JP6257856B2 - Antenna device and antenna excitation method - Google Patents

Description

  The present invention relates to an antenna device and an antenna excitation method for compensating for the influence of mutual coupling between a plurality of element antennas by changing the excitation phases of a plurality of element antennas constituting a phased array antenna in a time division manner. is there.

In an antenna device equipped with a phased array antenna, the antenna radiation pattern can be controlled electronically by controlling the amount of phase shift of a phase shifter connected to a plurality of element antennas. Widely used as an antenna for radar systems and satellites.
However, when the plurality of element antennas constituting the phased array antenna are arranged at a narrow interval, mutual coupling may occur between the plurality of element antennas.
When mutual coupling occurs, pay attention to a certain element antenna, and with all element antennas other than the element antenna of interest in a non-reflective termination state, the radiation pattern of the element antenna of interest When measured, the radiation pattern is different from the radiation pattern of the element antenna when only the element antenna of interest is present alone. For this reason, a desired antenna radiation pattern cannot be obtained, and the antenna characteristics may be deteriorated.

The following Patent Document 1 discloses an antenna device that compensates for the influence of mutual coupling between a plurality of element antennas.
In this antenna device, a mutual coupling matrix representing the influence of mutual coupling was calculated from the radiation pattern of the element antenna in a state where mutual coupling occurred and the radiation pattern of the element antenna in a state where mutual coupling did not occur. Thereafter, an inverse matrix of the mutual coupling matrix is calculated as a calibration matrix for compensating for the influence of the mutual coupling.
Also, in this antenna device, an excitation vector that compensates for mutual coupling is calculated by multiplying a calibration matrix for compensating for the influence of mutual coupling and an ideal excitation vector in a state where no mutual coupling occurs. Like to do.

In this antenna apparatus, each element antenna is excited by the excitation vector, thereby obtaining an antenna radiation pattern in which mutual coupling is compensated.
However, in this antenna apparatus, in order to freely control the excitation vector, an antenna configuration using a digital beam forming circuit or an amplitude control device such as a variable attenuator is provided for each element antenna. A phased array antenna is assumed.

Non-Patent Document 1 below is not a technique for compensating for the influence of mutual coupling, but in order to improve the performance of a phased array antenna, as a technique for controlling an excitation vector, a time-modulated array antenna that uses the concept of time weighting Has been proposed.
This time-modulated array antenna switches the excitation phase in a time-sharing manner, and performs a time average (time integration) on the received signal or the transmitted signal at each excitation phase to equivalently obtain a predetermined amplitude distribution. The same effect (antenna radiation pattern) as the given state is obtained.

Japanese Patent Laid-Open No. 9-148836 (paragraph [0010])

Nakanishi et al., “Phase-controlled time-modulated array antenna using conjugate relationship”, IEICE Transactions B, Vol.J97-B, No.7, pp.546-555, 2014

Since the conventional antenna apparatus is configured as described above, after calculating the mutual coupling matrix representing the influence of mutual coupling, the inverse matrix of the mutual coupling matrix is used as a calibration matrix for compensating for the mutual coupling effect. If a stepwise calculation process of calculating and multiplying the calibration matrix and the ideal excitation vector is performed, an excitation vector capable of compensating for mutual coupling can be calculated. However, in order to perform stepwise calculation processing, a large amount of memory is required, and much time is required until calculation processing is completed. When the calculation processing time becomes long, the switching period of the excitation phase has to be lengthened, and there is a problem that the control of the antenna radiation pattern is restricted.
In addition, in order to freely control the excitation vector, it is necessary to connect a device for amplitude control such as a variable attenuator to each element antenna, which causes a problem of increasing costs.

  The present invention has been made to solve the above-described problems, and can perform amplitude control that can quickly compensate for the influence of mutual coupling between a plurality of element antennas without performing stepwise arithmetic processing. It is an object to obtain an antenna device and an antenna excitation method that do not require a device for use.

  In the antenna device according to the present invention, mutual coupling occurs between the plurality of element antennas constituting the phased array antenna, the plurality of phase shifters for controlling the excitation phase of the element antenna, and the plurality of element antennas. The first radiation pattern storage unit storing the radiation pattern of each element antenna in the state, and the radiation pattern of the phased array antenna in a state where mutual coupling does not occur between the plurality of element antennas Compensation for compensating for the influence of mutual coupling received by the element antenna for each element antenna using the radiation pattern stored in the second radiation pattern storage unit and the first and second radiation pattern storage units A compensation vector calculation unit for calculating a vector, and the control unit uses the compensation vector calculated by the compensation vector calculation unit to generate a plurality of element antennas. Set the excitation phase, in which so as to instruct the excitation phase to a plurality of phase shifters.

  According to the present invention, the radiation pattern of each element antenna in a state where mutual coupling occurs between a plurality of element antennas and the phased array antenna in a state where mutual coupling does not occur between the plurality of element antennas. A compensation vector calculation unit that calculates a compensation vector that compensates for the influence of mutual coupling received by the element antenna is provided for each element antenna using the radiation pattern, and the control unit is calculated by the compensation vector calculation unit. Using the compensation vector, the excitation phase of a plurality of element antennas is set and the excitation phase is instructed to a plurality of phase shifters. There is an effect of obtaining an antenna apparatus that does not require an amplitude control device that can compensate for the influence of mutual coupling between element antennas.

It is a block diagram which shows the antenna apparatus by Embodiment 1 of this invention. It is a hardware block diagram which shows the digital signal processing part 20 of the antenna apparatus by Embodiment 1 of this invention. It is a hardware block diagram in case the digital signal processing part 20 is comprised with a computer. It is a flowchart which shows the processing content (antenna excitation method) of the digital signal processing part 20 of the antenna apparatus by Embodiment 1 of this invention. It is explanatory drawing which shows the specific example of an antenna radiation pattern. It is a block diagram which shows the antenna apparatus by Embodiment 2 of this invention. It is a flowchart which shows the processing content (antenna excitation method) of the digital signal processing part 20, the time average calculation part 65, etc. of the antenna device by Embodiment 2 of this invention.

  Hereinafter, in order to describe the present invention in more detail, modes for carrying out the present invention will be described with reference to the accompanying drawings.

Embodiment 1 FIG.
1 is a block diagram showing an antenna apparatus according to Embodiment 1 of the present invention. FIG. 2 is a hardware configuration diagram showing the digital signal processing unit 20 of the antenna device according to Embodiment 1 of the present invention.
1 and 2, the phased array antenna 1 is composed of N (N is an integer of 2 or more) element antennas 2-1 to 2-N.
The phase shifters 3-1 to 3 -N control the excitation phases of the element antennas 2-1 to 2 -N according to the excitation phase output from the excitation phase output unit 30 of the phase shifter controller 27.
That is, the phase shifters 3-1 to 3 -N change the phase of the high-frequency signals (arrival radio waves) output from the element antennas 2-1 to 2 -N according to the excitation phase output from the excitation phase output unit 30. .
The power combiner 4 is a signal combiner that combines high-frequency signals whose phases have been changed by the phase shifters 3-1 to 3 -N.

The receiver 11 is a communication device that detects a high-frequency signal synthesized by the power combiner 4.
The A / D converter 12 converts the analog high-frequency signal detected by the receiver 11 into a digital signal, and outputs the digital high-frequency signal to the digital signal processing unit 20.
The time average calculation unit 21 is realized by a time average calculation processing circuit 31 formed from, for example, a semiconductor integrated circuit on which a CPU (Central Processing Unit) is mounted, a one-chip microcomputer, or the like, and performs A / D conversion. The digital high-frequency signal output from the device 12 is accumulated, and the time average of the accumulated high-frequency signal is calculated.

The synchronization establishment unit 22 is realized by a synchronization establishment processing circuit 32 formed from, for example, a semiconductor integrated circuit on which a CPU is mounted or a one-chip microcomputer, and the excitation phase output from the excitation phase output unit 30 And a process for synchronizing the high-frequency signal accumulation cycle by the time average calculation unit 21 with the time average calculation unit 21.
The compensation vector calculation processing unit 23 is realized by, for example, a compensation vector calculation processing circuit 33 formed from a semiconductor integrated circuit or a one-chip microcomputer mounted with a CPU, a storage device such as a RAM or a hard disk, A process of calculating a compensation vector that compensates for the influence of mutual coupling received by the element antennas 2-1 to 2-N is performed.

The element radiation pattern storage unit 24 is a radiation pattern of each element antenna 2-n (n = 1, 2,..., N) in a state where mutual coupling occurs between the element antennas 2-1 to 2-N. Is a first radiation pattern storage unit.
The reference pattern storage unit 25 is a second radiation pattern storage unit that stores a radiation pattern of the phased array antenna 1 in a state where mutual coupling does not occur between the element antennas 2-1 to 2-N.
The compensation vector calculation unit 26 is stored in the radiation pattern of the element antenna 2-n (n = 1, 2,..., N) stored in the element radiation pattern storage unit 24 and in the reference pattern storage unit 25. Using the radiation pattern of the phased array antenna 1, a process of calculating a compensation vector that compensates for the influence of mutual coupling received by the element antenna 2-n is performed.

The phase shifter control device 27 is realized by, for example, a semiconductor integrated circuit on which a CPU is mounted, a phase shifter control processing circuit 34 formed from a one-chip microcomputer or the like, and is calculated by a compensation vector calculation unit 26. This is a control unit that sets the excitation phase of the element antennas 2-1 to 2-N using the compensated vector and instructs the phase shifters 3-1 to 3-N to determine the excitation phase.
The switching number setting unit 28 performs processing for setting the number of excitation phase switchings.

The excitation phase setting unit 29 uses the switching times set by the switching number setting unit 28 and the compensation vector calculated by the compensation vector calculation unit 26 to set the excitation phases of the element antennas 2-1 to 2-N. To implement.
That is, for each element antenna, the excitation phase setting unit 29 is updated from the excitation phase for the number of switching times and the excitation amplitude of the element antenna 2-n while updating the excitation phase for the number of switching times in the element antenna 2-n. The difference between the amplitude phase vector and the compensation vector of the element antenna 2-n calculated by the compensation vector calculation unit 26 is repeatedly calculated, the calculated plurality of differences are compared, and the excitation for the number of times of switching that is being updated. A process of selecting an excitation phase corresponding to the number of times of switching to be set as the excitation phase of the element antenna 2-n from the phases according to the comparison results of a plurality of differences is performed.
The excitation phase output unit 30 performs processing to instruct the phase shifters 3-1 to 3-N about the excitation phase of the element antennas 2-1 to 2-N set by the excitation phase setting unit 29.

In the example of FIG. 1, each of the time average calculation unit 21, the synchronization establishment unit 22, the compensation vector calculation processing unit 23, and the phase shifter control device 27, which are components of the digital signal processing unit 20 of the antenna device, is dedicated hardware. However, the digital signal processing unit 20 may be configured by a computer.
FIG. 3 is a hardware configuration diagram when the digital signal processing unit 20 is configured by a computer.
When the digital signal processing unit 20 is configured by a computer, the element radiation pattern storage unit 24 and the reference pattern storage unit 25 are configured on the memory 41 of the computer, and the time average calculation unit 21, the synchronization establishment unit 22, and the compensation vector calculation A program describing the processing contents of the unit 26 and the phase shifter control device 27 may be stored in the memory 41 of the computer, and the processor 42 of the computer may execute the program stored in the memory 41.
FIG. 4 is a flowchart showing the processing contents (antenna excitation method) of the digital signal processing unit 20 of the antenna apparatus according to Embodiment 1 of the present invention.

Next, the operation will be described.
When the element antennas 2-1 to 2-N constituting the phased array antenna 1 are arranged at a narrow interval, mutual coupling may occur between the element antennas 2-1 to 2-N.
The first embodiment aims to quickly compensate for the influence of mutual coupling occurring between the element antennas 2-1 to 2-N with a simple configuration.

The element radiation pattern storage unit 24 of the compensation vector calculation processing unit 23 stores each element antenna 2-n (n = 1, 2, n) in a state where mutual coupling occurs between the element antennas 2-1 to 2-N. .., N) radiation patterns g _n (θ _m ) (n = 1, 2,..., N: m = 1, 2,..., M) are stored (step of FIG. 4). ST1).
In g _n (θ _m ), n means a radiation pattern of the n-th element antenna 2-n, and m is M angular directions (radiation directions) in the radio wave radiated from the element antenna 2-n. Means the m-th angular direction.

In the first embodiment, it is assumed that the radiation pattern g _n (θ _m ) of the element antenna 2-n in a state where mutual coupling occurs is obtained in advance by computer simulation or measurement.
However, the radiation pattern g _n (θ _m ) is not limited to that obtained by computer simulation or measurement, and the radiation pattern g _n (θ _m ) is calculated as follows. May be.

Among the N element antennas 2-1 to 2-N, attention is paid to a certain element antenna 2-n, and all element antennas other than the element antenna 2-n of interest are non-reflective terminated. State.
For each angular direction m, After measuring the amplitude level A phase composite electric field of antenna arrays 1 before changing the excitation phase phi _n antenna elements 2-n, by changing the excitation phases phi _n antenna elements 2-n Then, the amplitude level B of the combined electric field of the phased array antenna is measured, and the amplitude level A and the change C (= AB) of the amplitude level B are calculated.
Then, the relative amplitude value and relative phase value of the element antenna 2-n are calculated from the change C between the amplitude level A and the amplitude level B, and the relative amplitude value and relative phase value of the element antenna 2-n are calculated. The n radiation pattern g _n (θ _m ) is stored in the element radiation pattern storage unit 24.
The process of calculating the relative amplitude value and the relative phase value of the element antenna 2-n from the change C between the amplitude level A and the amplitude level B is disclosed in Non-Patent Document 2 below, for example.

[Non-Patent Document 2]
Mano Kiyoji, Katagi Takashi, “Element Amplitude Phase Measurement Method for Phased Array Antennas — Element Electric Field Vector Rotation Method,” IEICE Theory (B), vol.J65-B, no.5, pp. 555-560, May 1982.

The reference pattern storage unit 25 of the compensation vector calculation processing unit 23 stores the radiation pattern E (θ _m ) (m) of the phased array antenna 1 in a state where no mutual coupling occurs between the element antennas 2-1 to 2-N. = 1, 2, ..., M) is stored (step ST2).
In E (θ _m ), m means the m-th angular direction out of M angular directions (radiation directions of the main beam).
In the first embodiment, an ideal radiation pattern E (θ _m ) of the phased array antenna 1 in a state where no mutual coupling occurs is obtained by a prior calculation or measurement by computer simulation. And

The compensation vector calculation unit 26 radiates the radiation pattern g _n (θ _m ) of the element antenna 2-n stored in the element radiation pattern storage unit 24 and the radiation of the phased array antenna 1 stored in the reference pattern storage unit 25. A compensation vector w _n (n = 1, 2,...) For compensating for the influence of mutual coupling received by the element antenna 2-n using the pattern E (θ _m ) as shown in the following equation (1). .., N) is calculated (step ST3).

ただし、添字のＨはエルミート転置、添字の−１は逆行列を表している。

Here, the subscript H represents Hermitian transpose, and the subscript -1 represents an inverse matrix.

Switching circuit number setting unit 28 of the phase shifter control unit 27 sets the switching circuit number k of excitation phase phi _n (step ST4).
Excitation phase setting unit 29, calculates sets the switching circuit number k of switching circuits number setting unit 28 is the excitation phase phi _n, the compensation vector calculation unit 26 compensates vector _{w n (n = 1,2, ···} , N) and Then, the switching circuits k of the excitation phase phi _n using compensation vector _{w n,} sets the excitation phase phi _n antenna elements 2-n (step ST5).
It will be specifically described below setting processing of the excitation phase phi _n antenna elements 2-n by the excitation phase setting unit 29.

If the number of switching times k of the excitation phase φ _n is 2, for example, the excitation phase setting unit 29 sets the excitation phase φ _n1 and the excitation phase φ _n2 having a conjugate relationship as the excitation phase φ _{nk corresponding to the} number of switching times (two times). prepare. In this example, φ _n2 = −φ _n1 because there is a conjugate relationship.
Further, if the number of times of updating the excitation phase φ _{nk for} the number of times of switching is, for example, G times, at least one of the excitation phase φ _{n1 and the} excitation phase φ _n2 is slightly changed, and the different excitation phases φ _n1 and φ _n2 Prepare G pairs.
The excitation phase setting unit 29 sequentially selects one set of excitation phases φ _n1 and φ _n2 from the G sets of excitation phases φ _n1 and φ _n2 , and the selected excitation phases φ _n1 and φ _n2 are known. using the amplitude a _n certain antenna elements 2-n, as shown in the following formula (2), calculates the amplitude-phase vector h _n.

The excitation phase setting unit 29 selects one set of excitation phases φ _n1 and φ _n2 in order from the G sets of excitation phases φ _n1 and φ _n2 and calculates G amplitude phase vectors h _n . One amplitude phase vector h _n is sequentially selected from the G amplitude phase vectors h _n , and the selected amplitude phase vector h _n and the compensation vector calculation unit are _expressed as shown in the following equation (3). the evaluation function f (n, k) indicating a difference between the compensation vector w _n calculated by 26 is calculated.

When the excitation phase setting unit 29 calculates G evaluation functions f (n, k), the G evaluation functions f (n, k) are compared by comparing the function values of the G evaluation functions f (n, k). , K), the evaluation function f (n, k) having the minimum function value (the difference between w _n and h _n is minimum) is specified, and the evaluation function f (n, k) is calculated. A set of excitation phases φ _n1 and φ _{n2 used} is specified.
When the excitation phase setting unit 29 specifies one set of excitation phases φ _n1 and φ _n2 , the excitation phase φ _{n1 is set} to the excitation phase φ _n of the first element antenna 2- _n (excitation phase before switching). The excitation phase φ _n2 is set to the excitation phase φ _n of the second element antenna 2- _n (excitation phase after switching).

Here, by comparing the function values of the G evaluation functions f (n, k), the evaluation function f () having the smallest function value among the G evaluation functions f (n, k). n, k) is specified, and an example of specifying one set of excitation phases φ _n1 and φ _n2 used for calculation of the evaluation function f (n, k) is shown. A set of excitation phases φ _n1 and φ _n2 that minimize the function value of k) may be calculated by a genetic algorithm or the like.

Further, here, the switching circuit number k of excitation phase phi _n indicates an example in which 2, switching circuit number k of excitation phase phi _n is not limited to 2, for example, it may be such as 4 or 6. _If the switching frequency k of the excitation phase φ _n is 4, a set of excitation phases φ _n1 , φ _n2 , φ _n3 , φ _n4 used for calculating the evaluation function f (n, k) that minimizes the function value. Is identified. Then, set the excitation phase phi _n1 to excitation phase phi _n of first antenna elements 2-n, and setting the excitation phase phi _n2 in excitation phase phi _n of the second antenna elements 2-n, the excitation set phase phi _n3 in excitation phase phi _n of third antenna elements 2-n, to set the excitation phase phi _n4 in excitation phase phi _n of fourth antenna elements 2-n.

Here, an example is shown in which an excitation phase φ _n1 and an excitation phase φ _n2 having a conjugate relationship are prepared as the excitation phase φ _nk for the number of switching times (two times), but the excitation phase φ _n1 and the excitation phase are shown. It is not essential that the phase φ _n2 is in a conjugate relationship. However, if the excitation phase phi _n1 and excitation phase phi _n2 are in conjugate relationship among the amplitude-phase vector _{h n} that shown in Formula (2), a portion except for the amplitude _{a n} antenna elements 2-n cos (phi _n1 ), the calculation can be simplified.

When receiving the excitation phase output command or the excitation phase switching command from the synchronization establishment unit 22, the excitation phase output unit 30 receives the excitation phase φ _{1 of} the element antennas 2-1 to 2-N set by the excitation phase setting unit 29. and it outputs the to [phi] _N to the phase shifter 3-1 to 3-N (step ST6).
That is, the excitation phase output section 30 is, for example, if the switching circuit number k of excitation phase phi _n set by the switch circuit number setting unit 28 2 receives an output command of the excitation phase from the synchronization establishing unit 22, the first as excitation phase phi ₁ to [phi] _N of antenna elements 2-1 to 2-N, and outputs the excitation phase phi ₁₁ to [phi] _N1 to the phase shifter 3-1 to 3-N. Thereafter, when the synchronization establishing unit 22 receives a switching instruction of the excitation phase, as the excitation phase phi ₁ to [phi] _N for the second antenna elements 2-1 to 2-N, phase shifter the excitation phase φ ₁₂ ~φ _N2 3 Output to -1 to 3-N.

The element antennas 2-1 to 2-N constituting the phased array antenna 1 receive high-frequency signals that are incoming radio waves and output the high-frequency signals to the phase shifters 3-1 to 3-N.
Phase shifter 3-1 to 3-N receives the excitation phase phi ₁ to [phi] _N from the excitation phase output section 30 of the phase shifter control unit 27, the antenna elements according to the excitation phase φ ₁ ~φ _N 2- The phase of the high frequency signal output from 1-2N is changed.
The power combiner 4 combines N high frequency signals whose phases are changed by the phase shifters 3-1 to 3 -N.

When the power combiner 4 combines N high frequency signals, the receiver 11 detects the combined high frequency signal.
The A / D converter 12 converts the analog high-frequency signal detected by the receiver 11 into a digital signal, and outputs the digital high-frequency signal to the time average calculation unit 21 of the digital signal processing unit 20.

The synchronization establishment unit 22 of the digital signal processing unit 20 performs a process of synchronizing the excitation phase switching cycle output from the excitation phase output unit 30 with the high-frequency signal accumulation cycle by the time average calculation unit 21.
That is, the synchronization establishing unit 22, for example, if the switching circuit number k of excitation phase phi _n set by the switch circuit number setting unit 28 2, the excitation phase of the first antenna elements 2-1 to 2-N phi ₁ as to [phi] _N, a high-frequency signal when the excitation phase phi ₁₁ to [phi] _N1 is set is accumulated in time average calculation unit 21, also, the excitation phase of the second antenna elements 2-1 to 2-N phi ₁ as to [phi] _N, since the high-frequency signal when the excitation phase phi ₁₂ to [phi] _N2 is set to be accumulated in the time average calculator 21, at the time of first setting of the excitation phase phi ₁ to [phi] _N, An excitation phase output command is output to the excitation phase output unit 30, and at the same time, a first high-frequency signal accumulation command is output to the time average calculation unit 21.
In addition, when setting the second excitation phase φ _{1 to} φ _N , an excitation phase switching command is output to the excitation phase output unit 30, and at the same time, a second high-frequency signal accumulation command is output to the time average calculation unit 21.
Further, when the setting period of the second excitation phase φ _{1 to} φ _N is completed, a time average calculation command is output to the time average calculation unit 21.

When receiving the digital high frequency signal from the A / D converter 12, the time average calculation unit 21 accumulates the high frequency signal, and calculates the time average of the accumulated high frequency signal under the instruction of the synchronization establishment unit 22.
That is, for example, _if the switching frequency k of the excitation phase φn set by the switching frequency setting unit 28 is 2, the time average calculation unit 21 receives the first high-frequency signal accumulation command from the synchronization establishing unit 22. The digital high-frequency signal output from the A / D converter 12 is accumulated (step ST7).
Time average calculator 21 is not accumulated in yet set by switch circuit number setting unit 28 excitation phase phi _n of switching circuits number k fraction of the high frequency signal is completed (step ST8: in the case of NO), the synchronization establishing unit 22 When the second high frequency signal accumulation command is received, the digital high frequency signal output from the A / D converter 12 is accumulated (step ST7).

Time average calculating unit 21 completes the accumulation of the set excitation phase phi _n of switching circuits number k fraction of the high-frequency signal by switching circuits number setting unit 28 (step ST8: YES), of the time average from the synchronization establishing unit 22 When the calculation command is received, the time average of the accumulated high-frequency signal is calculated (step ST9).

  Here, the time average calculation unit 21 stores the digital high-frequency signal output from the A / D converter 12 and calculates the time average of the stored high-frequency signal. The digital high-frequency signal output from the A / D converter 12 may be subjected to discrete Fourier transform to obtain a frequency band signal, thereby obtaining a time average of the high-frequency signal.

FIG. 5 is an explanatory diagram showing a specific example of the antenna radiation pattern.
In FIG. 5, the phased array antenna 1 is composed of 16 element antennas 2-1 to 2-16, the number of data in the angular direction is 181 (M = 181), and the excitation set by the switching number setting unit 28 is shown. An example in which the number of switching times k of the phase φ _n is 2 is shown. However, the number of element antennas, the number of data in the angular direction, switching circuit number k of excitation phase phi _n is only one example, may be changed arbitrarily.

In FIG. 5, the horizontal axis indicates the angular direction, the vertical axis indicates the amplitude, and X (solid line) is the ideal of the phased array antenna 1 in a state where the mutual coupling stored in the reference pattern storage unit 25 does not occur. It is a simple radiation pattern.
Y (dotted line) indicates a radiation pattern in a state where the influence of mutual coupling is not compensated, and Z (broken line) indicates a radiation pattern in a state where the influence of mutual coupling is compensated by the first embodiment.
From FIG. 5, in the state where the influence of mutual coupling is not compensated, the radiation pattern Y has a high sidelobe level. However, the ideal radiation pattern X is obtained by compensating the influence of mutual coupling according to the first embodiment. It can be seen that a radiation pattern Z close to is obtained.

As apparent from the above, according to the first embodiment, each element antenna 2-n (n = 1, 2, n) in a state where mutual coupling occurs between the element antennas 2-1 to 2-N. , N) radiation pattern E (θ _m ) of the phased array antenna 1 in a state where no mutual coupling occurs between the radiation pattern g _n (θ _m ) of the element antennas 2-1 to 2-N. with bets, the provided compensation vector calculation unit 26 for calculating a compensation vector w _n to compensate for the effect of mutual coupling undergoing the antenna elements 2-n, a phase shifter control unit 27, by the compensation vector calculation unit 26 using the calculated compensation vectors _{w n,} sets the excitation phase phi ₁ to [phi] _n antenna elements 2-1 to 2-n, phase shifter and the excitation phase φ ₁ ~φ _n 3-1~3- Since it is configured to instruct N, step-by-step arithmetic processing is performed. And without rapidly an effect of amplitude control device can be obtained unwanted antenna device capable of compensating for the effects of mutual coupling between the antenna elements 2-1 to 2-N.

Embodiment 2. FIG.
In the first embodiment, the phased array antenna 1 is used as a receiving antenna. However, the phased array antenna 1 may be used as a transmitting antenna.

6 is a block diagram showing an antenna apparatus according to Embodiment 2 of the present invention. In FIG. 6, the same reference numerals as those in FIG.
The transmitter 51 is a communication device that outputs a high-frequency signal to be transmitted to the power distributor 52.
The power distributor 52 is a distribution circuit that equally distributes the high-frequency signal output from the transmitter 51 to the phase shifters 3-1 to 3 -N.
The excitation time control unit 53 is composed of, for example, a semiconductor integrated circuit on which a CPU is mounted, a one-chip microcomputer, or the like, and performs processing for controlling the switching timing of the excitation phase output from the excitation phase output unit 30. .

In the example of FIG. 6, each of the compensation vector calculation processing unit 23, the phase shifter control device 27, and the excitation time control unit 53, which are components of the digital signal processing unit 20 of the antenna device, is configured by dedicated hardware. However, the digital signal processing unit 20 may be configured by a computer.
When the digital signal processing unit 20 is configured by a computer, the element radiation pattern storage unit 24 and the reference pattern storage unit 25 are configured on the memory 41 of the computer shown in FIG. 3, and the compensation vector calculation unit 26 and the phase shifter control are configured. A program describing the processing contents of the device 27 and the excitation time control unit 53 may be stored in the memory 41 of the computer, and the processor 42 of the computer may execute the program stored in the memory 41.
FIG. 7 is a flowchart showing processing contents (antenna excitation method) of the digital signal processing unit 20 and the time average calculation unit 65 of the antenna apparatus according to Embodiment 2 of the present invention.

The receiving antenna 61 is an antenna that receives high-frequency signals transmitted from the element antennas 2-1 to 2-N constituting the phased array antenna 1.
The receiver 62 is a communication device that detects a high-frequency signal received by the receiving antenna 61.
The A / D converter 63 converts the analog high-frequency signal detected by the receiver 62 into a digital signal, and outputs the digital high-frequency signal to the time average calculation unit 65.

The switching cycle storage unit 64 is configured by a storage device such as a RAM or a hard disk, for example. The switching time of the excitation phase is used as the time when the timing signal is first output from the excitation time control unit 53 and the switching timing of the excitation phase. Is remembered.
The time average calculation unit 65 is configured by, for example, a semiconductor integrated circuit on which a CPU is mounted, a one-chip microcomputer, or the like, and an A / D converter 63 is provided for each switching period stored in the switching period storage unit 64. The digital high-frequency signal output from is stored, and the time average of the stored high-frequency signal is calculated.

Next, the operation will be described.
In the element radiation pattern storage unit 24 of the compensation vector calculation processing unit 23, each element antenna 2 in a state where mutual coupling occurs between the element antennas 2-1 to 2-N, as in the first embodiment. −n (n = 1, 2,..., N) radiation pattern g _n (θ _m ) (n = 1, 2,..., N: m = 1, 2,..., M) It is stored (step ST11 in FIG. 7).
In the reference pattern storage unit 25 of the compensation vector calculation processing unit 23, as in the first embodiment, the phased array antenna 1 in a state where no mutual coupling occurs between the element antennas 2-1 to 2-N. A radiation pattern E (θ _m ) (m = 1, 2,..., M) is stored (step ST12).

The compensation vector calculation unit 26 stores the radiation pattern g _n (θ _m ) of the element antenna 2-n stored in the element radiation pattern storage unit 24 and the reference pattern storage unit 25 as in the first embodiment. As shown in the above equation (1), the compensation vector w that compensates for the influence of mutual coupling received by the element antenna 2-n using the radiation pattern E (θ _m ) of the phased array antenna 1 that is used. _n (n = 1, 2,..., N) is calculated (step ST13).

Switching circuit number setting unit 28 of the phase shifter control unit 27, as in the first embodiment, it sets the switching circuit number k of excitation phase phi _n (step ST14).
Excitation phase setting unit 29, calculates sets the switching circuit number k of switching circuits number setting unit 28 is the excitation phase phi _n, the compensation vector calculation unit 26 compensates vector _{w n (n = 1,2, ···} , N) and Then, as in the first embodiment, the switching circuits k of the excitation phase phi _n using compensation vector w _n, sets the excitation phase phi _n antenna elements 2-n (step ST15).

The excitation time control unit 53 controls the switching timing of the excitation phase φ _n according to the switching number k of the excitation phase φ _n set by the switching number setting unit 28.
For example, when the accumulation period of the high frequency signal by the time average calculator 65 and the T is, T × switching time t of the excitation phase phi _n from the current time (j-1) + b to determine only the time that time has passed Te, and it outputs a timing signal indicating a switching timing of the excitation phase phi _n to the switching time t excitation phase output section 30. However, j = 1, 2,..., K−1, b are constants. In this example, the first timing signal is output to the excitation phase output unit 30 at the time when time b has elapsed from the current time.

Excitation phase output section 30 receives the timing signal from the excitation time controller 53, the excitation of the set antenna elements 2-1 to 2-N by the excitation phase setting unit 29 the phase phi ₁ to [phi] _N phase shifter 3 Output to -1 to 3-N (step ST16).
That is, the excitation phase output section 30 is, for example, if the switching circuit number k of excitation phase phi _n set by the switch circuit number setting unit 28 2, receives a timing signal for the first time from the excitation time controller 53, 1 as excitation phase phi ₁ to [phi] _N times th antenna elements 2-1 to 2-N, and outputs the excitation phase phi ₁₁ to [phi] _N1 to the phase shifter 3-1 to 3-N. Thereafter, when receiving the second timing signal from the excitation time controller 53, as the excitation phase phi ₁ to [phi] _N for the second antenna elements 2-1 to 2-N, phase shifter the excitation phase phi ₁₂ to [phi] _N2 Output to 3-1 to 3-N.

The transmitter 51 outputs a high frequency signal to be transmitted to the power distributor 52.
When receiving the high frequency signal from the transmitter 51, the power distributor 52 equally distributes the high frequency signal to the phase shifters 3-1 to 3 -N.
Phase shifter 3-1 to 3-N receives the excitation phase phi ₁ to [phi] _N from the excitation phase output section 30 of the phase shifter control unit 27, power distributor 52 according to the excitation phase phi ₁ to [phi] _N To change the phase of the equally distributed high-frequency signal.
The element antennas 2-1 to 2-N constituting the phased array antenna 1 radiate high-frequency signals whose phases have been changed by the phase shifters 3-1 to 3-N to the space (step ST17).

The receiving antenna 61 receives the high frequency signal radiated from the element antennas 2-1 to 2-N constituting the phased array antenna 1 (step ST18).
The receiver 62 detects the high frequency signal received by the receiving antenna 61.
The A / D converter 63 converts the analog high-frequency signal detected by the receiver 62 into a digital signal, and outputs the digital high-frequency signal to the time average calculation unit 65.

The time average calculating unit 65 refers to the time when the timing signal is first output from the excitation time control unit 53 stored in the switching period storage unit 64 and the switching period of the excitation phase, and refers to the element antenna 2-1. knowing the switching timing of the exciting phase phi _n in to 2-n, it recognizes the storage time and the time average calculation time of the high-frequency signal.
The time average calculation unit 65 accumulates the high frequency signal output from the A / D converter 12 when the accumulation time of the high frequency signal is reached (step ST19).
Until the accumulation of the set by switching circuit number setting unit 28 excitation phase phi _n of switching circuits number k fraction of the high frequency signal is completed, the process of step ST16~ST19 are repeatedly performed (step ST20).

Time average calculating unit 65 completes the accumulation of the set excitation phase phi _n of switching circuits number k fraction of the high-frequency signal by switching circuits number setting unit 28 (step ST20: YES), of the made to calculate the time of the time average, The time average of the accumulated high-frequency signal is calculated (step ST21).
Here, the time average calculator 65 stores the digital high-frequency signal output from the A / D converter 63 and calculates the time average of the stored high-frequency signal. The time average of the high-frequency signal may be obtained by performing discrete Fourier transform on the high-frequency signal output from the A / D converter 63 to obtain a signal in the frequency band.

As is apparent from the above, according to the second embodiment, the radiation pattern g _n (θ of each element antenna 2-n in a state where mutual coupling occurs between the element antennas 2-1 to 2-N. _m ) and the radiation pattern E (θ _m ) of the phased array antenna 1 in a state where mutual coupling does not occur between the element antennas 2-1 to 2-N, the compensation vector calculation unit 26 for calculating a compensation vector w _n to compensate for the effects of mutual coupling which are provided, a phase shifter control unit 27, using the compensation vector w _n calculated by the compensation vector calculation unit 26, the antenna elements set the excitation phase phi ₁ to [phi] _N for 2-1 to 2-N, since it is configured to direct the excitation phase phi ₁ to [phi] _N to the phase shifter 3-1 to 3-N, stepwise Without performing arithmetic processing, the device An effect of amplitude control device which can compensate for the effects of mutual coupling between Na 2-1 to 2-N is obtained unnecessary antenna device.

  In the present invention, within the scope of the invention, any combination of the embodiments, or any modification of any component in each embodiment, or omission of any component in each embodiment is possible. .

  In the antenna device according to the present invention, it is necessary to compensate for the influence of mutual coupling between the plurality of element antennas by changing the excitation phases of the plurality of element antennas constituting the phased array antenna in a time division manner. Is suitable.

  1 phased array antenna, 2-1 to 2-N element antenna, 3-1 to 3-N phase shifter, 4 power combiner (signal combiner), 11 receiver, 12 A / D converter, 21 hour average Calculation unit, 22 synchronization establishment unit, 23 compensation vector calculation processing unit, 24 element radiation pattern storage unit (first radiation pattern storage unit), 25 reference pattern storage unit (second radiation pattern storage unit), 26 compensation vector calculation 27, phase shifter control device (control unit), 28 switching number setting unit, 29 excitation phase setting unit, 30 excitation phase output unit, 31 time average calculation processing circuit, 32 synchronization establishment processing circuit, 33 compensation vector calculation processing circuit , 34 phase shifter control processing circuit, 41 memory, 42 processor, 51 transmitter, 52 power distributor, 53 excitation time control unit, 61 receiving antenna, 62 receiver, 3 A / D converter, 64 switching period storage unit, 65 hours average calculation section.

Claims (11)

A plurality of element antennas constituting a phased array antenna;
A plurality of phase shifters for controlling the excitation phase of the element antenna;
A first radiation pattern storage unit storing a radiation pattern of each element antenna in a state where mutual coupling occurs between the plurality of element antennas;
A second radiation pattern storage unit storing a radiation pattern of the phased array antenna in a state where mutual coupling does not occur between the plurality of element antennas;
Compensation vector calculation for calculating, for each element antenna, a compensation vector that compensates for the influence of mutual coupling received by the element antenna, using the radiation patterns stored in the first and second radiation pattern storage units. And
An antenna device comprising: a control unit that sets an excitation phase of the plurality of element antennas using the compensation vector calculated by the compensation vector calculation unit, and instructs the plurality of phase shifters to determine the excitation phase. A signal synthesizer for synthesizing signals received by the plurality of element antennas;
A receiver for detecting the signal synthesized by the signal synthesis unit;
A time average calculation unit that accumulates signals detected by the receiver and calculates a time average of the accumulated signals;
The antenna apparatus according to claim 1, further comprising: a synchronization establishment unit configured to synchronize an excitation phase switching cycle output from the control unit and a signal accumulation cycle of the time average calculation unit.   The antenna device according to claim 2, wherein the time average calculation unit obtains a time average of the signal detected by the receiver by performing a discrete Fourier transform on the signal detected by the receiver. A receiving antenna for receiving signals transmitted from the plurality of element antennas;
A receiver for detecting a signal received by the receiving antenna;
A switching cycle storage unit that stores a switching cycle of the excitation phase output from the control unit;
A time average calculating unit that accumulates the signal detected by the receiver for each switching period stored in the switching period storage unit and calculates a time average of the accumulated signal. The antenna device according to claim 1.   The antenna apparatus according to claim 4, wherein the time average calculation unit obtains a time average of the signal detected by the receiver by performing a discrete Fourier transform on the signal detected by the receiver. The controller is
A switching frequency setting unit for setting the switching frequency of the excitation phase;
An excitation phase setting unit that sets an excitation phase of the plurality of element antennas using the number of switchings set by the switching number setting unit and the compensation vector calculated by the compensation vector calculation unit;
2. The antenna apparatus according to claim 1, further comprising: an excitation phase output unit that instructs the plurality of phase shifters on the excitation phases of the plurality of element antennas set by the excitation phase setting unit.   The excitation phase setting unit calculates an amplitude phase vector calculated from the excitation phase for the number of switching times and the excitation amplitude of the element antenna for each element antenna while updating the excitation phase for the number of switching times in the element antenna. And repeatedly calculating the difference between the compensation vector of the element antenna calculated by the compensation vector calculation unit, comparing the calculated differences, and from among the excitation phases corresponding to the number of times of switching The antenna device according to claim 6, wherein an excitation phase corresponding to the number of switching times set as the excitation phase of the element antenna is selected according to a comparison result of the plurality of differences.   8. The antenna apparatus according to claim 7, wherein the excitation phase setting unit uses an excitation phase having a conjugate relationship as an excitation phase corresponding to the number of times of switching.   The first radiation pattern storage unit changes the excitation phase of the element antenna for each element antenna, calculates a change in the amplitude level of the combined electric field of the phased array antenna, and calculates the element from the change The antenna apparatus according to claim 1, wherein a relative amplitude value and a relative phase value of the antenna are calculated, and a relative amplitude value and a relative phase value of the element antenna are stored as a radiation pattern of the element antenna.   The first radiation pattern storage unit obtains in advance a radiation pattern of each element antenna in a state in which mutual coupling occurs between the plurality of element antennas by a computer simulation, and the radiation pattern of each element antenna The antenna device according to claim 1, wherein: A plurality of phase shifters control the excitation phase of a plurality of element antennas constituting a phased array antenna,
The compensation vector calculation unit includes a radiation pattern of each element antenna in a state where mutual coupling occurs between the plurality of element antennas, and the phased state in which no mutual coupling occurs between the plurality of element antennas. Using the radiation pattern of the array antenna, for each element antenna, calculate a compensation vector that compensates for the influence of mutual coupling received by the element antenna,
An antenna excitation method, wherein a control unit sets excitation phases of the plurality of element antennas using the compensation vector calculated by the compensation vector calculation unit, and instructs the excitation phase to the plurality of phase shifters.

Images