NETWORK APPROACH FOR REDUCING THE NUMBER OF PHASE SHIFTERS IN A LIMITED SCAN PHASED ARRAY

• US 3,803,625 A
• Filed: 12/18/1972
• Issued: 04/09/1974
• Est. Priority Date: 12/18/1972
• Status: Expired due to Term

• Current Assignee: ITT Corporation (ITT, Inc.)
• Original Assignee: Jeffrey T. Nemit
• Inventors: Nemit, Jeffrey T.
• Primary Examiner(s): Borchelt, Archie R.
• Assistant Examiner(s): Nussbaum, Marvin
• Application Number:
  US05/316,046
• Time in Patent Office: 477 Days
• Field of Search: 343/778,854,853,777,844,754
• US Class Current: 342/368
• CPC Class Codes: H01Q 21/08 the units being spaced along or adjacent to a rectilinear path waveguide fed H01Q21/0037
• CPC Class Codes: H01Q 3/30 varying the relative phase between the radiating elements of an array H01Q3/2605, H01Q3/2658, H01Q3/2682, H01Q3/44 take precedence
• CPC Class Codes: H01Q 3/36 with variable phase-shifters

Abstract

An arrangement for scanning of an array by means of controllable phase shifters. A network approach is used to substantially reduce the number of phase shifters required for a limited-scan array. Each phase shifter output is distributed over more than one antenna element of the array. The concept is applicable to both one-dimensional and two-dimensional scanning. The grating lobes of the array factor are allowed to exist in real space but are excluded from the scan region by selecting the subarray spacing. The network is designed to suppress other grating lobes in real space.

Claims

1. A scanning phased array antenna system having a predetermined number N of antenna elements, and a distribution network having a common input terminal and a predetermined number of distribution ports M, where M is a smaller number than N, comprising:

M phase shifters each connected at its input discretely from a corresponding one of said M distribution ports;

a subarray interconnecting network having N output ports and M input ports, each of said N output ports being connected discretely to a corresponding one of said antenna elements, and each of said M input ports being connected discretely to the output of a corresponding one of said phase shifters;

divider means within said subarray interconnecting network for dividing the power input from each of said phase shifters into a primary branch and a plurality of secondary branches, said primary branch being connected to a selected one of said antenna elements and said secondary branches feeding an equal number of antenna elements adjacent on each side of said selected element; and

means associated with each antenna element fed from one of said secondary branches for combining feeds from said branches providing feed thereto from others of said phase shifters.

2. A scanning phased array antenna system comprising:

an array of antenna elements comprising a first group of main elements and a second group of spaced coupled intermingled elements comprising a subarray;

means including a plurality of discretely controllable phase shifters for providing excitation to corresponding ones of said main elements;

a plurality of power dividers connected, one to the output of each of said phase shifters, said dividers each having a main output and a plurality of branch outputs each providing power output at a predetermined fraction of the power supplied by the corresponding phase shifter, each of said main outputs being connected to an antenna element of said first group of main elements; and

a plurality of coupler means one of which is discretely connected to each element of said subarray, said couplers also being connected to mix power from at least one of said branch outputs from at least each of said power dividers corresponding to the adjacent main elements on each side of each of said subarray elements.

3. Apparatus according to claim 2 in which said array is a linear array.

4. Apparatus according to claim 2 in which said array comprises a linear array of plural subarrays, said main elements are first alternate elements of said array, and said subarrays comprise at least one element on each side of each of said main elements.

5. Apparatus according to claim 4 in which said subarray comprises one element on each side of said main element, and said main element.

6. Apparatus according to claim 2 in which said array is an area type array in which said main elements are distributed over a surface in a regular pattern, said subarray comprises an element spaced on a line between each of said maiN elements, said power divider branch outputs are six in number corresponding to six subarray elements comprising the nearest antenna elements surrounding each of said main elements, and each of said coupler means being connected to a branch output from the power dividers corresponding to a pair of adjacent, but oppositely disposed, main elements.

7. Apparatus according to claim 4 in which said divider is arranged to apportion the power in said branch outputs with respect to said main elements to produce a predetermined subarray pattern, the phase centers between said subarrays being greater than the element spacing of said array.