Adaptive array antenna

• US 6,624,784 B1
• Filed: 05/30/2000
• Issued: 09/23/2003
• Est. Priority Date: 07/13/1998
• Status: Expired due to Fees

• Current Assignee: NTT Mobile Communications Network Inc. (Nippon Telegraph and Telephone Corporation)
• Original Assignee: NTT Mobile Communications Network Inc. (Nippon Telegraph and Telephone Corporation)
• Inventors: Yamaguchi, Ryo
• Primary Examiner(s): PHAN, DAO LINDA
• Application Number:
  US09/508,079
• Time in Patent Office: 1,211 Days
• Field of Search: 342/368, 342/372, 342/378, 342/383
• US Class Current: 342/378
• CPC Class Codes: H01Q 3/2605 Array of radiating elements provided with a feedback control over the element weights, e.g. adaptive arrays
• CPC Class Codes: H01Q 3/2611 Means for null steering; Adaptive interference nulling
• CPC Class Codes: H01Q 3/2629 Combination of a main antenna unit with an auxiliary antenna unit
• CPC Class Codes: H01Q 3/2635 the auxiliary unit being composed of a plurality of antennas
• CPC Class Codes: H01Q 3/267 Phased-array testing or checking devices
• CPC Class Codes: H04B 17/20 of receivers
• CPC Class Codes: H04B 7/04 using two or more spaced independent antennas
• CPC Class Codes: H04B 7/0842 Weighted combining

Abstract

An adaptive array antenna having a plurality of array antennas including a plurality of antenna elements which are spaced at first intervals at which a large first correlation is exhibited, the array antennas being spaced at second intervals at which a second correlation is negligible, where a diversity of effects are produced, such as fading compensation, eliminating by interference waves coming from the same direction, and augmenting the gain by main beam tracking, providing one or more calibration signal coupling parts and multi-beam synthesizing circuit are so as to remove individual variations in calibration signals and to perform highly reliable calibration.

Claims

1. An adaptive array antenna comprising:

a plurality of array antennas, each array antenna including a plurality of antenna elements spaced at first intervals so that a first correlation is exhibited, said array antennas spaced at second intervals so that a second correlation compared to the first correlation is negligible;

an adaptive signal processing unit, wherein outputs of said antenna elements are converted into baseband and processed by the adaptive signal processing unit simultaneously;

a multi-beam synthesizing circuit to synthesize multiple beams;

a plurality of calibration signal coupling parts configured so that each array antenna is connected to said multi-beam synthesizing circuit through each of a respective calibration signal coupling part of the plurality of calibration coupling parts;

a plurality of receiving systems each connected to said multi-beam synthesizing circuit;

a calibration signal generator; and

a calibration amount calculator configured to communicate with the plurality of receiving systems and the adaptive signal processing unit, wherein said calibration signal generator applies a calibration signal to each of said plurality of calibration signal coupling parts, and said calibration amount calculator calculates a calibration amount for performing a calibration for each receiving system.

2. An adaptive array antenna comprising:

a plurality of array antennas, each array antennas including a plurality of antenna elements spaced at first intervals so that a first correlation is exhibited, said array antennas spaced at second intervals so that a second correlation compared to the first correlation is negligible;

a first adaptive signal processing unit, wherein an output of each of said plurality of array antennas is processed by the first adaptive signal processing unit independently; and

a second adaptive signal processing unit, wherein the output of each of said plurality of array antennas processed by the first adaptive signal processing unit is being further processed by a second adaptive signal processing unit.

4. The adaptive array antenna as claimed in one of claims 2-3, wherein said first adaptive signal processing unit performs one of interference suppression tracking and maximum gain tracking.

5. The adaptive array antenna as claimed in one of claims 2-3, wherein signals to which weights are assigned by said first adaptive signal processing unit are synthesized either before detection or after detection.

3. An adaptive array antenna comprising:

a plurality of array antennas, each array antenna including a plurality of antenna elements spaced at first intervals so that a first correlation is exhibited, said array antennas spaced at second intervals so that a second correlation compared to the first correlation is negligible;

a first adaptive signal processing unit, wherein an output of at least an array antenna of said plurality of array antennas is processed by the first adaptive signal processing unit and other array antennas adjust a phase and level of outputs of antenna elements of said other array antennas based on an output processed by the first adaptive signal processing unit from the at least an array antenna;

a second adaptive signal processing unit, wherein each output of the at least an array antenna processed by the first adaptive signal processing unit is further processed by the second adaptive signal processing unit.

6. An adaptive array antenna comprising:

an array antenna having a plurality of antenna elements;

a multi-beam synthesizing circuit for synthesizing multiple beams;

a calibration signal coupling part, provided between said multi-beam synthesizing circuit and one antenna element of the plurality of antenna elements, for inputting a calibration signal;

a plurality of receiving systems each connected to said multi-beam synthesizing circuit;

a calibration signal generator; and

a calibration amount calculator, wherein said calibration signal generator applies a calibration signal output to said calibration signal coupling part, said calibration amount calculator calculates a calibration amount for each of the plurality of receiving systems from baseband signals of said plurality of receiving systems performs a calibration of said plurality of receiving systems.

8. The adaptive array antenna as claimed in one of claims 6 or 7, further comprising a fast-fourier transform processing circuit configured to perform calculation of multi-beam resolution within a base station outside of said plurality of receiving systems.

7. An adaptive array antenna comprising:

an array antenna having a plurality of antenna elements;

a multi-beam synthesizing circuit for synthesizing multiple beams;

a plurality of calibration signal coupling parts, provided between said multi-beam synthesizing circuit and each of a respective antenna element of the plurality of antenna elements, for inputting a calibration signal;

a plurality of receiving systems each connected to said multi-beam synthesizing circuit;

a calibration signal generator; and

a calibration amount calculator, wherein said calibration signal generator applies a calibration signal output to the plurality of calibration signal coupling parts successively, said calibration amount calculator calculates a calibration amount for each of the plurality of receiving systems from baseband signals of said plurality of receiving systems every time said calibration signal output is applied to said calibration signal coupling part, and the calibration amount calculator performs a calibration of said plurality of receiving systems by using a mean value of calculated calibration amounts.

9. A calibration amount calculation method in a receiving system of an array antenna having a plurality of antenna elements, comprising:

applying a calibration signal generated by a calibration signal generator to a calibration signal coupling part provided in one antenna element;

sending said calibration signal to a plurality of receiving systems by a multi-beam synthesizing circuit; and

calculating a calibration amount of each of said plurality of receiving systems from baseband signals obtained by detecting calibration signals of said plurality of receiving systems.

10. A calibration amount calculation method in a receiving system of an array antenna having a plurality of antenna elements, comprising:

applying a calibration signal successively to a plurality of calibration signal coupling parts provided in the plurality of antenna elements;

sending said calibration signal simultaneously to a plurality of receiving systems by a multi-beam synthesizing circuit provided in the array antenna;

calculating, based on a calibration amount calculator connected to the plurality of receiving systems, calibration amounts of said plurality of receiving systems from baseband signals obtained by detecting calibration signals of said plurality of receiving systems; and

using a mean value of said calibration amounts as a calibration amount of said receiving system.

11. The calibration amount calculation method as claimed in claim 9 or 10, further comprising verifying the calibration amount calculation by providing, outside of said plurality of receiving systems of said array antenna, a fast-fourier transform processing circuit configured to calculate multi-beam resolution within a base station.

12. A calibration method for performing calibration of a receiving system of an array antenna by performing adaptive signal processing, comprising:

calculating a calibration amount in a plurality of receiving systems of the array antenna having a plurality of antenna elements;

applying a calibration signal generated by a calibration signal generator to a calibration signal coupling part provided in one antenna element;

sending said calibration signal to the plurality of receiving systems by a multi-beam synthesizing circuit;

calculating a calibration amount of each of the plurality of receiving systems from baseband signals obtained by detecting calibration signals of the plurality of receiving systems; and

performing adaptive signal processing after subtracting said calibration amount when performing adaptive signal processing for the adaptive array antenna.