JP5314315B2 - Array antenna - Google Patents

Description

  The present invention relates to an array antenna that forms a beam by forming several element antennas into a subarray antenna, bundling them by providing a phase shifter for each subarray antenna.

  Array antennas are often used as antennas for radar devices or radio wave monitoring devices. Such an array antenna is required to have a higher effective radiated power as antenna performance in order to detect a farther target or detect weaker radio waves.

  The effective radiated power is defined as the product of transmission power and antenna gain. In order to increase the transmission output, the output of the transmission module connected to the transmitter or each element antenna may be increased. On the other hand, since the antenna gain is proportional to the opening diameter of the antenna, it is necessary to increase the diameter of the antenna in order to obtain a larger antenna gain.

  In the array antenna, if the element antenna spacing is such that no grating lobe is generated, the element spacing cannot be increased. As a result, as the aperture diameter increases, the number of element antennas increases, and the number of phase shifters connected to the element antennas also increases. In general, phase shifters are expensive, and it is desirable to suppress the number of phase shifters in the entire antenna. Therefore, it is considered to reduce the number of phase shifters by combining several element antennas into subarrays and providing a phase shifter for each subarray. (For example, see Patent Document 1)

  In such a configuration, the unit for controlling the phase by the phase shifter is changed from the element antenna to the subarray. Therefore, in order to prevent the generation of grating lobes, it is necessary to provide a space between the centers of the subarrays. However, since the size of the element antenna is about a wavelength, it is difficult to set the center interval of the subarrays including the element antennas to one wavelength or less, and there is a problem that a grating lobe occurs.

  Due to the occurrence of the grating lobe, the antenna gain in the desired direction is lowered and incoming radio waves from directions other than the desired directivity direction are received, and ambiguity is generated in the direction detection. Therefore, a configuration for avoiding the generation of grating lobes while reducing the number of phase shifters connected to the element antenna is desired.

  In such a situation, a technique for reducing ambiguity due to grating lobes by arranging antennas at unequal intervals as intervals between array antennas having no periodicity is disclosed (for example, Patent Document 2 and Non-Patent Document 1). reference).

  Further, as a polygon arrangement method having no periodicity, a technique has been proposed in which a grating lobe is suppressed over a wide band by selecting a Penrose tile, an octagonal, a table, etc., and arranging an element antenna at the apex position (for example, Non-Patent Documents 2 and 3).

JP-A-5-291814 JP 2005-257384 A IEICE Transactions B Vol. J83-B No. 6 pp. 845-851 “Direction estimation using non-uniformly spaced arrays” Vincenzo Pierro et. Al. “Radiation Properties of Planar Antenna Arrays Based on Certain Categories of Aperiodic Tilings” IEEE TRANSACTION ON ANTENNAS AND PROPAGATION, vol.53, NO.2, pp.635-644, Feb 2005 Glassner, A. “Penrose tiling”, IEEE Computer Graphics and Applications, vol.18, Issue4, pp.78-86, July / Aug 1988

However, the prior art has the following problems.
As a method for reducing the grating lobe, assuming that the spacing between the element antennas is unequal, for example, when the spacing between the element antennas is set at random, there is no periodicity and the feed system connected to the element antenna is There was a problem of becoming complicated. In addition, there is a problem that the manufacturing cost of the antenna increases due to the high-mix low-volume product.

  The present invention has been made in order to solve the above-described problems, and constitutes a subarray antenna array having no periodicity to obtain an array antenna that suppresses grating lobes and suppresses an increase in manufacturing cost. Objective.

The array antenna according to the present invention is an array antenna that performs beam forming by providing a phase shifter for each subarray antenna in which a plurality of element antennas are grouped, and the subarray antenna is one kind of isosceles triangle or 1 A planar shape is formed by one type of rhombus combining the bases of various isosceles triangles, a plurality of element antennas are arranged in the planar shape, and each of the plurality of element antennas included in the subarray antenna is arranged. When expressed using a circle having a radius r with the position as the center position, the circle of each element antenna is in contact with at least one of the other element antenna circles, and all of the element antenna circles are planes of the subarray antenna. contact with the outer shape, and by being arranged such that the maximum radius and the size of the radius r, in each sub-array antenna On the antenna elements are non-periodically arranged, in which device the antenna the antenna as a whole is arranged in aperiodic.

  According to the present invention, a plurality of element antennas are arranged so as to satisfy a predetermined condition in one kind of subarray antenna having a specific planar shape, and an array antenna is configured by combining a plurality of such one kind of subarray antennas. By doing so, it is possible to obtain a sub-array antenna array having no periodicity, suppress the grating lobe, and obtain an array antenna that suppresses an increase in manufacturing cost.

  Hereinafter, preferred embodiments of the array antenna of the present invention will be described with reference to the drawings. In the following, in each figure, the same reference numerals indicate the same or corresponding parts.

Embodiment 1 FIG.
FIG. 1 is a perspective view showing a configuration of an array antenna according to Embodiment 1 of the present invention. In FIG. 1, the array antenna 1 according to the first embodiment is provided with one type of subarray antenna 2 and a phase shifter 3.

  The shape of each subarray antenna 2 is an isosceles triangle, is configured to include a plurality of element antennas 4, and is connected to a phase shifter 3 respectively. With such a configuration, phase control is performed for each subarray antenna 2, and beam formation, directivity control, and the like are performed.

  In the first embodiment, the apex angle of subarray antenna 2 is n ° (where n is n = 360 / N, where N is an integer of 3 or more). Furthermore, the array antenna 1 is configured by arranging the subarray antennas 2 so as to form a 360 / n square with the apex angle of the subarray antenna 2 as the center. FIG. 1 illustrates an array antenna 1 having a nine-sided (360/40 = 9) configuration with an apex angle of n = 40 °.

  FIG. 2 is a plan view showing one subarray antenna 2 constituting the array antenna 1 according to Embodiment 1 of the present invention. The planar shape of the subarray antenna 2 is an isosceles triangle.

  In the element antenna 4 in the subarray antenna 2, if the distance between the element antennas 4 can be separated as much as possible, the coupling between the elements becomes small, and the performance deterioration can be suppressed.

  On the other hand, when the distance between the element antennas is increased, a direction in which the radiated electric field from each element antenna is in phase other than the direction of the directivity angle occurs at a certain directivity angle or more, and a grating lobe is generated. For this reason, it is necessary to arrange the element antennas 4 at intervals such that no grating lobe is generated.

  Therefore, in the first embodiment, in order to suppress the grating lobe with the arrangement of the element antennas 4 widened, the center position P of the element antennas 4 is set as shown in FIG. And circles with a radius r centering on the center position P of the element antenna 4 are in contact with the outer shape of the isosceles triangle of the subarray antenna 2.

  Further, the size of the radius r with the center position P as the center is selected, and the element interval is set as large as possible. As a result, the element antennas 4 are arranged aperiodically, and the generation of grating lobes can be suppressed.

  As described above, according to the first embodiment, the planar shape of the subarray antenna is an isosceles triangle having an apex angle of a predetermined angle n °. Further, a plurality of such subarray antennas are arranged to form a 360 / n-square array antenna.

Further, in each subarray antenna, a plurality of element antennas represented by circles having a center position P and a radius r are arranged so as to satisfy the following conditions.
Condition 1) The circle of each element antenna touches at least one other circle of one or more element antennas.
Condition 2) The circles of all element antennas touch the outer shape of the subarray antenna.
Condition 3) The size of the radius r centering on the center position P is selected, and the element interval is set as large as possible.

  By configuring the array antenna in this way, the distance between the element antennas can be separated as much as possible to reduce the coupling between the elements, and the performance deterioration can be suppressed. Can be configured. As a result, it is possible to obtain an array antenna that can suppress the generation of grating lobes by arranging the element antennas aperiodically and suppress the increase in manufacturing cost.

Embodiment 2. FIG.
In the first embodiment, the case where the planar shape of the subarray antenna 2 is an isosceles triangle has been described. In the second embodiment, a case will be described in which the planar shape of the subarray antenna 2 is a parallelogram (diamond) combining two isosceles triangles.

  FIG. 3 is a perspective view showing the configuration of the array antenna according to Embodiment 2 of the present invention. In FIG. 3, the array antenna 1 according to the second embodiment is provided with one type of subarray antenna 2 and a phase shifter 3.

  The shape of each subarray antenna 2 is a parallelogram obtained by combining two isosceles triangles. The subarray antenna 2 includes a plurality of element antennas 4 to which a phase shifter 3 is connected. With such a configuration, phase control is performed for each subarray antenna 2, and beam formation, directivity control, and the like are performed.

  In the second embodiment, the apex angle of subarray antenna 2 is n ° (where n is n = 360 / N, where N is an integer of 3 or more). Furthermore, the array antenna 1 is configured by arranging the subarray antennas 2 so as to form a 360 / n square with the apex angle of the subarray antenna 2 as the center. FIG. 2 illustrates an array antenna 1 having a nine-sided (360/40 = 9) configuration with an apex angle of n = 40 °.

  FIG. 4 is a plan view showing one subarray antenna 2 constituting the array antenna 1 according to Embodiment 2 of the present invention. The planar shape of the subarray antenna 2 is a parallelogram obtained by combining two isosceles triangles.

  The arrangement method of the element antennas 4 in the subarray antenna 2 is the same as that of the first embodiment. As shown in FIG. 4, the size of the radius r centered on the center position P is selected, and the element spacing is set. Take as large as possible.

  By disposing the element antenna 4 in this way, when the plane is filled with the sub-array antenna 2, the element antennas 4 are arranged aperiodically, and generation of grating lobes can be suppressed.

  As described above, according to the second embodiment, the planar shape of the subarray antenna is a parallelogram (diamond) having a vertex angle of a predetermined angle n ° and combining two isosceles triangles. Also, the same effect as in the first embodiment can be obtained.

It is a perspective view which shows the structure of the array antenna which concerns on Embodiment 1 of this invention. It is a top view which shows one subarray antenna which comprises the array antenna which concerns on Embodiment 1 of this invention. It is a perspective view which shows the structure of the array antenna which concerns on Embodiment 1 of this invention. It is a top view which shows one subarray antenna which comprises the array antenna which concerns on Embodiment 2 of this invention.

Explanation of symbols

  1 array antenna, 2 subarray antenna, 3 phase shifter, 4 element antenna.

Claims (2)

An array antenna that forms a beam by forming a phase shifter for each sub-array antenna in which a plurality of element antennas are combined,
The subarray antenna has a planar shape composed of one type of isosceles triangle, or one type of rhombus combining the bases of the one type of isosceles triangle, and the plurality of element antennas are arranged in the planar shape,
When each of the plurality of element antennas included in the sub-array antenna is represented by a circle having a radius r with the position where the sub-array antenna is disposed as a center position, the circle of each element antenna is at least one or more other Each subarray is arranged so as to be in contact with the circle of the element antennas, so that all the circles of the element antennas are in contact with the outer shape of the planar shape of the subarray antenna and the maximum radius is the size of the radius r. An array antenna, wherein the element antennas are aperiodically arranged in the antenna and the element antennas are aperiodically arranged as a whole antenna. The array antenna according to claim 1, wherein
The subarray antenna has one type of isosceles triangle with an apex angle of n ° (where n is an integer equal to or larger than 3 and n = 360 / N), or a combination of the bases of the one type of isosceles triangle. The plane shape is composed of one type of rhombus,
An array antenna, wherein a plurality of subarray antennas are arranged so as to form a (360 / n) square centering on an apex angle of the subarray antenna.

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