JP2007251794A - Array antenna device, and transmission/reception module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain an array antenna device capable of suppressing a higher harmonic wave of a transmission signal without using a band pass or low-pass filter. <P>SOLUTION: A 90° hybrid circuit is provided in each transmission/reception module so that two signals having a 90° phase difference therebetween are generated from a transmission signal amplified by a power amplifier during transmission, power is fed to a corresponding cross dipole antenna and the two signals having the 90° phase difference therebetween received by the relevant cross dipole antenna during reception are composed to obtain a reception signal. In a configuration of the 90° hybrid circuit, a means for suppressing unwanted frequency waves is provided. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a radar array antenna device and a transmission / reception module used in the device.

  A dipole antenna typified by a linear antenna and having a length λ / 4 (λ: wavelength of radio waves) arranged on a straight line to have a total length λ / 2 is widely known as a half-wave dipole. Such a dipole antenna generates only linearly polarized wave due to its structure, but when two dipole antennas are arranged orthogonally in a cross shape in the same plane and excited with a phase shift of 90 degrees, two A circularly polarized wave is generated in a direction perpendicular to the plane including the dipole. Such a combination antenna is known as a cross dipole antenna. In addition, this cross dipole antenna generates circularly polarized waves in opposite directions in the direction perpendicular to the array surface of the dipoles, but a unidirectional circle can be obtained by placing a reflector at a position λ / 4 behind the array surface. It is known to be polarized.

  By the way, as an antenna applied to an atmospheric observation radar or the like, it has been proposed to use an array antenna in which a plurality of the above-mentioned cross dipole antennas are arranged in a straight line or a plane. In addition, a transmission / reception module is provided for each of the plurality of cross-dipole antennas to amplify and feed the transmission signal, amplify the reception signal, and control the gain and the plane of polarization of the transmission wave, thereby reducing the size and weight. Has been proposed (see, for example, Patent Document 1). The transmission / reception module disclosed in Patent Document 1 uses a circulator to guide the transmission power amplified by the power amplifier at the time of transmission to the cross dipole antenna and not to the reception low-noise amplifier, During reception, the circulator guides the received signal from the cross dipole antenna to the low noise amplifier. In addition, in order to generate a circularly polarized wave by giving a phase difference to the cross dipole antenna, signals are divided into two series using other circulators and individually connected to the cross dipole antenna.

  In addition to the cross dipole antenna, there is a phenomenon in which harmonic components of the transmission signal are mixed from the power amplifier side when power is supplied to the antenna. As a method for removing this unnecessary wave, a band-pass or low-pass filter is generally provided between the power amplifier and the antenna (see, for example, Patent Document 2).

JP-A-6-53726 JP-A-6-140835 (FIG. 10)

  As described above, the conventional transmission / reception module described in Patent Document 1 uses a circulator for switching between transmission and reception with respect to the cross dipole antenna. Such a circulator has a low frequency band such as HF, VHF, and UHF. When considering application to a band, a large one is required to cope with a low frequency. Therefore, the transmission / reception module cannot be reduced in size and weight in the low frequency band, and the circulator has a larger loss than the transmission / reception switching by the 90-degree hybrid circuit. In order to solve this problem, in the patent application (Japanese Patent Application No. 2004-36805) by the applicant of the present invention, a 90-degree hybrid circuit is used instead of a circulator, and a cross-dipole antenna that performs transmission and reception is divided into feeding and reception signals We have proposed a technology that can be automatically performed to reduce the size, weight, and efficiency of transmission / reception modules in the HF to UHF bands. However, in order to suppress unnecessary waves including harmonics of the transmission signal in this transmission / reception module, when a band-pass or low-pass filter as shown in Patent Document 2 is provided after the power amplifier, it is used. Loss of the filter that causes the transmission output is reduced. In particular, when the loss of the filter is large, it is necessary to configure so as to increase the output of the power amplifier in anticipation of the loss, resulting in a decrease in efficiency of the apparatus and an increase in scale. In addition, a space for mounting the filter is required, but the interval between the antenna elements constituting the array antenna is mainly limited by the frequency used, so the transmission / reception module placed behind each antenna element has a filter mounted. When the size is increased, it is difficult to secure the mounting space.

  The present invention has been made to solve the above problems, and provides an array antenna apparatus and a transmission / reception module that can suppress harmonics of a transmission signal without using a band-pass or low-pass filter. For the purpose.

  The array antenna apparatus according to the present invention uses an array antenna in which a plurality of cross dipole antennas are arranged, and each cross dipole antenna is provided with a transmission / reception module, and each transmission / reception module uses a 90-degree hybrid circuit, At the time of transmission, two signals having a phase difference of 90 degrees are generated from the transmission signal amplified by the power amplifier and fed to the corresponding cross dipole antenna. At the time of reception, the signals received by the cross dipole antenna are at the positions of 90 degrees. In an array antenna apparatus in which two signals having a phase difference are combined to obtain a received signal, a 90-degree hybrid circuit is provided with means for suppressing unnecessary frequency waves in its configuration.

  According to the present invention, not only can the harmonic suppression function be realized, but also the filter loss can be reduced compared to the use of a conventionally used band-pass or low-pass filter. While improving, it can attain size reduction.

Embodiment 1 FIG.
FIG. 1 is a block diagram showing a functional configuration example of an array antenna apparatus common to each embodiment of the present invention.
The array antenna apparatus includes a power distributor / combiner 10, a plurality of transmission / reception modules 20, and an array antenna 30.
As shown in FIG. 7, the array antenna 30 is a transmission / reception antenna in which a plurality of cross dipole antennas 31 configured by orthogonally dipole antennas 32 and 33 are arranged in a straight line or a plane. The power distributor / combiner 10 distributes and supplies transmission signals input from a transceiver (not shown) to a plurality of transceiver modules 20, and synthesizes the received signals from the transceiver module 20 and outputs the signals to the transceiver side during reception. It is means to do.

  Each transmitting / receiving module 20 has the same configuration, and includes a phase shifter 21, a transmission / reception switching device 22, a power amplifier 23, a 90-degree hybrid 24, a low noise amplifier 25, a semiconductor switch 26, and the like. The phase shifter 21 is means for adjusting the phase of the transmission signal and the reception signal to a value assigned to each transmission / reception module. The transmission / reception switcher 22 is a switch unit that outputs a transmission signal input from the phase shifter 21 during transmission to the power amplifier 23 and outputs a reception signal obtained from the low noise amplifier 25 to the phase shifter 21 during reception. . The power amplifier 23 is means for power-amplifying the transmission signal whose phase has been adjusted by the phase shifter 21. The 90-degree hybrid circuit 24 gives a 90-degree phase difference to the transmission signals fed to the antenna elements 32 and 33 of the cross-dipole antenna 31. From the two signals having the 90-degree phase difference received by each antenna element, This is a means for obtaining a combined received signal. The low noise amplifier 25 is means for amplifying the received signal from the 90-degree hybrid circuit 24 and outputting the amplified signal to the phase shifter. The semiconductor switch 26 is means for cutting off a signal to be input from the 90-degree hybrid circuit 24 to the low noise amplifier 25 during transmission.

Next, the operation of the array antenna apparatus will be described.
When a transmission signal generated by the transceiver at the time of transmission is input, the power distributor / combiner 10 distributes this signal and supplies it to the plurality of transceiver modules 20. In each transmitting / receiving module 20, the phase shifter 21 changes the transmission signal from the power distributor / combiner 10 to the phase assigned to each module in order to form a predetermined transmission beam by the array antenna 30. The transmission signal whose phase is adjusted by the phase shifter 21 is sent to the power amplifier 23 composed of one amplifier or a plurality of amplifiers via the transmission / reception switch 22 and is amplified. The transmission signal amplified to a required output by the power amplifier 23 is supplied to the 90-degree hybrid 24. In the 90-degree hybrid 24, the supplied transmission signal is divided into two signals whose phases are shifted from each other by 90 degrees as power and supplied to the corresponding dipole antenna elements 32 and 33 of the cross dipole antenna 31. Is done. The cross dipole antenna 31 radiates circularly polarized radio waves to the space by being fed with signals of the same level having a phase difference of 90 degrees.

  The radar receives the reflected wave reflected from the object by the transmission wave. For this purpose, the transmission / reception switch 22 and the semiconductor switch 26 are switched, and the power amplifier 23 and the low-noise amplifier 25 are activated and deactivated. Control takes place immediately. The reflected wave reflected on the object is reflected at the same distance and the same phase from the 90-degree hybrid 24 as in the case of the reflection at the cross dipole antenna 31 described above. Without being automatically guided to the receiving system. The reception signal guided to the reception system is given to the low noise amplifier 25 through the semiconductor switch 26 that protects the reception system at the time of transmission. In the low noise amplifier 25, the received signal is amplified while suppressing noise, and is supplied to the phase shifter 21. In the phase shifter 21, the phase of the reception signal is adjusted so that the reception beam of the array antenna 30 is directed. The received signal adjusted by the phase shifter 21 of each transmission / reception module 20 is combined by the power distributor / combiner 10, output to the transmitter / receiver, and used for signal processing as a radar.

Here, a 90-degree hybrid circuit will be described.
The 90-degree hybrid circuit is a directional coupler that distributes the output phase difference at 90 degrees, and has four ports P1, P2, P3, and P4. For example, when a signal is input to the port P1, a signal having half the power is output to the port P3. At the same time, a signal having a phase difference of 90 degrees from this output is output to the port P4. However, at this time, the port P2 has almost no output. This principle is also applicable when input is made to ports P3 and P4. When the circularly polarized wave is received by the cross dipole antenna 31, the signals (sinusoidal waves) obtained from the two dipole antenna elements constituting each have a phase difference of 90 degrees, so that they correspond to the ports P3 and P4. When input, the synthesized received signal appears at port P2.

  A basic circuit configuration of the 90-degree hybrid circuit is shown in FIG. As is well known, this is constructed on the basis of a microstrip, and a loop is formed by four inductors L1, L2, L3, and L4, and a capacitor C1 is connected between a connection point between adjacent inductors and the ground. , C2, C3, and C4 are connected to each other, and both ends of a pair of opposing inductors L1 and L3 are input and output ports. When this 90-degree hybrid circuit is used in the transmission module 20 of FIG. 1, since there is no suppression function for unnecessary harmonics of the transmission signal, the above-described conventional method, for example, the output side of the power amplifier 23, for example, A band-pass or low-pass filter must be provided on the input side of the port P1 or on the output side of the ports P2 and P4.

On the other hand, the 90-degree hybrid circuit used in the first embodiment has a configuration as shown in FIG. This circuit has four parallel resonant circuits comprising a combination of an inductor L10 and a capacitor C10, as well as L20 and C20, L30 and C30, and L40 and C40. These parallel resonant circuits form a loop, and capacitors C1, C2, C3, and C4 are respectively connected between the connection points of the adjacent parallel resonant circuits and the ground, and both ends of a pair of parallel resonant circuits facing each other are inserted. A circuit network is formed as an output port. The parallel resonant circuit has the same impedance as the inductance of the circuit shown in FIG. 3 with respect to the transmission frequency, and the values of the inductor and the capacitor are such that the resonant frequency is a harmonic (second harmonic) frequency. To decide.
Therefore, by using this circuit as a 90-degree hybrid circuit 24 used for transmission and distribution of transmission signals to the cross-dipole antenna and synthesis of reception signals, a general 90-degree hybrid circuit is used for the frequency of transmission signals. Because it has the equivalent inductance, it performs the same operation as before, and with respect to unnecessary harmonics (double wave), it is in parallel resonance and cut off in a circuit, so high isolation can be secured. . That is, a harmonic suppression function can be realized.

  As described above, according to the first embodiment, means for suppressing the harmonics of the transmission signal is provided in the configuration of the 90-degree hybrid circuit used to distribute and feed the transmission signal to the cross dipole antenna and to synthesize the reception signal. As a means, a parallel resonant circuit having a harmonic frequency as a resonance frequency is applied, so that a harmonic suppression function can be realized, and a conventionally used band-pass or low-pass filter can be used. Since the filter loss can be reduced as compared with the above, the efficiency of the array antenna device can be improved and the size can be reduced. In the above example, the suppression of the harmonics of the transmission signal has been described. However, when other unnecessary waves become a problem, a 90-degree hybrid circuit designed so that the resonance frequency of the parallel resonance circuit becomes the unnecessary frequency is used. It may be used.

Embodiment 2. FIG.
In the first embodiment, it has been described that the harmonic suppression is performed in the 90-degree hybrid circuit 24 used for the distributed power feeding to the cross dipole antenna and the synthesis of the received signal. However, in the second embodiment, the harmonics are suppressed in the power amplifier 23. Describes wave suppression.
In FIG. 1, a power amplifier 23 amplifies a transmission signal fed to the cross dipole antenna 31. A balanced amplifier as shown in FIG. 4 is applied to this power amplifier.
In FIG. 4, this balanced amplifier includes first and second 90-degree hybrid circuits 101 and 104 used as a distributor and a synthesizer, and first and second amplifiers 102 and 102 provided in the middle between them. 103. The input transmission signal is divided into two signals by the first 90-degree hybrid circuit (distributor) 101, and is amplified by the first and second amplifiers 102 and 103 having the same characteristics in both phase and amplitude, The signal is synthesized by the second 90-degree hybrid circuit (synthesizer) 104 and output. Here, looking at the phase relationship, the signal distributed to the second amplifier 103 and distributed by the first 90-degree hybrid circuit 101 is delayed in phase by 90 degrees with respect to the signal applied to the first amplifier 102. . On the other hand, since the signal synthesized by the second 90-degree hybrid circuit 104 through the first amplifier 102 is output 90 degrees behind the signal synthesized through the second amplifier 103, both signals are Eventually, it will be synthesized in phase.

In terms of gain, since the input signal is divided into two by the first 90-degree hybrid 101, each of the first and second amplifiers 102 and 103 receives a level that is half of the input level. . Normally, the second 90-degree hybrid circuit 104 on the synthesizing side also has a half level of attenuation, but the signal input from the first amplifier 102 and output to the insulation terminal of the second 90-degree hybrid circuit 104 The signal input from the second amplifier 103 and output to the insulation terminal has a phase difference of 180 degrees. Therefore, no signal appears at the insulated terminal, and there is no power consumption due to the connected resistor. That is, there is no loss in the second 90-degree hybrid circuit 104 on the synthesis side. In addition, since the amplified signals are synthesized in phase, the output signal is doubled. After all, since the signal attenuated to a half level on the distribution side becomes a double level on the synthesis side, the loss is totally zero.
In addition, this balanced amplifier has a feature that the reflection characteristic seen from the input side of the first amplifier 102 is improved even if the reflection characteristics of the first and second amplifiers 102 and 103 are poor.

The above is a general description of a balanced amplifier using a 90-degree hybrid circuit. In the second embodiment, the first and second 90-degree hybrid circuits 101 and 104 used in the balanced amplifier are described above. The 90-degree hybrid circuit including the parallel resonance circuit having the harmonic frequency as the resonance frequency described in FIG. 2 is used.
As described above, according to the second embodiment, the balanced amplifier is used as the power amplifier, and the means for suppressing the harmonics of the transmission signal is provided in the configuration of the 90-degree hybrid circuit of the balanced amplifier. The band-pass or low-pass filter that has been conventionally used to suppress harmonics is not required, and the efficiency and size of the array antenna device can be improved. In addition, when only a balanced amplifier having a harmonic suppression function cannot sufficiently remove harmonics, a 90-degree hybrid circuit having a harmonic suppression function that performs transmission / reception switching with respect to the crossed dipole antenna of the first embodiment. The transmitter / receiver module may be configured in combination, and the suppression of unnecessary harmonics can be enhanced.

Embodiment 3 FIG.
In the second embodiment, the use of a balanced amplifier having a 90-degree hybrid circuit having a harmonic suppression function as a power amplifier has been described. However, in the second embodiment, a Wilkinson divider (hereinafter simply referred to as a power amplifier) is used. The use of a balanced amplifier using “divider” as a power amplifier will be described.
The balanced amplifier (Balanced Amp) using a divider as shown in FIG. 5 is applied to the power amplifier 23 shown in FIG. This balanced amplifier is composed of first and second dividers 201 and 204 used as a distributor and a combiner, and first and second amplifiers 202 and 203 provided in the middle between them. The input transmission signal is distributed to two signals by the first divider (distributor) 201, amplified by the first and second amplifiers 202 and 203 having the same characteristics in both phase and amplitude, and the second It is synthesized by a divider (synthesizer) 204 and output.

In terms of gain, since the input signal is divided into two by the first divider 201, a level that is half of the input level is input to each of the first and second amplifiers 202 and 203. Normally, the second divider 204 on the synthesizing side also has a half level of attenuation, but the second divider 204 synthesizes the signals in phase, so that the balance of the synthesizer is maintained and the resistance is Power is not consumed. Therefore, no loss occurs in the second divider 204 on the synthesis side. In addition, since the amplified signals are combined in phase, the combined signal is doubled. After all, since the signal attenuated to a half level on the distribution side becomes a double level on the synthesis side, the loss is totally zero.
Also, this balanced amplifier is suitable for highly reliable applications because even if one of the amplifiers fails, if the other is operating, the gain is degraded from the normal value, but a certain degree of gain can be secured. It has the characteristics.

By the way, the Wilkinson divider used in the balanced amplifier shown in FIG. 5 is often used as an in-phase distributor. FIG. 6 shows its basic circuit and its operation principle will be described.
When the circuit of FIG. 6 is considered as a distribution circuit, P10 is an input, and P20 and P30 are outputs. A load R is connected to P20 and P30, and this is assumed to be 50Ω. Assuming that there are no Z1 and Z2 transmission lines, when the output side is viewed from the P10 side, the impedance viewed from the right side from the point a is 25Ω because 50Ω is connected in parallel. Therefore, 100Ω-50Ω impedance conversion circuits Z1 and Z2 using transmission lines are inserted between ab and ac. Using the Smith chart or the like, the impedance of these conversion portions is 70.7Ω. To move the circle on the Smith chart from 100Ω to 50Ω, the circle is moved by λ / 4, so the length of the transmission line is λ / 4. Now, looking at the right side from point a, two 100Ω are connected in parallel, so that 50Ω and matching is achieved.
Next, considering the case of inputting a signal from P20, half is output to P10 through point a, while the other half returns to point c through point a. However, the path length b → a → c has a line length of λ / 2, and the phase is inverted as compared with a signal transmitted from point b through R to point c. That is, the combined signals of these two paths cancel each other, and the signal input from P20 is not output to P30. As a result, the signal input from P20 is distributed by half to P10 and R and is not output to P30, so that power is absorbed by R.

The above is a general description of a balanced amplifier using a divider. In the third embodiment, the first and second dividers 201 and / or 204 used in the balanced amplifier suppress harmonics. Provide means. Specifically, a parallel resonance circuit having a harmonic frequency as a resonance frequency is provided on the transmission line forming the impedance conversion circuits Z1 and Z2 in the circuit of FIG.
As described above, according to the third embodiment, the balanced amplifier is used as the power amplifier, and the means for suppressing the harmonics is provided in the configuration of the divider of the balanced amplifier, so that it is conventionally used to suppress the harmonics. Thus, the band-pass or low-pass filter that has been used is not required, and the efficiency and size of the array antenna device can be improved. In addition, when only a balanced amplifier having a harmonic suppression function cannot sufficiently remove harmonics, a 90-degree hybrid circuit having a harmonic suppression function that performs transmission / reception switching with respect to the crossed dipole antenna of the first embodiment. The transmitter / receiver module may be configured in combination, and the suppression of unnecessary harmonics can be enhanced.
In the above example, the Wilkinson divider is used as the in-phase distributor for the balanced amplifier, but other in-phase distributors such as a T-branch may be used, and similar effects can be obtained.

It is a block diagram which shows the function structure of the array antenna apparatus which concerns on each embodiment of this invention. It is a circuit diagram which shows the structure of the 90 degree hybrid circuit used for the array antenna apparatus of Embodiment 1 of this invention. It is a circuit diagram which shows the basic composition of a 90 degree hybrid circuit. It is a block diagram which shows the structure of the balanced amplifier using the 90 degree hybrid which concerns on Embodiment 2 of this invention. It is a block diagram which shows the structure of the balanced amplifier using the divider concerning Embodiment 3 of this invention. It is a circuit diagram which shows the fundamental structure of the divider which concerns on Embodiment 3 of this invention. It is explanatory drawing which shows the array antenna using a cross dipole antenna.

Explanation of symbols

  20 transceiver module, 23 power amplifier, 24, 101, 104 90 degree hybrid, 25 low noise amplifier, 30 array antenna, 31 cross dipole antenna, 201, 204 divider, C10, C20, C30, C40 capacitor, L10, L20, L30 , L30 Inductor.

Claims (7)

An array antenna having a plurality of cross dipole antennas is used, and a transmission / reception module is provided for each cross dipole antenna. Each transmission / reception module uses a 90-degree hybrid circuit, and during transmission, is amplified by a power amplifier. Two signals having a phase difference of 90 degrees from each other are generated and fed to the corresponding cross dipole antenna, and at the time of reception, the two signals having a phase difference of 90 degrees received by the cross dipole antenna are synthesized. In the array antenna apparatus adapted to obtain the received signal by
An array antenna apparatus, wherein the 90-degree hybrid circuit includes means for suppressing unnecessary frequency waves in its configuration.   2. The array antenna apparatus according to claim 1, wherein the power amplifier is constituted by a balanced amplifier, and a means for suppressing unnecessary frequency waves is provided in the configuration of the distributor and / or the combiner of the balanced amplifier. An array antenna having a plurality of cross dipole antennas is used, and a transmission / reception module is provided for each cross dipole antenna. Each transmission / reception module uses a 90-degree hybrid circuit, and during transmission, is amplified by a power amplifier. Two signals having a phase difference of 90 degrees from each other are generated and fed to the corresponding cross dipole antenna, and at the time of reception, the two signals having a phase difference of 90 degrees received by the cross dipole antenna are synthesized. In the array antenna apparatus adapted to obtain the received signal by
An array antenna apparatus characterized in that a balanced amplifier is used as the power amplifier, and a means for suppressing unnecessary frequency waves is provided in the configuration of a distributor and / or a combiner of the balanced amplifier.   4. The array antenna apparatus according to claim 2, wherein the distributor and the combiner of the balanced amplifier are 90-degree hybrid circuits.   4. The array antenna apparatus according to claim 2, wherein the divider and synthesizer of the balanced amplifier are dividers.   6. The array antenna apparatus according to claim 1, wherein the means for suppressing the unnecessary frequency is a parallel resonance circuit having the unnecessary frequency as a resonance frequency.   The transmission / reception module which comprises the array antenna apparatus of any one of Claims 1-6.

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