JPH0666580B2 - Array antenna - Google Patents

Description

Detailed Description of the Invention [Industrial applications]

The present invention relates to an array antenna that controls an antenna excitation distribution by interposing light.

[Prior art]

FIG. 3 is a block diagram showing a conventional array antenna disclosed in Japanese Patent Application No. 1-180768, for example.
Reference numeral 1 is a light radiator, and 2 is a wireless signal source which is connected to the light radiator 1 and sends a wireless signal having a frequency f _{1 to} the light radiator 1. 3 is a light beam emitted from the light radiator 1 into space, 4 is a light beam emitted from the light radiator 1 into space, and the light beam 3 has a frequency
Only f ₁ is different. Reference numeral 5 is a reflecting mirror that bends the direction of the light beam 3 at a right angle, and 6 is the light beam 3 that is bent at a right angle by the reflecting mirror 5 and enters the light beam 3 into a desired antenna radiation pattern shape. Image mask to be output as Reference numeral 7 denotes mask output light emitted from the image mask 6. Reference numeral 8 is a Fourier transform lens for spatially Fourier transforming the mask output light 7, and 9
Represents the Fourier transform light emitted from the Fourier transform lens 8. Reference numeral 10 is a beam combiner for combining the Fourier transform light 9 and the light beam 4, and 11 is a mixed light emitted from the beam combiner 10. A fiber array 12 spatially samples the mixed light 11. 13a to 13n are optical fibers connected to the fiber array 12, and 14a to 14n are the optical fibers 13a to 13n.
Are photoelectric converters respectively connected to. 15a to 15n are
One ends are transmission lines connected to the photoelectric converters 14a to 14n, and 16a to 16n are amplifiers connected to the other ends of the transmission lines 15a to 15n. 17a to 17n are
One end of each is a feeder line connected to the output part of the amplifiers 16a to 16n, and 18a to 18n are element antennas connected to the other ends of the feeder lines 17a to 17n. FIG. 4 is a configuration diagram of the light radiator 1 described above, and includes 19a and 19b.
Is a laser diode whose oscillation frequency is different from each other by a frequency f ₁ , and 20a and 20b are laser diodes 19a and 19b.
Laser lights emitted from a and 19b in space are shown. Reference numerals 21a and 21b are branching devices that branch the laser beams 20a and 20b into two directions, respectively. 22a and 22b are the branching devices
It is a beam adjuster which outputs the above-mentioned light beam 3 and light beam 4 upon incidence of laser light 20a and 20b respectively transmitted through 21a and 21b. Reference numeral 23 is a combiner for mixing and outputting the laser lights 20 and 20b reflected by the branchers 21a and 21b, and 24 is the combined light output from the combiner 23.
Reference numeral 25 is a photoelectric converter that converts the combined light 24 into a wireless signal, and 26 is a transmission line connected to the photoelectric converter 25. Reference numeral 27 compares the frequency of the wireless signal from the photoelectric converter 25 transmitted through the transmission line 26 with the frequency of the wireless signal output from the wireless signal source 2 and outputs a control signal to the laser diode 19b. Reference numeral 28 is a frequency comparator, and 28 is a control line for sending the control signal output from the frequency comparator 27 to the laser diode 19b. Next, the operation will be described. The laser light 20a emitted from the laser diode 19a in the light emitter 1 enters the splitter 21a and is split into two directions. The laser light 20a that has passed through the splitter 21a enters the beam conditioner 22a and is emitted into space from the light emitter 1 as a light beam 3 having a required beam width. Further, the laser light 20a reflected by the branching device 21a
Enters the combiner 23. Laser light 20b emitted from a laser diode 19b having an oscillation frequency different from that of the laser diode 19a by f ₁ enters a branching device 21b and is split into two directions. The laser light 20b that has passed through the branching device 21b is incident on the beam conditioner 22b, and is emitted into space from the light emitter 1 as a light beam 4 having a required beam width. Further, the laser light 20b reflected by the branching device 21b enters the combiner 23. The laser lights 20a and 20b that have entered the combiner 23 are output as combined light 24 that is mixed by the combiner 23 and enter the photoelectric converter 25. This photoelectric converter 25 has a laser beam 20a.
A radio signal having a frequency difference between the frequency of the laser beam and the frequency of the laser beam 20b is output. If the oscillation frequencies of the laser diodes 19a and 19b are accurate, the frequency difference is f ₁ , but here it is the frequency f. The radio signal of frequency f output from the photoelectric converter 25 is input to the frequency comparator 27 via the transmission line 26. The frequency comparator 27 compares the radio signal of the frequency f with the radio signal of the frequency f ₁ input from the radio signal source 2, and the frequency of the laser diode 19b of the laser diode 19b is changed so that the frequency f becomes f = f ₁ . A control signal for controlling the oscillation frequency is output. This control signal is
Is input to this laser diode 19b via, and by controlling the oscillation frequency of the laser diode 19b,
Light beams 3 and 4 output from the beam conditioners 22a and 22b
The frequency difference between and is f ₁ . The light beam 3 is bent at a right angle by the reflecting mirror 5 and enters the image mask 6. The image mask 6 converts the light beam 3 into mask output light 7 having a beam shape corresponding to a desired antenna radiation pattern, such as a fan-shaped beam pattern, and emits the mask output light 7. The mask output light 7 is incident on a Fourier transform lens 8 composed of, for example, a convex lens as shown in the drawing, and the Fourier transform lens 8 spatially stores the amplitude distribution and the phase distribution (hereinafter referred to as the amplitude / phase distribution) of the mask output light 7. Fourier transform is performed, and the transformed Fourier transform light 9 is output to the beam combiner 10.
Here, the Fourier transform lens is described, for example, in K. Ogoshi, "Optical Electronics," edited by The Institute of Electronics, Information and Communication Engineers, The Institute of Electronics, Information and Communication Engineers, Series, F-10, 55-58.
Page, published on August 15, 1982. The Fourier transform light 9 and the light beam 4 are combined by a beam combiner 10 to form a mixed light 11. The mixed light 11 is spatially sampled by a fiber array 12, transmitted through optical fibers 13a to 13n connected to the fiber array 12, and input to photoelectric converters 14a to 14n. In these photoelectric converters 14a ~ 14n known heterodyne detection (or,
Also called optical heterodyne detection. For example, edited by Hisayoshi Yanai, "Optical Communication Handbook," pages 108-110, Asakura Shoten, 1982.
Refer to the occurrence on September 1, 2014. ), The radio signals of frequency f ₁ are extracted respectively. That is, each photoelectric converter 14a ~ 1
4n is the Fourier transform light 9 included in the mixed light 11 as the signal light, the light beam 4 also included in the mixed light 11 is the local oscillation light, and the signal light and the local oscillation light are superposed and squared. By performing the detection, heterodyne detection is performed to obtain a radio signal of frequency f ₁ . In other words,
Each of the photoelectric converters 14a to 14n outputs the mixed light 11 including the Fourier transform light 9 and the light beam 4 to the frequency of the difference between the Fourier transform light 9 and the light beam 4, that is, the wireless signal output from the wireless signal source 2. Frequency f ₁ which is the same as the frequency of the signal,
A photoelectric signal is converted into a radio signal that is proportional to the amplitude of the mixed light 11 that is input and that matches the phase thereof. Each radio signal of the frequency f ₁ output from each photoelectric converter 14a ~ 14n is respectively transmitted through the transmission lines 15a ~ 15n, is then amplified by the amplifier 16a ~ 16n, respectively via the power supply line 17a ~ 17n. Electric power is supplied to the element antennas 18a to 18n, so that the element antennas 18a to 18n radiate the light into the space. As described above, the mask output light 7 emitted from the image mask 6 is Fourier-transformed once by the Fourier transform lens 8 to be a Fourier transform image (that is, Fraunhofer diffraction image) of the beam light 7, and then the element antenna 18
By radiating from the array antenna consisting of a to 18n, the radiation pattern of the array antenna becomes a Fourier transform image (that is, Fraunhofer diffraction image) of the amplitude and phase distribution of the aperture. That is, since the amplitude / phase distribution of the mask output light 7 emitted from the image mask 6 is Fourier-transformed twice, the amplitude / phase distribution of the mask output light 7 is, as is well known, the far-field micro-radiation emitted by the array antenna. This will uniquely correspond to the amplitude / phase distribution of the wave signal.

[Problems to be Solved by the Invention]

The conventional array antenna is configured as above,
Frequency of the radio signal is radiated into space from the antenna elements 18a~18n is, laser with a control signal outputted from the frequency comparator 27 to be equal to the frequency f ₁ of the radio signal output from the wireless signal source 2 It controls the oscillation frequency of the diode 19b. However, the laser diode 19b
The oscillation frequency of the laser diode 19b is several hundred THz and is a high frequency of 10,000 times or more the frequency of the radio signal. Therefore, in order to secure the frequency stability necessary for radio communication, it is necessary to control the oscillation frequency of the laser diode 19b. This is difficult, and in order to solve this, it is indispensable to use a laser diode having an extremely high frequency stability and an accurate frequency comparator 27 capable of controlling the laser diode at high speed, which causes a problem that it costs a lot. It was The present invention has been made to eliminate the above-described problems, and an object of the present invention is to provide an array antenna that can obtain high frequency stability without using a special device.

[Means for Solving the Problems]

The array antenna according to the present invention is input from first light emitting means (19a, 22a) for generating and emitting a first beam light having a predetermined frequency, and the frequency of the first beam light. Second light emitting means (19b, 22b) for generating and emitting a second light beam having a frequency shifted by the frequency of the radio signal, and emitted from the first light emitting means (19a, 22a) First done
Is converted into a beam light having a beam shape corresponding to the pattern shape of a predetermined antenna radiation pattern, and is emitted, and the first conversion means (6) is emitted. Second conversion means (8) for receiving the beam light, spatially Fourier transforming the amplitude distribution and the phase distribution of the received light beam, and radiating the beam light after the Fourier transform; A combining means (10) for combining and emitting the beam light emitted from the converting means (8) and the second beam light emitted from the second emitting means (19b, 22b), and the combining means (10). ), The sampling means (12) for spatially sampling the beam light emitted from the light source) and converting the light beam into a plurality of beam light, and emitting the plurality of light beams emitted from the sampling means (12). Photoelectric conversion And a plurality of element antennas (18a-) for respectively radiating a plurality of radio signals output from the first photoelectric conversion means (14a-14n) into space. In the optically controlled phased array antenna including the light receiving means (30, 13z) for receiving and outputting the light beam emitted from the combining means (10), and the light receiving means (30, 13z). Second photoelectric conversion means (14z) for converting the output light beam into a radio signal and outputting the radio signal
A wireless signal source (31) for generating and outputting a second wireless signal having a predetermined second frequency, and the first photoelectric conversion stage (14z) for outputting the first wireless signal.
And a second radio signal having the second frequency output from the radio signal source (31) are mixed, and a sum frequency or a difference frequency of both the mixed signals is calculated. First mixing means (32) for outputting the third wireless signal that it has, and the third wireless signal output from the first mixing means (32) is distributed to a plurality of third wireless signals and output. Power distribution means (34), a plurality of third wireless signal sources output from the power distribution means (34), and a plurality of wireless signals output from the first photoelectric conversion means (14a-14n) Are mixed, and when the first mixing means (32) outputs a third radio signal having the sum frequency, the second frequency, which is the difference frequency between the mixed signals, is set to Each of the plurality of fourth radio signals having the plurality of element antennas (18a-18n On the other hand, when the second frequency is higher than the first frequency and the first mixing means (32) outputs the third radio signal having the difference frequency, Second mixing means (36a-36n) for outputting to the plurality of element antennas (18a-18n) a plurality of fourth radio signals having the second frequency, which is the sum frequency of both mixed signals It is characterized by having and.

[Action]

According to the above configuration, for example, the frequency of the first wireless signal input from the wireless signal source (2) to the array antenna is f ₁
And the frequency of the radio signal output from the radio signal source (31) is f ₂ , the first photoelectric conversion means (14a-1)
4n) and the frequency f ₁ from the second photoelectric conversion means (14z)
The wireless signal of is obtained. The first mixing means (32) is
The frequency f output from the second photoelectric conversion means (14z)
_From the radio signal of _{1 and} the radio signal of frequency f ₂ output from the second radio signal source (31), for example, frequency f ₃ = f ₁
Create a third radio signal at + f ₂ . The third wireless signal is distributed to a plurality of wireless signals by the power distribution means (34),
Said second mixing means (36a-36n) includes a plurality of radio signals of the distributed frequency f _3, said second photoelectric conversion means (14a-14n) plurality of frequency f ₁ output from the radio A fourth radio signal having a frequency f ₄ = f ₃ −f ₁ = (f ₁ + f ₂ ) −f ₁ = f ₂ is created by mixing the signals with each other, for example, by taking the frequency difference between the two signals. The fourth radio signal is fed to each element antenna (18a-18n). Since the fourth radio signal does not include the frequency f ₁ , the first photoelectric conversion means (14a-14n) and the second photoelectric conversion means (14z) are included.
Be varied is the frequency f ₁ of each radio signal more output, the frequency of the radio signals fed to each element antenna (18a-18n) are fixed to f _2, it is not affected by the variation of the frequency f _1. On the other hand, the second mixing means (36a-36n) are, f _2> in the case of f _1, the first mixing means (32) of the difference frequency (f ₃ = f ₂ -f ₁₎ When outputting a third radio signal having the following, the sum frequency f ₄ = f ₃ + f ₁ = (f ₂ −f ₁ ) + f of both signals mixed by the second mixing means (36a-36n) ₁ = each a plurality of fourth radio signal with f ₂ is f ₂ emits and outputs to the plurality of antenna elements (18a-18n).

【Example】

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows an embodiment of the present invention. The same parts as those of the conventional example of FIG. 3 are designated by the same reference numerals, and the description thereof will be omitted. The Fourier transform light 9 and the light beam 4 are beam combiners.
The mixed light 11 is obtained in the direction of the Fourier-transformed light 9 (rightward in the figure), and at the same time, the mixed light 11z is obtained in the direction of the light beam 4 (upward in the figure). Reference numeral 30 denotes a condenser lens that condenses the mixed light 11z. 13z is an optical fiber for transmitting the light beam condensed by the condenser lens 30, and 14 is a photoelectric converter connected to the other end of the optical fiber 13z. 15z is a transmission line connected to the output of the photoelectric converter 14z. 31 is a wireless signal source that outputs a wireless signal of frequency f ₂ , 32 is more than the wireless signal output from the wireless signal source 31 and the photoelectric converter 14z transmitted via the transmission line 15z It is a mixer for mixing with a radio signal. Reference numeral 34 is a power distributor that distributes the mixed radio signal transmitted from the mixer 32 via the transmission line 33 to n systems. 36a to 36n are transmission lines from the power distributor 34.
A distributed radio signal transmitted via 35a-35n,
It is a mixer that mixes with the radio signals from the photoelectric converters 14a to 14n transmitted via the transmission lines 15a to 15n. 37a to 37n are transmission lines for inputting the radio signals mixed by the mixers 36a to 36n to the amplifiers 16a to 16n. Next, the operation will be described. Similar to the conventional example, the Fourier transform light 9 from the Fourier transform lens 8 and the light beam 4 are combined by the beam combiner 10, one mixed light 11 is incident on the fiber array 12, and the other mixed light 11z. Is condensed by the condenser lens 30 and then inputted to the photoelectric converter 14z through the optical fiber 13z. This photoelectric converter 14z, similarly to the operation of the photoelectric converter 14a ~ 14n in the conventional example, a radio signal of frequency f ₁ is taken out by known heterodyne detection,
It is input to the mixer 32 via the transmission line 15z. That is, each of the photoelectric converters 14z uses the Fourier transform light 9 included in the mixed light 11z as signal light, the light beam 4 included in the mixed light 11z as local oscillation light, and the signal light and the local oscillation light. Are superimposed and squared to perform heterodyne detection to obtain a radio signal of frequency f ₁ . In other words, the photoelectric converter 14z outputs the mixed light 11 including the Fourier transform light 9 and the light beam 4 to the frequency of the difference between the Fourier transform light 9 and the light beam 4, that is, the wireless signal output from the wireless signal source 2. The frequency f ₁ is the same as the frequency of ₁ and is photoelectrically converted into a radio signal that is proportional to the amplitude of the mixed light 11z to be input and has the same phase. This mixer 32
Includes the radio signal of frequency f _1, and a second radio signal of frequency f ₂ inputted from the radio signal source 31 are mixed, the frequency f ₃
The third wireless signal of = f ₂ + f ₁ is output. This third radio signal is input to the power distributor 34 via the transmission line 33, where it is divided into n equal parts, and the respective distributed radio signals are respectively transmitted via the transmission lines 35a to 35n to the corresponding mixer 36a. Input to ~ 36n. Each mixer 36a~36n mixes the radio signal of frequency f _3, and a radio signal of a frequency f ₁ which is input via each top feed lines 15a - 15n, the frequency f ₄ = f ₃ -f ₁ = (F ₂ + f ₁ )
A fourth radio signal of −f ₁ = f ₂ is created, and each transmission line 37a-3
Output to 7n. Frequency output to each transmission line 37a-37n
The radio signal of f ₂ is amplified by each amplifier 16a to 16n, and then fed to each element antenna 18a to 18n via each feed line 17a to 17n, so that the space from these element antennas 18a to 18n is increased. Is emitted. FIG. 2 shows another embodiment of the present invention. The difference from FIG. 1 is that the optical fiber 13 whose one end is connected to the fiber array 12 is the same as the above-mentioned optical fibers 13a to 13n.
This is that part of the mixed light transmitted from z is input to the photoelectric converter 14z, and the operation after this photoelectric converter 14z is the same as the first operation. In the above embodiment, the frequency f ₁ of the wireless signal and the frequency f ₂ of the second wireless signal can be determined independently.
The wireless signal source 2 and the wireless signal source 31 may be the same wireless signal source. The second wireless signal is not limited to a sine wave signal, but may be a square wave signal, a pulse signal, or a signal modulated based on various communication systems. Further, in the above embodiment, the frequency f ₃ of the third radio signal output from the mixer 32 is set to f ₃ = f ₂ + f _1, and the frequency of the fourth radio signal output from each of the mixers 36a to 36n. Although f ₄ = f ₃ −f ₁ = f ₂ is set, when the frequency f _{2 of the second} radio signal exceeds the frequency f ₁ of the radio signal, the third radio signal of the third radio signal output from the mixer 32 is output. The frequency f _{3 is set} to f ₃ = f ₂ −f _1, and the mixers 36a to 3a
The frequency f ₄ of the fourth radio signal output from 6a is set to f ₄ = f ₃ +
It may be f ₁ = f ₂ .

【The invention's effect】

As described above, according to the present invention, in order to eliminate the frequency fluctuation of the input radio signal, the second photoelectric conversion means (14
z) a radio signal having a frequency f ₁ obtained by z and a radio signal having a frequency f ₂ output from the second radio signal source (31)
The mixing means (32), and the mixed radio signal,
The original frequency f ₁ radio signal is further mixed with second mixing means (36a
-36n) is used to obtain the radio signal of frequency f ₂ excluding frequency f ₁ , so it is not necessary to use an expensive laser diode with high frequency stability or a high-speed frequency comparator. In addition, an array antenna with excellent frequency stability can be obtained.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the array antenna of the present invention, FIG. 2 is a block diagram showing another embodiment of the array antenna of the present invention, and FIG. 3 is a block diagram showing a conventional array antenna, FIG. 4 is a block diagram showing details of the light radiator in FIG. 1 ... Light emitter, 2 ... Radio signal source, 3, 4 ... Light beam, 5 ... Reflector, 6 ... Image mask, 7 ... Mask output light, 8 ... Fourier transform lens, 9 ... … Fourier transform light, 10 …… Beam combiner, 11,11z …… Mixed light, 12 …… Fiber array, 13a to 13n, 13z …… Optical fiber, 14a to 14n, 14z …… Photoelectric converter, 16a to 16n ...... Amplifier, 18a-18n …… Element antenna, 19a, 19b …… Laser diode, 21a, 21b …… Brancher, 22a, 22b …… Beam conditioner, 23 …… Synthesis machine, 25 …… Photoelectric converter, 27 …… Frequency comparator, 30 …… Condenser lens, 31 …… Wireless signal source, 32 …… Mixer, 34 …… Power distributor, 36a-36n …… Mixer.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor, Koji Yasukawa, 5 Seiraya, Seika-cho, Seika-cho, Soraku-gun, Kyoto, Japan

Claims (1)

[Claims] 1. A first light emitting means (19a, 22a) for generating and emitting a first light beam having a predetermined frequency, and a radio signal input from the frequency of the first light beam. Second light emitting means (19b, 22b) for generating and emitting a second light beam having a frequency shifted by a frequency; and a first light emitting means (19a, 22a) for emitting light. 1
Is converted into a beam light having a beam shape corresponding to the pattern shape of a predetermined antenna radiation pattern, and is emitted, and the first conversion means (6) is emitted. Second conversion means (8) for receiving the beam light, spatially Fourier transforming the amplitude distribution and the phase distribution of the received light beam, and radiating the beam light after the Fourier transform; A combining means (10) for combining and emitting the beam light emitted from the converting means (8) and the second beam light emitted from the second emitting means (19b, 22b), and the combining means (10). ), The sampling means (12) for spatially sampling the beam light emitted from the light source) and converting the light beam into a plurality of beam light, and emitting the plurality of light beams emitted from the sampling means (12). Photoelectric conversion And a plurality of element antennas (18a-) for respectively radiating a plurality of radio signals output from the first photoelectric conversion means (14a-14n) into space. In the optically controlled phased array antenna including the light receiving means (30, 13z) for receiving and outputting the light beam emitted from the combining means (10), and the light receiving means (30, 13z). Second photoelectric conversion means (14z) for converting the output light beam into a radio signal and outputting the radio signal
A wireless signal source (31) for generating and outputting a second wireless signal having a predetermined second frequency; and the first frequency output from the second photoelectric conversion means (14z). Radio signal and the radio signal source (31)
A first mixing means for mixing the second radio signal having the second frequency output from the second radio signal and outputting the third radio signal having the sum frequency or the difference frequency of both the mixed signals ( 32), power distribution means (34) for distributing and outputting the third wireless signal output from the first mixing means (32) into a plurality of third wireless signals, and the power distribution means (34 ) And a plurality of wireless signals output from the first photoelectric conversion means (14a-14n) are mixed together to generate the first wireless signals.
When the mixing means (32) of (3) outputs the third radio signal having the above sum frequency, a plurality of fourth radio signals having the second frequency, which is the difference frequency of both the mixed signals, are generated. While outputting to the plurality of element antennas (18a-18n), respectively, while the second frequency is higher than the first frequency, the first mixing means (32) has the difference frequency. When outputting the third wireless signal, the plurality of fourth wireless signals having the second frequency, which is the sum frequency of both mixed signals, are output to the plurality of element antennas (18a-18n), respectively. Second mixing means (36
a-36n) and an array antenna.