JPH0630405B2 - Phased array antenna device - Google Patents

Description

TECHNICAL FIELD The present invention controls the relative phase of microwaves radiated from an array of a plurality of antennas to change the direction and shape of a combined radiation pattern. The present invention relates to a phase shifter of an antenna device.

[Conventional technology]

FIG. 5 is a diagram of P.1 of “Antenna Engineering Handbook” edited by the Institute of Electronics and Communication Engineers, for example. It is a block diagram which shows the conventional phase scan type phased array antenna apparatus disclosed by 216. As shown in the figure, the output of the reference microwave oscillator 1 is given an independent amount of phase shift by a plurality of phase shifters 2, then power amplified by a microwave amplifier 3, and then radiated from an element antenna 4. The phase shift amount control circuit 5 controls the difference in the amount of phase shift given to each phase shifter 2, and the direction and pattern of the combined beam 6 of the microwaves emitted change depending on the relationship of the amount of phase shift. .

As the phase shifter 2, a ferrite phase shifter utilizing a difference in magnetic permeability in different magnetization states of ferrite, and a diode phase shifter for switching a combination of phase shift circuits by switching diodes are widely used. .

[Problems to be solved by the invention]

Since the phase shifter of the conventional phased array antenna device is configured as described above, the phase shift amount of the phase shifter 2 is
Corresponding to the ratio of the wavelength of the microwave to be handled and the size of the phase shifter 2, the same phase shifter 2 can handle a narrow frequency range of microwaves, and the phase shifter for low frequency has a size There was a problem that it became large.

The present invention has been made to solve the above problems, and an object thereof is to obtain a phased array antenna device including a phase shifter that is small and is effective for microwaves in a wide frequency range. To do.

[Means for solving problems]

The phased array antenna device according to the present invention, as a phase shifter, a laser diode whose intensity is modulated by microwaves, a photodiode for returning the output light of the laser diode to microwaves, and a bias current of the laser diode are changed. It was realized by a combination of the three with the circuit.

[Operation] In the phased array antenna device of the present invention,
The phase shifter is constructed by utilizing the degree to which the intensity of the output light is delayed with respect to the intensity of the modulation signal in the vicinity of the resonance frequency of the laser diode, and the property that the resonance frequency of the laser diode changes depending on the bias current. is doing.

〔Example〕

FIG. 1 is a configuration diagram showing a circuit of a phase shifter of a phased array antenna device according to an embodiment of the present invention. As shown in the figure, the bias current 9 and the microwave signal 10 are input to the laser diode 7 via the bias circuit 8.
The intensity of the emitted light 11 of the laser diode 7 changes depending on the frequency of the microwave signal 10. However, the phase relationship between the intensity of the emitted light 11 of the laser diode 7 and the microwave signal 10 depends on the magnitude of the bias current 9 as described later. Change. The emitted light 11 of the laser diode 7 is the optical fiber 1.
It is incident on the avalanche photodiode 13 via 2. The output of the avalanche photodiode 13 has the same frequency component as the microwave signal 10 and is taken out from the output terminal 14.

Next, the phase relationship between the input / output signal and the output light when the laser diode 7 is modulated at a high frequency will be described.
For example, Yasuharu Suematsu, "Semiconductor Laser and Optical Integrated Circuits"
According to (Ohm Co., Ltd., 1984), the frequency response S _m (ω) of the intensity-modulated laser diode 7 is given as follows.

here, Where ω: Angular frequency of modulated signal τ _s : Carrier lifetime τ _p : Photon lifetime I _b : Bias current I _th : Threshold current Phase difference P _h (ω) between modulated signal and output light from the above equation (1)
Is Becomes

FIG. 2 is a diagram showing an example in which the phase delay for each modulation frequency in the phase shifter of FIG. 1 is calculated by changing the bias current. In Fig. 2, the phase delay (phase difference) P _h (ω) for each frequency when τ _s = 1.5 nsec and τ _p = 1.58 _p sec
An example is shown in which is calculated by changing the bias currents I _b / I _th . From the above equation (1), ω _r0 may be accompanied by an increase in the bias current I _b / I _th , and from the above equation (3), P _h (ω) may change greatly at frequencies near ω _r0. Although qualitatively understood, FIG. 2 shows this quantitatively.

FIG. 3 is a diagram showing an example of calculating a phase delay for a specific frequency in the phase shifter of FIG. 1 with respect to a bias current. Here, 2.8 GHz is considered as the modulation frequency. As is clear from FIG. 3, the bias current I _b / I _th
It can be understood that the phase difference between the modulation signal of the laser diode 7 and the output light can be changed by changing the.

Since the laser diode 7 is small, and can modulate from a direct current component to several tens of GHz, and the phase delay as described above occurs in the frequency range in which the laser diode 7 can modulate, FIG. The phase shifter shown in (1) is not only effective in a wide frequency band, but also can be made compact regardless of the target frequency.

FIG. 4 is a block diagram showing a phased array antenna device according to an embodiment of the present invention. As shown in the figure, the output of the reference microwave oscillator 1 enters the optical fiber 12 as an optical signal modulated by the laser diode optical transmitter 15. The optical receiver 17 using a photodiode converts this optical signal into an electric signal again. The microwave signal thus converted is radiated from the element antenna 4 through the microwave amplifier 16. The laser diode bias control circuit 18 gives an independent bias current to each laser diode optical transmitter 15, and the phase delay in the laser diode optical transmitter 15 can be controlled according to this bias current. The direction and pattern of the combined beam 6 of the microwaves radiated from the element antenna 4 are determined by the relative relationship of the phase shift amount, as in the conventional device.

In the above-mentioned embodiment, an example of a phased array antenna device for transmission is described, but reception can be easily realized by simply changing the order of the laser diode 7 and the photodiode 13.

Further, in the above embodiment, since the output light of the laser diode 7 is immediately incident on the photo diode 13 via the optical fiber 12, the phase shifter portion and the antenna portion can be separated, and each channel can be separated. The advantage is that there is little interference between them.

〔The invention's effect〕

As described above, in the phased array antenna device of the present invention, the phase shifter includes a laser diode whose intensity is modulated by microwaves, a photo diode for returning the output light of the laser diode to microwaves, and a bias of the laser diode. Since it has a configuration realized by a combination of a circuit for changing current and a circuit for changing the current, it is effective for microwaves in a wide frequency range and a small phase shifter can be obtained. It has excellent effects such as separation of the channels and reduction of interference between channels.

[Brief description of drawings]

FIG. 1 is a block diagram showing a circuit of a phase shifter of a phased array antenna device according to an embodiment of the present invention, and FIG. 2 is a phase delay for each modulation frequency in the phase shifter of FIG. FIG. 3 is a diagram showing an example in which the phase shift for a specific frequency in the phase shifter in FIG. 1 is calculated with respect to a bias current, and FIG. FIG. 5 is a configuration diagram showing a phased array antenna device according to an embodiment, and FIG. 5 is a configuration diagram showing a conventional phase scanning type phased array antenna device. In the figure, 1 ... Reference microwave oscillator, 2 ... Phase shifter, 3 ... Microwave amplifier, 4 ... Element antenna, 5
...... Phase shift amount control circuit, 6 ...... Synthetic beam, 7 ...... Laser diode, 8 ...... Bias circuit, 9 ...... Bias current, 10 ...... Microwave signal, 11 ...... Radiant light, 12 ...
… Optical fiber, 13… Avalanche photodiode, 14… Output terminal, 15… Laser diode optical transmitter, 16… Microwave amplifier, 17… Optical receiver,
18 ... Laser diode bias control circuit. In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (2)

[Claims] 1. A reference microwave oscillator, a plurality of phase shifters for receiving independent outputs of the reference microwave oscillator, and providing independent phase shift amounts, and a microwave amplifier provided for each phase shifter. A phased array antenna device comprising an array of antennas provided for each microwave amplifier, wherein the phase shifter is a laser diode, and a bias circuit for adding a microwave signal to the laser diode by superimposing it on a bias current. A phased circuit comprising a photodiode for converting the output light of the laser diode into an electric signal and a circuit for changing the amount of the bias current applied to the laser diode in accordance with a target phase shift amount. Array antenna device. 2. The phased array antenna device according to claim 1, wherein the output light of the laser diode is incident on the photodiode through an optical fiber.