Multi-beam antenna
AssigneeChannel Master LLC
InventorsScott J. Cook, Bruce W. Barratt
Life of this patent
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Abstract
A modified offset parabolic antenna is disclosed which provides improved gain when receiving satellite broadcasts from geosynchronous transmission sources spaced substantially 10 degrees apart. The surface of the reflector is defined by a Zernike expansion mapped to a unit circle. The values of the parameters of the Zernike expansion are selected to provide a shaped reflector surface which focuses beams from the three separate sources onto three focal points such that the gain of the antenna is maximized. A peak beam gain for an offset beam of substantially 33.9 dBi has been achieved.
Claims7
A multibeam antenna system comprising:
- a modified offset parabolic antenna including a reflector;
- a shape G(x,y) of the reflector, when mapped to a unit circle, is determined by the Zernike expansion:
- 5 G ( x , y ) = ∑ m = 0 M ∑ n = m N ( m ) c mn Z mn ( x , y ) + d mn U mn ( x , y )
- where Zmn(x,y)=Rmn(ρ)cos φ, Umn(x,y)=Rmn(ρ)sin φ, ρ and φ being polar coordinates, and where 6 R mn ( ρ ) = ∑ s = 0 ( n - m ) / 2 ( - 1 ) s ( n - s ) ! s ! [ ( n + m ) / 2 - s ] ! [ ( n - m ) / 2 - s ] ! ρ n - 2 s ;
- the values of the parameters cmn and dmn being selected so that the reflector surface focuses beams from three separate sources spaced at approximately −10 degrees, approximately zero degrees, and approximately +10 degrees along an arc onto three focal points and maximizes the gain of the multibeam antenna system for at least the beams located at approximately +10 and approximately −10 degrees.
Dependencies are inferred from the claim text.