Communications: directive radio wave systems and devices (e.g. – Directive – Including a steerable array
Patent
1992-11-13
1994-04-26
Issing, Gregory C.
Communications: directive radio wave systems and devices (e.g.,
Directive
Including a steerable array
342368, 359191, 359238, 359578, H01Q 322, H04B 1000, G02F 200, G02B 2606
Patent
active
053070739
ABSTRACT:
A compact, stable, and optically efficient two dimensional spatial light modulator-based electro-optical control system for large (>1000 elements) phase-based phased array antennas uses two externally phase-locked lasers to generate respective pluralities of first and second light beams that are respectively mutually orthogonally polarized. Respective ones of the first and second light beams are combined to pass along collinear and coincident paths to form a plurality of combined light beams. The frequency difference between the first and second light beams which form the constituent beams in each combined beam cause an interference pattern that, upon heterodyne detection of the optical signal and conversion to an electrical antenna drive signal, provides control of the carrier frequency for driving the antenna. A phase delay is introduced via electrical control of an array of birefringent-mode nematic liquid crystal pixels that selectively phase delay one of the constituent light beams having a predetermined linear polarization in each combined light beam, while the other constituent beam is not phase delayed and is used as a reference for microwave/millimeter wave signal generation via interferometric detection through a photodiode. Further, a frequency shift unit coupled to the laser assembly enable an intermediate frequency offset to be selectively introduced, such as during receive cycles of the radar, such that electrical output signals generated by the optical signal processing system exhibit a desired intermediate frequency.
REFERENCES:
patent: 5117239 (1992-05-01), Riza
patent: 5187487 (1993-02-01), Riza
patent: 5191339 (1993-03-01), Riza
Riza, Nabeel A., An Acoustooptic Phased Array Antenna Beamformer with Independent Phase and Carrier Control Using Single Sideband Signals, Feb. 1992, IEEE Photonics Technology Letters, vol. 4, No. 2, pp. 177-179.
Day, T. et al., Active Frequency Stabilization of a 1.062-um, Nd:GGG, Diode-Laser-Pumped Nonplanar Ring Oscillator to Less Than 3 Hz of Relative Linewidth, Feb. 15, 1990, Optics Letters, vol. 15, No. 4, pp. 221-223.
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Riza, N. A., White Paper, Millimeter Wave Optically Controlled Phased Array Radar, Proposal to Wright Labs, BAA No. 92-05 and U.S. Army CECOM, Space Systems Directorate DAA B07, pursuant to Request for Proposal, submitted as confidential proprietary information (not published), Apr. 15, 1992.
Riza, N. A., Time-Multiplexed Phased-Array Antenna Beam Switching System, Copending patent application Ser. No. 07/826,501, filed 27 Jan. 1992.
Riza, N. A., Optical Time Delay Units for Phased Array Antennas, Ser. No. 07/900,877, filed 18 Jun. 1992.
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General Electric Co.
Issing Gregory C.
Meise W. H.
Nieves C. A.
Young S. A.
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