JP2018078483A - Slot array antenna - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a slot array antenna capable of achieving desired properties as well as a simple structure.SOLUTION: A slot array antenna 1 includes: a feeding unit 2 having a plurality of feeding slots 4 supplied with signal power; a radiant unit 10 which is disposed to oppose to the feeding unit 2 and which has a plurality of radiation slots 12 for being radiated with electromagnetic waves generated by power supply from the plurality of feeding slots 4; and a slow wave layer 20 which is formed between the radiant unit 10 and the feeding unit 2, delays a plane wave generated between the radiant unit 10 and the feeding unit 2 by power supply from the feeding unit 2 and which generates a standing wave between the radiant unit 10 and the feeding unit 2.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a structure of a slot array antenna.

  In recent years, research and development of ultrahigh-speed wireless communication technology using millimeter-wave band radio waves has been underway. As an antenna that emits millimeter waves with high directivity, an array antenna in which many antenna elements are arranged on a plane is used. For example, Patent Document 1 discloses a power feeding circuit that distributes signal power, a power feeding slot that feeds the distributed signal power, a cavity that excites power from the power feeding slot, and an electromagnetic wave that is excited in the cavity. A slot array antenna having a radiating slot for radiating is described. In the slot array antenna, each of the above components is formed by stacking metal conductor plates. In this slot array antenna, the respective metal conductor plates are joined to each other using diffusion joining.

  In diffusion bonding, the base materials are brought into close contact with each other and pressurized to the extent that plastic deformation does not occur as much as possible under a temperature condition below the melting point of the base materials, and the base materials are joined using the diffusion of atoms generated between the joining surfaces. Is the method. When diffusion bonding is used, the metal conductor plate and the metal conductor plate can be bonded without a gap. If there is a gap between the metal conductor plate and the metal conductor plate that are joined together, this gap will act as a slot antenna and radiate unintended electromagnetic noise, while receiving electromagnetic noise in a specific frequency band There is. Accordingly, in the related technology, diffusion bonding in which no gap is formed between the metal conductor plate and the metal conductor plate is used for manufacturing the slot array antenna.

JP 2014-170989 A

  The diffusion bonding used in the manufacturing process of the slot array antenna according to Patent Document 1 takes time during manufacturing, and thus the productivity deteriorates. Further, when trying to configure a slot array antenna without using diffusion bonding, there arises a problem that unintended electromagnetic noise occurs and a desired characteristic of the slot array antenna cannot be obtained.

  An object of the present invention is to provide a slot array antenna capable of obtaining desired characteristics while simplifying the structure.

The slot array antenna according to the present invention is:
A power supply unit having a plurality of power supply slots to which signal power is supplied;
A radiating section that is disposed opposite to the power feeding section and has a plurality of radiation slots for radiating electromagnetic waves generated by being fed from the plurality of power feeding slots;
It is formed between the radiating unit and the power feeding unit, and a plane wave fed between the radiating unit and generated between the radiating unit and the power feeding unit is delayed to delay between the radiating unit and the power feeding unit. A slow wave layer that generates a standing wave;
Is provided.

  The slow wave layer may be configured to generate the standing wave so as to feed the plurality of radiation slots with the same amplitude and the same phase.

  The slow wave layer may be configured to include a dielectric that delays the plane wave generated between the radiation part and the power feeding part.

  The dielectric may be configured such that a plurality of dielectrics having different relative dielectric constants are combined.

  Further, the slow wave layer may be configured to have a corrugation structure that delays the plane wave generated between the radiating unit and the power feeding unit so as to generate the standing wave.

The corrugation structure may be configured to have a plurality of protrusions formed so as to surround the periphery of the power supply slot.

  According to the present invention, the slow wave layer provided between the radiating unit and the power feeding unit generates a standing wave W while eliminating the diffusion junction between the radiating unit and the power feeding unit. The slots can be fed with the same amplitude and the same phase.

  The slot array antenna according to the present invention can obtain desired characteristics while simplifying the structure.

It is a perspective view which shows the structure of the slot array antenna which concerns on 1st Embodiment. It is a perspective view which shows a part of element of a slot array antenna as an analysis model. It is a perspective view which shows a part of element of a slot array antenna as an analysis model. It is sectional drawing which shows the standing wave distributed in a slow wave layer. It is a graph which shows the simulation result about the characteristic of a slot array antenna. It is a graph which shows the simulation result about the characteristic of a slot array antenna. It is a perspective view which shows the slot layer which makes a slot array antenna highly functional. It is a perspective view which shows the slot layer which makes a slot array antenna highly functional. It is a perspective view which shows the slot layer which makes a slot array antenna highly functional. It is sectional drawing which shows the structure of the slot array antenna which concerns on 2nd Embodiment. It is a figure which shows the projection part of a slot array antenna.

  Hereinafter, a slot array antenna according to an embodiment of the present invention will be described with reference to the drawings.

[First Embodiment]
As shown in FIG. 1, the slot array antenna 1 is a planar antenna in which a plurality of antenna elements are arranged in a matrix. In FIG. 1, elements of an 8 × 8 antenna element of the slot array antenna 1 having a 16 × 16 antenna element are cut out. That is, a quarter portion of the slot array antenna 1 is shown. The slot array antenna 1 is configured by connecting the quarter portions. Hereinafter, the ¼ portion of the slot array antenna 1 will be described, but the ¼ portion will be described as the slot array antenna 1 for convenience in consideration of the symmetry of the structure and the property of polarization.

  The slot array antenna 1 is provided between a power feeding unit 2 that feeds signal power, a radiation unit 10 that radiates signal power fed from the power feeding unit 2, and the power feeding unit 2 and the radiation unit 10. And the slow wave layer 20. In FIG. 1, the slow wave layer 20 and the power feeding unit 2 are illustrated as being separated from each other, but actually, the radiating unit 10 is stacked without a gap.

The power feeding unit 2 includes a rectangular plate-shaped conductor plate 3. As the conductor plate 3, for example, a metal plate is used. The conductor plate 3 is provided with a plurality of power supply slots 4 through which electromagnetic waves are supplied. The power supply slot 4 is a rectangular through hole. The plurality of power supply slots 4 are arranged in a matrix on the plane of the conductor plate 3, for example. The plurality of power supply slots 4 are provided in a total of 16 in a 4 × 4 arrangement, and are arranged at equal intervals in two-dimensional two directions (x-axis and y-axis directions). The distance between the two directions is not necessarily the same, but is adjusted in a range of a length of 1 free space wavelength (λ ₀ ) or more and less than 2 free space wavelengths (2λ ₀ ). A radiation unit 10 is disposed above the power supply unit 2 (+ z-axis direction).

  The radiating unit 10 is disposed in parallel so as to be opposed to the upper side (+ z direction) of the power feeding unit 2. The radiating portion 10 is composed of a rectangular plate-shaped conductor plate 11. For example, a metal plate is used as the conductor plate 11. The conductor plate 11 is provided with a plurality of radiation slots 12 that radiate electromagnetic waves. The radiation slot 12 is an antenna element that radiates electromagnetic waves that are fed from the plurality of power feeding slots 4 and excited. The radiation slot 12 is a rectangular through hole. The plurality of radiation slots 12 are arranged in a matrix on the plane of the conductor plate 11, for example. The plurality of radiation slots 12 are arranged at equal intervals in two two-dimensional directions (x-axis and y-axis directions).

The distance between the two adjacent radiation slots 12 in the two directions is half of the distance between the two adjacent feed slots 4. That is, the interval between the adjacent radiation slots 12 is 0.5 free space wavelength (0.5λ ₀ ) or more and less than 1 free space wavelength (λ ₀ ). A plurality of radiation slots 12 are arranged so that one feeding slot 4 is located at the center of four radiation slots 12 arranged at 2 × 2 when viewed from the z-axis direction. A slow wave layer 20 is provided between the radiating unit 10 and the power feeding unit 2.

  The slow wave layer 20 has a plate-like dielectric 21 formed of a material having a dielectric constant. The dielectric 21 is molded from a resin foamed body such as Teflon (registered trademark) or polyethylene. The dielectric 21 may be formed of one type of material, or may be formed by combining a plurality of dielectrics having different relative dielectric constants. For example, the slow wave layer 20 may be formed by laminating a plurality of dielectrics having different relative dielectric constants. The plurality of dielectric layers may include an air layer. When an air layer is included in the dielectric layer, a structure (not shown) that maintains the distance between the radiating unit 10 and the power feeding unit 2 is provided.

  The upper surface 21a and the lower surface 21b of the dielectric 21 are in contact with the radiating unit 10 and the power feeding unit 2 without a gap, respectively. The dielectric 21, the radiating unit 10, and the power feeding unit 2 are joined with, for example, an adhesive. Thus, the slot array antenna 1 has a parallel plate structure formed by the radiating unit 10 and the power feeding unit 2. The slow wave layer 20 is supplied with power from the power supply slot 4 and delays the plane wave generated between the power supply unit 2 and the radiation unit 10 by the dielectric 21. The slow wave layer 20 generates a standing wave W between the power feeding unit 2 and the radiating unit 10 by a delayed plane wave. The standing wave W will be described in detail later.

  Hereinafter, the operating principle of the slot array antenna 1 will be described.

  In FIG. 2, an element M which is 1/64 of the radiating portion of the slot array antenna 1 is shown as an analysis model. In the analysis model, a portion where a plurality of radiation slots 12 of the slot array antenna 1 are arranged in 2 × 2 is defined as one element M. In FIG. 2, a space is shown so that the feeding slot 4 can be seen between the radiating unit 10 provided with the dielectric 21 and the feeding unit 2, but actually the radiating unit 10, the dielectric 21, and The electric power feeding part 2 is piled up without gap. The analysis model is a parallel plate structure formed by the radiation part 10 and the power feeding part 2. Below the power supply slot 4 (−z direction), a rectangular waveguide 6 for power supply is provided.

  Consider a uniformly excited two-dimensional infinite array in which an infinite number of elements M are infinitely arranged on a two-dimensional plane of xy. Considering the mutual coupling of the elements M and the characteristics of the radiated polarization, the complete electric conductor E and the complete magnetic conductor G are appropriately set at the boundary around the elements M. Specifically, the complete electric conductor E is set on both side surfaces of the element M in the x-axis direction, and the complete magnetic conductor G is set on both side surfaces of the element M in the y-axis direction. A radiation boundary H is set in the external region above the radiation slot 12. Note that the interval between the feeding slots 4 is set at, for example, 1.72 free space wavelength, and the interval between the radiation slots 12 is set at 0.86 free space wavelength, which is half of that.

  FIG. 3 shows an analysis model of a quarter portion of the slot array antenna 1 having the 8 × 8 radiation slots 12 by connecting the elements M of the analysis model. As in FIG. 2, FIG. 3 also shows a space so that the power supply slot 4 can be seen between the radiation unit 10 provided with the dielectric 21 and the power supply unit 2. The body 21 and the power feeding unit 2 are overlapped without a gap. As in FIG. 2, complete electrical conductors E are set on both side surfaces in the x-axis direction of the analysis model, and complete magnetic conductors G are set on both side surfaces in the y-axis direction. A radiation boundary H is set in the external region above the radiation slot 12.

  Terminals of a waveguide circuit (not shown) including a rectangular waveguide 6 are connected to the plurality of power supply slots 4. The waveguide circuit is composed of, for example, a rectangular waveguide 6 branched at an equal length from one inlet, and a plurality of power supply slots 4 are connected to the ends of the branched waveguide, respectively. In the analysis model shown in FIG. 3, a total of 16 feeding rectangular waveguides are provided. As a result, power can be supplied to the plurality of power supply slots 4 simultaneously with the same amplitude and the same phase. Examples of the power supply circuit that supplies power to the plurality of power supply slots 4 include an H-plane branch parallel power supply circuit made of a rectangular waveguide and an E-plane branch parallel power supply circuit made of a rectangular waveguide. These power supply circuits may be provided in non-contact with the power supply unit 2 by a gap gap waveguide structure having a gap between the power supply unit 2 and the like.

  When signal power is input from the entrance of the waveguide circuit, an electromagnetic wave is guided by the waveguide circuit, and the signal is transmitted from the lower surface side 3b of the power feeding unit 2 with a substantially equal amplitude and a substantially equal phase with respect to the plurality of power feeding slots 4. Power is input. Thereby, polarized waves are excited from the plurality of power supply slots 4 respectively. Here, when the polarized light is radiated only by the power supply slot 4 of the power supply unit 2, the distance between the adjacent power supply slots 4 is 1 free space wavelength or more and less than 2 free space wavelengths. In addition to radiating electromagnetic waves in the z-axis direction), electromagnetic waves are radiated in other directions, generating unnecessary grating lobes.

  Therefore, the radiating unit 10 is provided above the power feeding unit 2 (+ z direction). Since the interval between the radiation slots 12 of the radiating unit 10 is not less than 0.5 free space wavelength and less than 1 free space wavelength, which is half of the interval between the feed slots 4, the grating lobe is suppressed. Further, a standing wave is generated between the parallel plates of the radiating unit 10 and the feeding unit 2 in order to simultaneously feed electromagnetic waves to the plurality of radiating slots 12 with the same amplitude and phase to excite polarized waves. Therefore, the slow wave layer 20 is provided between the power supply unit 2 and the radiation unit 10 with the dielectric 21 interposed therebetween.

The standing wave W is generated when the slow wave layer 20 provided between the radiating unit 10 and the power feeding unit 2 delays a plane wave generated between the radiating unit 10 and the power feeding unit 2. In order to generate the standing wave W, the conditions of the position of the radiation slot 12, the width w _r , the length l _r , the thickness t _{d of} the dielectric 21, and the relative dielectric constant ε _r of the dielectric 21 are adjusted. The

By adjusting these values, the wavelength of the plane wave in the parallel plate structure composed of the radiation unit 10 and the power feeding unit 2 is appropriately shortened. Specifically, each of the above values is adjusted so that the interval between the feeding slots 4 is effectively twice the wavelength of the plane wave guided in the slow wave layer 20. The wavelength λ _ε of the plane wave (standing wave W) generated in the slow wave layer 20 between the radiating unit 10 and the power feeding unit 2 is the wavelength λ ₀ in the parallel plate, and the relative dielectric constant of the dielectric 21 is ε _r. Then
λ _ε = λ ₀ / √ (ε _r ) (1)
It is expressed.

As shown in FIG. 4, the wavelength λ _ε of the plane wave delayed by the slow wave layer 20 between the radiating unit 10 and the power feeding unit 2 coincides with the interval between the radiating slots 12, and the wavelength λ _{ε of the} plane wave. Is equal to the interval between the power supply slots 4. This plane wave is distributed as a uniform standing wave W in the slow wave layer 20. The wavelength λ _{ε of the} standing wave W coincides with the interval between the radiation slots 12, and the position of the wave front of the standing wave W coincides with the position of the radiation slot 12. Therefore, electric power is supplied to the radiation slot 12 with the same amplitude and the same phase by the standing wave W, and the polarized wave is excited.

Since the standing wave W is uniformly distributed in the slow wave layer 20, the boundary condition for the complete magnetic conductor G in the actually manufactured antenna structure is substantially the parallel plate structure at the boundary position shown in FIG. Can be closed. The boundary condition for the perfect electric conductor E may be that the parallel plate structure is cut off at a position of a quarter wavelength λ _ε from the boundary position shown in FIG.

  Hereinafter, the simulation result about the characteristic of the slot array antenna 1 is shown.

FIG. 5 shows the frequency characteristics of the reflection of the slot array antenna 1 when the relative permittivity ε _{r of the} dielectric 21 of the slow wave layer 20 is 1.0, that is, when the slow wave layer 20 is air. The design frequency of the slow wave layer 20 is 61.5 GHz. Each condition (see FIG. 2) of the length l _r , the width w _{r of} the radiation slot 12 and the thickness t _d of the dielectric 21 (air layer) is, for example, l _r = 2.20 mm (= 0.45λ ₀ ), It is set with w _r = 1.60 mm (= 0.32λ ₀ ) and t _d = 0.98 (= 0.20λ ₀ ). The dotted line represents the reflection from the rectangular waveguide 6 for feeding in the analytical model of FIG.

  The sixteen solid lines in the analytical model of FIG. 3 indicate the respective rectangular waveguides for feeding when signal power is input from the sixteen feeding rectangular waveguides 6 to the feeding slot 4 with the same amplitude and phase. 6 reflections are shown. The 16 solid lines show different reflection characteristics, and do not match the dotted line results. This indicates that when the dielectric 21 of the slow wave layer 20 is air, the excitation intensity of the 8 × 8 radiation slot 12 is not uniform.

FIG. 6 shows the frequency characteristics of reflection of the slot array antenna 1 when the relative dielectric constant ε _{r of the} dielectric 21 of the slow wave layer 20 is 1.28. The design frequency of the slow wave layer 20 is 61.5 GHz. Each condition (see FIG. 2) of the length l _r , the width w _{r of} the radiation slot 12 and the thickness t _d of the dielectric 21 is, for example, l _r = 1.80 mm (= 0.37λ ₀ ), w _r = 1. .75 mm (= 0.36λ ₀ ), t _d = 1.60 (= 0.33λ ₀ ).

The frequency characteristics of the 16 solid lines are almost overlapped, and they are almost the same as the frequency characteristics of the dotted line. The 16 solid lines indicate the respective conditions (see FIG. 2) of the relative permittivity ε _{r of} the dielectric material 21, the thickness t _d of the dielectric material 21, and the shape (length l _r , width w _r) of the radiation slot 12. By selecting appropriately, it is shown that all the radiation slots 12 are uniformly excited without providing a metal wall for each feeding slot 4 as in the prior art.

  The above-described slot array antenna 1 (see FIG. 1) can be multi-functionalized by providing another slot layer above the radiating portion 10 (+ z direction). As shown in FIG. 7, for example, a parasitic slot layer 30 for widening the bandwidth may be added to the slot array antenna 1. FIG. 7 shows 1/64 of the parasitic slot layer 30. The parasitic slot layer 30 includes a rectangular conductor plate 31 and a parasitic slot 32 provided in the conductor plate 31.

  Further, as shown in FIG. 8, a 45-degree slot layer 33 that changes the angle of linearly polarized waves by 45 ° may be added to the slot array antenna 1. FIG. 8 shows 1/64 element of the 45 degree slot layer 33. The 45-degree slot layer 33 includes a rectangular conductor plate 34 and a 45-degree slot 35 provided in the conductor plate 34 so as to be inclined 45 degrees with respect to the y-axis.

  Furthermore, as shown in FIG. 9, a circularly polarized slot layer 36 that releases circularly polarized waves may be added to the slot array antenna 1. FIG. 9 shows 1/64 element of the circularly polarized slot layer 36. The circularly polarized slot layer 36 includes a rectangular conductor plate 37 and a circularly polarized slot 38 that is provided on the conductor plate 37 and excites circularly polarized waves. By using each slot layer described above, the slot array antenna 1 can be enhanced in function.

  As described above, according to the slot array antenna 1, the electromagnetic field distribution of the slow wave layer 20 between the radiating unit 10 and the power feeding unit 2 becomes a standing wave W. It is no longer necessary to provide the power, and the power leaking from the parallel plate structure can be suppressed as much as possible. The slow wave layer 20 does not need to be diffusion bonded to the radiating unit 10 and the power feeding unit 2, and the structure can be simplified. Further, according to the slot array antenna 1, even if the structure is simplified, a desired gain can be obtained without degrading the performance.

[Second Embodiment]
In the first embodiment, the slot array antenna 1 generates a standing wave W by delaying a plane wave guided between the radiating unit 10 and the power feeding unit 2 using the dielectric 21 in the slow wave layer 20. I was letting. In the second embodiment, the slot array antenna 1 generates a standing wave W using a corrugation structure that causes the slow wave layer 20 to slow down the plane wave. In the following description, the same reference numerals are used for the same configurations as those in the first embodiment, and duplicate descriptions are omitted.

  As shown in FIG. 10 and FIG. 11, there is an air layer A that is separated from the radiating unit 10 and the power feeding unit 2, and the conductor plate 3 of the power feeding unit 2 has a protrusion Q provided on the upper surface 3 a. Have. The protrusion Q has a plurality of protrusions Q1,..., Qn (n is a natural number). The plurality of protrusions Q1,..., Qn are formed to protrude upward (in the + z direction) from the upper surface 3a of the power feeding unit 2. The plurality of protrusions Q1,..., Qn are formed so as to surround the power supply slot 4, for example. Thereby, the slow wave layer 20 is formed by the corrugation structure which consists of several protrusion Q1, ..., Qn. The protrusion Q may be provided around the radiation slot 12.

  A plane wave guided between the radiating unit 10 and the power feeding unit 2 is delayed by the protrusion Q. Then, the standing wave W is generated in the slow wave layer 20 by adjusting the number of the plurality of protrusions Q1,..., Qn, the height and interval of the protrusions, and the like. When the slot array antenna 1 is actually constructed using this structure, a structure (not shown) that supports the radiation unit 10 and the power feeding unit 2 at a certain distance is used.

  As described above, according to the slot array antenna 1 according to the second embodiment, the slow wave layer 20 is formed by the corrugation structure composed of the plurality of protrusions Q1,..., Qn, and is fixed between the radiating unit 10 and the power feeding unit 2. The standing wave W can be generated. According to the slot array antenna 1 according to the second embodiment, since the slow wave layer 20 is configured without using the dielectric 21, the device configuration can be simplified.

DESCRIPTION OF SYMBOLS 1 ... Slot array antenna, 2 ... Feeding part, 3 ... Conductor plate, 4 ... Feeding slot, 6 ... Rectangular waveguide, 10 ... Radiation part, 11 ... Conductor plate, 12 ... Radiation slot, 20 ... Slow wave layer, 21 ... Dielectric material, 30 ... parasitic slot layer, 31 ... conductor plate, 32 ... parasitic slot, 33 ... 45 degree slot layer, 34 ... conductor plate, 35 ... 45 degree slot, 36 ... circularly polarized slot layer, 37 ... Conductor plate, 38 ... circularly polarized slot, A ... air layer, E ... perfect electrical conductor, G ... perfect magnetic conductor, H ... radiation boundary, M ... element, Q ... projection, Q1-Qn ... projection, W ... constant Standing wave

Claims (6)

A power supply unit having a plurality of power supply slots to which signal power is supplied;
A radiating section that is disposed opposite to the power feeding section and has a plurality of radiation slots for radiating electromagnetic waves generated by being fed from the plurality of power feeding slots;
It is formed between the radiating unit and the power feeding unit, and a plane wave fed between the radiating unit and generated between the radiating unit and the power feeding unit is delayed to delay between the radiating unit and the power feeding unit. A slow wave layer that generates a standing wave;
Comprising
Slot array antenna. The slow wave layer generates the standing wave to feed the plurality of radiation slots with the same amplitude and the same phase;
The slot array antenna according to claim 1. The slow wave layer includes a dielectric that slows the plane wave generated between the radiation part and the power feeding part.
The slot array antenna according to claim 1 or 2. The dielectric is formed by combining a plurality of dielectrics having different relative dielectric constants.
The slot array antenna according to claim 3. The slow wave layer has a corrugation structure for slowing the plane wave generated between the radiating unit and the power feeding unit so as to generate the standing wave.
The slot array antenna according to claim 1 or 2. The corrugation structure has a plurality of protrusions formed so as to surround the power supply slot.
The slot array antenna according to claim 5.

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