Feed network scanning antenna employing rotating directional coupler

• US 4,241,352 A
• Filed: 09/15/1976
• Issued: 12/23/1980
• Est. Priority Date: 09/15/1976
• Status: Expired due to Term

• Current Assignee: Ball Aerospace & Technologies Corporation (Ball Corporation)
• Original Assignee: Ball Brothers Research Corporation (Ball Corporation)
• Inventors: Alspaugh, Mark H., Murphy, Lawrence R.
• Primary Examiner(s): Lieberman, Eli
• Application Number:
  US05/723,643
• Time in Patent Office: 1,560 Days
• Field of Search: 343/778, 343/854, 343/876, 343/100 SA, 333/31 R, 333/84 M, 333/98 TN, 333/116, 333/261
• US Class Current: 343/700.0MS
• CPC Class Codes: H01P 5/04 with variable factor of coupling
• CPC Class Codes: H01P 5/16 Conjugate devices, i.e. devices having at least one port decoupled from one other port
• CPC Class Codes: H01Q 3/32 by mechanical means
• CPC Class Codes: H01Q 9/0407 Substantially flat resonant element parallel to ground plane, e.g. patch antenna dipole H01Q9/285; monopole H01Q9/40

Abstract

A method and system for beam steering of a spatially fixed microwave antenna array. The phase of radiating elements and hence the beam position is established by the relative positions of a microwave disc or scan network having concentric microstrip paths thereon and a mechanically driven rotating directional coupler. The directional coupler is the single point feed for the antenna array.

Claims

1. A microwave beam scanning antenna system having an antenna array comprising a plurality of antenna elements, a single point signal feed network, and a scan network coupling the single point signal feed network to said antenna array, said scan network comprising a plurality of coupling paths extending between said single point feed network and said antenna elements and including a planar portion and further including a cyclically mechanically displaced coupler spaced from but coplanar to said planar portion for electrically coupling said single point feed network to varying locations along said plurality of coupling paths, whereby the respective lengths of said plurality of coupling paths and hence phasing of the signals thereon vary in a cyclic fashion to achieve beam scanning of said antenna array.

2. A microwave beam scanning antenna system in accordance with claim 1 wherein said planar portion of said plurality of coupling paths are formed at least in part by conducting elements disposed in planar concentric circular segments, and wherein said cyclically mechanically displaced coupler comprises a rotating directional coupler coplanar to and cyclically rotating about the center of said concentric circular segments.

4. A microwave beam scanning antenna system in accordance with claim 1 wherein said plurality of coupling paths are formed of microstrip transmission lines.

5. A microwave beam scanning antenna system in accordance with claim 4 wherein said plurality of coupling paths are all the same physical length, with their electrical length and hence phase of the signals thereon being cyclically varied by said cyclically mechanically displaced coupler.

6. A microwave beam scanning antenna system in accordance with claim 5 wherein said cyclically mechanically displaced coupler is displaced in a linear fashion to achieve linear variation of phase in signals on said plurality of coupling paths.

3. A microwave beam scanning antenna system having an antenna array comprising a plurality of antenna elements, a single point signal feed network, and a scan network coupling the single point signal feed network to said antenna array, said scan network comprising a plurality of coupling paths extending between said single point feed network and said antenna elements and including a planar portion formed at least in part by conducting elements disposed in planar concentric circular segments, and further including a cyclically mechanically displaced coupler comprising a rotating directional coupler spaced from and coplanar to and cyclically rotating about the center of said concentric circular segments for electrically coupling said single point feed network to varying locations along said plurality of coupling paths, whereby the respective lengths of said plurality of coupling paths and hence phasing of the signals thereon vary in a cyclic fashion to achieve beam scanning of said antenna array, and wherein said concentric circular segments are formed as a plurality of concentric sets of approximate semicircles, each set comprising two facing approximate semicircles having the same radius, the two approximate semicircles in each set being coupled to corresponding respective elements in said antenna array on opposite sides of the center line of said array, with semicircle sets of increased radius coupled to antenna elements of increased distance from the center line of said antenna array.

7. A microwave beam scanning antenna system having an antenna array comprising a plurality of antenna elements, a single point signal feed network, and a scan network coupling the single point signal feed network to said antenna array, said scan network comprising a plurality of coupling paths formed of microstrip transmission lines extending between said single point feed network and said antenna elements and including a planar portion, and further including a cyclically mechanically displaced coupler spaced from but coplanar to said planar portion for electrically coupling said single point feed network to varying locations along said plurality of coupling paths, whereby the respective lengths of said plurality of coupling paths and hence phasing of the signals thereon vary in a cyclic fashion to achieve beam scanning of said antenna array, wherein said plurality of coupling paths are all the same physical length, with their electrical length and hence phase of the signals thereon being cyclically varied by said cyclically mechanically displaced coupler which is displaced in a linear fashion to achieve linear variation of phase in signals on said plurality of coupling paths, and wherein said cyclically mechanically displaced coupler comprises a rotating directional coupler having two radial arms spaced one-quarter wavelength apart and rotating at a constant predetermined speed.

8. A method of achieving beam scanning of a microwave antenna system of the type comprising a single point system signal feed and a plurality of spatially fixed antenna elements comprising the steps of coupling the single point system signal feed through a plurality of coupling paths to the spatially fixed antenna elements, and cyclically varying the lengths of the coupling paths so as to achieve a cyclic variation in the phase of electrical signals carried thereon, wherein the coupling paths have planar concentric circular segment portions, and in which the lengths of the coupling paths are varied by rotating about the center of the concentric circular segments a directional coupler to which the single point system signal feed is connected, whereby the coupling point along the circular segments varies to vary the effective length of the overall coupling paths of which the circular segments are a part.