JP2010028236A - Optically controlled multibeam antenna system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optically controlled phased array antenna system simultaneously forming excitation amplitude phases to respective element antennas corresponding to a plurality of microwave beams by a single spatial light modulator. <P>SOLUTION: The optically controlled multibeam antenna system includes: a first light source 10 for outputting first signal light and local light; a second light source 20 for outputting second signal light and local light; a spatial light phase modulator 30 for phase-modulating the beams of each signal light; and a photocoupler 70 for emitting first synthesized beam light B1 from a signal light beam 17 and a first local light beam 42 through the spatial light phase modulator 30, emitting second synthesized beam light B2 from a second signal light beam 27 and a second local light beam 44 through the spatial light phase modulator 30 and inputting each beam light to the same optical fiber array 54. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an optically controlled phased array antenna device.

  An optical control type microwave amplitude phase control device used in a conventional optical control type phased array antenna device emits first and second light beams having different frequencies by the frequency of the microwave signal, and outputs the first light beam. As a signal light beam, the spatial light modulator converts the power supply amplitude and phase distribution to each antenna element of the array antenna, and the signal light beam and the local light beam are spatially superimposed using the second light beam as a local light beam. In addition, sampling is performed spatially, and after sampling light is converted into a microwave signal by heterodyne detection by a photoelectric converter, it is configured to radiate into space using an array antenna (see, for example, Patent Document 1). .

Japanese Patent Laid-Open No. 7-202547 (FIG. 2)

  In the conventional optical control type microwave amplitude phase control apparatus of the optical control type phased array antenna apparatus, the amplitude and phase signals formed by each element of the spatial light modulator and the feeding signal to each element of the array antenna are in a one-to-one relationship. Therefore, only one microwave amplitude phase wavefront can be formed with one spatial light modulator, and a feed signal for an array antenna that radiates a plurality of microwave beams cannot be generated. There was a problem.

  The present invention has been made to solve the above-described problems, and is a light control type capable of simultaneously forming amplitude distributions and phase distributions corresponding to a plurality of microwave beams with one spatial light modulator. An object is to obtain a phased array antenna device.

  A light control type multi-beam antenna device according to the present invention includes a first light source that outputs first signal light and first local light, and a second light source that outputs second signal light and first local light. And a spatial light phase modulator that phase-modulates each signal light beam, and a first combined beam light emitted from the first signal light phase-modulated by the spatial light phase modulator and the first local light. And a light beam combiner that emits a second combined beam light from the second signal light phase-modulated by the spatial light phase modulator and the second local light, and the light beam combiner And an optical coupler that couples each light beam to the same optical fiber array.

  In addition, the first microwave modulated light source that outputs the first signal light and the first local light that are shifted in frequency by the frequency of the first microwave signal, and the frequency of the second microwave signal. A second microwave-modulated light source that outputs the second signal light and the second local light that are frequency-shifted from each other in an optical wavelength band different from that of the first signal light and the first local light; First and second signal lights are respectively incident on different regions and spatially separated so as to obtain a desired phase distribution and phase modulated by the spatial phase modulator. A first combined beam obtained by combining the first signal light and the first local light is output, and a second combined light obtained by combining the second signal light phase-modulated by the spatial phase modulator and the second local light. Light beam combiner that outputs a beam A plurality of first optical fiber arrays in which the first combined beam combined by the light beam combiner is separated into a plurality of optical fibers and respectively combined; and a second combined by the light beam combiner A plurality of second optical fiber arrays in which the combined beam is separated into a plurality of optical fibers and coupled to each other, and a plurality of optical couplers for optically coupling the optical fibers of the respective first and second optical fiber arrays. A photoelectric converter that photoelectrically converts the combined light coupled by each of the optical couplers, and an array antenna that is fed with a microwave signal photoelectrically converted by each of the photoelectric converters and radiates radio waves into space. And a plurality of configured antenna elements.

  According to the present invention, it is possible to radiate a plurality of microwave beams from an array antenna, and to independently control the excitation amplitude and phase of each of the plurality of microwave beams for each antenna element.

Embodiment 1.
FIG. 1 is a block diagram showing an optical control type phased array antenna apparatus according to Embodiment 1 of the present invention.
In FIG. 1, the optically controlled phased array antenna apparatus includes first and second microwave modulated light sources 10 and 20 and first and second microwave signals that individually capture first and second microwave signals. Input terminals 14 and 24 are provided.

  The optically controlled phased array antenna device includes first and second signal light beam emitting devices 15 and 25, a spatial light phase modulator 30, a spatial light phase modulator controller 31, and first and second Local light beam emitting devices 41 and 43, a light beam combiner 50, a lens array 53, an optical fiber array 54, a plurality of photoelectric converters 55, and an array antenna 56 composed of a plurality of antenna elements are provided. .

The first microwave modulated light source 10 includes a first signal light and a first local light that are frequency-shifted by the frequency of the first microwave signal input via the first microwave signal input terminal 14. Two laser beams consisting of
Similarly, the second microwave modulation light source 20 includes the second signal light shifted by the frequency of the second microwave signal input via the second microwave signal input terminal 24 and the second signal light. Two laser beams composed of local light are output.

The first signal light beam emitting device 15 converts the first signal light into a predetermined beam width and emits it as a first signal light beam 16 into the space.
Similarly, the second signal light beam emitting device 25 converts the second signal light into a predetermined beam width and emits it as a second signal light beam 26 to the space.
Each of the first signal light beam 16 and the second signal light beam 26 has an optical axis parallel to each other and is emitted after being offset.
The spatial light phase modulator 30 functions under the control of the spatial light phase modulator controller 31, and spatially separates the first and second signal light beams 16 and 26 input to different regions and performs phase modulation. And converted into a desired phase distribution.

The first local light beam emitting device 41 converts the first local light into a predetermined beam width and emits it as a first local light beam 42 to the space.
Similarly, the second local light beam emitting device 43 converts the second local light into a predetermined beam width and emits it as a second local light beam 44 to the space.
The first local light beam 42 and the second local light beam 44 have optical axes parallel to each other and are emitted with an offset.

The light beam combiner 50 transmits the first signal light beam 17 emitted via the spatial light phase modulator 30 and the first local light beam 42 emitted from the first local light beam emitting device 41. Are reflected, the first signal light beam 17 and the first local light beam 42 are converted into a coaxial optical path, and the first combined light beam B1 is emitted.
The light beam combiner 50 transmits the second signal light beam 27 emitted via the spatial light phase modulator 30 and the second local light emitted from the second local light beam emitting device 43. The beam 44 is reflected, the second signal light beam 27 and the second local light beam emitting device 43 are converted into a coaxial optical path, and the second combined beam light B2 is emitted.

The optical fiber array 54 spatially samples the first and second combined beam lights B1 and B2 emitted from the light beam combiner 50.
Optically coupling each optical fiber of the first optical fiber array 54a sampled from the first combined beam light B1 and each optical fiber 54b of the second optical fiber array sampled from the second combined beam light B2, Each fiber is provided with an optical coupler 70 for entering the same optical fiber. The first and second combined lights output from each optical coupler 70 are converted into a first microwave signal and a second microwave signal by heterodyne detection in a photoelectric converter 55 connected to each optical fiber. Is done.
By using different wavelength bands for the first signal light and local light wavelength band f1 and the second signal light and local light wavelength band f2, for example, an array that has already been put into practical use as the optical coupler 70. A waveguide diffraction grating (AWG: Arrayed Waveguide Grating) or the like is applicable.
The plurality of photoelectric converters 55 convert the first and second combined beam lights B1 and B2 received by the optical fibers of the optical fiber array 54 into microwave signals by heterodyne detection.
The array antenna 56 radiates the microwave signals output from the plurality of photoelectric converters 55 that form the first microwave beam 61 and the second microwave beam 62 to the space.

Next, the operation of the optical control type phased array antenna apparatus according to Embodiment 1 of the present invention shown in FIG. 1 will be described.
First, the first microwave-modulated light source 10 includes a first local light composed of continuous wave (CW) light and a frequency offset by a frequency of the first microwave signal with respect to the first local light. Two component laser light with one signal light is output.
Similarly, the frequency of the second microwave modulated light source 20 is offset by the frequency of the second microwave signal with respect to the second local light composed of continuous wave (CW) light and the second local light. A two-component laser beam with the second signal light is output.

  Such microwave modulation light sources 10 and 20 can be realized by combining, for example, a laser, a Mach-Zehnder type optical modulator (MZ modulator), an optical wavelength filter, and the like. That is, by modulating the CW light emitted from the laser with the MZ modulator, a sideband wave offset by the microwave frequency with respect to the CW light is generated. By separating the sideband and CW light with an optical wavelength filter, it is possible to output two light waves consisting of signal light and local light.

  The first and second signal lights from the microwave modulated light sources 10 and 20 are respectively transmitted through the first and second signal light beam emitting devices 15 and 25 each composed of an optical fiber or a lens. Are converted into signal light beams 16 and 26 having a beam width of 2 mm and input to different regions on the spatial light phase modulator 30.

The first and second signal light beams 16 and 26 input to different regions on the spatial light phase modulator 30 are spatially modulated in phase according to a control signal from the spatial light phase modulator controller 31. The signal light beams 17 and 27 converted into a desired spatial phase distribution are emitted from the spatial light phase modulator 30. As the spatial light phase modulator 30, for example, a liquid crystal element or the like is applied.
The first and second signal light beams 17 and 27 emitted from the spatial light phase modulator 30 are converted into first and second combined beam lights B1 and B2 through the light beam combiner 50, as will be described later. , And enters the optical fiber array 54.

  On the other hand, the first and second local light beams emitted from the microwave modulation light sources 10 and 20 are transmitted through the first and second local light beam emitting devices 41 and 43 configured by optical fibers and lenses, respectively. To the first and second local light beams 42 and 44 having a predetermined beam width.

The first and second local light beams 42 and 44 are spatially superimposed on the first and second signal light beams 17 and 27 in the light beam combiner 50, respectively. At the same time, the first and second combined beam lights B1 and B2 are converted into light and incident on the optical fiber array 54 to be spatially sampled.
Here, the first local light beam 42 is overlapped with the first signal light beam 17, and the second local light beam 44 is overlapped with the second signal light beam 27.

  Here, a lens array 53 is provided on the incident end side of the optical fiber array 54 (54a, 54b) to increase the coupling efficiency of input light to each optical fiber constituting the optical fiber array 54. If the amount of the first and second combined beam lights B1 and B2 incident on the array 54 is sufficient, the lens array 53 may be omitted.

The first and second combined beam lights B1 and B2 (signal light and local light) incident on each optical fiber in the optical fiber array 54 propagate through each optical fiber, and are transmitted through the first optical fiber array 54a. The first combined beam light propagating in each optical fiber and the second combined beam light propagating in each optical fiber of the second optical fiber array 54 b are combined through the optical coupler 70. The combined light from each optical coupler 70 is input to each photoelectric converter 55 connected to the subsequent stage of each optical coupler 70 through an optical fiber.
The first and second combined beam lights B1 and B2 input to each photoelectric converter 55 are converted into microwave signals by heterodyne detection and output.
The microwave signal output from each photoelectric converter 55 is input to each antenna element in the array antenna 56, and is radiated into the space as first and second microwave beams 61 and 62.

  An amplifier or an attenuator for adjusting the intensity of the microwave signal may be provided between each photoelectric converter 55 and the antenna element in the array antenna 56, and in order to limit the signal band. A band filter or the like may be provided.

Next, the microwave signal output from each photoelectric converter 55 will be specifically described.
Here, the frequency of the signal light S input to the photoelectric converter 55 is fS1, and the frequency of the local light L is fL1. However, | fL1-fS1 | is the frequency (fm1) of the first or second microwave signal.

  Assuming that the phase modulation amount of each of the signal light beams 16 and 26 by the spatial light phase modulator 30 is φ1, the signal light S and the local light L (first and second combined beam lights) input to each photoelectric converter 55. (Included in B1 and B2) is represented by the following formulas (1) and (2).

S = cos {2π (fs1) t + φ1} (1)
L = cos {2π (fL1) t}
= Cos {2π (fs1-fm1) t} (2)

However, in Equation (1) and Equation (2), the amplitude is “1” and the initial phase is “0”.
Each photoelectric converter 55 outputs a difference D between the two components expressed as the following equation (3).

D = cos {2π (fs1) t + φ1} −cos {2π (fs1−fm1) t}
= Cos (2π (fm1) t + φ1) (3)

As described above, the photoelectric converter 55 generates a microwave signal having the phase amount φ1 modulated by the spatial light phase modulator 30 based on the frequency fm1 of the microwave signal input to each of the microwave modulation light sources 10 and 20. Is done.
Therefore, the phase distribution of the microwave signal fed to each antenna element of the array antenna 56 is the same as the phase distribution modulated by the spatial light phase modulator 30.

  As described above, according to the first embodiment (FIG. 1) of the present invention, the first signal light and the second signal light are spatially separated and separated by the spatial light phase modulator 30 in different regions. An optical fiber, a photoelectric converter, and an antenna element that perform phase modulation, the first combined light beam B1 of the phase-modulated first signal light beam 17 and the first local light beam 42 enters, and phase modulation The optical coupler 70 is used to put the optical fibers into which the second combined light beam B2 of the second signal light beam 27 and the second local light beam 44 incident on the same optical fiber for each fiber. In order to synthesize and convert the first microwave signal and the second microwave signal by the photoelectric converter and the antenna element connected to each fiber, one array antenna 56 is shared, and the first and second Composite beam B1, B2 becomes a can be controlled independently.

  Therefore, the first microwave beam 61 and the second microwave beam 62 can be formed by the array antenna 56.

  In this way, the phase distribution of the first and second signal light beams 16 and 26 is independently controlled in different regions in the spatial light phase modulator 30, and the respective signal light beams 16 and 26 are controlled by the optical coupler 70. By combining and converting the first microwave signal and the second microwave signal by the photoelectric converter and the antenna element connected to each fiber, a plurality (first and second) of array antenna 56 are used. It becomes possible to radiate the microwave beams 61 and 62 and to control the excitation amplitude phase for each antenna element independently of the plurality of microwave beams 61 and 62.

Thus, a multi-beam can be easily formed in an optically controlled multi-beam antenna device applying optical technology to a beam forming network (BFN). At this time, one spatial light phase modulator area is provided for each beam of the multi-beam. By dividing into two, it is possible to set different phases for each beam with one spatial light phase modulator, and to control phase distribution different for each beam, so that flexible beam formation is possible.
In addition, by dividing one spatial light phase modulator area for each multi-beam, it is possible to form a multi-beam with one spatial light phase modulator, and to reduce the size, weight and simplification of BFN. It becomes.

Embodiment 2.
In the first embodiment (FIG. 1), the spatial light phase modulator 30 is provided only on the signal light beam side. However, as shown in FIG. 2, the spatial light intensity modulator 32 is provided on the local light beam side.
2 is a block diagram showing an optical control type phased array antenna apparatus according to Embodiment 2 of the present invention. The same components as those described above (see FIG. 1) are denoted by the same reference numerals as those described above and described in detail. Is omitted.

2, in addition to the configuration described above (FIG. 1), a spatial light intensity modulator 32 and a spatial light intensity modulator controller 33 are provided.
That is, the spatial light intensity modulator 32 that functions under the control of the spatial light intensity modulator controller 33 is inserted between the first and second local light beam emitting devices 41 and 43 and the light beam combiner 50. ing.
The spatial light intensity modulator 32 intensity-modulates the first and second local light beams 42 and 44 input to different regions, and converts the first and second local light beams 45 and 45 into a desired spatial intensity distribution. The light is emitted as 46.

Next, the operation of the optically controlled phased array antenna device according to Embodiment 2 shown in FIG. 2 will be described.
Similarly to the above, the first and second local lights emitted from the first and second microwave modulated light sources 10 and 20 are predetermined via the first and second local light beam emitting devices 41 and 43, respectively. Are converted into the first and second local light beams 42 and 44.

Subsequently, the first and second local light beams 42 and 44 are input to different regions on the spatial light intensity modulator 32.
The spatial light intensity modulator 32 spatially modulates the intensity of the first and second local light beams 42 and 44 in accordance with a control signal from the spatial light intensity modulator controller 33 and converts it into a desired spatial intensity distribution. The local light beams 45 and 46 are emitted.
As the spatial light intensity modulator 32, a liquid crystal element or the like can be applied as in the spatial light phase modulator 30.

  Thereafter, the first and second local light beams 45 and 46 emitted from the spatial light intensity modulator 32 are incident on the light beam combiner 50 in the same manner as in the first embodiment described above, The first and second combined light beams B 1 and B 2 are spatially combined with the second signal light beams 17 and 27, and are spatially sampled in the optical fiber array 54.

Each optical fiber of the first optical fiber array that samples the first combined beam light B1 and each optical fiber of the second optical fiber array that samples the second combined beam light B2 are the same for each fiber. The first and second combined lights output from each optical coupler 70 are connected to the respective fibers by the heterodyne detection by the photoelectric converter, and are coupled to the first microcoupler. Converted into a wave signal and a second microwave signal.
By using different wavelength bands for the first signal light and local light wavelength bands and the second signal light and local light wavelength bands, for example, an array waveguide that has already been put into practical use as the optical coupler 70. A diffraction grating (AWG: Arrayed Waveguide Grating) or the like is applicable.
At this time, since the intensity of the microwave signal generated by each photoelectric converter 55 is the product of the intensity of the signal light and the local light, the spatial light intensity modulator 32 determines the intensity distribution of the local light beams 45 and 46. By controlling, the intensity of the microwave signal can be controlled.

  As a result, the intensity distribution of the microwave signal fed to each antenna element of the array antenna 56 can be controlled, so that the side lobe control and beam width control of the first and second antenna radiation beams 61 and 62 can be performed. Flexibility with respect to shape can be improved by excitation amplitude phase control for each antenna element.

Thus, the optical control type multi-beam antenna device applying the optical technology to the beam forming network (BFN) can easily form multi-beams.
In addition, by dividing one spatial light amplitude modulator area for each beam of multi-beams, it is possible to set different amplitudes for each beam with one spatial light amplitude modulator, and different amplitude distribution control for each beam. It is possible and flexible beam forming is possible.
Furthermore, by dividing one spatial light amplitude modulator area for each multi-beam, a single spatial light amplitude modulator can form a multi-beam, and the BFN can be made smaller, lighter and simplified. It becomes.

  In the first and second embodiments, two light beams are generated using the two microwave modulation light sources 10 and 20, but three or more microwave modulation light sources (not shown) are used. As in FIGS. 1 and 2, the spatial light phase modulator 30 and the spatial light intensity modulator 32 are divided into three or more spaces, and the combined light beams are combined by the optical coupler 70, and the photoelectric converter 55 It goes without saying that three or more multi-beams can be realized by converting each microwave signal and radiating from the array antenna 56.

Further, although the transmissive spatial light phase modulator 30 and the spatial light intensity modulator 32 are used, it is needless to say that a reflective spatial light modulator may be used, and the same effects as described above can be obtained. .
Furthermore, although an example in which the spatial light phase modulator 30, the spatial light intensity modulator 32, the array antenna 56, and the like are divided in a one-dimensional direction (vertical direction in FIGS. 1 and 2) is shown, the two-dimensional division is performed. Needless to say.

It is a block block diagram which shows the optical control type phased array antenna apparatus which concerns on Embodiment 1 of this invention. It is a block block diagram which shows the optical control type | mold phased array antenna device which concerns on Embodiment 2 of this invention.

Explanation of symbols

  10 first microwave modulated light source (first light source), 20 second microwave modulated light source (second light source), 14 first microwave signal input terminal, 24 second microwave signal input terminal, 15 First signal light beam emitting device, 25 Second signal light beam emitting device, 16, 17 First signal light beam, 26, 27 Second signal light beam, 30 Spatial light phase modulator, 31 Spatial light Phase modulator controller, 32 spatial light intensity modulator, 33 spatial light intensity modulator controller, 41 first local light beam emitting device, 43 second local light beam emitting device, 42, 45 first local light beam, 44, 46 second local light beam, 50 light beam combiner, B1 first combined beam light, B2 second combined beam light, 54 optical fiber array, 55 photoelectric converter, 6 array antenna, 70 light couplers.

Claims (3)

A first light source that outputs a first signal light and a first local light;
A second light source that outputs a second signal light and a first local light;
A spatial light phase modulator that phase modulates the beam of each signal light;
The first combined beam light is emitted from the first signal light phase-modulated by the spatial light phase modulator and the first local light, and the second signal light phase-modulated by the spatial light phase modulator. A light beam combiner that emits a second combined beam light from the second local light; and
An optical coupler that couples the light beams synthesized by the light beam combiner to the same optical fiber array;
An optical control type multi-beam antenna device comprising: A first microwave modulated light source that outputs a first signal light and a first local light that are frequency-shifted from each other by the frequency of the first microwave signal;
The second signal light and the second local light that are shifted in frequency by the frequency of the second microwave signal are output in an optical wavelength band different from that of the first signal light and the first local light. Two microwave modulated light sources;
A spatial light phase modulator that the first and second signal lights are respectively incident on different regions and spatially separated and phase-modulated;
A first combined beam obtained by combining the first signal light phase-modulated by the spatial phase modulator and the first local light is output, and the second signal light phase-modulated by the spatial phase modulator and the second signal light A light beam combiner that outputs a second combined beam obtained by combining the two local lights;
A plurality of first optical fiber arrays in which the first combined beam combined by the light beam combiner is separated into a plurality of optical fibers and respectively coupled;
A plurality of second optical fiber arrays in which the second combined beams combined by the light beam combiner are separated into a plurality of optical fibers and respectively coupled;
A plurality of optical couplers for optically coupling optical fibers included in each of the first and second optical fiber arrays;
A photoelectric converter that photoelectrically converts the combined light combined by each of the optical couplers;
A plurality of antenna elements constituting an array antenna, which are fed with microwave signals photoelectrically converted by the respective photoelectric converters and radiate radio waves into space,
An optical control type multi-beam antenna device comprising: A first microwave modulated light source that outputs a first signal light and a first local light that are frequency-shifted from each other by the frequency of the first microwave signal;
The second signal light and the second local light that are shifted in frequency by the frequency of the second microwave signal are output in an optical wavelength band different from that of the first signal light and the first local light. Two microwave modulated light sources;
A first spatial light phase modulator in which the first and second signal lights are respectively incident on different regions and spatially separated and phase modulated;
A second spatial light intensity modulator that the first and second local lights are respectively incident on different regions and spatially separated and intensity-modulated;
A first combined beam obtained by combining the first signal light phase-modulated by the first spatial phase modulator and the first local light intensity-modulated by the second spatial intensity modulator; A light beam synthesizer that outputs a second combined beam obtained by combining the second signal light phase-modulated by the spatial phase modulator and the second local light intensity-modulated by the second spatial intensity modulator;
A plurality of first optical fiber arrays in which the first combined beam combined by the light beam combiner is separated into a plurality of optical fibers and respectively coupled;
A plurality of second optical fiber arrays in which the second combined beams combined by the light beam combiner are separated into a plurality of optical fibers and respectively coupled;
A plurality of optical couplers for optically coupling optical fibers included in each of the first and second optical fiber arrays;
A photoelectric converter that photoelectrically converts the combined light combined by each of the optical couplers;
A plurality of antenna elements that are fed with microwave signals photoelectrically converted by the respective photoelectric converters and radiate radio waves into space,
An optical control type multi-beam antenna device comprising:

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