JPH09214238A - Active phased array antenna - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an active phased array antenna suitable for the use of a radio wave for a millimeter wave band. SOLUTION: The active phases array antenna is provided with plural radiation elements 101 plural transmission reception modules connected to the radiation elements 101 and the whose number is equal to the number of the radiation elements 101, a power distributer 104 distributing a signal to transmission reception modules 103 and combining the signals from the transmission reception modules 103, and a beam scanning controller providing a control signal to the transmission reception modules 103 and the plural radiation elements 101 are arranged on a same plane as the transmission reception modules 103 so as to allow ends of the radiation elements 101 to draw a circumference.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an active phased array antenna, and more particularly to an active phased array antenna suitable for application in the millimeter wave band.

[0002]

2. Description of the Related Art In an active phased array antenna in which a plurality of radiating elements are arranged in a straight line or in a plane, the spacing between the radiating elements is narrowed in order to widen the beam scanning range so that no grating lobe appears in the visible region. There is a need. That is, if the beam scanning range is ± θ ° and the wavelength of the used frequency is λ, the required element spacing d is expressed by the following equation.

[0003]

Here, k is a constant determined by the scale of the phased array.

Conventionally, as a radiating element of an active phased array antenna having a wide beam scanning range, "Ph
assed Array Antena with a
"Multi Layer Substrate" (I
EEE, Proc. H, Vol. 141, No. 4, A
ug. As disclosed in 1994), a MicrostripPatch Antenna (hereinafter referred to as MSPA), which has a small mutual coupling between elements and a small gain reduction during beam scanning, has been widely used. MSPA
When used as a radiating element, the structure of the active phased array antenna is shown in FIG.
A method of separately configuring the 201 array and the transmission / reception module 202 and a method of mounting a multi-chip module IC (MMIC) such as a phase shifter and an amplifier on the back surface of the MSPA have been considered.

Although the above method has been put to practical use in an active phased array antenna used in the microwave band, the configuration in which the MSPA 201 and the transmission / reception module 202 shown in FIG. 8 are separated is used in a high frequency band such as a millimeter wave band. It is very difficult to apply it to the active phased array antenna which is considered in consideration of the limit of machining accuracy and maintainability.

That is, the transmission / reception module 202 uses the MSPA2 to replace / repair when it fails.
01 array needs to be removed. Here, the connector interval of the coaxial connector 203 for connecting the transmitting / receiving module 202 and the MSPA201 array is ± 45 to ±.
In the case of an active phased array antenna with a beam scanning range of 60 °, it becomes λ / 2 (λ: wavelength). For example, the connector spacing is about 4.3 mm in the case of an active phased array antenna in the millimeter wave band of 35 GHz, 9 mm.
In the microwave band of GHz, it is 16 mm. Therefore, in the millimeter-wave band active phased array antenna, it is necessary to use the microminiature coaxial connector 203.
However, this microminiature coaxial connector 203 has a very thin center conductor, and it is very difficult to manually fit it.

Regarding the structure in which the MMIC is mounted on the back surface of the MSPA, considering, for example, an active phased array antenna usable in the 35 GHz band, FIG.
As shown in (a), MMIC mountable area 204
Area is about 20mm ² and MMIC mounting area is 4 ~ 8
Since mm ² / chip is required, there is a limit to the number of packages that can be mounted. However, the chip used in the transmission / reception module generally requires 6 amplifiers, 3 switches, 1 phase shifter and 1 attenuator, as shown in FIG. The mounting area is about 4 mm ² , and the mounting area of the phase shifter and the attenuator is about 6 mm ^2. Therefore, the occupied area of the MMIC is 48 mm ² . Further, considering the connection between the MMICs and the connection with the external lead, the actual area becomes larger, and as a result, it is extremely difficult to mount the MMIC on the back surface of the MSPA. Further, in the structure in which the MMIC is mounted on the back surface of the MSPA, it is necessary to solve the problem of heat dissipation. Thus, it was extremely difficult to apply the above structure to an active phased array antenna in the millimeter wave band.

Therefore, in the millimeter-wave band active phased array antenna, a slot line antenna or a dipole antenna is selected as the radiating element 205 as shown in FIG.
A configuration in which the transmission / reception module 206 is mounted on the extension of No. 7 has been applied.

[0010]

However, when the slot line antenna is used as the radiating element of the active phased array antenna and the configuration shown in FIG. 10 is adopted, if the beam width is widened, the array element pattern (radiating element The ripples and distortions of the single element pattern (when arrayed) are increased. Therefore, slot line antennas have not been suitable as radiating elements for wide-angle scanning active phased array antennas.

Further, when a dipole antenna is used as a radiating element of the active phased array antenna and the configuration as shown in FIG. 10 is adopted, mutual coupling between the elements becomes large. Further, when the elements are arranged closely, the distortion of the array element pattern is large and the gain change at the time of beam scanning becomes large. FIG. 11 is a diagram showing an array element pattern when dipole antennas are arranged at element intervals required to achieve the beam scanning ranges ± 45 ° and ± 60 °, and the solid line indicates ± 4.
The 5 ° and dotted lines correspond to the beam scanning range of ± 60 °. Referring to FIG. 11, when the beam is scanned at ± 60 °, the vertical plane (−60 °) is 4.6 dB, and the horizontal plane (+6).
At 0 °), a gain decrease of 11.7 dB occurs. When such an active phased array antenna is applied to a radar device, changes in the system gain cause respective gain reductions of 9.2 dB and 23.4 dB, which has a serious adverse effect on the system design.

[0012]

In order to solve the above problems, the active phased array antenna of the present invention comprises:
A plurality of radiating elements and a plurality of transmitting / receiving modules provided corresponding to the respective radiating elements are mounted on the same plane, and the plurality of radiating elements are arranged on the circumference in the mounting plane.

In particular, in order to suppress the side lobe,
The transmission / reception module is operated by the phase weight and the amplitude weight obtained by the maximum S / N method.

In order to perform two-dimensional beam scanning, the active phased array antenna of the present invention has a plurality of radiating elements and a plurality of transmitting / receiving modules provided corresponding to the respective radiating elements mounted on the same plane. Along with
An active phased array antenna comprising a plurality of one-dimensional beam scanning active phased array antennas arranged on the circumference in the plane, wherein the one-dimensional beam scanning active phased array antennas are arranged in parallel at equal intervals. And the aperture centers of the respective one-dimensional beam scanning active phased array antennas are arranged on the circumference in a plane perpendicular to the mounting surface of each radiating element of the one-dimensional beam scanning active phased array antenna. It is a thing.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the active phased array antenna of the present invention will be described in detail with reference to the drawings.

In the first embodiment of the present invention, the transceiver module and the radiating element are mounted on the same plane, and the radiating element group is arranged so as to be circumferentially arranged in the mounting plane. With this configuration, the coupling degree of the radiating element is reduced, and as a result, it is possible to suppress the gain reduction during beam scanning.

FIG. 1 is a perspective view showing the structure of the present embodiment. A plurality of radiating elements 101 arranged on the circumference and a transmitting / receiving module connected to each of the radiating elements 101 via a feeder line 102. 103 and 103 are mounted on the same plane. The power distributor 104 distributes and supplies high-frequency power to each transmitting / receiving module 103. A control signal for controlling each transmission / reception module 103 is input from the signal input terminal 105.

FIG. 2 is a block diagram showing the configuration of this embodiment. The operation of this embodiment will be described with reference to FIG.

First, when the radar signal is transmitted, the radar signal generated by the exciter 106 is uniformly distributed by the power distributor 104. The distributed radar signal is input to each transmitting / receiving module 103 and given a predetermined amplitude / phase weight. The amplitude / phase weight given to the radar signal in each transmission / reception module 103 is stored in the beam scanning controller 107 in advance for each beam pointing direction. Then, based on the beam scanning control signal from the beam scanning controller 107, each transmission / reception module 103 gives a desired amplitude / phase weight to the radar signal. The radar signal given the predetermined amplitude and phase weight is amplified and then radiated into space from the radiating element 101 arranged on the circumference.

Next, the reception will be described. The signal received by each radiating element 101 is guided to the corresponding transmitting / receiving module 103, amplified, and then given a predetermined phase / amplitude weight for beam forming. To be The phase / amplitude weight given to this received signal is also based on the beam scanning control signal from the beam scanning controller 107 as in the case of transmission. The output signals of the transmission / reception modules 103 are combined by a power distributor 104B prepared separately from the power distributor for transmission, and sent to the receiver 109.

Next, the transmission / reception module in this embodiment will be described with reference to FIGS.

FIG. 3 is a block diagram showing the configuration of the transmission / reception module 103. In the figure, the position of the switch shows the state at the time of transmission. The radar signal from the power distributor 104A is input from the input terminal 115 and given a phase weight by the phase shifter 110. The radar signal given the phase weight is amplified by the power amplifier 111 and then supplied to the variable attenuator 112 to be given the amplitude weight. The radar signal provided with the amplitude / phase weight is sent to the radiating element 101 via the input / output terminal 113.

On the other hand, at the time of reception, each switch in the figure comes into contact with the opposite side, and the reception signal from the radiating element 101 is given to the input / output terminal 113. The received signal is
The variable attenuator 11 is amplified by the low noise amplifier 114.
Amplitude weights are given by 5. The received signal is
Further, the phase shifter 110 provides a phase weight. The received signal provided with the amplitude / phase weight is sent from the output terminal 116 to the power distributor 104B.

Here, the control circuit 117 sends the beam scanning control signal from the beam scanning controller 107 to the variable attenuator 1.
12 and 115, the phase shifter 110 is decoded according to the interface, and the variable attenuators 112 and 115 and the phase shifter 110 are drive-controlled based on the control signal.

According to the experiment, the array element pattern in the case where a plurality of radiating elements are arranged at equal intervals in the circumferential arrangement as in this embodiment can be approximated by cos θ,
It is possible to suppress the gain reduction during the beam scanning. This is because the radiation pattern of a single element can be approximated by cos θ, so that when a plurality of radiating elements are circumferentially arranged, mutual coupling between the elements is small.

Here, FIG. 4 shows the result of calculation of the radiation pattern of the active phased array antenna of this embodiment under the following conditions.

Number of elements: 16 Element spacing: 0.5λ Frequency: 35 GHz (millimeter wave band) Arrangement circumference radius: 50 mm Beam scanning direction: 60 ° Setting weight: Taylor distribution (side lobe level -30 dB, n = 4) elements Pattern: cos θ Next, the active phased array antenna of the second embodiment of the present invention will be described with reference to FIGS. 2, 4 and 5.

Referring to FIG. 4, since the first embodiment of the present invention is a conformal array in which the radiating elements are arranged on the circumference, it is possible to apply a tailor weight of -30 dB to the side lobe level. No, a side lobe of -18 dB is generated. Therefore, in the second embodiment of the present invention, unnecessary lobes (see FIG.
The maximum S / N method is applied to the above-described first embodiment in order to suppress the side lobes having a relatively large level occurring at 70 ° to 80 ° in (1).

The maximum S / N method is shown in "Adaptive formation in a curved array" (1994 Spring Meeting of the Institute of Electronics, Information and Communication Engineers, pp2 to 157). The specific method is shown in the flow chart of FIG. It will be described with reference to FIG.

First, the shape of the antenna and the arrangement of the radiating elements are determined (S101). Further, the irradiation direction of the main beam in the beam search direction is determined (S102). A reference weight that maximizes the directional gain is calculated in the determined main beam irradiation direction (S103). With respect to the side rope characteristic formed by the calculated reference weight, an unnecessary signal is assumed in the direction in which a lower side rope is desired, and power distribution is set (S104). An autocorrelation value and a crosscorrelation value between each radiating element with respect to the assumed unnecessary signal are calculated (S105). Calculate a covariance matrix with each calculated correlation value as an element (S
106). The inverse matrix of the calculated covariance matrix is calculated, and S1 described above is calculated using the calculated inverse matrix.
The reference weight calculated in 03 is corrected to calculate the adaptive weight (S107). Where S
The covariance matrix calculated in 106 represents the power distribution in the search space of the unwanted signal received by each radiating element. Therefore, in S107, the inverse matrix of the covariance matrix is calculated and multiplied by the reference weight. Then, correcting this means that the beam directivity determined by the reference weight is adapted to cancel the unnecessary signal.

In the beam scanning controller 107 shown in FIG. 2, the phase / amplitude weight obtained by applying the maximum S / N method is applied to the radar signal input to each transmitting module 103 to obtain the beam directivity. The side lobe level can be suppressed while maximizing the gain.
Here, FIG. 6 shows calculation under the same conditions as described above in the present embodiment in which the maximum S / N method is applied to the above-mentioned first embodiment showing the radiation pattern as shown in FIG. 3 shows the emitted radiation pattern. Referring to FIG. 6, it can be seen that the sidelobe level is improved by 7 dB to −23 dB as compared with the radiation pattern shown in FIG. Further, in the present embodiment, the gain variation during beam scanning is
It is 2.6 dB, which is improved by 1.7 dB as compared with the case where the irradiation elements are linearly arranged.

Next, a third embodiment of the present invention will be described with reference to FIG.
This will be described with reference to FIG.

The third embodiment of the present invention performs two-dimensional beam scanning, whereas the active phased array antenna of the first embodiment described above performs one-dimensional beam scanning.

FIG. 7 is a perspective view showing the structure of the present embodiment. The two-dimensional active phased array antenna of this embodiment has the one-dimensional beam scanning active phased shown in FIG. 1 for performing two-dimensional beam scanning. Array antenna 118
Are prepared and arranged in parallel and at equal intervals. Here, in order to make the array of the radiating elements 101 into a conformal array also in the XY plane in FIG. 7,
The aperture center 120 of the one-dimensional active phased array antenna 118 is drawn in a plane (XY plane) perpendicular to the mounting surface (XZ plane in FIG. 7) of each radiating element 101 of the one-dimensional active phased array antenna 118. The one-dimensional active phased array antennas are arranged so as to be shifted back and forth so as to be arranged on the circumference 119. Here, the radiation pattern in the plane including the circumference 119 is also similar to the characteristic shown in FIG. In addition,
Also in the present embodiment, the side lobe can be suppressed by applying the maximum S / N method described above.

[0035]

As described above, in the active phased array antenna of the present invention, the radiating element group and the transmitting / receiving module provided corresponding thereto are mounted on the same plane, and each radiating element is arranged on the circumference. Therefore, it is possible to suppress the gain fluctuation at the time of beam scanning and to realize a wide beam scanning range.

Furthermore, since no precise connection structure is required, maintenance and the like can be easily performed when applied to the millimeter wave band.

Further, by applying the maximum S / N method, it is possible to suppress unnecessary lobes (side lobes having a relatively large level) that occur when the radiating elements are circumferentially arranged.

Further, in the present invention, a plurality of one-dimensional active phased array antennas are arranged in parallel, and the aperture center of each one-dimensional active phased array antenna is with respect to the mounting surface of each radiating element of the one-dimensional active phased array antenna. The two-dimensional beam scanning can be easily expanded by arranging the one-dimensional active phased array antennas so that they are arranged on the circumference drawn in a vertical plane. .

[Brief description of drawings]

FIG. 1 is a perspective view showing a configuration of a first exemplary embodiment of the present invention.

FIG. 2 is a block diagram illustrating a configuration of a first exemplary embodiment of the present invention.

3 is a block diagram showing a configuration of a transmission / reception module in FIG.

FIG. 4 is a diagram showing an example of a radiation pattern calculated under a predetermined condition for the first embodiment of the present invention.

FIG. 5 is a maximum S / N applied to the second embodiment of the present invention.
It is a flow chart which shows the processing procedure of a method.

FIG. 6 is a diagram showing an example of a radiation pattern calculated under a predetermined condition for the second embodiment of the present invention.

FIG. 7 is a perspective view showing a configuration of a third exemplary embodiment of the present invention.

FIG. 8 is a perspective view showing a configuration of a main part of a conventional active phased array antenna.

9A and 9B are diagrams illustrating a configuration of a conventional active phased array antenna, FIG. 9A is a diagram showing an area of a back surface of an MSPA on which an MMIC can be mounted, and FIG. 9B is a diagram showing a general MMIC; It is a figure which shows a structure.

FIG. 10 is a perspective view showing a configuration of a main part of a conventional millimeter-wave band active phased array antenna.

11 is a diagram showing an example of an array element pattern in the conventional active phased array antenna shown in FIG.

[Explanation of symbols]

 101 Radiating Element 102 Feed Line 103 Transmitting / Receiving Module 104 Power Distributor 105 Signal Input Terminal 106 Exciter 107 Beam Scanning Controller 108 Receiver 109 Input Terminal 110 Phase Shifter 111 Power Amplifier 112, 115 Variable Attenuator 113 Input / Output Terminal 114 Low Noise amplifier 116 Output terminal 117 Control circuit 118 One-dimensional active phased array Antenna 119 Circumference 120 Center of aperture

Claims (5)

[Claims] 1. A plurality of radiating elements and a plurality of transmitting / receiving modules provided corresponding to the respective radiating elements are mounted on the same plane, and the plurality of radiating elements are arranged circumferentially in the plane. An active phased array antenna characterized by that. 2. A plurality of radiating elements, transmission / reception modules of the same number as the plurality of radiating elements, which are respectively connected to the radiating elements, distribute signals to the transmission / reception modules, and combine signals from the transmission / reception modules. In an active phased array antenna including a power distributor for controlling the transmission / reception module and a beam scanning controller for providing a control signal to the transmission / reception module, the radiating elements are arranged and mounted so as to draw a circle on the same plane as the transmission / reception module. Active phased array antenna characterized by. 3. The beam scanning controller outputs a phase weight and an amplitude weight obtained by a maximum S / N method as the control signal, and the transceiver module receives the reception signal from the radiating element to be connected and the The active phased array antenna according to claim 2, wherein the phase weight and the amplitude weight obtained from the beam scanning controller are given to the radar signal from the power distributor. 4. The beam scanning controller for executing the maximum S / N method comprises: means for determining the shape of an antenna and an array of radiating elements; and means for determining an irradiation direction of a main beam in a beam search direction. A means for calculating a reference weight that maximizes the directivity gain in the irradiation direction of the main beam, and a direction in which a side rope having a lower side rope characteristic with respect to the side rope characteristic formed by the calculated reference weight is desired. Means for setting the power distribution by assuming an unnecessary signal, and a means for calculating the autocorrelation value and the crosscorrelation value between the radiating elements for the assumed unnecessary signal, the calculated autocorrelation value and the mutual correlation value. A means for calculating a covariance matrix having a correlation value as an element, and an inverse matrix of the calculated covariance matrix, and the calculated inverse Using Torikusu, corrects to the reference weight, the active phased array antenna according to claim 3, characterized in that it comprises a means for calculating the phase weight and amplitude weights. 5. A plurality of radiating elements and a plurality of transmitting / receiving modules provided corresponding to the respective radiating elements are mounted on the same plane, and the plurality of radiating elements are arranged on the circumference in the plane. An active phased array antenna including a plurality of one-dimensional beam scanning active phased array antennas, wherein the one-dimensional beam scanning active phased array antennas are arranged in parallel at equal intervals, and each of the one-dimensional beam scanning active phased array antennas An active phased array antenna, characterized in that the center of apertures of the one-dimensional beam scanning active phased array antenna are arranged on the circumference in a plane perpendicular to the mounting surface of each radiating element.