

introducing phase offsets (14) into signals received from/transmitted to each element (12) in the antenna, to provide directional transmit or receive sensitivity in a first direction;

summing (22) signals received from each element in each sub-array to provide respective sub-array signals (38);

introducing respective phase offsets (48) into the respective sub-array signals to adjust the direction of maximum sensitivity (52, 54, 56) within a sensitivity envelope (50) defined by the phase offsets applied to each element of the antenna as a whole;

further comprising the step of;

adjusting the phase offset (14) of each element (12) of each respective sub-array (36) by a respective amount, thereby to alter the directional sensitivity of each respective sub-array, respective sub-arrays having the phase offset of their elements adjusted by differing amounts (φ

1-φ

9), thereby providing the sub-arrays with a variety of directional sensitivities diverging from the first direction.

2. A method according to claim 1 wherein each sub-array (36) is controlled such that each signal produced by an antenna element (12) is adjusted to direct the maximum sensitivity of the sub-array in a different direction from the maximum sensitivity of other sub-arrays.

3. A method according to claim 1 or claim 2 wherein adjustment of the phase offsets (48) applied to the sub-array signals (38) allows the maximum sensitivity of the whole phased array antenna to be adjusted over a range varying between extremes of the directional sensitivities of the sub-arrays.

4. A method according to any preceding claim wherein the sub-arrays are arranged in a one-dimensional or two-dimensional array, and that the phase offsets applied to the antenna elements (12) and the sub-array signals (38) provide beam steering respectively in one or two dimensions.

20. A method or an antenna according to any preceding claim wherein the direction(s) of maximum response of the antenna are scanned across a certain angle by adjusting the phase shifts applied to the signals from/to each antenna element.

21. A method or an antenna according to any preceding claim wherein the direction(s) of maximum response of the antenna are scanned across a certain angle by adjusting the phase shifts applied to the signals from/to each sub-array.

22. A method according to any of claims 1-4 or 20-21 further comprising the steps of scanning the direction(s) of maximum response through an angle in order to locate an object, then tracking the location of that object by suitable adjusting the phase shifts applied to the antenna element signals and/or the sub-array signals, thereby to maintain a maximum response in a direction substantially corresponding to the direction of the location of the object.

23. A method according to claim 22 wherein the sub-arrays of the antenna are configured such that all sub-array signals (38) have a same phase shift (48) applied, the tracking of the object being achieved by adjusting the phase shifts (14) applied to the individual antenna elements.

24. A method according to claim 22 wherein the sub-arrays of the antenna are configured such that the antenna elements of each respective sub-array all have a same phase shift (14) applied, the tracking of the object being achieved by adjusting the phase shifts (44) applied to the sub-array signals.

5. A phased array antenna comprising a matrix of sub-arrays (36), each sub-array having a corresponding plurality of antenna elements (12), each antenna element having an associated phase shifting element (14) applying a phase shift to a signal received by the phase shifting element

for transmission by,

or in response to reception by,

a corresponding antenna element (12), each antenna element of a first subarray having a first value (φ

1) of a phase shift applied to the corresponding signal (38), each antenna element of a second sub-array having a second value (φ

2) of a phase shift applied to the corresponding signal.

6. A phased array antenna according to claim 5 wherein each sub-array further comprises a sub-array summing unit (22) for summing the signals received from each of the antenna elements.

7. A phased array antenna according to claim 6 wherein the sub-array summing unit applies differing weighting values to signals received from differing antenna elements, thereby to provide a degree of aperture shading.

8. A phased array antenna according to any of claims 5-7, further comprising a further summing unit (40) for summing the signals (38) produced by each of the sub-array summing units to produce a received antenna signal (42) having a response equivalent to a combination of the responses of each sub-array.

9. A phased array antenna according to claim 8 wherein the further summing unit applies differing weighting values to signals received from differing sub-arrays, thereby to provide a degree of beam steering.

10. A phased array antenna according to claim 9 wherein the summing unit is arranged to apply a zero weighting to the signals received from certain sub-arrays, thereby eliminating the contribution of the corresponding sub-arrays from the response of the antenna.

11. A phased array antenna according to any of claims 5-10 wherein each antenna element (12) of a first sub-array has a first value ( 

1) of a phase shift applied to the corresponding signal (38), each antenna element of a second sub-array having a second value (φ

2) of a phase shift applied to the corresponding signal.

12. A phased array antenna according to any of claims 5-11, comprising a plurality of sub-arrays, each sub-array having different phase shifts applied to the signals received from/supplied to their antenna elements, wherein at least two different combinations of sub-array signals are summed to provide an antenna response comprising a corresponding at least two response maxima representing a combination of the individual responses of such sums, each of such maxima representing an antenna response corresponding to a combination of the responses of the sub-arrays whose output is summed.

13. A phased array antenna according to claim 12 wherein the resultant antenna response comprises a plurality of relatively high gain responses in first directions separated by a corresponding plurality of relatively low gain responses in second directions, each of said first directions lying between a pair of second directions.

14. A phased array antenna according to claim 13 wherein all of first and second directions lie substantially in a first plane and wherein the first plane is swept through an angle, itself in a plane substantially orthogonal to the first plane.

15. A phased array antenna according to claim 14 wherein the antenna is arranged to perform sweeping by adjustment of phase shifts applied to individual antenna elements, and/or to sub-array signals.

16. A phased array antenna according to any of claims 5-15 wherein the antenna comprises a face divided into regions, each region containing the antenna elements of a respective sub-array.

17. A phased array antenna according to claim 16 wherein the boundaries between the regions are randomised.

18. A phased array antenna according to any of claims 5-17 further comprising a digital converter (44) associated with each sub-array signal for providing a digital representation of the sub-array signal.

19. A phased array antenna according to claim 18 wherein the digital representation of the sub-array signals are provided to at least one digital summing unit to provide a digital representation of the sum of the corresponding sub-array signals.

25. A method substantially as described and/or as illustrated in FIGS. 4 et seq. of the accompanying drawings.

26. A phased array antenna substantially as described and/or as illustrated in FIGS. 4 et seq. of the accompanying drawings.