JPH0680975B2 - Dielectric loaded array antenna - Google Patents

Description

TECHNICAL FIELD The present invention relates to a dielectric loaded antenna having a wave source, a reflector and a dielectric, and more particularly to such a dielectric loaded antenna arranged in an array.

[Conventional technology]

Conventionally, the above-mentioned dielectric loaded antenna includes, for example, one disclosed in Japanese Patent Laid-Open No. 19802/1988. One example is shown in FIGS. 11 and 12. In this example,
An open waveguide 1 is used as a wave source, and a reflector 2 is provided around the opening.
And the dielectric 3 is provided so as to face the reflector 2. The above publication also discloses, as another example, those shown in FIG. 13 and FIG. In this example, a patch antenna 1a provided on a dielectric plate 4 is used as a wave source, a reflection plate 2a is provided on the surface of the dielectric plate 4 opposite to the patch antenna 1a, and the reflection plate 2a is sandwiched between the patch antenna 1a. The dielectric 3a is provided so as to face with.

In such a dielectric loaded antenna, multiple reflection is performed between the reflectors 2 and 2a and the dielectrics 3 and 3a, and the dielectric 3 and
Reflected waves and diffracted waves occur within 3a. Dielectric 3,3a
A high gain and high efficiency dielectric loaded antenna can be obtained by appropriately selecting the dimensions t and D of the respective parts and the distance h from the reflectors 2 and 2a. For example D = 1.5λ ₀ (λ ₀ is the free space wavelength), when _{t = 1.874λ 0, h = λ} 0/8, the maximum efficiency
It is described in the above publication that 225% was obtained.

[Problems to be Solved by the Invention]

By the way, in such a dielectric loaded antenna, 2n (n is a positive integer) of such dielectric loaded antennas may be arrayed to form an array antenna in order to obtain a higher gain antenna. Examples of such array antennas are shown in FIGS. 15 and 16. In this example, a patch antenna 1a is used as the wave source shown in FIGS. 13 and 14 for each dielectric loaded antenna, and these dielectric loaded antennas are arrayed in a square matrix at an array pitch L ₁ . In both figures, 5 is a feeder line for feeding each patch antenna. In addition, in this example, a cylindrical material 3b is used as the dielectric.

FIG. 17 is a solid line showing the relationship between the number of elements of the dielectric loaded antenna and the gain in the above-mentioned dielectric loaded array antenna, and no dielectric is loaded in the above dielectric loaded array antenna. The relationship between the number of elements and the gain is shown by a chain double-dashed line. FIG. 18 is a solid line showing the relation between the number of elements of the dielectric loaded antenna and the aperture efficiency in the dielectric loaded array antenna as described above. Although not shown, the relationship between the number of elements and the aperture efficiency is shown by a chain double-dashed line. In FIG. 18, it can be seen that the loss due to the feeder line 5 due to the increase in the number of elements can be almost ignored because the slope of the chain double-dashed line is parallel to the X axis. However, in the dielectric-loaded array antenna shown by the solid line, it can be seen that when the number of elements is increased from 2 elements to 4 elements, the aperture efficiency is drastically reduced. This is because the mutual coupling between adjacent elements is too strong,
As shown in FIG. 19 (a), the opening range a formed by each element with the number of elements 4 overlaps with each other as shown by hatching and influences each other, resulting in a decrease in the opening efficiency. It is believed that In order to prevent the overlapping of the aperture ranges a, as shown in FIG. 7B, when the distance between the patch antennas 1a and the distance between the dielectrics 3b are widened to L1 ', the hatching is added. In addition, the range that is not covered by each opening range a becomes wider than in the case of FIG. In addition,
17 and 18 show that L ₁ of FIGS. 15 and 16 is approximately 1.3λ _0.
It was measured as.

It is an object of the present invention to prevent a sharp decrease in aperture efficiency even if a dielectric loaded antenna is configured by a dielectric loaded antenna element to increase gain.

[Means for Solving the Problems]

In order to achieve the above-mentioned object, the present invention is arranged in a state in which it is substantially positioned at each apex of a parallelogram that can be drawn in the plane parallel to the reflector in the vicinity of the reflector and the reflector. A wave source and a three-dimensional dielectric provided on the opposite side of the wave source to the wave source at a position spaced apart from the wave reflector by a predetermined distance are provided. In the parallelogram, each side and one diagonal line have the same length, and the length is about 1.5λ ₀ (λ ₀ is a free space wavelength of a radio wave to be received or transmitted).

The three-dimensional dielectric body has two surfaces that are parallel to each other with an interval of about λ ₀ , one surface of which is close to the reflector and the other surface is far from the reflector. Position so that both surfaces are substantially parallel to the reflection plate, and the distance between the reflection plate and the one surface is about
And 2/5 [lambda] _0, the area of the duplex was about lambda ₀ ^2, dielectric constant of 2 to 2.5, a dielectric loss factor can be assumed to be 1 to 5 × 10 ^-4.

[Action]

According to the present invention, the wave source and the three-dimensional dielectric are arranged in a state in which they are located at the respective vertices of a parallelogram having the same length of each side and one diagonal line, and the length of each side of the parallelogram is set. Since it is set to about 1.5λ ₀ , the overlapping of the aperture ranges can be eliminated, and the range that cannot be covered by each aperture range can be minimized, and the dielectric loaded array antenna in which the wave source and the three-dimensional dielectric are each composed of at least four It is possible to prevent a significant decrease in the opening efficiency of the.

Further, when the shape of the three-dimensional dielectric, the size of each part, the distance between the three-dimensional dielectric and the reflector, and the material of the three-dimensional dielectric are set as described above, the aperture efficiency becomes clear as will be apparent from the examples described later. Also, the gain can be improved.

[Embodiment 4] In this embodiment, as shown in FIG. 2, a patch antenna 12 serving as a wave source is provided on one surface of a dielectric plate 10. As shown in FIG. 1, a total of 16 patch antennas 12 are provided as a set of four patch antennas 12. The patch antenna 12 in each set is a dielectric plate so that it is located at each apex of a parallelogram formed by combining two equilateral triangles (a parallelogram in which the length of each side and the length of one diagonal are equal). Formed on 10. Therefore, as shown in FIG. 1, the distance L ₂ between the patch antennas 12 in one set is equal, and in this embodiment, it is selected to be about 1.5λ ₀ (λ ₀ is the free space wavelength of the radio wave to be received or transmitted). Has been done. The patch antennas 12 of each set are connected to each set by a feed line 14, and finally are also connected to a feed point 16 by the feed line 14.

A reflection plate (18) is formed over the entire surface of the dielectric plate (10) opposite to the surface on which the patch antenna (12) is provided. Therefore, each patch antenna 12 is located near the reflection plate 18 and in parallel with the reflection plate 18.

Also, so as to face each patch antenna 12,
On the surface side where each patch antenna 12 is provided, a three-dimensional, for example, columnar dielectric material 20 is provided at a distance from the reflection plate 18. These cylindrical dielectrics 20 have two surfaces that are spaced apart from each other, that is, circular surfaces, one surface of which is closer to the reflector 18 and the other surface of which is farther from the reflector 18. , So that they are respectively located, and these surfaces are reflectors
It is arranged to be parallel to 18. The distance t between the two circular surfaces, that is, the thickness t of the cylindrical dielectric 20 is selected to be about λ ₀ , and the distance h from the one circular surface to the reflection plan 18 is set to about 2 / 5λ ₀ . The area S of both circular surfaces is selected to be about λ ₀ ² . As the dielectric 20, polypropylene having a relative permittivity εr of 2 to 2.1 and a dielectric loss coefficient tan δ = 2 × 10 ⁻⁴ was used. As the dielectric 20, other than this, polyethylene, polystyrene, having equivalent electrical characteristics,
Polytetrafluoroethylene resin or the like can also be used. In this case, the relative permittivity εr is 2 to 2.5 and the dielectric loss coefficient tan
δ is 1 to 5 × 10 ⁻⁴ .

After all, in this embodiment, the patch antenna 12 and the dielectric body 20 form a total of 16 dielectric-loaded antenna elements, and four such antenna elements are arranged at each vertex of the parallelogram described above. It will be arranged.

In FIG. 3, the change in gain when the number of the dielectric loaded antenna elements is increased to 1, 2, 4, 8, 16 in this embodiment is shown by a solid line. The number of those not loaded with 20 is 1, 2,
The change in gain when increasing to 4, 8, and 16 is shown by a chain double-dashed line. FIG. 4 shows a change in aperture efficiency with a solid line when the number of dielectric loaded antenna elements is increased to 1, 2, 4, 8, 16 in this embodiment. The two-dot chain line shows the change in the opening efficiency when the number of those not loaded with 20 was increased to 1, 2, 4, 8, and 16 as well. As is apparent from the comparison between FIG. 4 and FIG. 18, according to this embodiment, even if the number of dielectric loaded antenna elements is increased from 2 to 4, a large decrease in aperture efficiency occurs. Absent. This is because each dielectric loaded antenna element is located at each vertex of an equilateral triangle and is also arranged in a shape that forms a parallelogram, so that mutual coupling between elements can be significantly reduced. is there. That is, as shown in FIG. 20, when the dielectric loaded antenna elements are arranged at the vertices of a parallelogram in which each side and one diagonal line have the same length, the aperture ranges a do not overlap each other and This is because the range not covered by the range a is the smallest as shown by hatching. According to FIG. 4, as the number of the dielectric loaded antenna elements is increased, the aperture efficiency is gradually decreased with the increase, which is considered to be due to the loss due to the feeder line 14.

FIG. 5 shows the change in the gain when the thickness t of the dielectric 20 is changed in this embodiment, and when the thickness t of the dielectric 20 is set to about λ ₀ , the gain is changed. It turns out that is the maximum.

Further, FIG. 6 shows a change in gain when the distance h between the dielectric 20 and the reflector 18 is changed in this embodiment, and when h is set to about 2 / 5λ _0. It turns out that the gain is maximum.

FIG. 7 shows a change in gain when L ₂ is changed in this embodiment, and FIG. 8 shows a change in aperture efficiency when L ₂ is similarly changed. From these, it is found that the aperture efficiency becomes maximum when L _{2 is set} to about 1.5λ _0, and the gain also becomes a value close to the maximum value.

FIG. 9 shows a change in gain when the area S of the dielectric 20 is changed, and FIG. 10 shows a change in aperture efficiency when the area S of the dielectric 20 is changed in this embodiment. From these, it is found that the gain and the aperture efficiency are maximized when the area S is λ ₀ ² .

In the above-mentioned embodiment, the three-dimensional dielectric 20 has a columnar shape, but a rectangular parallelepiped shape as shown in FIGS. 11 and 13 can also be used. Further, in the above-mentioned embodiment, 16 dielectric loaded antennas are provided in total, but the number can be arbitrarily changed as long as it is a multiple of 4.

〔The invention's effect〕

As described above, according to the present invention, the wave source and the corresponding three-dimensional dielectric are arranged in a state of being positioned at each vertex of a parallelogram in which each side and one diagonal length are equal, and Since the length of each side of each parallelogram is approximately 1.5λ ₀ , it is possible to minimize the area not covered by each aperture range by eliminating the overlap of the aperture ranges, and to reduce the wave source and the three-dimensional dielectric material by 4 Even if a dielectric loaded array antenna is configured by using individual pieces, it is possible to prevent a large decrease in aperture efficiency.

Further, when the shape of the three-dimensional dielectric, the size of each part, and the distance between the three-dimensional dielectric and the reflector are set as described in claim 2, FIG. 5, FIG. 6, FIG. 9 and FIG. As is clear from FIG. 10, the aperture efficiency and gain of the dielectric loaded array antenna could be improved.

[Brief description of drawings]

1 is a plan view of an embodiment of a dielectric loaded array antenna according to the present invention, FIG. 2 is a partially omitted perspective view of the same embodiment, and FIG. 3 is the number and gain of dielectric loaded antenna elements in the same embodiment. 4 is a diagram showing the relationship between the number of dielectric loaded antenna elements and aperture efficiency in the same embodiment, and FIG. 5 is a diagram showing the relationship between dielectric thickness and gain in the same embodiment. FIG. 6 is a diagram showing the relationship between the gain and the distance between the dielectric plate and the reflector in the same embodiment, and FIG. 7 is a diagram showing the relationship between the spacing and the gain of each patch antenna in the same embodiment. FIG. 8 is a diagram showing the relationship between the patch antenna spacing and aperture efficiency in the same embodiment, FIG. 9 is a diagram showing the relationship between the cross-sectional area of the dielectric and the gain in the same embodiment, and FIG. 10 is the same embodiment. Of the relationship between the cross-sectional area of the dielectric and the aperture efficiency in
Fig. 11 is a perspective view of an example of a conventional dielectric loaded antenna,
FIG. 13 is a cross sectional view of a conventional dielectric loaded antenna, FIG. 13 is a perspective view of another example of a conventional dielectric loaded antenna, and FIG. 14 is a cross sectional view of another example of a conventional dielectric loaded antenna. FIG. 15 is a plan view of a dielectric loaded array antenna using the dielectric loaded antennas shown in FIGS. 13 and 14, and FIG. 16 uses the dielectric loaded antennas shown in FIGS. 13 and 14. FIG. 17 is a perspective view showing the relationship between the number of elements and the gain in the dielectric loaded array antenna shown in FIGS. 15 and 16, and FIG. 18 is FIG. And 16th
FIG. 19 is a diagram showing the relationship between the number of elements and the aperture efficiency of the dielectric loaded array antenna shown in FIG.
The figure which shows the opening range in the dielectric loading array antenna shown in the figure, FIG. 19 (b) is the distance between the dielectrics of the dielectric loading array antenna shown in FIG. 15 and FIG. FIG. 20 is a diagram showing the opening range when the distance is increased, and FIG. 20 is a diagram showing the opening range in the present embodiment. 12 …… Patch antenna (wave source), 18 …… Reflector, 20 ……
Dielectric.

Claims (2)

[Claims] 1. A reflection plate, a wave source arranged substantially at each vertex of a parallelogram that can be drawn in a plane parallel to the reflection plate in the vicinity of the reflection plate, and with respect to these wave sources. The three-dimensional dielectric provided corresponding to each of the wave sources at a position separated from the reflector by a predetermined distance on the side opposite to the reflector, the parallelogram has one side and one side. A dielectric loaded array antenna, wherein the lengths of the diagonal lines are equal to each other and the lengths are approximately 1.5λ ₀ (λ ₀ is the free space wavelength of the radio wave to be received or transmitted). 2. The dielectric-loaded array antenna according to claim 1, wherein the three-dimensional dielectric has two surfaces that are parallel to each other with a spacing of about λ ₀ , and one of the surfaces is the reflection surface. At a position close to the plate, the other surface is located far from the reflection plate, and both surfaces are arranged substantially parallel to the reflection plate, and the distance between the reflection plate and the one surface is about 2 / 5λ.
₀ , the area of both surfaces is about λ ₀ ² , the relative permittivity is 2 to 2.5, and the dielectric loss coefficient is 1 to 5 × 10 ⁻⁴ .