JP6721354B2 - Antenna element, array antenna and plane antenna - Google Patents

Description

The present invention relates to an antenna element having high radiation efficiency and wide-angle directivity, and an array antenna and a plane antenna that suppress a grating lobe.

The following Patent Document 1 and Non-Patent Document 1 disclose a dipole array antenna and a patch array antenna, respectively. Each dipole element or each patch element is coupled to the feed line by direct coupling or electromagnetic coupling.

Patent No. 3306592

Hashiki Misao, "Latest Planar Antenna Technology," General Technology Center, January 1993, pp. 353-354.

The above-mentioned Patent Document 1 and Non-Patent Document 1 are considered to leave room for pursuing the following problems for the dipole array antenna and the patch array antenna, respectively: (1) The radiation efficiency of the antenna element Improvement of design freedom, (2) improvement of wide-angle directivity of antenna element, (3) suppression of grating lobe of array antenna.

Therefore, in order to solve the above problems, the present invention realizes a further improvement in the design freedom of the radiation efficiency in the antenna element and a further improvement in the wide-angle directivity, and further, the grating lobe of the array antenna and the planar antenna. The purpose is to realize further suppression.

In order to achieve the above object, the antenna element conductor partially overlaps the feed line when viewed from the stacking direction of the antenna elements, and is electromagnetically coupled to the feed line through the electromagnetic coupling layer. The reflection suppressing unit suppresses the power reflection in the direction opposite to the power feeding direction of the power feeding line.

Specifically, the present invention is an antenna element formed on a dielectric substrate, the ground plane conductor formed on one surface of the dielectric substrate and the other surface of the dielectric substrate. From a stacking direction of a power feeding line, a reflection suppressing unit that suppresses power reflection in a direction opposite to the power feeding direction of the power feeding line, an electromagnetic coupling layer formed on the surfaces of the power feeding line and the reflection suppressing unit, and a stacking direction of the antenna element. When viewed, the antenna element conductor partly overlaps the feed line, and the antenna element conductor is electromagnetically coupled to the feed line via the electromagnetic coupling layer.

According to this configuration, the size of the antenna element can be reduced in the direction perpendicular to the feeding direction, and the element spacing between the array antenna and the planar antenna can be reduced in the direction perpendicular to the feeding direction. Therefore, further suppression of the grating lobes in the array antenna and the plane antenna can be realized. And, even when all the antenna elements of the array antenna are excited in the same phase, reflection in the same phase from all the antenna elements of the array antenna is hard to occur. Can emit radiation.

Further, according to the present invention, the antenna element conductor partially overlaps with the reflection suppressing section when viewed from a stacking direction of the antenna element, and is electromagnetically coupled to the reflection suppressing section via the electromagnetic coupling layer, and the reflection suppressing section is provided. The section is an antenna element characterized in that the degree of electromagnetic coupling with the antenna element conductor is adjusted.

According to this configuration, not only the amount of reflection from the antenna element is adjusted, but also the size and position of the feeding line and the antenna element conductor are used as adjustment parameters when adjusting the amount of radiation from the antenna element. The size and position of the suppression unit can be used as the adjustment parameter. Therefore, it is possible to further improve the degree of freedom in designing the radiation efficiency of the antenna element.

Further, the present invention is the antenna element, further comprising a dielectric layer formed on the surface of the antenna element conductor.

According to this configuration, when the dielectric layer is formed on the surface of the antenna element conductor, the effective dielectric constant in the environment around the antenna element conductor is higher than when the dielectric layer is not formed on the surface of the antenna element conductor. Become. Therefore, the size of the antenna element conductor can be reduced, and the wide-angle directivity of the antenna element can be further improved. Then, the element spacing between the array antenna and the plane antenna can be reduced in the direction perpendicular to the feeding direction, and further suppression of the grating lobes in the array antenna and the plane antenna can be realized.

Further, according to the present invention, the antenna element is linearly arranged, and the single dielectric substrate, the ground plane conductor, and the electromagnetic coupling layer are shared by a plurality of the reflection suppressing units and the antenna element conductor. The array antenna is characterized in that

According to this configuration, it is possible to further improve the degree of freedom in designing the radiation efficiency of the antenna element and further improve the wide-angle directivity, and also to further suppress the grating lobe in the array antenna. In particular, a center-feeding traveling-wave array antenna, which will be described later, has advantageous effects.

Further, according to the present invention, the antenna elements are arranged in a grid pattern, and the single dielectric substrate, the ground plane conductor, and the electromagnetic coupling layer are shared by a plurality of the reflection suppressing units and the antenna element conductors. It is a planar antenna characterized in that.

According to this configuration, it is possible to further improve the degree of freedom in designing the radiation efficiency of the antenna element and further improve the wide-angle directivity, and also to further suppress the grating lobe in the planar antenna. In particular, a center-fed traveling wave type planar antenna, which will be described later, has advantageous effects.

As described above, the present invention realizes further improvement in design freedom of radiation efficiency in the antenna element and further improvement in wide-angle directivity, and further realizes further suppression of grating lobes in the array antenna and the planar antenna. be able to.

It is a figure which shows the structure of the antenna element of 1st Embodiment. It is a figure which shows the structure of the antenna element of 2nd Embodiment. It is a figure which shows the dimension of the antenna element of 2nd Embodiment. It is a figure which shows the radiation efficiency of the antenna element of 2nd Embodiment. It is a figure which shows the structure of the antenna element of 3rd Embodiment. It is a figure which shows the structure of the array antenna of 4th Embodiment. It is a figure which shows the structure of the planar antenna of 4th Embodiment. It is a figure which shows the structure of the planar antenna of 4th Embodiment.

Embodiments of the present invention will be described with reference to the accompanying drawings. The embodiments described below are examples of the embodiments of the present invention, and the present invention is not limited to the following embodiments.

(First embodiment)
The configuration of the antenna element of the first embodiment is shown in FIG. The upper stage and the lower stage of FIG. 1 show a plan view (view seen from the stacking direction of the antenna element 1) and a side view (view seen from the feed direction of the feed line 13), respectively. The antenna element 1 includes a dielectric substrate 11, a ground plane conductor 12, a feed line 13, a reflection suppressing section 14, an electromagnetic coupling layer 15, and an antenna element conductor 16.

The antenna element 1 is formed on the dielectric substrate 11. The ground plane conductor 12 is formed on one surface of the dielectric substrate 11. The power supply line 13 is formed on the other surface of the dielectric substrate 11.

The reflection suppressing unit 14 suppresses power reflection in the direction opposite to the power feeding direction of the power feeding line 13. In the first embodiment, the reflection suppressing unit 14 is a stub formed on the power feeding line 13. As a modified example, the reflection suppressing unit 14 may be a notch formed in the power feeding line 13.

The electromagnetic coupling layer 15 is formed on the surfaces of the power feeding line 13 and the reflection suppressing unit 14. The antenna element conductor 16 partially overlaps the feed line 13 when viewed from the stacking direction of the antenna element 1, and is electromagnetically coupled to the feed line 13 via the electromagnetic coupling layer 15. In the first embodiment, the antenna element conductor 16 is a dipole element conductor inclined by 45 degrees with respect to the feeding direction of the feeding line 13. As a modification, the antenna element conductor 16 may be a dipole element conductor inclined by an arbitrary angle with respect to the feeding direction of the feeding line 13 or a patch element conductor.

In this way, the size of the antenna element 1 can be reduced in the direction perpendicular to the feeding direction, and the element spacing between the array antenna (FIG. 6) and the planar antenna (FIGS. 7 and 8) can be reduced in the direction perpendicular to the feeding direction. be able to. Therefore, further suppression of the grating lobes in the array antenna and the plane antenna can be realized.

Further, even when all the antenna elements 1 of the array antenna (FIG. 6) are excited in the same phase, reflection in the same phase from all the antenna elements 1 of the array antenna is hard to occur, so the reflection loss should be reduced at this frequency. It is possible to generate radiation in the front direction.

(Second embodiment)
The configuration of the antenna element of the second embodiment is shown in FIG. In the second embodiment, in addition to the first embodiment, the antenna element conductor 16 partially overlaps the reflection suppressing section 14 when viewed from the stacking direction of the antenna element 1, and the reflection suppressing section 14 is interposed via the electromagnetic coupling layer 15. Electromagnetically coupled to the reflection suppressing unit 14, the reflection suppressing unit 14 adjusts the degree of electromagnetic coupling with the antenna element conductor 16.

The dimensions of the antenna element of the second embodiment are shown in FIG. Let λ be the wavelength of the electromagnetic wave in free space. The lengthwise dimension of the antenna element conductor 16 is 0.217λ. The widthwise dimension of the antenna element conductor 16 is 0.077λ. The inclination angle of the antenna element conductor 16 with respect to the feed line 13 in the plan view is 45 degrees. The distance in the plan view between the center of the antenna element conductor 16 and the center line of the feeding line 13 extending in the feeding direction is 0.128λ. The extension length of the reflection suppressing unit 14 from the power supply line 13 is i and is variable. The distance in the plan view between the center line extending in the extending direction of the reflection suppressing portion 14 and the center portion of the antenna element conductor 16 is x, which is variable. Here, when x=0, the reflection suppressing unit 14 is within an acute angle formed by the antenna element conductor 16 and the feed line 13. Then, as x increases in the positive direction, the degree of overlap between the reflection suppression unit 14 and the antenna element conductor 16 gradually increases, reaches a maximum, and then gradually decreases.

The radiation efficiency of the antenna element of the second embodiment is shown in FIG. The vertical axis of FIG. 4 represents the ratio of radiated power to input power. The horizontal axis of FIG. 4 represents x in the reflection suppressing unit 14. FIG. 4 simulates the ratio of radiated power to input power by varying x and i in the reflection suppressing unit 14. As x increases, the ratio of the radiated power to the input power gradually increases at 0.025λ<x<0.075λ, corresponding to the degree of overlap between the reflection suppressing unit 14 and the antenna element conductor 16, and x It goes through a maximum at 0.075λ and gradually decreases at 0.075λ<x<0.100λ. As i increases, the ratio of the radiated power to the input power increases in the range of 0.013λ<i<0.051λ (the rate of increase is as follows) in accordance with the degree of overlap between the reflection suppressing unit 14 and the antenna element conductor 16. , And gradually becomes gentle.), it is almost saturated at 0.051λ<i<0.077λ.

As described above, in adjusting not only the amount of reflection from the antenna element 1 but also the amount of radiation from the antenna element 1, not only the size and position of the feed line 13 and the antenna element conductor 16 are used as adjustment parameters. The size and position of the reflection suppressing unit 14 can be used as the adjustment parameter. Therefore, as compared with the first embodiment, the second embodiment can further improve the degree of freedom in designing the radiation efficiency of the antenna element 1.

(Third Embodiment)
The structure of the antenna element of the third embodiment is shown in FIG. In the third embodiment, in addition to the first and second embodiments, the antenna element 1 further includes a dielectric layer 17 formed on the surface of the antenna element conductor 16. Here, the thickness of the dielectric layer 17 can be adjusted so that the directivity of the antenna element 1 has wide-angle directivity and does not cause a null in the front direction.

Here, in the case where the dielectric layer 17 is formed on the surface of the antenna element conductor 16, the effective permittivity in the environment around the antenna element conductor 16 is larger than that in the case where the dielectric layer 17 is not formed on the surface of the antenna element conductor 16. Becomes higher. Therefore, as compared with the first and second embodiments, the size of the antenna element conductor 16 can be reduced in the third embodiment, and the wide angle directivity of the antenna element 1 can be further improved. In the third embodiment, compared with the first and second embodiments, the element spacing of the array antenna (FIG. 6) and the planar antenna (FIGS. 7 and 8) can be reduced in the direction perpendicular to the feeding direction, and the array antenna can be made smaller. Further suppression of grating lobes in antennas and planar antennas can be achieved.

(Fourth Embodiment)
The configuration of the array antenna of the fourth embodiment is shown in FIG. In the array antenna 2 of the fourth embodiment, the antenna elements 1 of the first to third embodiments are arranged linearly, and the single dielectric substrate 11, the ground plane conductor 12, and the electromagnetic coupling layer 15 are provided as a plurality of reflection suppressing units. 14 (not shown in FIG. 6) and the antenna element conductor 16 in common. In the fourth embodiment, the array antenna 2 is a center-fed traveling-wave array antenna, and the plurality of antenna arrays that extend in the vertical direction in FIG. 6 each include one power supply circuit 21 (for example, transmission line/waveguide). Power is supplied by the conversion circuit).

The configuration of the flat antenna of the fourth embodiment is shown in FIGS. In the planar antenna 3 of the fourth embodiment, the antenna elements 1 of the first to third embodiments are arranged in a grid, and the single dielectric substrate 11, the ground plane conductor 12, and the electromagnetic coupling layer 15 are provided as a plurality of reflection suppressing units. 14 (not shown in FIGS. 7 and 8) and the antenna element conductor 16. In the fourth embodiment, as shown in FIG. 7, the plurality of array antennas 2 are arranged so that the plurality of feeding circuits 21 are linearly arranged in the direction perpendicular to the feeding direction. As described above, the plurality of array antennas 2 are arranged such that the plurality of feeding circuits 21 are arranged in a zigzag pattern in the direction perpendicular to the feeding direction.

While the resonant wave type array antenna has a narrow band characteristic, the traveling wave type array antenna has a wide band characteristic, so that the traveling wave type array antenna is used for wide band applications. The inventor of the present application has identified the following problems regarding the traveling wave array antenna.

That is, when all the antenna elements of the traveling-wave array antenna are excited in the same phase, reflection occurs in the same phase from all the antenna elements, so that the reflection loss increases and the radiation efficiency decreases at this frequency. On the other hand, when each antenna element of the traveling-wave array antenna is excited in a different phase, reflection occurs in a different phase from each antenna element, so radiation occurs in the direction tilted from the front direction, but the reflection loss in the wide band decreases. Radiation efficiency is high.

When the traveling wave array antenna is fed at one end, when the operating frequency changes, the angle of the radiation direction with respect to the front direction changes. On the other hand, when the traveling wave array antenna is fed at the center, the angle of the radiation direction with respect to the front direction does not change even if the operating frequency changes. Therefore, when the traveling-wave array antenna is used in a wide band, power is fed in the center of the array as shown in FIGS.

INDUSTRIAL APPLICABILITY The antenna element, array antenna, and plane antenna of the present invention can be applied to applications such as radar where it is desired to expand the monitoring area in the azimuth direction.

1: Antenna element 2: Array antenna 3: Planar antenna 11: Dielectric substrate 12: Ground conductor 13: Feed line 14: Reflection suppressing section 15: Electromagnetic coupling layer 16: Antenna element conductor 17: Dielectric layer 21: Feed circuit 22 : Termination antenna

Claims (4)

An antenna element formed on a dielectric substrate,
A ground plane conductor formed on one surface of the dielectric substrate,
A feed line formed on the other surface of the dielectric substrate,
A reflection suppressing unit that suppresses power reflection in a direction opposite to the power feeding direction of the power feeding line,
An electromagnetic coupling layer formed on the surface of the feed line and the reflection suppressing section,
An antenna element conductor that partially overlaps with the feeding line and the reflection suppressing section when viewed from the stacking direction of the antenna element, and that is electromagnetically coupled to the feeding line and the reflection suppressing section via the electromagnetic coupling layer , and
The reflection suppressing unit adjusts the degree of electromagnetic coupling with the antenna element conductor,
An antenna element characterized by the above. A dielectric layer formed on the surface of the antenna element conductor,
And further comprising the antenna device according to claim 1. The antenna element according to claim 1 or 2 is linearly arranged,
An array antenna, wherein the single dielectric substrate, the ground plane conductor, and the electromagnetic coupling layer are shared by a plurality of the reflection suppressing units and the antenna element conductor. The antenna elements according to claim 1 or 2 are arranged in a grid pattern,
A planar antenna, wherein a single dielectric substrate, the ground plane conductor, and the electromagnetic coupling layer are shared by a plurality of the reflection suppressing units and the antenna element conductor.

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