Phased array antenna and its phase calibration method

Patent metadata

Field	Value
Publication number	US-8957808-B2
Application number	US-201113314354-A
Country	US
Kind code	B2
Filing date	Dec 8, 2011
Priority date	Dec 9, 2010
Publication date	Feb 17, 2015
Grant date	Feb 17, 2015

Abstract

A phase array antenna includes an oscillator, a plurality of antenna elements, a phase shifter, a distributor, a receiving unit, and a control processor. The control processor performs a calibration process to select, from the antenna elements, a reference and target antenna elements to allow the radio waves generated by the oscillator to be provided for the reference and target antenna elements via the distributor, obtain a pattern of a change in a received power of radio waves received at the receiving unit, when a phase of the phase shifter for the reference antenna element is fixed and a phase of the phase shifter for the target antenna element is changed, extract, from the pattern obtained, the phase of the phase shifter for the target antenna element at which the received power becomes a local minimal value, and add the phase extracted to 180° to set its resultant value to a calibration value for the phase of the phase shifter for the target antenna element.

First claim

What is claimed is:

1. A phased array antenna, comprising:
an oscillator that generates radio waves;
a plurality of antenna elements that radiates radio waves:
a phase shifter that is connected to each of the plurality of antenna elements and changes a phase of radio waves radiated by the plurality of antenna elements;
a distributor that distributes radio waves generated by the oscillator to the plurality of antenna elements via the phase shifter;
a receiving unit that receives radio waves radiated by the plurality of antenna elements; and
a control processor that performs a calibration process to
select, from the plurality of antenna elements, a reference antenna element to be a reference of a phase calibration for the phased array antenna and a target antenna element to be a target of the phase calibration with respect to the reference antenna element to allow the radio waves generated by the oscillator to be provided for the reference antenna element and the target antenna element via the distributor,
obtain, as a received power variation pattern, a received power of radio waves received at the receiving unit, while a phase of the phase shifter connected to the reference antenna element is fixed and a phase of the phase shifter connected to the target antenna element is changed within a range of 0° to 360° by a predetermined phase amount of a necessary accuracy, the received power variation pattern being graphically represented by the received power and the phase of the phase shifter connected to the target antenna element,
extract, from the obtained received power variation pattern, the phase of the phase shifter connected to the target antenna element at which the received power becomes a local minimal value, and
add the extracted phase to 180° to set its resultant value to a calibration value for the phase of the phase shifter connected to the target antenna element.

2. The phased array antenna according to claim 1 , wherein
the control processor repeats the calibration process while changing the target antenna element until the calibration values for all of the plurality of antenna elements are obtained.

3. The phased array antenna according to claim 2 , wherein
the reference antenna element is one antenna element that is arbitrarily selected from the plurality of antenna elements and is kept selected until the calibration values for all of the plurality of antenna elements are obtained, and
the target antenna element is one antenna element that is selected from the plurality of antenna elements except for the reference antenna element and is repeatedly changed to another antenna element until the calibration values for all of the plurality of antenna elements are obtained.

4. The phased array antenna according to claim 1 , wherein
the control processor repeats the calibration process while changing the reference antenna element and the target antenna element until the calibration values for all of the plurality of antenna elements are obtained.

5. The phased array antenna according to claim 4 , wherein
the reference antenna element is one antenna element that is selected from the plurality of antenna elements and is repeatedly changed to another antenna element that was used as the target antenna element and its calibration value was obtained until the calibration values for all of the plurality of antenna elements are obtained, and
the target antenna element is one antenna element that is selected from the plurality of antenna elements adjacent to the reference antenna element and is repeatedly changed until the calibration values for all of the plurality of antenna elements are obtained.

6. A phase calibration method for a phased array antenna that comprises an oscillator that generates radio waves, a plurality of antenna elements that radiates radio waves, phase shifter that is connected to each of the plurality of antenna elements and changes a phase of radio waves radiated by the plurality of antenna elements, distributor that distributes radio waves generated by the oscillator to the plurality of antenna elements via the phase shifter, receiving unit that receives radio waves radiated by the plurality of antenna elements, and a control processor that performs a calibration process for the phased array antenna, the phase calibration method comprising:
at the control processor,
selecting, from the plurality of antenna elements, a reference antenna element to be a reference of a phase calibration for the phased array antenna and a target antenna element to be a target of the phase calibration with respect to the reference antenna element to allow the radio waves generated by the oscillator to be provided for the reference antenna element and the target antenna element via the distributor;
obtaining, as a received power variation pattern, a received power of the radio waves received at the receiving unit, while a phase of the phase shifter connected to the reference antenna element is fixed and a phase of the phase shifter connected to the target antenna element is changed within a range of 0° to 360° by a predetermined phase amount of a necessary accuracy, the received power variation pattern being graphically represented by the received power and the phase of the phase shifter connected to the target antenna element;
extracting, from the obtained received power variation pattern, the phase of the phase shifter connected to the target antenna element at which the received power becomes a local minimal value; and
adding the extracted phase to 180° to set its resultant value to a calibration value for the phase of the phase shifter connected to the target antenna element.

7. The phase calibration method according to claim 6 , further comprising:
repeating, at the control processor, the calibration process while changing the target antenna element until the calibration values for all of the plurality of antenna elements are obtained.

8. The phase calibration method according to claim 7 , wherein
the reference antenna element is one antenna element that is arbitrarily selected from the plurality of antenna elements and is kept selected until the calibration values for all of the plurality of antenna elements are obtained, and
the target antenna element is one antenna element that is selected from the plurality of antenna elements except for the reference antenna element and is repeatedly changed to another antenna element until the calibration values for all of the plurality of antenna elements are obtained.

9. The phase calibration method according to claim 6 , further comprising:
repeating, at the control processor, the calibration process while changing the reference antenna element and the target antenna element until the calibration values for all of the plurality of antenna elements are obtained.

10. The phase calibration method according to claim 9 , wherein
the reference antenna element is one antenna element that is selected from the plurality of antenna elements and is repeatedly changed to another antenna element that was used as the target antenna element and its calibration value was obtained until the calibration values for all of the plurality of antenna elements are obtained, and
the target antenna element is one antenna element that is selected from the plurality of antenna elements adjacent to the reference antenna element and is repeatedly changed until the calibration values for all of the plurality of antenna elements are obtained.

Assignees

• Ookawa Kunihiko
• Denso Corp

Inventors

• Ookawa Kunihiko

Classifications

• G01S7/4004 Primary

  of parts of a radar system · CPC title

• H01Q3/267

  Phased-array testing or checking devices · CPC title

• G01S7/40

  Means for monitoring or calibrating · CPC title

• H01Q3/36

  with variable phase-shifters · CPC title