Narrow-band beam steering system
AssigneeHughes Aircraft Company
InventorsSamuel W. Autrey, Harold G. Drab
Life of this patent
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Abstract
A narrow-band phase shift beamformer system is disclosed. The outputs from the elements in a transducer array are each divided into two components whose amplitudes are respectively proportional to the sine and cosine of the required phase shift, which are then processed so that the steered beam may be formed by coherent summation. The proportionalities of the respective sine and cosine components are achieved by switched capacitor circuits, which are preferably implemented by LSI circuits, permitting substantial hardware savings and yielding highly accurate component proportionalities.
Claims16
In a phase shift beamforming system adapted to form a beam directed in a predetermined direction for a signal at a predetermined signal frequency, comprising (i) a plurality of spatially disposed energy transducers providing respective transducer signals, (ii) coupling means coupled to each transducer and adapted to form first and second transducer component signals, the amplitude of the first component signal being proportional to the sine of the desired phase shift for the respective transducer and the amplitude of the second component signal being proportional to the cosine of the desired phase shift for the respective transducer, and (iii) summing means adapted to introduce a relative phase shift between the two component signals and combine such signals to provide a sum signal, the improvement wherein:
- said coupling means comprises:
- (i) first switched capacitor circuit means coupling such transducer to such summing means for transferring to said summing means a precise charge amplitude comprising said first component signal;
- and
- (ii) second switched capacitor circuit means coupling such transducer to such summing means for transferring to said summing means a precise charge amplitude comprising said second component signal;
- said first and second circuit means being cooperativley arranged so that said charge amplitudes form a predetermined ratio;
- and
- wherein said summing means comprises means for collecting the charges transferred from said respective circuit means and coverting said charges into working voltages which may be combined to form said sum signal.
A phase shift beamformer system operable on the transducer signals of an array of energy transducers to form a plurality of beams respectively steered to a predetermined direction, comprising, for each transducer:
- sine circuit branch means coupled to such transducer and adapted to provide a sine component signal whose amplitude is proportional to the sine of the phase shift desired to be introduced to said transducer signal, said sine branch means comprising a first input node, a first summing node, and a first switched capacitor circuit means for transferring a precise charge amplitude comprising said sine component signal from said first input node to said first summing node;
- cosine circuit branch means coupled to such transducer and adapted to provide a cosine component signal whose amplitude is proportional to the cosine of said desired phase shift, said cosine branch means comprising a second input node, a second summing node and a second switched capacitor circuit means for transferring a precise charge amplitude comprising said cosine component signal from said second input node to said second summing node;
- said sine circuit branch means and said cosine circuit branch means being adapted such that the ratio of said sine component signal to said cosine component signal is substantially proportional to the tangent of said desired phase shift;
- and
- summing means coupled to said respective first and second summing nodes for respectively collecting the charges transferred by each of the respective sine branch means and the respective cosine branch means, converting said respective collected charges into working first and second voltages to provide a composite sine signal and a composite cosine signal, introducing a predetermined relative phase shift between said respective composite signals, and summing said composite signals to provide one such beam.
A phase shift beamformer system operable on the transducer signals of an array of energy transducers to form a plurality of beams respectively steered to predetermined directions, comprising, for each transducer:
- sine circuit branch means coupled to such transducer and adapted to provide a sine component signal whose amplitude is proportional to the sine of the phase shift desired to be introduced to said transducer signal, said sine branch means comprising a first input node, a first summing node, and a first switched capacitor circuit means for transferring a precise charge level comprising said sine component signal from said first input node to said first summing node;
- cosine circuit branch means coupled to such transducer and adapted to provide a cosine component signal whose amplitude is proportional to the cosine of said desired phase shift, said cosine branch means comprising a second input node, a second summing node, and a second switched capacitor circuit means for transferring a precise charge level comprising said sine component signal from said second input node to said second summing node;
- said sine circuit branch means and said cosine circuit branch means being fabricated on one or more MOS integrated circuits and wherein said first and second switched capacitor circuits each comprise MOS capacitors and MOS transistor switches, said respective sine and cosine circuit branch means being adapted such that the ratio of said sine component signal to said cosine component signal is substantially proportional to the tangent of said desired phase shift;
- and
- summing means coupled to said respective first and second summing nodes of sine and cosine circuit branch means for respectively collecting the charges transferred by each of the respective sine branch means and the respective cosine branch means, converting said respective collected charges into working first and second voltages to provide a composite sine signal and a composite cosine signal, introducing a predetermined relative phase shift between said respective composite signal, and summing said composite signals to provide one such beam.
Dependencies are inferred from the claim text.