Phased array antenna and its phase calibration method

• US 8,593,337 B2
• Filed: 12/08/2011
• Issued: 11/26/2013
• Est. Priority Date: 12/09/2010
• Status: Active Grant

• Current Assignee: DENSO Corporation
• Original Assignee: DENSO Corporation
• Inventors: Ookawa, Kunihiko
• Primary Examiner(s): Keith, Jack W
• Assistant Examiner(s): BYTHROW, PETER M
• Application Number:
  US13/314,343
• Publication Number:
  US 20120146841A1
• Time in Patent Office: 719 Days
• Field of Search: 342/147, 342/157, 342159-175
• US Class Current: 342/174
• CPC Class Codes: H01Q 3/267 Phased-array testing or checking devices
• CPC Class Codes: H01Q 3/36 with variable phase-shifters

Abstract

A phased array antenna includes an oscillator, a plurality of antenna elements, a phase shifter, a distributor, a receiver, and a control processor. The control processor performs a first calibration process to calibrate a phase of the phase shifter connected to a pair of antenna elements that is selected from the antenna elements and are located at a pair of positions symmetric with respect to a central axis of an array formed by the phased array antenna, and a second calibration process to calibrate a phase of the phase shifter connected to a pair of target antenna elements with respect to a phase of the phase shifter connected to a reference antenna elements located at a central portion of the array. The pair of target antenna elements are located at a pair of positions that are symmetric with respect to the central axis of the array.

Claims

1. A phase calibration method for a phased array antenna,

the phased array antenna comprising:

an oscillator that generates radio waves;

a plurality of antenna elements;

a plurality of phase shifters, each of which is connected to each of the plurality of antenna elements and changes a phase of radio waves radiated by the plurality of antenna elements;

means for distributing radio waves generated by the oscillator to the plurality of antenna elements via the plurality of phase shifters;

means for controlling the plurality of phase shifters and the distributing means; and

a signal input part that inputs received signals outputted from a receiver that detects power of radio waves radiated by the plurality of antenna elements; and

the phase calibration method comprising;

at the controlling means,

calibrating a phase of each of the phase shifters for each pair of antenna elements located at a pair of positions symmetric with respect to a central axis of an array of the phased array antenna, among the plurality of antenna elements; and

subsequently performing, with respect to an antenna element located at a position of the central axis of the array and all pairs of antenna elements located at positions symmetric with respect to the central axis of the array, the steps of;

supplying radio waves from the oscillator via the distributing means to an antenna element located at a position of the central axis of the array and a pair of antenna elements located at positions symmetric with respect to the central axis of the array, among the plurality of antenna elements;

obtaining a directivity pattern formed by the antenna element and the pair of antenna elements from a distribution in a received power of the radio waves, received at the receiver via the signal input part, along a horizontal direction with respect to an array direction of the plurality of antenna elements, while changing a phase of each of the phase shifters connected to the pair of antenna elements in the same manner; and

setting a value of the phase of each of the phase shifters in such a manner that a level of side lobes, which occur in the directivity pattern obtained, becomes a predetermined value.

2. A phased array antenna, comprising:

an oscillator that generates radio waves;

a plurality of antenna elements;

a plurality of phase shifters, each of which is connected to each of the plurality of antenna elements and changes a phase of radio waves radiated by the plurality of antenna elements;

means for distributing radio waves generated by the oscillator to the plurality of antenna elements via the plurality of phase shifters;

means for supplying radio waves from the oscillator via the distributing means to, among the plurality of antenna elements, an antenna element located at a position of the central axis of the array and a pair of antenna elements located at positions symmetric with respect to the central axis of the array, when a phase of the plurality of antenna elements are calibrated;

a signal input part that inputs received signals outputted from a receiver that detects power of radio waves radiated by the plurality of antenna elements; and

a calibrating unit configured to;

calibrate a phase of each of the phase shifters for each pair of antenna elements located at a pair of positions symmetric with respect to a central axis of an array of the phased array antenna, among the plurality of antenna elements; and

subsequently perform, with respect to an antenna element located at a position of the central axis of the array and all pairs of antenna elements located at positions symmetric with respect to the central axis of the array, a process to;

supply, when a phase of the plurality of antenna elements are calibrated, radio waves from the oscillator via the distributing means to an antenna element located at a position of the central axis of the array and a pair of antenna elements located at positions symmetric with respect to the central axis of the array, among the plurality of antenna elements;

obtain a directivity pattern formed by the antenna element and the pair of antenna elements from a distribution in a received power of the radio waves, received at the receiver via the signal input part, along a horizontal direction with respect to an array direction of the plurality of antenna elements, while changing a phase of each of the phase shifters connected to the pair of antenna elements in the same manner; and

set a value of the phase of each of the phase shifters in such a manner that a level of side lobes, which occur in the directivity pattern obtained, becomes a predetermined value.