Radar antenna system

• US 6,531,980 B1
• Filed: 07/12/1994
• Issued: 03/11/2003
• Est. Priority Date: 03/12/1991
• Status: Expired due to Term

• Current Assignee: Thales Holdings UK Plc (Thales SA)
• Original Assignee: Airsys Atm Limited
• Inventors: Jones, David Kelvin
• Primary Examiner(s): Blum, Theodore M.
• Application Number:
  US08/274,119
• Time in Patent Office: 3,164 Days
• Field of Search: 342/374, 342/372, 342/154, 342/157
• US Class Current: 342/157
• CPC Class Codes: G01S 7/2813 Means providing a modification of the radiation pattern for cancelling noise, clutter or interfering signals, e.g. side lobe suppression, side lobe blanking, null-steering arrays specially adapted to secondary radar systems G01S13/762; aerials or aerials systems H01Q21/29, H01Q25/00
• CPC Class Codes: G01S 7/42 Diversity systems specially adapted for radar
• CPC Class Codes: H01Q 21/061 Two dimensional planar arrays

Abstract

In a radar antenna system comprising antenna elements arranged in an active array, the elements are located in predetermined groups such that an individual group can be selected electronically from within the whole array aperture, the said selection being effected by variable attenuator means. This produces a phase difference between direct and multipath reflections so that the radar information from a direct reflection can be distinguished from multipath information.

Claims

1. A method of operating a radar antenna system comprising an active antenna array formed of antenna elements each of which is connected directly to a respective RF transceiver module, the method of operation comprising the steps of:

establishing a first element group consisting of a predetermined number of antenna elements within the array,

establishing a second element group consisting of said predetermined number of antenna elements within the array by shifting a block of the same number of elements about the array,

transmitting a radar signal from at least one of said element groups,

receiving a return signal at said element groups, and

producing a variation in phase difference between a direct and a multipath reflection of the transmitted signal by switching a radar receiver electronically between said first and said second element groups to change a phase centre of the antenna array.

2. A method as claimed in claim 1, in which the antenna elements of said second block include some of said elements present in said first block.

3. A method as claimed in claim 1, in which two or more element groups of the array are arranged such that an antenna phase centre is established and is movable vertically as well as horizontally within the array area.

4. A method as claimed in claim 3, in which the element groups are arranged such that the antenna phase center is able to be rotated one of circularly or elliptically within the array area.