Digital beamforming for multiple independent transmit beams
First Claim
1. In a phased array system having an antenna aperture divided into a plurality of subarrays, a method of digital beamforming of multiple independent transmit beams, comprising a sequence of the following steps:
- (i) generating in-phase (I) and quadrature (Q) sequential digital samples of a desired signal wave-form to be transmitted;
(ii) for each transmit beam to be formed, providing a different set of beamsteering phasors in digital form, each phasor representing the amplitude and phase distribution for the desired beam position and sidelobe distribution;
(iii) applying the respective sets of beamsteering phasors in digital form to said in-phase and quadrature signal components to provide resulting I and Q coefficients in digital form for each subarray;
(iv) upconverting the digital I and Q coefficients for each subarraay to an intermediate frequency (IF);
(v) converting the IF digital I and Q coefficients for each subarray into analog form;
(vi) upconverting the analog IF I and Q coefficients for each subarray to the desired RF transmit frequency;
(vii) amplifying the RF signals for each subarray; and
(viii) feeding the corresponding RF signals to the appropriate subarrays for transmission out of the array.
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Accused Products
Abstract
A phased array antenna system is disclosed which employs digital beamforming of multiple independent transmit beams. A waveform generator provides successive digitized time samples of a desired waveform, and the respective beamforming coefficients which produce the desired amplitude and phase distribution for each beam are applied to the waveform samples. The resulting digital samples are then mixed up to IF, converted to digital form, frequency converted to the desired RF frequency, amplified and passed to the respective antenna subarrays. The transmit system permits fine granularity phase control, providing accurate beamforming and positioning and improved sidelobe control.
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Citations
12 Claims
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1. In a phased array system having an antenna aperture divided into a plurality of subarrays, a method of digital beamforming of multiple independent transmit beams, comprising a sequence of the following steps:
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(i) generating in-phase (I) and quadrature (Q) sequential digital samples of a desired signal wave-form to be transmitted; (ii) for each transmit beam to be formed, providing a different set of beamsteering phasors in digital form, each phasor representing the amplitude and phase distribution for the desired beam position and sidelobe distribution; (iii) applying the respective sets of beamsteering phasors in digital form to said in-phase and quadrature signal components to provide resulting I and Q coefficients in digital form for each subarray; (iv) upconverting the digital I and Q coefficients for each subarraay to an intermediate frequency (IF); (v) converting the IF digital I and Q coefficients for each subarray into analog form; (vi) upconverting the analog IF I and Q coefficients for each subarray to the desired RF transmit frequency; (vii) amplifying the RF signals for each subarray; and (viii) feeding the corresponding RF signals to the appropriate subarrays for transmission out of the array. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A phases array system employing digital beamforming of multiple independent transmit beams, comprising:
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an antenna aperture divided into a plurality of subarrays; means for generating in-phase (I) and quadrature (Q) sequential digital samples of a desired signal waveform to be transmitted; means for providing, for each transmit beam to be formed, a different set of beamsteering phasors in digital form, each phasor representing the amplitude and phase distribution for the particular desired beam position and sidelobe distribution; means for applying the respective sets of beamsteering phasors in digital form to said in-phase and quadrature signal components to provide resulting I and Q coefficients in digital form for each subarray; means for upconverting the digital I and Q coefficients for each subarray to an intermediate frequency (IF); means for converting the digital IF I and Q coefficients for each subarray into analog form; means for upconverting the analog IF I and Q coefficients for each subarray to the desired RF transmit frequency; means for amplifying the RF signals for each subarray; and means for feeding the corresponding RF signals to the appropriate subarrays for transmission out of the array. - View Dependent Claims (8, 9, 10, 11, 12)
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Specification