Communications: directive radio wave systems and devices (e.g. – Directive – Including a steerable array
Reexamination Certificate
2002-03-13
2003-01-14
Blum, Theodore M. (Department: 3662)
Communications: directive radio wave systems and devices (e.g.,
Directive
Including a steerable array
C342S372000, C342S157000
Reexamination Certificate
active
06507314
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates generally to beamformers for arrays of receiving or transmitting elements. More specifically, but without limitation thereto, the present invention relates to ground-based digital beamforming for stratospheric communications platforms.
In ground-based digital beam forming, the individual element signals of an antenna array on a stratospheric platform are linked with a ground station so that the beamforming calculations may be performed by hardware that is not subject to the power, size, and weight constraints of the stratospheric platform. In conventional digital beamforming methods, each element signal is multiplied by a different phasor corresponding to a selected beam, for example e
j&thgr;
i
, where &thgr;
i
is a phase angle calculated for each element i. The phasor products are then summed to form the selected beam. The phasors are selected so that signals arriving from a preferred direction add substantially coherently, while signals arriving from other directions add incoherently. The result is a spatial discrimination favoring signals arriving from the preferred direction and a corresponding enhancement of their signal-to-noise ratio. A problem with conventional digital beamformers is the requirement of a phasor multiplication for each element signal, typically N
2
for an N×N array. A reduction in the number of multiplications required would save processing time and resources that could be dedicated to other tasks.
SUMMARY OF THE INVENTION
The present invention advantageously addresses the needs above as well as other needs by providing a method and apparatus for beamforming signals for an array of receiving or transmitting elements.
In one embodiment, the present invention may characterized as a method for beamforming that includes the steps of selecting a beam elevation and azimuth and grouping elements of an antenna array into element ensembles that are substantially aligned with a wavefront projection on the antenna array corresponding to the selected beam elevation and azimuth.
In another embodiment, the present invention may characterized as a beamformer that includes a beam selector for selecting a desired beam elevation and azimuth and an ensemble selector for grouping elements of an antenna array into element ensembles that are substantially aligned with a wavefront projection on the antenna array corresponding to the selected beam elevation and azimuth.
The features and advantages summarized above in addition to other aspects of the present invention will become more apparent from the description, presented in conjunction with the following drawings.
REFERENCES:
patent: 4635063 (1987-01-01), Chang et al.
patent: 5017927 (1991-05-01), Agrawal et al.
patent: 5077562 (1991-12-01), Chang et al.
patent: 5218619 (1993-06-01), Dent
patent: 5550809 (1996-08-01), Bottomley et al.
patent: 5555257 (1996-09-01), Dent
patent: 5572216 (1996-11-01), Weinberg et al.
patent: 5594941 (1997-01-01), Dent
patent: 5612701 (1997-03-01), Diekelman
patent: 5810284 (1998-09-01), Hibbs et al.
patent: 5856804 (1999-01-01), Turcotte et al.
patent: 5903549 (1999-05-01), Von der Embse et al.
patent: 5909460 (1999-06-01), Dent
patent: 5917447 (1999-06-01), Wang et al.
patent: 5949766 (1999-09-01), Ibanez-Meier et al.
patent: 5973647 (1999-10-01), Barrett et al.
patent: 6111542 (2000-08-01), Day et al.
patent: 6147658 (2000-11-01), Higashi et al.
patent: 6151308 (2000-11-01), Ibanez-Meier et al.
Chan, K. K., et. al, “A Circularly Polarized Waveguide Array for Leo Satellite Communications”, Antennas and Propagation Society, 1999, IEEE International Symposium, vol. 1, Jul. 11-16, 1999, pp. 154-157.
Oodo, M., et al, “Onboard DBF Antenna for Stratospheric Platform”, 2000 IEEE International Conference on Phased Array Systems and Technology, Proceedings, May 21-25, 2000, pp. 125-128.
Yokosuka Research Park, “The First Stratospheric Platforms Systems Workshop”, May 12-13, 1999, pp. 1-216.
Chiba, Isamu et. al, “Digital Beam Forming (DBF) Antenna System for Mobile Communications”, IEEE AES Systems Magazine, Sep. 1997, pp. 31-41.
Miura, Ryu et. al, “A DBF Self-Beam Steering Array Antenna for Mobile Satellite Applications Using Beam-Space Maximal-Ratio Combination”, IEEE Trans. On Vehicular Technology, vol. 48, No. 3, May 1999, pp. 665-675.
Sato, Kazuo et al., “Development And Field Experiments of Phased Array Antenna For Land Vehicle Satellite Communications”, IEEE Antennas and Propagation Society International Symposium, 1992, Jul. 1992, vol. 2, pp. 1073-1076.
Sakakibara, Kunio et. al, “A Two-Beam Slotted Leaky Waveguide Array for Mobile Reception of Dual-Polarization DBS”, IEEE Transactions on Vehicular Technology, vol. 48, No. 1, Jan. 1999, pp. 1-7.
U.S. patent application Ser. No. 09/611,753, filed Jul. 7, 2000, Donald C. D. Chang et al.
U.S. patent application Ser. No. 09/652,862, filed Aug. 31, 2000, Donald C. D. Chang et al.
U.S. patent application Ser. No. 09/655,498, filed Sep. 5, 2000, Donald C. D. Chang et al.
Chang Donald C. D.
Hagen Frank A.
Wang Weizheng
Yung Kar
Blum Theodore M.
Duraiswamy V. D.
Hughes Electronics Corporation
Sales M. W.
LandOfFree
Ground-based, wavefront-projection beamformer for a... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Ground-based, wavefront-projection beamformer for a..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Ground-based, wavefront-projection beamformer for a... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3018086