JP2005150958A - Array antenna - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain an array antenna capable of reducing increase in side lobe level caused by variations in the characteristics of components, without increasing the cost at manufacturing or without causing troubles in the operation. <P>SOLUTION: When a phase amount is set for each of a plurality of antenna elements constituting an array, a phase amount calculated, by adding or subtracting an offset amount to or from a predetermined phase amount is set. Consequently, increase in the side-lobe level of an antenna array caused by the variations in the characteristics of components is reduced electrically, while keeping original components, as they are, without replacing or redesigning them. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an array antenna apparatus in which a plurality of antenna elements are arranged.

  An array antenna device that forms a desired beam pattern electrically by arranging a plurality of antenna elements and controlling the excitation amplitude and phase for each antenna element has been conventionally used in radar systems and the like. An example of the configuration of this type of antenna device is shown in Non-Patent Document 1.

  FIG. 6 is a diagram illustrating an example of a configuration of a conventional array antenna device disclosed in Non-Patent Document 1. In FIG. Since the antenna is reciprocal for transmission and reception, the case of transmission will be described here. The array antenna apparatus 50 shown in FIG. 6 includes a plurality (n) of (n) antenna elements 511 to 51n arranged at a constant interval in a specific direction and a plurality (n) of transmission signals from the transmission signal source 54. The power feeding circuit 53 that feeds power to the antenna elements 511 to 51n, and the power feeding circuit 53 and the antenna elements 511 to 51n are provided corresponding to the antenna elements 511 to 51n and supplied to the antenna elements 511 to 51n. Phase shifters 521 to 52n that change the phase of the transmitted signal.

  Next, the operation of the array antenna apparatus 50 will be described. The transmission signals supplied from the transmission signal source 54 are distributed into a plurality (n) by the power feeding circuit 53, subjected to phase control by the phase shifters 521 to 52n, and then connected to the corresponding antenna elements 511. To 51n. Furthermore, a transmission signal is radiated | emitted to space from each antenna element 511-51n, and a beam is formed by being combined spatially. The beam shape formed at this time is controlled by the excitation amplitude and phase of the transmission signal supplied to each of the antenna elements 511 to 51n.

  In the array antenna apparatus 50 configured as described above, when the transmission signal from the transmission signal source 54 is distributed to a plurality (n) of signals by the power feeding circuit 53, each antenna element 511 is temporarily divided into n. When the excitation amplitudes of the transmission signals supplied to .about.51n are made equal, that is, when the excitation amplitudes are uniformly distributed, the level of the first side lobe of the formed beam is assumed to be n = 16. Is about -13.5 dB.

In general, a radar system or the like requires an antenna device having a low sidelobe characteristic according to various operational needs. For this reason, when a lower sidelobe level is required, the excitation amplitude of each antenna element is not uniformly distributed, but is high in the central part of the antenna element array and low in the peripheral part, for example, Taylor distribution. Weighting is performed (for example, see Non-Patent Document 2). That is, in the array antenna device 50, a Taylor distribution is applied to the distribution ratio of transmission signals from the power feeding circuit 53 to the antenna elements 511 to 51n, or between the power feeding circuit 53 and the antenna elements 511 to 51n, respectively. A beam characteristic with a low sidelobe level is obtained by adding an attenuator having a different attenuation factor or an amplifier having a different amplification factor to give a distribution to the excitation amplitude of the antenna element.
Supervised by Takashi Yoshida, “Revised Radar Technology”, The Institute of Electronics, Information and Communication Engineers, October 1, 1996, p. 123 Supervised by Takashi Yoshida, “Revised Radar Technology”, The Institute of Electronics, Information and Communication Engineers, October 1, 1996, p. 134

  By the way, various microwave circuit components that constitute such an array antenna device have variations in characteristics among individuals with respect to characteristics important for the array antenna device, such as amplitude passing characteristics and phase passing characteristics. I can't deny it. Therefore, in the design stage, a design is made in which these various factors affecting the characteristics of the array antenna apparatus are sufficiently taken into consideration.

  However, the beam shape, particularly the side lobe level, may be at an unacceptable level for the operation of the apparatus after the manufacture or operation of the array antenna apparatus. In particular, in an active array antenna apparatus in which an active element such as an amplifier that amplifies a transmission signal is provided for each antenna element, the influence due to fluctuations and variations in the amplitude and phase characteristics of the components is significant.

  In such a case, it is necessary to take measures such as improving the characteristics and replacement of the target component or reviewing the design, which has been a major factor in increasing the cost of manufacturing the device. In addition, during the operation of the apparatus, the operation is seriously hindered, such as being forced to interrupt the operation.

  The present invention has been made in consideration of the above-mentioned circumstances, and does not increase the cost of manufacturing the apparatus, and does not hinder the operation of the apparatus. An object of the present invention is to provide an array antenna apparatus capable of reducing an increase in lobe level.

  In order to achieve the above object, an array antenna apparatus according to a first invention includes a plurality of antenna elements arranged in a specific direction, a plurality of phase shifters provided corresponding to the plurality of antenna elements, A distribution synthesizer that distributes a transmission signal to a plurality of phase shifters with a predetermined amplitude distribution and synthesizes reception signals from the plurality of phase shifters with a predetermined amplitude distribution; When a predetermined phase shift amount is set to form a transmission beam and a reception beam directed in a predetermined direction, a predetermined offset amount is alternately increased or decreased according to the arrangement order with respect to the predetermined phase shift amount. It is characterized by setting.

  The array antenna apparatus of the second invention is provided corresponding to the plurality of antenna elements arranged in a specific direction and the plurality of antenna elements, amplifies the transmission signal and the reception signal, and transmits and receives the transmission signal and reception signal. A plurality of transmission / reception modules for controlling the phase of the signal, a distribution synthesizer for distributing the transmission signals to the plurality of transmission / reception modules with a predetermined amplitude distribution and combining the reception signals from the plurality of transmission / reception modules with a predetermined amplitude distribution; A predetermined offset amount with respect to the predetermined phase shift amount when a predetermined phase shift amount is set for the plurality of transmission / reception modules to form a transmission beam and a reception beam directed in a predetermined direction. Are set by alternately increasing or decreasing according to the order of the arrangement.

  According to the present invention, since the increase in the side lobe level of the array antenna device due to the characteristic fluctuations and variations of the components is electrically reduced by simple phase control with the original components, the device manufacture It is possible to obtain an array antenna apparatus that can suppress an increase in cost and reduce the influence on the operation of the apparatus even when the side lobe level is improved.

  Hereinafter, the best mode for carrying out an array antenna apparatus according to the present invention will be described with reference to FIGS.

  FIG. 1 is a block diagram showing a first embodiment of an array antenna apparatus according to the present invention. The array antenna device 1 includes an array antenna 11, a plurality (n) of phase shifters 121 to 12n, a distribution synthesizer 13, and a beam controller 14.

  The array antenna 11 includes a plurality (n) of antenna elements 111 to 11n arranged in a specific direction, and each of the antenna elements 111 to 11n includes a plurality of (n) phase shifters 121 provided correspondingly. To 12n. And while transmitting the transmission signal from each phase shifter 121-12n to space, an incoming signal is received and it transmits to each phase shifter 121-12n. In this embodiment, the antenna elements 111 to 11n are arranged in a one-dimensional manner at equal intervals.

  A plurality (n) of phase shifters 121 to 12 n control the phase of the transmission signal from the distribution synthesizer 13 based on the phase control signal from the beam controller 14, and the array antennas 11 connected correspondingly. It sends out to each antenna element 111-11n. Further, based on the phase control signal from the beam controller 14, the phase of the received signal received by each of the antenna elements 111 to 11n of the array antenna 11 connected correspondingly is controlled and transmitted to the distribution synthesizer 13.

  The distribution synthesizer 13 distributes a transmission source signal from a transmitter / receiver or the like (not shown) connected to the previous stage in an amplitude distribution based on the amplitude control signal from the beam controller 14, and a plurality (n) of them. Send to phase shifters 121-12n. Also, a received signal from a plurality (n) of phase shifters 121 to 12n is synthesized with an amplitude distribution based on an amplitude control signal from the beam controller 14, and a transmitter / receiver connected to a subsequent stage as a synthesized received signal, etc. (Not shown).

  The beam controller 14 calculates an amplitude distribution and a phase amount necessary for forming and scanning a predetermined transmission beam and reception beam, and the distribution synthesizer 13 and each of the shift synthesizers 13 are used as an amplitude control signal and a phase control signal, respectively. Send to phasers 121 to 12n.

  Next, the operation of the array antenna apparatus according to the present invention configured as described above will be described with reference to FIGS. Since the antenna is reciprocal for transmission and reception, the case of transmission will be described in detail.

First, in the case of transmission, generation of an amplitude control signal and a phase control signal in the beam controller 14 will be described. In the beam controller 14, the amplitude distribution and the phase amount for each of the antenna elements 111 to 11n necessary for forming the transmission beam are expressed as complex weights W _i (1 ≦ i ≦ n) as shown in Expression (1). Expressed and calculated.

Here, A _i (1 ≦ i ≦ n) is the excitation amplitude for the i-th antenna element 11i, λ is the wavelength of the transmission signal, d is the spacing between the arrangements of the antenna elements 111 to 11n, and θ is the directivity angle of the transmission beam. It is.

In the present invention, in order to obtain a desired low sidelobe characteristic, the predetermined offset amount α is alternately increased or decreased according to the arrangement order of the antenna elements 111 to 11n with respect to θ in the equation (1). That is, when the first sequence (n = 1) is increased by the offset amount alpha and by (θ + α), the second is (θ-α), and the following complex weight _{W i} for each antenna element 111~11n Is expressed as in equations (2) and (3).

From the beam controller 14, A _i (1 ≦ i ≦ n) of the complex weight W _i is sent to the distribution synthesizer 13 as an amplitude control signal according to the above equations (2) and (3), and (θ + α) Or ((theta)-(alpha)) is each sent to each phase shifter 121-12n of the arrangement position corresponding as a phase control signal.

  When the transmission source signal is input to the distribution synthesizer 13 after the amplitude distribution and the phase amount for forming the transmission beam are set in this way, the distribution synthesizer 13 is based on the amplitude control signal. This transmission source signal is distributed in n with an amplitude distribution, and is sent to the corresponding phase shifters 121 to 12n. In each of the phase shifters 121 to 12n, these distributed signals are phase-controlled based on the phase control signal, and are supplied to the corresponding antenna elements 111 to 11n that are connected correspondingly as transmission signals. These transmission signals are radiated into the space from the antenna elements 111 to 11n, and a desired transmission beam having a low sidelobe characteristic is spatially synthesized.

On the other hand, in the case of reception, a complex weight W _i (1 ≦ i ≦ n) including an offset amount α for forming a reception beam having a desired low sidelobe characteristic is subjected to beam control according to Equations (2) and (3). Is calculated by the device 14 and sent to the distribution synthesizer 13 and the phase shifters 121 to 12n as an amplitude control signal and a phase control signal, respectively. The received signals received by the antenna elements 111 to 11n are subjected to phase control based on the phase control signal in the corresponding phase shifters 121 to 12n, and then converted to amplitude control signals in the distribution synthesizer 13. Based on the amplitude distribution based on this, it is sent to the subsequent stage as a composite received signal.

  An example of the beam pattern of the array antenna apparatus 10 configured as described above is shown in FIG. In FIG. 2, the number (n) of antenna elements is 16, the antenna element interval is half wavelength, the beam half width is 7.5 degrees, the amplitude distribution in the distribution synthesizer 13 is uniform, and the offset amount α is about 2.25. This is a simulation of the beam pattern. The beam pattern without an offset (thin line in FIG. 2) is based on Expression (1), and the beam pattern with an offset (thick line in FIG. 2) is based on Expression (2) and Expression (3).

  By performing the phase control including the offset amount α, the first side lobe level can be lowered by about 2.4 dB in FIG.

  FIG. 3 shows the relationship between the offset amount α and the first side lobe level reduction amount. FIG. 3 is a graph showing the relationship between the value obtained by normalizing the offset amount α with the half width of the beam and the first side lobe level reduction amount when the amplitude distribution is uniform. As in the case of FIG. 2, when the beam half width is 7.5 degrees and the offset amount is about 2.25 degrees, the normalized value is 0.3, and according to FIG. 3, the first value of about 2.4 dB is obtained. A side lobe level reduction amount can be obtained. Further, an offset amount α for obtaining a desired first side lobe level reduction amount can be derived from FIG.

  As described above, in this embodiment, when setting the phase amount for each of the plurality of antenna elements constituting the array, a simple procedure of adding or subtracting the offset amount with respect to the predetermined phase amount. The side lobe level is lowered by setting the phase amount calculated by adding. For this reason, the increase in the side lobe level of the array antenna device due to the characteristic variation or characteristic variation of the component can be electrically maintained without replacing or redesigning the corresponding component. Therefore, it is possible to obtain an array antenna apparatus that can suppress an increase in cost at the time of manufacturing the apparatus and reduce the influence on the operation of the apparatus due to operation interruption or the like.

  FIG. 4 is a block diagram showing a second embodiment of the array antenna apparatus according to the present invention. In each part of the array antenna apparatus 2 of the second embodiment, the same parts as those of the first embodiment of FIG. 1 are denoted by the same reference numerals, and the description thereof is omitted. The second embodiment differs from the first embodiment in that a plurality (n) of transmission / reception modules 151 to 15n are used instead of the plurality of (n) phase shifters 121 to 12n. Hereinafter, only the difference will be described with reference to FIG.

  In FIG. 4, a plurality (n) of transmission / reception modules 151 to 15 n amplify the power of the transmission source signal distributed by the distribution synthesizer 13 and perform phase control based on the phase control signal from the beam controller 14. Then, it transmits as a transmission signal to each antenna element 111-11n of the array antenna 11 connected correspondingly. In addition, the received signals received by the antenna elements 111 to 11n of the array antennas 11 connected in a corresponding manner are amplified with low noise, phase control is performed based on the phase control signal from the beam controller 14, and then distribution and synthesis are performed. To the device 13.

  Here, each of the plurality (n) of transmission / reception modules 151 to 15n, in the present embodiment, for example, as shown in the block diagram of FIG. From the low noise amplifier 1512, the reception phase shifter 1513 for controlling the phase of the amplified reception signal, the power amplifier 1514 for power amplification of the transmission signal, and the transmission phase shifter 1515 for controlling the phase of the amplified transmission signal It is configured.

Next, the operation of the array antenna apparatus configured as shown in FIG. 4 will be described with reference to FIGS. First, in the case of transmission, the beam controller 14, based on equation (2) and (3), complex weight W _i for forming a transmission beam, the offset amount α to obtain a low sidelobe It is calculated including it. Based on this calculation result, an amplitude control signal and a phase control signal are generated and sent to the distribution synthesizer 13 and the respective transmission / reception modules 151 to 15n at the corresponding array positions, and the amplitude required for forming the transmission beam. Distribution and phase amount are set.

  Thereafter, when the transmission source signal is input to the distribution synthesizer 13, the distribution synthesizer 13 distributes the transmission source signal by n with an amplitude distribution based on the amplitude control signal, and each of the transmission / reception modules connected correspondingly. 151 to 15n. In each of the transmission / reception modules 151 to 15n, each of the distributed signals is power amplified by the power amplifier 1514, and then phase-controlled by the transmission phase shifter 1515 based on the phase control signal to be a transmission signal. It is supplied to each of the connected antenna elements 111 to 11n. These transmission signals are radiated into the space from the antenna elements 111 to 11n, and a desired transmission beam having a low sidelobe characteristic is spatially synthesized.

On the other hand, as in the case of reception, the beam controller 14, equation (2) and is calculated according to equation (3), based on the complex weight W _i for forming a receive beam, the amplitude control signal and phase control A signal is generated. These control signals are sent to the distribution synthesizer 13 and the transmission / reception modules 151 to 15n, respectively, and the amplitude distribution and the phase amount necessary for forming the reception beam are set.

  Thereafter, the received signals received by the respective antenna elements 111 to 11n are amplified by the low noise amplifier 1512 in the corresponding transmitting / receiving modules 151 to 15n, and further received for reception based on the phase control signal. The phase is controlled by the phase shifter 1513 and sent to the distribution synthesizer 13. Then, the signal is synthesized by the distribution synthesizer 13 with the amplitude distribution based on the amplitude control signal, and is sent to the subsequent stage as a synthesized received signal.

  As described above, in this embodiment, as in the first embodiment, when setting the phase amount for each of the plurality of antenna elements constituting the array, the offset amount with respect to the predetermined phase shift amount. The side lobe level is lowered by setting the phase amount obtained by adding or subtracting. For this reason, the increase in the side lobe level of the array antenna device due to the characteristic variation or characteristic variation of the component can be electrically maintained without replacing or redesigning the corresponding component. Therefore, it is possible to obtain an array antenna apparatus that can suppress an increase in cost at the time of manufacturing the apparatus and reduce the influence on the operation of the apparatus due to operation interruption or the like.

  In any of the two embodiments described above, the amplitude distribution may be a Taylor distribution weighted at the center of the antenna element array, for example, in addition to the uniform distribution. The number of antenna elements, the spacing between the arrays, the beam half width, and the like can be selected in various ways according to the requirements for the array antenna apparatus. Furthermore, various expansions are possible, for example, the configurations of these embodiments are applied in both the azimuth direction and the elevation direction to form a two-dimensional configuration.

The block diagram which shows the 1st Example of the array antenna apparatus which concerns on this invention. The figure which shows an example of the beam pattern of the array antenna apparatus of FIG. The figure which shows an example of the relationship between offset amount (alpha) and 1st side lobe level fall amount in case amplitude distribution is uniform distribution. The block diagram which shows the 2nd Example of the array antenna apparatus which concerns on this invention. The block diagram which shows an example of the transmission / reception module in the array antenna apparatus of FIG. The block diagram which shows an example of the conventional array antenna apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 2 Array antenna apparatus 11 Array antenna 13 Distribution combiner 14 Beam controller 121-12n Phase shifter 151-15n Transmission / reception module 1511 Circulator 1512 Low noise amplifier 1513 Reception phase shifter 1514 Power amplifier 1515 Transmission phase shifter

Claims (3)

A plurality of antenna elements arranged in a specific direction;
A plurality of phase shifters provided corresponding to the plurality of antenna elements;
A distribution synthesizer that distributes a transmission signal to the plurality of phase shifters with a predetermined amplitude distribution and combines reception signals from the plurality of phase shifters with a predetermined amplitude distribution,
When a predetermined phase shift amount is set for the plurality of phase shifters to form a transmission beam and a reception beam directed in a predetermined direction, a predetermined offset amount is set with respect to the predetermined phase shift amount. An array antenna apparatus characterized by being set by alternately increasing / decreasing in accordance with the arrangement order. A plurality of antenna elements arranged in a specific direction;
A plurality of transmission / reception modules that are provided corresponding to the plurality of antenna elements, amplify the transmission signal and the reception signal, and control the phase of the transmission signal and the reception signal;
A distribution synthesizer that distributes transmission signals with a predetermined amplitude distribution to the plurality of transmission / reception modules and synthesizes reception signals from the plurality of transmission / reception modules with a predetermined amplitude distribution,
When a predetermined phase shift amount is set for the plurality of transmission / reception modules to form a transmission beam and a reception beam directed in a predetermined direction, a predetermined offset amount is arranged with respect to the predetermined phase shift amount. The array antenna apparatus is characterized in that it is set by increasing / decreasing alternately according to the order. Each of the plurality of transmission / reception modules includes a circulator that switches a signal path by transmission and reception;
A receiving amplifier that amplifies and outputs the received signal from the circulator;
A first phase shifter for controlling and outputting the phase of the output signal from the receiving amplifier;
A power amplifier that amplifies and outputs a transmission signal; and
The array antenna apparatus according to claim 2, further comprising a second phase shifter that controls a phase of an output signal from the power amplifier and outputs the phase to the circulator.

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