Optical system for microwave beamforming using intensity summing
AssigneeThe United States of America as represented by the Secretary of the Air Force
InventorsDonald W. Hanson, David L. Fried
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Abstract
An optically based feed structure is used to distribute appropriately phased signals from a central signal generator to the individual elements of a phased array antenna. Any phase can be generated by adding together four phased signals (phased by 90 degree increments) if the amplitudes of the individual phased signals are appropriately controlled. By appropriately controlling the amplitude of the individual phased signals the amplitude of the resultant can also be controlled. In many cases it is desired to keep this amplitude constant. In some cases an amplitude taper across the phased array is desired.
Claims25
An optical microwave beamforming network comprising;
- a means for producing a plurality of modulated light beams which all have the same modulation frequency but are separated from each other by a first difference in phase of the modulation signal;
- a plurality of banks of variable attenuators in which each variable attenuator produces an optical output signal by receiving and attenuating one of the modulated coherent light beams from producing means;
- a plurality of detectors, each of which outputs an RF electrical signal with adjusted phase by processing the optical output signals of all the variable attenuators in one of the banks of variable attenuators;
- a means for amplifying the RF electrical signals produced by the plurality of detectors, said amplifying means producing thereby a plurality of amplified RF electrical signals with adjusted phase;
- and
- a plurality of radiating antenna elements, each of which are electrically connected to said amplifying means to receive therefrom one of said plurality of amplified RF electrical signals, said plurality of radiating RF antenna elements thereby radiating an RF waveform which is steered by the adjusted phase between the different amplified RF electrical signals.
A process for microwave beamforming comprising the steps of:
- producing a plurality of modulated light beams which are separated from each other by first differences in phase of the modulation signals;
- adjustably attenuating each of said plurality of light beams to produce thereby a plurality fo combined beams which are separated from each other by second differences in phase of the modulation signals;
- electrooptically converting the plurality of combined beams into RF electrical signals which remain separated from each other by said second differences in phase;
- and
- radiating said RF electrical signals using an array of antenna elements to produce thereby a radiated waveform which is steered by the second differences in phase.
Dependencies are inferred from the claim text.