Phased array antenna calibration system and method

• US 6,208,287 B1
• Filed: 03/16/1998
• Issued: 03/27/2001
• Est. Priority Date: 03/16/1998
• Status: Expired due to Term

• Current Assignee: Raytheon Company (Rtx Corporation)
• Original Assignee: Raytheon Company (Rtx Corporation)
• Inventors: Bedigian, Oscar J., Sikina, Thomas V.
• Primary Examiner(s): Issing, Gregory C.
• Application Number:
  US09/042,474
• Time in Patent Office: 1,107 Days
• Field of Search: 342/174, 342/360, 342/368, 342/371, 342/372
• US Class Current: 342/174
• CPC Class Codes: H01Q 3/267 Phased-array testing or checking devices

Abstract

Apparatus and method for self-contained calibration and failure detection in a phased array antenna having a beamforming network. The beamforming network includes a plurality of array ports and a plurality of beam ports or a space fed system. A plurality of antenna elements and a plurality of transmit/receive modules are included. Each one of the modules is coupled between a corresponding one of the antenna elements and a corresponding one of the array ports. A calibration system is provided having: an RF input port; an RF detector port; an RF detector coupled to the RF detector port; and an antenna element port. A switch section is included for sequentially coupling each one of the antenna elements through the beam forming/space-fed network and the one of the transmit/receive modules coupled thereto selectively to either: (a) the detector port during a receive calibration mode; or, (b) to the RF input port during a transmit calibration mode. The switch section includes a switch for selectively coupling a predetermined one of the antenna elements, i.e., a calibration antenna element, selectively to either: (a) the RF test input of the calibration system during the receive calibration mode through a path isolated from the beamforming network; or, (b) to the detector port during the transmit calibration mode through a path isolated from the beamforming network.

Claims

1. An antenna system, comprising:

a calibration system having;

an RF input port;

an RF detector port; and

an RF detector coupled to the RF detector port;

a beamforming network having a plurality of array ports and a plurality of beam ports;

a plurality of antenna elements;

a plurality of transmit/receive modules, each one being coupled between a corresponding one of the antenna elements and a corresponding one of the array ports; and

wherein the calibration system includes;

a switch section for sequentially coupling each one of the antenna elements through the beam forming network and the one of the transmit/receive modules coupled thereto selectively to either;

(a) the detector port during a receive calibration mode;

or, (b) to the RF input port during a transmit calibration mode; and

wherein the switch section includes a switch for coupling a predetermined one of the antenna elements selectively to either;

(a) the RF input of the calibration system during the receive calibration mode through a path isolated from the beamforming network;

or, (b) to the detector port during the transmit calibration mode through a path isolated from the beamforming network.

2. The antenna system recited in claim 1 wherein the predetermined one of the plurality of antenna elements is disposed near a peripheral region of the plurality of antenna elements.

3. The system recited in claim 1 including a beam steering computer responsive to beam steering command signals for producing gain and phase control signals for the plurality of transmit/receive modules, such beam steering commands being modified by gain and phase calibration data stored in the beam steering computer and calculated in response to signals produced by the RF detector.

13. The antenna system recited in claim 1 wherein the predetermined one of the antenna elements has a pair of ports, one of such ports being coupled to the one of the transmit/receive modules coupled to such predetermined one of the antenna elements and the other one of the ports being coupled to the switch of the switch section.

4. A method for calibrating an antenna system having a plurality of antenna elements, a beamforming network having a plurality of array ports and a plurality of beam ports, and a plurality of transmit/receive modules, each one of the transmit/receive modules being coupled to a corresponding one of the plurality of array ports and to a corresponding one of the plurality of antenna elements, comprising the steps of:

providing a calibration system having;

an RF input port;

an RF detector port; and

an RF detector coupled to the RF detector port;

sequentially coupling each one of the antenna elements through the beam forming network and the one of the transmit/receive modules coupled thereto selectively to either;

(a) the detector port during a receive calibration mode;

or, (b) the RF input port during a transmit calibration mode; and

coupling a predetermined one of the plurality of antenna elements selectively to either;

(a) the RF input during the receive calibration mode through a path isolated from the beam forming network;

or, (2) the detector port during the transmit calibration mode through a path isolated from the beam forming network.

5. The method recited in claim 4 wherein the predetermined one of the plurality of antenna elements is disposed near a peripheral region of the plurality of antenna elements.

6. The method recited in claim 4 wherein the system includes a beam steering computer responsive to beam steering command signals for producing gain and phase control signals for the plurality of transmit/receive modules, such method including the step of:

modifying the beam steering commands by gain and phase calibration data stored in the beam steering computer and calculated in response to signals produced by the RF detector.

14. The method recited in claim 4 including providing the predetermined one of the antenna elements with a pair of ports, one of such ports being coupled to the one of the transmit/receive modules coupled to such predetermined one of the antenna elements and the other one of the ports being coupled to the calibration system.

7. A method for calibrating an antenna phase system having a plurality of antenna elements coupled to a beamforming network through a plurality of transmit/receive modules, such method comprising the steps of:

transmitting a radio frequency energy test signal to a first predetermined one of the plurality of antenna elements through a path isolated from the beamforming network during a receive calibration mode;

coupling the transmitted energy from the first predetermined one of the antenna elements to the other ones of the antenna elements during the receive calibration mode;

passing a portion of the energy coupled to a first selected one of the antenna elements during the receive calibration mode through the beamforming network to a detector;

transmitting a radio frequency energy test signal to a second selected one of the plurality of antenna elements through a path passing through the beamforming network during a transmit calibration mode;

coupling the transmitted energy from the second selected one of the antenna elements to the other ones of the antenna elements during the transmit calibration mode;

passing a portion of the energy coupled to a second predetermined one of the antenna elements during the transmit calibration mode to the detector through a path isolated from the beamforming network; and

measuring the amplitude and phase of the radio frequency energy passed to a detector.

8. The method recited in claim 7 wherein the system includes a beam steering computer responsive to beam steering command signals for producing gain and phase control signals for the plurality of transmit/receive modules, such method including the step of:

modifying the beam steering commands by gain and phase calibration data stored in the beam steering computer and calculated in response to signals produced by the RF detector.

9. The method recited in claim 7 wherein the first predetermined one of the antenna elements is the second predetermined one of the antenna elements and the first selected one of the antenna elements is the second selected one of the antenna elements.

15. The method recited in claim 7 including providing the second predetermined one of the antenna elements with a pair of ports, one of such ports being coupled to one of the transmit/receive modules coupled to such second predetermined one of the antenna elements and the other one of the ports being coupled to the detector.

10. A method for calibrating an antenna phase system having a plurality of antenna elements, each one of the antenna elements being coupled to a corresponding one of a plurality of array ports of a beamforming network through a corresponding one of a plurality of array transmit/receive modules, such beamforming network having a plurality of beam ports, such method comprising the steps of:

transmitting a radio frequency energy test signal to a first predetermined one of the antenna elements through a path isolated from the beamforming network during a receive calibration mode;

coupling the transmitted energy from the first predetermined one of the antenna elements to other ones of the plurality of antenna elements during the receive calibration mode;

sequentially activating each one of the array transmit/receive modules to couple portions of the radio frequency energy coupled to the other ones of the antenna elements during the receive calibration mode to a detector through a path passing through the beamforming network;

sequentially activating each one of the array transmit/receive modules to couple a radio frequency energy test signal to the antenna element coupled to the activated one of the antenna elements through a path passing through the beamforming network during a transmit calibration mode;

coupling the transmitted energy from the antenna elements to a second predetermined one of the plurality of antenna elements during the transmit calibration mode;

coupling the energy coupled to the second predetermined one of the antenna elements during the transmit calibration mode to the detector through a path isolated from the beamforming network; and

measuring the amplitude and phase of the radio frequency energy coupled to a detector.

11. The method recited in claim 10 wherein the system includes a beam steering computer responsive to beam steering command signals for producing gain and phase control signals for the plurality of transmit/receive modules, such method including the step of:

modifying the beam steering commands by gain and phase calibration data stored in the beam steering computer and calculated in response to signals produced by the RF detector.

12. The method recited in claim 10 wherein the first predetermined one of the plurality of antenna elements is the second predetermined one of the plurality of antenna elements.

16. The method recited in claim 10 including providing the second predetermined one of the antenna elements with a pair of ports, one of such ports being coupled to one of the transmit/receive modules coupled to such second predetermined one of the antenna elements and the other one of the ports being coupled to the detector.