JP2996203B2 - Phased array antenna - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a phased array antenna, and more particularly, to a phased array antenna using digital beam forming (DBF).

[0002]

2. Description of the Related Art An example of this kind of phased array antenna is disclosed in Japanese Utility Model Laid-Open No. 63-174708. FIG. 6 is a configuration diagram of an example of this conventional phased array antenna. This figure shows only the receiving system.

A receiving system of a conventional phased array antenna for performing digital beam forming includes a plurality of antenna elements 1.
-1 to 1-n (n is a positive integer), receiving modules 2-1 to 2-n connected corresponding to these antenna elements 1-1 to 1-n, respectively, and signal processing for performing beam combining. And part 3.

Further, a receiving module 2 (for example, 2
In -1), the received signal received by the antenna element 1-1 is amplified by the amplifier 4, and the amplified received signal is converted into I / Q signals.
The detector 5 detects an I (Inphase) signal and a Q (Quadr) signal.
ature) signal, and the detected I / Q
The signals are converted into digital data by A / D converters 6-1 and 6-2. This corresponds to the receiving modules 2-2 to 2-n
The same applies to.

[0005] Then, the I
The / Q signal (hereinafter referred to as I / Q data) is input to the signal processing unit 3.

The signal processing unit 3 includes a plurality of antenna elements 1-
A weight buffer unit 8 for generating weight data for weighting 1 to 1-n, and a product for performing a product-sum operation on the weight data and the I / Q data received by the plurality of antenna elements 1-1 to 1-n And a sum operation unit 9.

[0007] The result of the product-sum operation of the weight data and the I / Q data is converted into beam synthesized data by the signal processing unit 3.
Output.

Japanese Patent Laid-Open Publication No. Hei 6-77720 and Japanese Patent Laid-Open Publication No. Hei 3-77720 disclose techniques relating to this type of I / Q data calculation method.
46402.

[0009] Broadening the bandwidth of an antenna element is generally determined by the size of the antenna element. In order to increase the bandwidth, it is necessary to increase the size of the antenna element compared to the wavelength of the received wave.

FIG. 7 is an external perspective view of an example of a spiral antenna. For example, the band of the spiral antenna 21 is determined by the ratio between the maximum diameter 23 and the minimum diameter 22 of the spiral antenna. Therefore, if the size of the antenna element is made larger than the wavelength, the maximum radius becomes larger, thereby making it possible to widen the band.

On the other hand, in the case of a linear array (arranging antennas in a straight line), the antenna element spacing for preventing generation of grating lobes (maximum beams other than the main beam) is generally expressed by the following equation (1). Is determined.

D / λ <1 / (1+ | sin θm |) (1) where d is the element interval, λ is the wavelength corresponding to the maximum frequency of the band, and θm is the maximum beam scanning angle.

Now, the beam scanning angle is set to ± 4 in consideration of practical use.
Assuming that the angle is 5 degrees, the antenna element interval must be suppressed to about 0.6 wavelength or less based on the maximum frequency of the frequency band. Therefore, the size of the element antenna is about 0.6 wavelength or less that does not contact the adjacent antenna. It was kept to size.

[0014]

However, in order to increase the bandwidth of the antenna, the size of the antenna element must be increased. When the size of the antenna element is increased, the antenna element interval is reduced to about 0.6 wavelength or less. There was a disadvantage that it could not be suppressed.

That is, since the size of the antenna element is limited by the interval between the antenna elements, it is not possible to further widen the bandwidth of the antenna element.

SUMMARY OF THE INVENTION An object of the present invention is to provide a phased array antenna capable of increasing the bandwidth of an antenna element as compared with the related art.

[0017]

According to the present invention, there is provided a phased array antenna including a plurality of antenna elements and a signal synthesizing means for beam synthesizing signals received by these antenna elements. The signal combining means converts a signal received by a virtual antenna element assumed to be present in an area surrounded by the plurality of antenna elements into a position vector of the plurality of antenna elements and a position vector of the virtual antenna element. Signal estimating means for estimating based on the signals received by the plurality of antenna elements, and logical operation means for performing a logical operation on the signal estimated by the signal estimating means and the signal received by the plurality of antenna elements And characterized in that:

According to the present invention, a signal received by a plurality of antenna elements and a signal estimated to be received by a virtual antenna element are beam-synthesized.

[0019]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a configuration diagram of a preferred embodiment of a phased array antenna according to the present invention. This figure shows only the receiving system. The same components as in the conventional example (FIG. 6) are assigned the same reference numerals.

The receiving system of the phased array antenna has 3
One or more independently arranged antenna elements 1-1 to 1--1
n (n is a positive integer, where n ≧ 3 in the present embodiment)
And receiving modules 2-1 to 2-n connected to these antenna elements 1-1 to 1-n, respectively, and a signal processing unit 3 for performing beam combining.

The configuration of the receiving modules 2-1 to 2-n is the same as that of the conventional example (FIG. 6), and the description is omitted.

Now, it is assumed that the virtual antenna element 1-N is set in a region surrounded by the antenna elements 1-1 to 1-n.

The signal processing unit 3 includes the antenna elements 1-1 to 1
−n and the antenna elements 1-1 to 1−1
The estimation unit estimates the reception I / Q data of the virtual antenna element 1-N which is assumed to be installed in the area surrounded by the antenna elements 1-1 to 1-n from the reception I / Q data received at n. 7, a weight buffer unit 8 for weighting the reception I / Q data estimated by the estimation unit 7 and the reception I / Q data of the antenna elements 1-1 to 1-n, and weighting by the weight buffer unit 8. And a product-sum operation unit 9 for performing a product-sum operation on the received I / Q data.

Next, the estimating unit 7 will be described. FIG. 2 is a configuration diagram of the estimation unit. The estimating unit 7 is a virtual antenna element 1
-N: a coefficient generator 11 for generating a coefficient for calculating the received I / Q data, and a coefficient generated by the coefficient generator 11 and the received I / Q data of the antenna elements 1-1 to 1-n. And a product-sum operation unit 12 and 13 for performing a product-sum operation on the received I / Q data of the virtual antenna element 1-N based on the result.

Next, the operation of this embodiment will be described with reference to FIGS.
This will be described with reference to FIG. The signal received by the antenna element 1 (for example, 1-1) is
-1 is input.

Further, in the receiving module 2-1, the received signal received by the antenna element 1-1 is amplified by the amplifier 4, and the amplified received signal is converted by the I / Q detector 5 into an I signal and a Q signal. And the detected I / Q signal is A
The data is converted into digital data by the / D converters 6-1 and 6-2 and input to the signal processing unit 3.

The digital I / O input to the signal processing unit 3
The Q data is divided in the signal processing unit 3, and one of them is input to the estimation unit 7 for estimating the reception data of the virtual antenna element 1-N.

The other is input to the product-sum operation unit 9. The sum-of-products calculation unit 9 receives reception I /
The virtual antenna element 1-N from the estimation unit 7 together with the Q data
Is also input. The received I / Q data of the antenna elements 1-1 to 1-n and the virtual antenna element 1-N input to the product-sum operation unit 9 are first weighted for beam forming by the weight buffer unit 8, Next, the weighted received I / Q data is subjected to a product-sum operation in a product-sum operation unit 9 to generate beam combined data.

Next, the operation of the estimating unit 7 will be described with reference to FIG. The coefficient generation unit 11 includes the antenna element 1-
A coefficient for estimating the received I / Q digital data of the virtual antenna element 1-N is generated from the position vectors of the virtual antenna element 1-N and the position vectors of the virtual antenna element 1-N.

The position vector r of the virtual antenna element 1-N
N is rN = a1r1 + a2r2 +... + Anrn (2)
(Where rN is the position vector of the antenna element 1-N,
r1, r2,... rn are antenna elements 1-1, 1--1, respectively.
2, ..., 1-n. ) And a1 + a2 +... + An = 1 (3)
a1, a2,..., an are coefficients.

As shown in the equation (3), a1, a2,.
The sum of n is 1. That is, the antenna element 1-1
Irrespective of where the position of 1-n is located, the coefficients a1, a
The sum of 2,..., An is always set to 1.

The digital I / Q data received from the antenna elements 1-1 to 1-n and the coefficients a1, a
2, ..., an, and IN = a1I1 + a2I2 + ... + anIn (4)
(However, I1, I2,..., In are antenna elements 1-1.
1 to 1-n. ) And QN = a1Q1 + a2Q2 +... + AnQn (5)
(However, Q1, Q2,..., Qn are antenna elements 1-1.
1 to 1-n show received digital Q data. ), The received I / Q digital data of the virtual antenna element 1-N is estimated.

Here, IN indicates the I signal of the virtual antenna element 1-N, and QN indicates the Q signal of the virtual antenna element 1-N.

In this case, the interval between the virtual antenna element 1-N and the adjacent antenna elements 1-1, 1-2 and 1-n is about 0.6 wavelength or less which can prevent the generation of the grating lobe described above. It is necessary to determine the position of the virtual antenna element 1-N in such a manner.

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

[0036]

FIG. 3 is a block diagram showing an embodiment of a phased array antenna according to the present invention. This figure shows only the receiving system. Note that the same components as those of the embodiment (FIG. 1) are assigned the same reference numerals and description thereof is omitted.

This embodiment is different from the embodiment (FIG. 1) in that four antenna elements (1-1 to 1-4) are used, and the antenna elements 1-1 to 1-4 are square. It has been arranged.

It is assumed that the virtual antenna element 1-N exists at the center of the antenna elements 1-1 to 1-4.

FIG. 4 is a block diagram of the estimating unit of the embodiment. This configuration diagram is different from the configuration diagram of the embodiment (FIG. 2) only in that the number of data received from the antenna element is four for both I data and Q data. I do. The same components as those in the embodiment (FIG. 2) are denoted by the same reference numerals.

The position vector r of the virtual antenna in this case
N is rN = a1r1 + a2r2 + a3r3 + a4r4 ...
(6) is represented by

The coefficients a1 to a4 are expressed as follows: a1 = a2 = a3 = a4 = 1/4 (7)

In this case, it is assumed that the virtual antenna element 1-N exists at the center of the antenna elements 1-1 to 1-4.
All the values of the coefficients a1 to a4 are "1/4". Then, the sum of the coefficients a1 to a4 is "1", as in the equation (3).

Next, a case where the number of four antenna elements according to this embodiment is further increased will be described. FIG. 5 is a plan view showing the arrangement of antennas when the total number of antenna elements is increased to five or more.

1-11 to 1-mn (m and n are both positive integers) shown in FIG.
1-N11 to 1-N22 indicate the positions of the virtual antenna elements.

A portion 32 surrounded by a broken line in the figure corresponds to the four rectangularly arranged antenna elements according to the embodiment and a virtual antenna element assumed to be present at the center thereof.

As shown in the figure, four antenna elements arranged in a square are extended at equal intervals in the vertical and horizontal directions, and virtual antenna elements are also increased accordingly. They will be arranged at equal intervals.

That is, the number of existing antenna elements can be reduced to about half as compared with the conventional case.

As a result, the interval between the antenna elements can be set twice as large as the conventional one, and the size of the antenna can be increased. This makes it possible to widen the band of the antenna element.

[0049]

According to the present invention, there is provided a phased array antenna including a plurality of antenna elements and signal combining means for beam combining signals received by these antenna elements, wherein the signal combining means comprises: A signal received by a virtual antenna element assumed to exist in a region surrounded by a plurality of antenna elements, a position vector of the plurality of antenna elements, and a position vector of the virtual antenna element,
A signal estimating means for estimating based on the signals received by the plurality of antenna elements, and a logical operation means for performing a logical operation on the signal estimated by the signal estimating means and the signal received by the plurality of antenna elements. Because of the included configuration, the number of actual antenna elements can be reduced to about half as compared with the related art.

As a result, the interval between the antenna elements can be set twice as large as the conventional one, and the size of the antenna can be increased. This makes it possible to widen the band of the antenna element.

Further, since the number of antenna elements can be reduced, the weight and cost of the antenna can be reduced.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a preferred embodiment of a phased array antenna according to the present invention.

FIG. 2 is a configuration diagram of an estimation unit of the antenna.

FIG. 3 is a configuration diagram of an embodiment of the antenna.

FIG. 4 is a configuration diagram of an estimation unit of the embodiment of the antenna.

FIG. 5 is a plan view showing an antenna arrangement when the total number of antenna elements is increased to five or more.

FIG. 6 is a configuration diagram of an example of a conventional phased array antenna.

FIG. 7 is an external perspective view of an example of a spiral antenna.

[Explanation of symbols]

 1-1 to 1-n Antenna element 1-N Virtual antenna element 3 Signal processing unit 7 Estimation unit 8 Weight buffer unit 9 Product sum operation unit 11 Coefficient generation unit 12, 13 Product sum operation unit

Claims (4)

(57) [Claims] 1. A phased array antenna comprising: a plurality of antenna elements; and signal combining means for beam combining signals received by the antenna elements, wherein the signal combining means is surrounded by the plurality of antenna elements. The signal received by the virtual antenna element assumed to be present in the region, the position vector of the plurality of antenna elements, the position vector of the virtual antenna element, based on the signal received by the plurality of antenna elements A phased array antenna, comprising: signal estimating means for estimating; and logical operation means for performing logical operation on a signal estimated by the signal estimating means and a signal received by the plurality of antenna elements. 2. The signal estimating means calculates a predetermined coefficient from a position vector of each of the plurality of antenna elements and a position vector of the virtual antenna element, and the first calculating means calculates the predetermined coefficient. 2. A phased array antenna according to claim 1, further comprising: second calculating means for calculating a signal estimated to be received by said virtual antenna element based on the coefficient obtained and signals received by said plurality of antenna elements. . 3. The logic operation means according to claim 1, wherein said logic operation means includes weighting means for weighting a signal estimated by said signal estimation means and a signal received by said plurality of antenna elements. Phased array antenna. 4. The phased device according to claim 1, wherein an interval between the virtual antenna element and the antenna element adjacent to the virtual antenna element is set to a distance at which no grating lobe is generated. Array antenna.