Multi-arm elliptic logarithmic spiral arrays having broadband and off-axis application
AssigneeThe Boeing Company
InventorJames R. Underbrink
Life of this patent
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Abstract
A multi-arm elliptic logarithmic spiral array that is particularly effective in off-axis beamforming applications. The array is formed by providing an elliptic logarithmic spiral and a plurality of concentric ellipses which intersect with angularly spaced apart sample points on the elliptic logarithmic spiral. An odd number of sample points are included on each ellipse. The array of the present invention is particularly effective in off-axis beamforming applications, such as aeroacoustic test applications within wind tunnels, where the location of the array is fixed and the source of noise is positioned off axis of the array.
Claims13
A non-redundant planar array for reducing sidelobes in at least one of source maps and projected beams during beam forming, said array comprising:
- an elliptical logarithmic spiral having a plurality of sample points spaced apart thereon;
- a plurality of multi-arm elliptic logarithmic arrays formed by a plurality of ellipses, wherein said ellipses are each formed off of a respective one of said sample points on said elliptical logarithmic spiral so as to each intersect a respective one of said sample points;
- wherein each said ellipse includes an odd number of equi-angularly spaced sample points;
- and
- wherein a plurality of array elements are disposed at said sample points.
A non-redundant planar array for reducing sidelobes in source maps or projected beams during off axis beam forming, said array comprising:
- an elliptical logarithmic spiral having a plurality of sample points spaced apart thereon;
- a plurality of multi-arm elliptic logarithmic arrays formed by a plurality of ellipses, wherein said ellipses are each formed off of a respective one of said sample points on said elliptical logarithmic spiral so as to each intersect a respective one of said sample points;
- wherein each said ellipse includes an odd number of equi-angularly spaced sample points and said ellipses are disposed concentrically with one another;
- and
- wherein a plurality of array elements are disposed at said sample points.
A method for forming a non-redundant planar array having reduced sidelobes in source maps or projected beams during off axis beam forming, said method comprising:
- forming an elliptical logarithmic spiral having a maximum desired radius;
- selecting a plurality of angularly spaced apart sample points on said elliptical logarithmic spiral;
- forming a plurality of multi-arm elliptic logarithmic arrays via a plurality of ellipses, wherein said ellipses are each formed to intersect a respective one of said sample points on said elliptical logarithmic spiral;
- including an odd number of equi-angularly spaced sample points on each said ellipse;
- and
- disposing an array element at a plurality of said sample points.
Dependencies are inferred from the claim text.