JPH0728173B2 - Antenna device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention emits a beam in a desired direction to transmit and receive a radio wave or has a directivity to an interfering wave at the time of reception for detection by radio communication or radar. The present invention relates to an antenna device in which a pointing direction is variably controlled such as creating a zero point.

[Prior Art and Its Deficiencies] An antenna device having directional characteristics is configured, for example, as shown in FIG. This antenna device shows the structure of a normal phase array antenna device. A plurality of antenna elements 11 to 14, for example, four antenna elements 11 to 14 are connected to phase shifters 15 to 18, respectively. line
It is adapted to be connected to the synthesizer / distributor 23 via 19-22. The phase shifters 15 to 18 are for controlling the directivity of the beam 24a synthesized by the antenna elements 11 to 14, and by controlling the phase shifters 15 to 18 by the control device 25, the phase shifters 15 to 18 are controlled. By changing the phase of part or all of the signal that passes through 15 to 18, the beam
The directivity can be changed as shown by 24b.

The phased array antenna scans by changing its phase electronically.However, in the antenna device having such a configuration, when handling a wideband signal frequency, the phase change amount due to the frequency in the phase shifters 15 to 18 is used. Has a problem that the directivity changes depending on the frequency. Moreover, since the phase amount changes significantly depending on the change of the antenna impedance, it is difficult to control the directivity with high accuracy.

[Object of the Invention] The present invention has been made in view of the above points, and provides an antenna device having a simple structure, preventing a change in directivity due to frequency, and capable of highly accurate directivity control over a wide band. It is a thing.

That is, according to the present invention, a mixer is inserted in a signal line from an antenna element, a signal generated by a local phase signal generator is supplied to the mixer, and a phase of a signal positioned in the antenna element is supplied. Is controlled, and in particular, the phase control can be processed by a local phase shifter composed of a digital circuit.

[Embodiment of the Invention] An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows the configuration of the antenna device according to the present invention, in which the antenna elements 11 to 14 are connected to the mixers 30 to 33 via the films 26 to 29. And this mixer 30-33
From the intermediate frequency signal lines 34 to 37 to the synthesis / distribution circuit
Connected to 38. Then, the local oscillator signal from the local oscillator phase generator 39 is applied to each of the mixers 30 to 33 via local oscillator phase lines 40 to 43. A part of a rectangular wave from the input terminal 44 is supplied to the local phase signal generator 39.

FIG. 2 shows the configuration of the local oscillator phase shifter 391 provided in the local oscillator phase signal generator 39 in FIG. Although the local oscillator phase signal generator 39 is provided with four local oscillator phase shifters, FIG. 2 shows only one local oscillator phase shifter 391. In this local oscillator phaser 391, a rectangular wave signal (waveform a) having a duty ratio of "1" shown in FIG. 3A is added as a local oscillator signal which is a reference signal built in the input terminal 44. The input terminal 44 has a trigger flip-flop circuit 45,
Trigger flip-flop circuit 47 via inverter 46
Are connected. The output sides of these trigger flip-flop circuits 45 and 47 are branched in the middle, and inverters 48 and 49 are connected to the output lines of one side of each.

The output lines of the trigger flip-flop circuits 45 and 47 branched in this way so as to obtain four types of waveforms are connected to the switch circuit 50, respectively. Then, the signal selected by the switch circuit 50 is transferred to the buffer amplifier 51.
Through the output terminal 52.

In the local oscillator phase shifter 391 configured as described above, when the waveform a shown in FIG. 3 (A) is input to the input terminal 44 as a local oscillator signal, the following four types of outputs are generated in the local oscillator phase shifter 391. The waveform is obtained. First, when the waveform a is input to the trigger flip-flop circuit 45, a waveform b shown in FIG. 3 (B) obtained by dividing the waveform a by 1/2 is obtained as the output. Further, when this waveform b is partially branched and input to the inverter 48, a waveform c shown in FIG. 3 (C) in which the phase is changed by 180 ° from the waveform b is output.

On the other hand, the waveform a is also input to the inverter 46 separately from the trigger flip-flop circuit 45, the phase is inverted by the inverter 46, and the waveform d is output as shown in FIG. Then, the waveform d is input to the trigger flip-flop circuit 47 in the same manner as the above-mentioned waveform b, and the waveform d is divided by 1/2 to output the waveform e shown in FIG. 3 (E). When a part of the output waveform e is branched and input to the inverter 49 similarly to the waveform b, the phase of the waveform e is changed by 180 °, and the waveform f shown in FIG. 3 (F) is obtained. That is, these output waveforms b, c, e, f are 1/2 of the local input waveform a.
The frequency is divided, and the phases are different by 90 °.

The switch circuit 50 is configured to select any one of these waveforms b, c, e, and f, and the selected waveform is input to the buffer amplifier 51. The signal output whose phase has been switched by the switch circuit 50 is amplified by the buffer amplifier 51, obtained from the output terminal 52, and supplied to the local phase lines 40 to 43.

When the antenna device configured as described above is operated for reception, a plurality of antenna elements 11 to 14 transmit incoming radio waves.
The received radio waves are selected by the filters 26 to 29 and transmitted to the mixers 30 to 33. On the other hand, in the local oscillator phase signal generator 39, the local oscillator signal input from the input terminal 44 is received and the signal changed to the desired phase is transmitted by the local oscillator phase line.
Output to mixers 30-33 via 40-43. Here, for each of the mixers 30 to 33, the local phase signal generator 39
When the phases of the local oscillation power from the
The phase difference between the 14 side received signals is
It is kept the same as the phase difference between the sides. This is apparent from the basic properties of known mixers. That is, one mixer has a function of producing a product of the input power and the local power by an arbitrary non-linear element. From the product of the above two signals, the sum and difference signals of the frequencies and phases of the two signals are obtained. Produced. From the formula of the triangular relation, the mixing action of the mixer is sin (ω ₁ t + φ ₁ ) ・ sin (ω ₂ + φ ₂ ) = (1/2) {− cos ((ω ₁ + ω ₂ ) t + φ ₁ + φ ₂ ) + cos ( (Ω ₁ −ω ₂ ) t + φ ₁ −φ ₂ )}. In the above equation, suffixes 1 and 2 represent a signal and a local oscillator, and when the phase φ _{2 of the} local oscillator is used as a reference, _two of the sum and difference frequencies (abbreviation of angular frequency, angular frequency ω = 2πf) are converted. The signal retains the original phase information φ ₁ even after conversion. In this embodiment, a plurality of signals will store their respective phase information.

In general, in a wireless device, a mixer is also called a down converter for converting a high frequency radio frequency to an intermediate frequency and an up converter for converting an intermediate frequency to a high frequency.

The phase difference between the received signals on the side of the antenna elements 11 to 14 does not change depending on the frequency. Also,
When the phase of the local oscillation power is changed by the local oscillation phase signal generator 39, the position on the side of the composite distribution circuit 38 via the intermediate frequency signal lines 34 to 37 is the local oscillation phase as is clear from the above description. A phase change equal to the phase change amount in the signal generator 39 is generated. Therefore, the overall directivity of the antenna elements 11 to 14 can be variably controlled by the local phase signal output from the local phase signal generator 39 to the local phase lines 40 to 43.

For example, when the spacing between the antenna elements 11 to 14 is 0.75λ, the local phase signal generator 39 to the local phase line 40 to
When the local phase signal output to 43 is set to 0 ° by the switch circuit 50, the total directivity becomes a beam having the maximum gain in the front direction of the antennas 11-14. Further, the local oscillator phase signal output from the local oscillator phase signal generator 39 to the local oscillator phase lines 40 to 43 is switched by the switch circuit 50 to 0 °, 90 °, 180 °.
When set to ゜ and 270 ゜, the total directivity is a beam that is deviated to the left from the front by 19.5 ゜.

Further, according to the present invention, even if the instantaneous bandwidth of the local phase signal generator 39 is a narrow band, if the mixers 30 to 33 have a wide band, the antenna device as a whole can control the directivity over a wide band. . This is because the phase φ ₁ of the converted signal is a parameter independent of the frequency ω ₁ , as described in the explanation of the mathematical formulas above. Therefore, even if the local signal is fixed and the input frequency is changed to a wide band, This is because the quantity φ ₁ does not depend on the characteristics of the mixer.

Further, even when this antenna device is operated for transmission, when a plurality of transmission frequency signals are produced from one intermediate frequency signal by a plurality of mixers, the transmission antenna is changed by changing the local oscillation phase of each mixer. The phase can be similarly controlled for the signal to the element.

Further, since the local oscillation phase signal generator 39 using the local oscillation phase shifter 391 performs signal processing by the digital circuit on the local oscillation side, there is no phase change even if the local oscillation signal frequency is changed, and , The phase does not change even if the impedance of the connected load changes, and therefore, highly stable phase control can be performed.

Further, the antenna device may include antenna elements 11 to 14 if necessary.
It is also possible to insert a transmission amplifier, a reception low noise amplifier, or a directivity-controlled variable attenuator between the mixer and the mixers 30 to 33.

FIG. 4 shows another example of the local phase signal generator 39. This device is equipped with a digital local oscillator phase shifter 54 which operates similarly to the local oscillator phase shifter 391 shown in FIG.
A first local oscillator signal of Hz or less is input from the input terminal 53 to the digital local oscillator phase shifter 54. This digital station phaser 54
Outputs the signal of the selected phase to the mixer 55. on the other hand,
A second local oscillator signal of, for example, 1 GHz, which is higher than the first local oscillator signal, is input to a separately provided input terminal 56 and sent from the input terminal 56 to the mixer 55. And this mixer
55, the sum frequency by the up-converter method
A mixed output of a desired frequency, which is either a 1.1 GHz signal or a signal having a difference frequency of 0.9 GHz, is input to the band amplifier 57, and the amplified signal is obtained from the output terminal 58. The circuit shown in FIG. 4 is a local oscillator phase signal generator 39
Four of them are provided inside, and the output signals of the respective output terminals 58 are sent to the mixers 30 to 33 as local phase signals via the local phase lines 40 to 43 shown in FIG. In the local oscillator phase signal generator 39 configured by using the up-converter system as described above, a local oscillator signal having a frequency higher than the operating frequency of the frequency divider can be easily obtained.

[Effects of the Invention] As described above, according to this antenna device, the phase control of the antenna element can be performed in a wide band with a simple circuit configuration. Further, by performing the local phase control by the digital circuit, not only the cost can be reduced, but also the control of the directivity can be made very accurate. Furthermore, by using the local oscillator phase signal generator using the up-converter system, local oscillators having a frequency higher than the operating frequency of the frequency divider such as the microwave band can be easily obtained.

[Brief description of drawings]

1 is a configuration diagram of an antenna device according to an embodiment of the present invention, FIG. 2 is a circuit configuration diagram of a local oscillator phase signal generator in FIG. 1, and FIG. 3 is a local oscillator phase shifter in FIG. FIG. 4 is a diagram showing an example of a time chart, FIG. 4 is a circuit configuration diagram of a local oscillator phase signal generator which is another embodiment of the present invention, and FIG. 5 is a configuration diagram of a conventional antenna device. 11 to 14 ... Antenna element, 15 to 18 ... Phaser, 25 ... Control device, 30 to 33, 55 ... Mixer, 38 ... Combining / dividing circuit, 39 ... Local phase signal generator, 391 ...... Local oscillator, 45,47 …… Trigger flip-flop circuit, 46,4
8, 49 ... Inverter, af ... Waveform.

Claims (1)

[Claims] 1. A plurality of antenna elements for transmitting and receiving radio waves, a plurality of mixers provided corresponding to these antenna elements and connected to the respective antenna elements, and a part or all of the mixers selected. And a local phase signal generator for supplying a signal of a selected phase, and the local directivity signal generated by the local phase signal generator controls the total directivity of the plurality of antenna elements variably. In the antenna device according to the above, the local oscillator phase signal generator includes a means for generating a plurality of signals having different phases by combining a frequency dividing circuit for frequency-dividing the first local oscillator signal and a phase inverting circuit, and this means. A digital local oscillator phase shifter comprising switch means for selecting and outputting one of the generated plurality of signals, and an output signal of the digital local oscillator phase shifter and a second local oscillator signal are mixed or summed. An antenna device comprising a plurality of circuits configured by a mixer that outputs a difference frequency signal and a band amplifier that extracts the output signal of the mixer as a local oscillation phase signal.