Electro-optically controlled wideband multi-beam phased array antenna

Claim 2

A radiant energy receiving system having a plurality (N) of antenna elements (20...24N) for producing radio frequency (RF) signals of different phases as a function of an angle of inclination of the same wavefront of an electromagnetic wave characterised in N sets of an RF amplifier (25...29N) and a light modulator (30....34N) connected in succession from each respective one of said antenna elements(20....24N), each modulator including a lasar for producing a light output intensity modulated in accordance with the RF signal appearing at the output of the amplifier connected thereto, first, (second)...N th optical dividers (35...39N) connected from respective ones of said modulators(30...34N), a beam port (48....52M) corresponding to each one of a plurality M of different wavefront angles, a receiver (56...60M) coupled to each beam port, a light intensity demodulator (66...70M) connected to each beam port, first (second)...M th optical combiners (40....44M) connected to respective ones of said light intensity demodulators, each optical divider having a set (46) of first (second)...M th optical fibres connected therefrom, said first, (second)...M th optical fibers of said first optical divider (35) being connected from said first optical divider to said first, (second)...M th optical combiners,respectively, said first (second)...M th optical fibers of said second optical divider (36) being connected from said second optical divider to said first, (second)...M th optical combiners, respectively; ...said N th optical divider having first, (second)...M th optical fibers connected therfrom to said first, (second) ...M th optical combiners, respectively: all of said first optical fibers having lengths different from each other, all of said second optical fibers having lengths different from each other, ... and all of said M th optical fibers having lengths different from each other, said optical fibers having lengths chosen to cause signals appearing at one of said first, second, ...M th beam ports to arrive simultaneously and be in phase for received plane waves of first, second ...M th beam angles, respectively.

Claim 3

A radiant energy receiving system as claimed in claim 1, characterised in a plurality of detectors (66...70M) each comprising a conventional photodiode detector.

Claim 4

A radiant energy receiving system as claimed in claim 1 or 2, characterised in that each of the amplifiers (25....29N) comprises a gallium arsenide amplifier chip.

Claim 5

A radiant energy receiving system as claimed in any one of claims 1 to 3, characterised in that said set (46) of optical fibers provides a direct connection between said plurality of optical dividers (35....39N) and said plurality of optical combiners (40...44M).

Claim 6

A radiant energy receiving system as claimed in any one of claims 1 to 4, characterised in that each of said "N" optical dividers (35....39N) has "M" optical fibers extending therefrom, each of said "M" optical fibers being routed to one of said "M" optical combiners (40...44M) with each of "M" optical fibers carrying one of "N" optical signals derived from the radio frequency signals of each of said "N" antenna elements (20....24N).

Claim 7

A radiant energy receiving system as claimed in any one of claimes 1 to 5, characterised in that each of said "M" beam ports (48...52M) is arranged to intercept a radio frequency signal wavefront corresponding to a specific beam direction for determining the direction of propagation of said wavefront.

Claim 8

A radiant energy receiving system as claimed in any one of claims 1 to 6, characterised in that each fiber of said set of optical fibers (46) having said particularized length with each length being chosen such that each of the signals corresponding to said wavefront of a single direction are in time and phase synchronism at one and only one of said plurality of "M" beam ports (48...52M) said lengths of fiber providing a required time delay for said time and phase synchronism.

Claim 9

A radiant energy receiving system as claimed in claim 7, characterised in that the difference in lengths of said fibers for providing said time delay for a linear array is described by the general formula Δtβ - Δtα = (N-1) (d sin ϑ)/c where (Δtβ) is the length of the fiber (β -1), (Δtα) is the length of the fiber (a-1). "N" comprises the set of optical fibers, "d" is the antenna element spacing, "ϑ" is th angle of inclination of said wavefront and "c" is the speed of light.

Claim 10

A radiant energy receiving system as claimed in claim 8, characterised in that said wavefront is intercepted by a first antenna element (24N) of said plurality of "N" antenna elements and wherein said fibers of said set of optical fibers (46) extend between a first divider (35) of said plurality of optical dividers and a first combiner (40) of said plurality of optical combiners associated with said first antenna element, said fibers being of greater length than the ramaining fibers of said plurality of optical fibers for providing a longer time delay in said linear array.

Claim 11

A radiant energy receiving system as claimed in any one of the preceding claims, characterised in that each of said "N" antenna elements has an antenna spacing "d" equal to λ/2.

Claim 12

A radiant energy receiving system as claimed in any one of the preceding claims, characterised in that each of said receiver means (56...60M) at each of said beam ports (48....52M) provides for simultaneous reception of said RF signals at "M" beam directions.

Claim 13

A radiant energy receiving system as claimed in any one of claims 1 to 10, characterised in that means (144) for commutating a single receiver among the plurality of beam ports (150...153M).

Claim 14

A radiant energy receiving system as claimed in claim 12, characterised in that said means (144) for commutating a single receiver among the plurality of beam ports comprises a selector switch.

Claim 15

A radiant energy transmitting system having a plurality of N antenna elements (160..164N) for radiating electromagnetic waves at first, second ...M th angles of radio frequency (RF) signals characterised in N sets of an amplifier (168...172N) and a light intensity demodulator (176..180N) connected in succession to each respective one of said antenna elements, first, second, ...N th optical combiners (184...188N) connected to respective ones of said demodulators, a beam port (208....212M) respectively corresponding to each one of said plurality of M different wavefront angles, tranmitter means (218) connected to each beam port, a light intensity modulator (202-206) connected from each beam port; first, second, ... M th optical dividers (192...196M) connected from respective ones of said light intensity modulators, each optical divided having a set (200) of first, second, ...N th optical fibers connected therefrom, said first, second, ...N th optical fibers of said first optical divider being connected from said first optical divider to said first, second, ...N th optical combiners, respectively; said first, second, ...N th optical fibers of said second optical divider being connected from said second optical divider to said first, second, ...N th optical combiners, respectively; ...said M th optical divider having first, second, ...N th optical fibers connected therefrom to said first, second, ...N th optical combiners, respectively, all of said first optical fibers having lengths different from each other, all of said second optical fibers having lengths different from each other, ...and all of said N th optical fibers having lengths different from each other, said optical fibres having lengths chosen to cause signals applied at one of said first, second, ...M th beam ports to be translated into signals at said antenna elements to product plane waves propagated at said first, second, ...M th angles, respectively.

Claim 16

A radiant energy transmitting system having a plurality of N antenna elements (160..164N) for radiating electromagnetic waves at first, second ...M th angles of radio frequency (RF) signals characterised in N sets of an amplifier (168...172N) and a light intensity demodulator (176..180N) connected in succession to each respective one of said antenna elements, first, second, ...N th optical combiners (184...188N) connected to respective ones of said demodulators, a beam port (208....212M) respectively corresponding to each one of said plurality of M different wavefront angles, tranmitter means (218) connected to each beam port, a light intensity modulator (202-206) connected from each beam port; first, second, ... M th optical dividers (192...196M) connected from respective ones of said light intensity modulators, each optical divided having a set (200) of first, second, ...N th optical fibers connected therefrom, said first, second, ...N th optical fibers of said first optical divider being connected from said first optical divider to said first, second, ...N th optical combiners, respectively; said first, second, ...N th optical fibers of said second optical divider being connected from said second optical divider to said first, second, ...N th optical combiners, respectively; ...said M th optical divider having first, second, ...N th optical fibers connected therefrom to said first, second, ...N th optical combiners, respectively, all of said first optical fibers having lengths different from each other, all of said second optical fibers having lengths different from each other, ...and all of said N th optical fibers having lengths different from each other, said optical fibres having lengths chosen to cause signals applied at one of said first, second, ...M th beam ports to be translated into signals at said antenna elements to product plane waves propagated at said first, second, ...M th angles, respectively.

Claim 17

A radiant energy transmitting system as claimed in claim 14, characterised in means for commutating a single transmitter (218) among the plurality of beam ports comprises a selector switch (216),

Claim 18

A radiant energy transmitting system as claimed in claim 14 wherein said transmitter means comprises a plurality of transmitters, one at each of said "M" beam ports, which provide for simultaneous transmission of said RF signals at "M" beam directions.

Claim 19

A is provided a radiant energy receiving and transmitting system, the combination comprising: a plurality of "N" antenna elements (84..87N) for providing radio frequency signals of different phases as a function of an angle of inclination of the same wavefront of an electromagnetic wave and for radiating electromagnetic waves at a first, second, ...M th angles of radio frequency signals characterised in a plurality of "N" sets of a first amplifier (96...99N) and a first light modulator (102...105N) connected in succession from each respective one of said plurality of antenna elements, each modulator including a laser for producing a light output intensity modulated in accordance with the radio frequency signal appearing at the output of the amplifier connected thereto, a plurality of "N" sets of a second amplifier (92....95N) and a first light intensity demodulator (108..111N) connected in succession to each respective one of said plurality of antenna elements (84...87N), a plurality of first, second, ...N th optical divider-combiners (114...117N) connected from repective ones of said first light modulators and demodulators for dividing and combining said modulated light, a plurality of "M" beam ports (150...153M) for receive and "M" beam ports (146...149M) for transmit with each beam port corresponding to one of a plurality of "M" different radiant wavefront angles, a receiver means (82) connected from each receive beam port for receiving said radio frequency signals and a transmitter means (80) connected to each transmit beam port for transmitting said radio frequency signals, a plurality of second light intensity demodulators (138...141M), each second demodulator connected to one of said plurality of receive beam ports (150...153M) for demodulating said radio frequency signals and a plurality of second light intensity modulators (132...135M), each second modulator connected to one of said plurality of transmit beam ports (146..149M) for modulating said radio frequency signals, a plurality of first, second, ...M th optical combiner-­dividers (125...128M) connected to respective ones of said second light intensity demodulators and said second light intensity modulators for dividing and combining said modulated light, said plurality of optical divider-­combiners having a set of first, second, ...M th optical fibers connected therefrom, said first, second, ...M th optical fibers of said first optical divider-combiner being connected from said first optical divider-combiner to said first, second, ...M th optical combiner-dividers, respectively, said first, second, ...M th optical fibers of said second optical divider-combiner being connected from said second optical divider-combiner to said first, second, ...M th optical combiner-dividers, respectively, ... said N th optical divider-combiner having first, second, ...M th optical fibers connected therefrom to said first, second, ...M th optical combiner-dividers, respectively, all of said first, second, ...M th optical fibers having lengths different from each other, said optical fibers having lengths chosen for appropriate time delays to cause signals appearing at one of said first, second, ...M th beam ports to be in time and phase synchronism for received plane waves of first, second, ...M th angles, respectively.

Claim 20

A is provided a radiant energy receiving and transmitting system, the combination comprising: a plurality of "N" antenna elements (84..87N) for providing radio frequency signals of different phases as a function of an angle of inclination of the same wavefront of an electromagnetic wave and for radiating electromagnetic waves at a first, second, ...M th angles of radio frequency signals characterised in a plurality of "N" sets of a first amplifier (96...99N) and a first light modulator (102...105N) connected in succession from each respective one of said plurality of antenna elements, each modulator including a laser for producing a light output intensity modulated in accordance with the radio frequency signal appearing at the output of the amplifier connected thereto, a plurality of "N" sets of a second amplifier (92....95N) and a first light intensity demodulator (108..111N) connected in succession to each respective one of said plurality of antenna elements (84...87N), a plurality of first, second, ...N th optical divider-combiners (114...117N) connected from repective ones of said first light modulators and demodulators for dividing and combining said modulated light, a plurality of "M" beam ports (150...153M) for receive and "M" beam ports (146...149M) for transmit with each beam port corresponding to one of a plurality of "M" different radiant wavefront angles, a receiver means (82) connected from each receive beam port for receiving said radio frequency signals and a transmitter means (80) connected to each transmit beam port for transmitting said radio frequency signals, a plurality of second light intensity demodulators (138...141M), each second demodulator connected to one of said plurality of receive beam ports (150...153M) for demodulating said radio frequency signals and a plurality of second light intensity modulators (132...135M), each second modulator connected to one of said plurality of transmit beam ports (146..149M) for modulating said radio frequency signals, a plurality of first, second, ...M th optical combiner-­dividers (125...128M) connected to respective ones of said second light intensity demodulators and said second light intensity modulators for dividing and combining said modulated light, said plurality of optical divider-­combiners having a set of first, second, ...M th optical fibers connected therefrom, said first, second, ...M th optical fibers of said first optical divider-combiner being connected from said first optical divider-combiner to said first, second, ...M th optical combiner-dividers, respectively, said first, second, ...M th optical fibers of said second optical divider-combiner being connected from said second optical divider-combiner to said first, second, ...M th optical combiner-dividers, respectively, ... said N th optical divider-combiner having first, second, ...M th optical fibers connected therefrom to said first, second, ...M th optical combiner-dividers, respectively, all of said first, second, ...M th optical fibers having lengths different from each other, said optical fibers having lengths chosen for appropriate time delays to cause signals appearing at one of said first, second, ...M th beam ports to be in time and phase synchronism for received plane waves of first, second, ...M th angles, respectively.

Claim 21

A radiant energy receiving and transmitting system as claimed in claim 17, characterised in that each of said plurality of optical divider-combiners (114...117N) provides an optical divider during the receive mode of operation and provides an optical combiner during the transmit mode of operation.

Claim 22

A radiant energy receiving and transmitting system as claimed in claim 17 or 18, characterised in that each of said plurality of optical combiner-dividers (125...128M) provides an optical divider in the transmit mode of operation and provides an optical combiner in the receive mode of operation.

Claim 23

A radiant energy receiving and transmitting system as claimed in any one of claims 17 to 19, characterised in a plurality of light splitters (119...122N), each ligh splitter being connected between one of said plurality of "N" optical divider-combiners (114...117N) and a parallel combination of said first light modulator (102...105N) and said first light demodulator (108...111N).

Claim 24

A radiant energy receiving and transmitting system as claimed in any one of claims 17 to 22 characterised in a plurality of light splitters (155...158M), each light splitter connected between one of said plurality of "M" optical combiner-dividers (125...128M) and a parallel combination of said second light modulator (132...135M) and said second light demodulator (138-141M).