JP2022177343A - Antenna and wireless communication device - Google Patents

Abstract

To provide an antenna capable of changing an operating frequency without changing the shape of an antenna element and a wireless communication device including the antenna.SOLUTION: An antenna includes: a substrate having a front surface and a back surface; at least one antenna element provided on the front surface or inside the substrate and having a main radiation direction facing an opposite side to the back surface; and a dielectric cover that overlaps the antenna element as viewed from the front of the substrate and is detachably attached to the front surface. Attachment or detachment of the dielectric cover changes an operating frequency. A wireless communication device includes the antenna. For example, the antenna is for a base station and is used by installing it so that the back surface faces a front surface of an object.SELECTED DRAWING: Figure 1

Description

The present disclosure relates to antennas and wireless communication devices.

Conventionally, an antenna is known that is connected to a small cell base station via a cable and attached to a peripheral portion of a window glass such as an indoor ceiling or inner wall (see, for example, Patent Document 1).

JP 2014-165599 A

However, with conventional technology, it is difficult to change the operating frequency of the antenna without changing the shape of the antenna element.

The present disclosure provides an antenna capable of changing the operating frequency without changing the shape of the antenna element, and a wireless communication device including the antenna.

This disclosure is
a substrate having a front surface and a back surface;
at least one antenna element provided on the front surface or inside the substrate and having a main radiation direction opposite to the back surface;
a dielectric cover that overlaps the antenna element in a front view of the substrate and is detachably attached to the front surface,
Provided are an antenna and a wireless communication device including the antenna, the operating frequency of which is changed by attaching and detaching the dielectric cover.

According to the technique of the present disclosure, it is possible to change the operating frequency of the antenna without changing the shape of the antenna element.

FIG. 2 is a cross-sectional view schematically showing an example of a laminated structure of an antenna; FIG. 4 is a cross-sectional view schematically showing an example in which the entire dielectric cover is detachable; FIG. 4 is a cross-sectional view schematically showing an example in which a part of the dielectric cover is detachable; FIG. 4 is a perspective view schematically showing a first mounting example of the antenna; FIG. 11 is a perspective view schematically showing a second mounting example of the antenna; FIG. 4 is a perspective view schematically showing a first connection example between the power supply wiring and the connector; FIG. 10 is a perspective view schematically showing a second connection example between the power supply wiring and the connector; FIG. 12 is a perspective view schematically showing a third connection example between the power supply wiring and the connector; FIG. 4 is a cross-sectional view schematically showing a feeder line connecting a connector and an antenna element; It is an exploded view which shows an antenna by planar view. FIG. 2 is a cross-sectional view schematically showing a first configuration example of a substrate; FIG. 10 is a cross-sectional view schematically showing a second configuration example of the substrate; FIG. 11 is a cross-sectional view schematically showing a third configuration example of the substrate; FIG. 10 is a diagram showing an example of frequency characteristics of reflection intensity due to a difference in thickness of a dielectric cover; FIG. 4 is a diagram showing an example of frequency characteristics of total radiation efficiency due to different thicknesses of a dielectric cover; FIG. 4 is a diagram showing an example of the relationship between the thickness of a dielectric cover, the center frequency, and the total radiation efficiency; FIG. 5 is a diagram showing an example of frequency characteristics of reflection intensity due to differences in dielectric constants of dielectric covers; FIG. 4 is a diagram showing an example of frequency characteristics of total radiation efficiency due to differences in dielectric constants of dielectric covers; FIG. 3 is a diagram showing an example of the relationship between the dielectric constant of a dielectric cover, the center frequency, and the total radiation efficiency; FIG. 4 is a diagram showing an example of the relationship between total radiation efficiency and dielectric loss tangent at operating frequencies; FIG. 5 is a diagram showing an example of results of simulating the directivity of an antenna provided with the substrate of the first configuration example; FIG. 5 is a diagram showing an example of results of simulating the directivity of an antenna provided with the substrate of the first configuration example; FIG. 10 is a diagram showing an example of results of simulating the frequency characteristics of the reflection intensity of the antenna provided with the substrate of the second configuration example; FIG. 10 is a diagram showing an example of results of simulating the directivity of an antenna provided with the substrate of the second configuration example; FIG. 10 is a diagram showing an example of results of simulating the directivity of an antenna provided with the substrate of the second configuration example; FIG. 12 is a front perspective view schematically showing a fourth connection example between the power supply wiring and the connector; FIG. 11 is a back side perspective view schematically showing a fourth connection example between the power supply wiring and the connector; FIG. 12 is a side view schematically showing a fourth connection example between the power supply wiring and the connector;

Hereinafter, embodiments will be described with reference to the drawings. For ease of understanding, the scale of each member in the drawings may differ from the actual scale. In this specification, a three-dimensional orthogonal coordinate system with three axial directions (X-axis direction, Y-axis direction, and Z-axis direction) is used, the width direction of the substrate is the X-axis direction, and the height direction of the substrate is the Y-axis direction. , the thickness direction of the substrate is the Z-axis direction.

In directions such as parallel, right angle, orthogonal, horizontal, vertical, up and down, left and right, misalignment to the extent that the effect of the technology of the present disclosure is not impaired is allowed. The X-axis direction, Y-axis direction, and Z-axis direction represent directions parallel to the X-axis, directions parallel to the Y-axis, and directions parallel to the Z-axis, respectively. The X-axis direction, the Y-axis direction, and the Z-axis direction are orthogonal to each other. The XY plane, YZ plane, and ZX plane are virtual planes parallel to the X-axis direction and Y-axis direction, virtual planes parallel to the Y-axis direction and Z-axis direction, and virtual planes parallel to the Z-axis direction and X-axis direction, respectively. represents

FIG. 1 is a cross-sectional view schematically showing an example of a laminated structure of an antenna according to one embodiment. Antenna 100 shown in FIG. 1 is an antenna for a base station. A base station may include a relay station. A base station is an example of a wireless communication device that covers a desired communication area, and performs wireless communication with a wireless communication terminal or the like. Base station 400 shown in FIG. 1 includes antenna 100 and communication control section 300 .

A communication control unit 300 controls wireless communication by the antenna 100 . The communication control unit 300 has known configurations such as a baseband unit and an RF (Radio Frequency) unit.

Since the communication control unit 300 is connected to the antenna 100 via the power supply wiring 53 such as a coaxial cable, the installation locations of the antenna 100 and the communication control unit 300 can be separated, and the degree of freedom in installation is improved. For example, the antenna 100 can be installed on the wall surface 201 side of the wall 200 , and the communication control unit 300 can be installed on the back side of the wall surface 201 (wall surface 202 side) or inside the wall 200 . As a result, the communication control unit 300 is hidden behind the wall 200, and the design is improved.

The antenna 100 is a directional antenna that forms a communication area on the front side of the antenna 100 (in this example, on the positive side in the Z-axis direction with respect to the XY plane). Antenna 100 is an example of an antenna that is installed to face the surface of an object (eg, a building or part thereof). The object may be a natural object such as a tree. A building may be a building or a construction. Examples of structures include ground facilities (buildings, bridges, towers, stadiums, ground stations, tunnels, etc.), underground facilities (underground stations, underground tunnels, etc.), gates, fences, utility poles, signboards, etc. , other than these. A part of the building is a part that constitutes a part of the building. Specific examples of a part of a building include walls, ceilings, window glass, floors, pillars, doors, etc., but may be other than these.

In the example shown in FIG. 1, the antenna 100 is an antenna unit that is installed and used so that its rear surface faces the wall surface 201 of the wall 200 . The wall 200 has a wall surface 201 and a wall surface 202 . Wall 201 is an example of a first surface of a building or part thereof, and wall 202 is an example of a second surface opposite the first surface. The normal direction of the wall surface 201 and the wall surface 202 is parallel to the Z-axis direction. The wall surface 201 is not limited to a flat surface and may be a curved surface. When the communication area by the antenna 100 is formed indoors, the wall surface 201 is the inner wall on the indoor side, but when the communication area by the antenna 100 is formed outdoors, the wall surface 201 is the outer wall on the outdoor side. .

The antenna 100 is a device that is attached to a wall surface 201 for use, and emits an electromagnetic wave toward the opposite side of the antenna 100 from the wall surface 201 (in the case of FIG. 1, the positive side of the XY plane in the Z-axis direction). Send and receive. For example, the antenna 100 can transmit and receive radio waves corresponding to the fifth generation mobile communication system (so-called 5G), wireless communication standards such as Bluetooth (registered trademark), and wireless LAN (Local Area Network) standards such as IEEE 802.11ac. formed. Note that the antenna 100 may be formed to be able to transmit and receive electromagnetic waves conforming to standards other than these, or may be formed to be able to transmit and receive electromagnetic waves of a plurality of different frequencies.

The antenna 100 radiates radio waves to form a communication area on its front side (the positive side in the Z-axis direction with respect to the XY plane in FIG. 1). The antenna 100 shown in FIG. 1 comprises a substrate 10 , at least one antenna element 20 and a dielectric cover 30 .

The substrate 10 is provided, for example, with the front surface 12 parallel to the wall surface 201 . The substrate 10 is, for example, rectangular in plan view (front view) from the positive side in the Z-axis direction, and has a front surface 12 and a back surface 11 . The front face 12 is provided so as to face the side from which the antenna 100 radiates radio waves, and is provided so as to face the same direction as the wall surface 201 in the form shown in FIG. The back surface 11 is the surface opposite to the front surface 12 and faces the wall surface 201 . The back surface 11 may be in contact with the wall surface 201 or may have a dielectric (air may be present) between it and the wall surface 201 . Both the front surface 12 and the back surface 11 are flat, but at least one of them may be curved. The substrate 10 may be formed in a shape different from a rectangle (for example, a polygon such as a circle or a triangle) when viewed from the positive side in the Z-axis direction (front view).

The substrate 10 may be provided such that the front surface 12 has a predetermined angle with respect to the wall surface 201 . The antenna 100 may radiate electromagnetic waves in a state in which (the direction of the normal) of the substrate 10 on which the antenna element 20 is installed is inclined with respect to the (the direction of the normal) of the wall surface 201 . For example, the antenna 100 installed at a location relatively above the bottom surface such as the floor surface or the ground surface (such as the inner wall near the ceiling or the outer wall of the building) radiates electromagnetic waves toward the bottom surface to form a communication area. There are cases where The entire substrate 10 may be inclined with respect to the wall surface 201 , or the back surface 11 may be parallel to the wall surface 201 and the front surface 12 may be inclined with respect to the wall surface 201 .

The material forming the substrate 10 is designed according to the antenna performance such as the power and directivity required for the antenna element 20. For example, dielectrics such as glass and resin, metals, or composites thereof can be used. .

The antenna element 20 is at least one radiating element whose main radiation direction is directed to the side opposite to the back surface 11 (the positive side in the Z-axis direction with respect to the XY plane in FIG. 1). "The direction of the main radiation is on the positive side of the Z-axis direction with respect to the XY plane" means that the direction of the main radiation is parallel to the ZX plane or the YZ plane on the positive side of the Z-axis direction with respect to the XY plane. In the case of tilting to the positive side or the negative side of the Y-axis direction with respect to the ZX plane, in the case of tilting to the positive side or the negative side of the X-axis direction with respect to the YZ plane, or in both cases may contain

Antenna element 20 is an antenna conductor formed to be able to transmit and receive radio waves in a desired frequency band. Desired frequency bands include, for example, a UHF (Ultra High Frequency) band with a frequency of 0.3 to 3 GHz, an SHF (Super High Frequency) band with a frequency of 3 to 30 GHz, and an EHF (Extremely High Frequency) band with a frequency of 30 to 300 GHz. etc. The antenna element 20 functions as a radiator (radiator). Antenna element 20 may be a single antenna element, or may include a plurality of antenna elements having different feeding points. A plurality of antenna elements 20 may realize MIMO (Multiple-Input and Multiple-Output).

An antenna element 20 is provided on the front surface 12 of the substrate 10 . Note that the antenna element 20 may be provided inside the substrate 10 . For example, a coiled antenna element 20 can be provided inside the substrate 10 .

The antenna element 20 is, for example, a planar conductor. As a metal material forming the antenna element 20, a conductive material such as gold, silver, copper, aluminum, chromium, lead, zinc, nickel or platinum can be used. The conductive material may be an alloy, such as an alloy of copper and zinc (brass), an alloy of silver and copper, an alloy of silver and aluminum, and the like. Antenna element 20 may be a thin film. The shape of the antenna element 20 may be rectangular or circular, but is not limited to these shapes.

The antenna element 20 is fed by a feeding point with a ground layer formed inside the substrate 10 or on the rear surface 11 as a ground reference, for example. Examples of the antenna element 20 include a patch-shaped element (patch antenna), a dipole element (dipole antenna), and a slot antenna.

Other materials for forming the antenna element 20 include fluorinated tin oxide (FTO) and indium tin oxide (ITO).

FIG. 2 is a diagram schematically showing an example in which the entire dielectric cover is detachable. FIG. 3 is a diagram schematically showing an example in which a part of the dielectric cover is detachable. As shown in FIGS. 2 and 3, the dielectric cover 30 overlaps the antenna element 20 when viewed from the front of the substrate 10 and is detachably attached to the front surface 12 . Since the dielectric cover 30 is detachable, the dielectric constant of the area close to the antenna element 20 changes depending on the state of the dielectric cover 30 being attached or detached. The frequency can be changed easily. The dielectric cover 30 is in contact with the front face 12 when attached to the front face 12, but there may be a gap therebetween.

Since the dielectric cover 30 is detachable, the dielectric cover 30 can be retrofitted at a stage different from the manufacturing of the substrate 10, so that the substrate 10 can be used in common even if the frequency of the radio waves used differs from region to region or country to country. can. As a result, an increase in the product number and cost of the substrate 10 can be suppressed.

Since the dielectric constant around the antenna element 20 changes depending on the presence or absence of the dielectric cover 30, the operating frequency of the antenna 100 can be easily changed. The operating frequency of the antenna 100 can be easily changed by replacing the dielectric cover 30 with another dielectric cover having at least one different characteristic of the dielectric constant and thickness.

In terms of ensuring both the reflection intensity and the total radiation efficiency of the antenna 100 at the operating frequency, the thickness t of the plate-shaped dielectric cover 30 in the Z-axis direction is preferably 4.5 mm or less, and 3.0 mm or less. More preferably, 2.6 mm or less is more preferable, and 2.2 mm or less is even more preferable. When the thickness t exceeds 4.5 mm, it is difficult to ensure both the reflection strength and the total radiation efficiency of the antenna 100 at the operating frequency. The lower limit of the thickness t is preferably a value larger than 0 mm that can ensure the strength required for the dielectric cover 30 .

In terms of ensuring both the reflection intensity and the total radiation efficiency of the antenna 100 at the operating frequency, the dielectric constant εr of the dielectric cover 30 is preferably 11 or less, more preferably 9 or less. When the dielectric constant εr exceeds 11, it is difficult to ensure both the reflection intensity and the total radiation efficiency of the antenna 100 at the operating frequency. The lower limit of the dielectric constant εr should be greater than 1.

In terms of ensuring both the reflection intensity and the total radiation efficiency of the antenna 100 at the operating frequency, the dielectric loss tangent tan δ at the operating frequency of the dielectric cover 30 is preferably 0.13 or less, more preferably 0.05 or less, and 0. 0.01 or less is even more preferred. When the dielectric loss tangent tan δ at the operating frequency exceeds 0.13, it is difficult to ensure both the reflection intensity and the total radiation efficiency of the antenna 100 at the operating frequency. The lower limit of the dielectric loss tangent tan δ at the operating frequency should be greater than zero.

As shown in FIG. 3, a portion of the dielectric cover 30 may be removable. Dielectric cover 30 has covers 31 and 32 . The cover 31 is fixed to the front face 12 by adhesion or the like, and the cover 32 is detachably attached to the front face 12 .

Antenna 100 may be attached to a wall, hooked, or screwed. Installation methods such as these improve ease of installation and design. FIG. 4 is a perspective view schematically showing a first mounting example of the antenna. As shown in FIG. 4, the antenna 100 may be fixed to the wall surface 201 with fixtures 40. FIG. As shown in FIG. 5, the antenna 100 may be hung on the wall surface 201 by fixtures 40. FIG.

Dielectric cover 30 may be fixed to front face 12 by at least one fixture 40 for fixing antenna 100 . As a result, the common fixture 40 can be used both for fixing the dielectric cover 30 and for fixing the antenna 100 .

Antenna 100 may be installed to face ceiling 203 .

FIG. 6 is a perspective view schematically showing a first connection example between the power supply wiring and the connector, and illustrates a form in which the connectors are provided on each of a pair of opposite sides forming part of the outer periphery of the substrate 10. . The board 10 has connectors 51 and 52 used for connection with a feeder wiring 53 outside the antenna. A power supply wiring 53 connected to a connector 51 provided on one of the pair of opposite sides passes through a wall hole 204 formed in the wall surface 201 and is connected to the communication control unit 300 arranged on the back side of the wall surface 201. be done. A power supply wiring 54 connected to a connector 52 provided on the other side of the pair of opposite sides passes through a wall hole 205 formed in the wall surface 201 and is connected to the communication control unit 300 arranged on the back side of the wall surface 201. be done. Thereby, the communication control unit 300 can be hidden behind the wall surface 201 . Connectors 51 and 52 each have a plurality of terminals connected to corresponding antenna elements among the plurality of antenna elements 20 .

FIG. 7 is a perspective view schematically showing a second connection example between the power supply wiring and the connector, and illustrates a form in which the connectors are provided on each of a pair of opposite sides forming part of the outer periphery of the substrate 10. . In this example, the power supply wirings 53 and 54 are connected to the communication control section 300 through a common wall hole 204 . By passing the power supply wirings 53 and 54 through the common wall hole 204, the number and size of the wall holes provided in the wall surface 201 can be reduced, and the design and workability are improved. The feed wiring 54 is routed along the wall surface 201 to the wall hole 204 , but may pass between the wall surface 201 and the substrate 10 of the antenna 100 .

FIG. 8 is a perspective view schematically showing a third connection example between the power supply wiring and the connector. In this example, the connector 51 is provided only on one side of a pair of opposing sides forming part of the outer periphery of the substrate 10 . As a result, the number and size of the wall holes provided in the wall surface 201 can be reduced, and the design and construction easiness are improved.

26, 27, and 28 are diagrams schematically showing a fourth connection example between the power supply wiring and the connector, and illustrate a form in which the connector is provided on the rear surface 11 of the substrate 10. FIG. 26, 27, and 28 are a perspective view showing the front side of the substrate 10, a perspective view showing the back side of the substrate 10, and a side view of the substrate 10, respectively. 26, 27 and 28 omit the illustration of the dielectric cover, omit the illustration of the power supply wiring 53 in FIGS. 27 and 28, and omit the illustration of the wall 200 in FIG.

The substrate 10 has a connector 58 on the back surface 11 for connection with the feeder wiring 53 outside the antenna. The connector 58 has a plurality of terminals 57 arranged vertically and horizontally on the back surface 11 . Since the connector 58 is provided on the rear surface 11, not only the connector 58 but also part or all of the power supply wiring 53 can be hidden between the wall surface 201 and the substrate 10, thereby improving the design.

In FIG. 27, substrate 10 has feeder line 18 connecting connector 58 and antenna element 20 . In the example shown in FIG. 27 , at least part of the feeder line 18 is provided on the back surface 11 . The feeder line 18 has a plurality of lines 19 connecting between corresponding antenna elements among the plurality of antenna elements and corresponding terminals among the plurality of terminals. The feeder line 18 may connect the connector 58 and the antenna element 20 via a contactless feeder such as slot feeder.

FIG. 9 is a cross-sectional view schematically showing a feeder line connecting the connector and the antenna element. The connector 51 is provided on the outer peripheral edge of the substrate 10 (in this example, the outer peripheral edge on the positive side in the Y-axis direction). The substrate 10 has a feeder line 18 connecting between the connector 51 and the antenna element 20 . The connector 51 has a plurality of terminals (terminals 55 and 56 in this example). The feeder line 18 has a plurality of lines connecting between corresponding antenna elements among the plurality of antenna elements and corresponding terminals among the plurality of terminals. In the example shown in FIG. 9 , the feeder line 18 has a line 13 connecting the antenna element 21 and the terminal 55 and a line 14 connecting the antenna element 22 and the terminal 56 . The feeder line 18 may connect the connector 51 and the antenna element 20 via a contactless feeder such as slot feeder.

If line 13 and line 14 have the same electrical length as each other, antenna calibration can be minimized. A coupler for calibration may be placed near the connector 51 or on the lines 13,14.

Dielectric cover 30 may have a light shielding region facing antenna element 20 . As a result, the antenna element 20 cannot be visually recognized when viewed from the front, so the design can be enhanced. The color of the light shielding area may be black or may be other than black. By making the color of the dielectric cover 30 similar to that of the wall surface 201, the dielectric cover 30 and the antenna 100 become inconspicuous and the design is improved. The presence of the dielectric cover 30 and the antenna 100 may be obscured by printing or displaying a picture, pattern, character, or the like on the dielectric cover 30 .

FIG. 10 is an exploded view showing the antenna element in plan view. An antenna 100A shown in FIG. 10 is an example of the antenna 100. As shown in FIG. The substrate 10 of the antenna 100A has a plurality of rectangular antenna elements 20 arranged vertically and horizontally on the front surface 12 . By attaching the dielectric cover 30 to the front face 12 side, the antenna element 20 becomes difficult to see, thereby improving visibility.

FIG. 11 is a diagram showing a first configuration example of the substrate. The substrate 10B is an example of the substrate 10, and the antenna 100B including the substrate 10B is an example of the antenna 100. FIG. The substrate 10B has a dielectric substrate 61 , a ground layer 62 , an adhesive layer 63 , a dielectric substrate 64 and a feed line 15 . The feed line 15 connects between the antenna element 20 and the connector via at least one via. The feed line 15 may connect between the antenna element 20 and the connector via a non-contact feeding section such as slot feeding. The adhesive layer 63 is, for example, a substrate adhesive such as prepreg.

The substrate 10B has a dielectric substrate 61 between the front face 12 and the feed line 15. As shown in FIG. Dielectric substrate 61 has a front surface (front surface 12 ) on which antenna element 20 is formed and a back surface on which a conductor functioning as ground layer 62 is formed, and holds antenna element 20 on front surface 12 . The dielectric substrate 61 operates the antenna 100B together with the antenna element 20 and the ground layer 62 . Dielectric substrate 61 is an example of a first dielectric layer.

The substrate 10B has a dielectric substrate 64 between the dielectric substrate 61 and the feed line 15, which is in contact with the feed line 15. As shown in FIG. The dielectric substrate 64 has a front surface adhered to the ground layer 62 by an adhesive layer 63 and a back surface (rear surface 11) on which the feed line 15 is formed. form a stable transmission line. Dielectric substrate 64 is an example of a second dielectric layer.

The substrate 10B has a ground layer 62 between the dielectric substrate 61 and the feed line 15. As shown in FIG. Since the ground layer 62 is interposed between the antenna element 20 and the feeder line 15, the presence or absence of the dielectric cover 30 covering the antenna element 20 can be controlled by the shielding effect of the ground layer 62. can suppress the influence on the characteristics of The ground layer 62 functions as a ground for the antenna element 20 and a ground for transmission lines including the feeder line 15 .

FIG. 12 is a diagram showing a second configuration example of the substrate. The substrate 10C is an example of the substrate 10, and the antenna 100C including the substrate 10C is an example of the antenna 100. FIG. The substrate 10C has dielectric substrates 65, 68, 70, 73, 75, ground layers 67, 71, 76, power supply lines 16, 17, and adhesive layers 66, 69, 72, 74. Feed lines 16 and 17 connect between antenna element 20 and the connector via at least one via. The feeder lines 16 and 17 may connect between the antenna element 20 and the connector via a contactless feeder such as slot feeder. The adhesive layers 66, 69, 72, and 74 are substrate adhesives such as prepreg, for example.

Substrate 10C has a dielectric substrate 65 between front face 12 and feed line 16 . Dielectric substrate 65 has a front surface (front surface 12 ) on which antenna element 20 is formed and a back surface which is adhered to ground layer 67 by adhesive layer 66 to hold antenna element 20 on front surface 12 . Dielectric substrate 65, together with antenna element 20 and ground layer 67, operate antenna 100C. Dielectric substrate 65 is an example of a first dielectric layer.

The substrate 10C has a second dielectric layer (adhesive layer 69 and dielectric substrate 68 in this example) in contact with the feeder line 16 between the dielectric substrate 65 and the feeder line 16 . Dielectric substrate 68 has a front surface formed with a conductor functioning as ground layer 67 and a back surface bonded to the front surface of dielectric substrate 70 by adhesive layer 69 . Ground layer 67 is adhered to the back surface of dielectric substrate 65 by adhesive layer 66 . A ground layer 67 may be formed on the back surface of the dielectric substrate 65 . Dielectric substrate 70 has a front surface on which feeder line 16 is formed and a back surface on which a conductor functioning as ground layer 71 is formed. The feed line 16 may be formed on the back surface of the dielectric substrate 68 . Dielectric substrate 68 and dielectric substrate 70 together with feed line 16 and ground layers 67 and 71 form a transmission line, such as a stripline. In addition, depending on the thicknesses of the adhesive layer 69 and the dielectric substrate 68, the distance between the dielectric cover 30 and the feeder lines 16 and 17 can be increased. , 17 can be suppressed.

The substrate 10C has a ground layer 67 between the dielectric substrate 65 and the feed line 16. As shown in FIG. Since the ground layer 67 is interposed between the antenna element 20 and the feeder lines 16 and 17, the presence or absence of the dielectric cover 30 depends on the characteristics of the transmission line including the feeder lines 16 and 17 due to the shielding effect of the ground layer 67. You can control the impact. The ground layer 67 functions as a ground for the antenna element 20 .

The substrate 10C has a ground layer 71 between the dielectric substrate 65 and the feed line 17. As shown in FIG. Since the ground layer 71 is interposed between the antenna element 20 and the feeder line 17, the influence of the presence or absence of the dielectric cover 30 on the characteristics of the transmission line including the feeder line 17 is suppressed by the shielding effect of the ground layer 71. can. The ground layer 71 functions as a ground for transmission lines including the feeder lines 16 and 17 .

The substrate 10</b>C has a third dielectric layer (dielectric substrate 73 in this example) in contact with the feeder line 17 between the ground layer 67 and the feeder line 17 . The dielectric substrate 73 has a front surface adhered to the ground layer 71 by the adhesive layer 72 and a rear surface on which the feed line 17 is formed. A ground layer 71 may be formed on the front side of the dielectric substrate 73 . The dielectric substrate 75 has a front surface adhered to the back surface of the dielectric substrate 73 by an adhesive layer 74 and a rear surface formed with a conductor functioning as a ground layer 76 . The feed line 17 may be formed on the front surface of the dielectric substrate 75 . The dielectric substrate 73 and the dielectric substrate 75 form a transmission line, such as a stripline, together with the feed line 17 and ground layers 71 and 76 . In addition, the thickness of the dielectric substrate 73 can increase the distance between the dielectric cover 30 and the feeder line 17, and whether or not the dielectric cover 30 is attached affects the characteristics of the transmission line including the feeder line 17. You can control the impact.

FIG. 13 is a diagram showing a third configuration example of the substrate. The substrate 10D is an example of the substrate 10, and the antenna 100D including the substrate 10D is an example of the antenna 100. FIG. The substrate 10D has dielectric substrates 65 , 68 , 70 , ground layers 67 , 71 , feeder lines 16 , and adhesive layers 66 , 69 . As in the case of FIGS. 11 and 12, the shielding effect of the ground layer is exhibited, and the distance between the dielectric cover 30 and the feed line 16 can be lengthened. 16 can be suppressed.

FIG. 14 is a diagram showing an example of frequency characteristics of reflection intensity |S11| depending on the thickness of the dielectric cover. As shown in FIG. 14, changing the thickness t of the dielectric cover 30 changed the operating frequency of the antenna 100 . FIG. 15 is a diagram showing an example of frequency characteristics of the total radiation efficiency η depending on the thickness difference of the dielectric cover. As shown in FIG. 15, even when the thickness t of the dielectric cover 30 was changed, the total radiation efficiency η at the operating frequency was kept high. FIG. 16 is a diagram showing an example of the relationship between the thickness of the dielectric cover, the center frequency, and the total radiation efficiency. As shown in FIG. 16, when the thickness t of the dielectric cover 30 was 4.5 mm or less, a decrease in the total radiation efficiency η at the operating frequency (center frequency fc) was suppressed.

14, 15, and 16 show an example of results of simulating the operation of an antenna comprising substrate 10D (FIG. 13). In the simulations of FIGS. 14, 15, and 16, the dimensions and characteristics of each part shown in FIG.
L1: 50mm
L2: 50mm
L3: 50mm
L4: 50mm
L5: 16.46mm
Number of antenna elements 20: 1 (= 1 horizontal x 1 vertical)
Relative permittivity of dielectric cover 30: 4
Dielectric loss tangent of dielectric cover 30: 0.004
and

FIG. 17 is a diagram showing an example of frequency characteristics of the reflection intensity |S11| depending on the difference in dielectric constant of the dielectric cover. As shown in FIG. 17, when the dielectric constant εr of the dielectric cover 30 was changed, the operating frequency of the antenna 100 changed. FIG. 18 is a diagram showing an example of frequency characteristics of total radiation efficiency η depending on the difference in dielectric constant of the dielectric cover. As shown in FIG. 18, even when the dielectric constant εr of the dielectric cover 30 was changed, the total radiation efficiency η at the operating frequency was kept high. FIG. 19 is a diagram showing an example of the relationship between the dielectric constant of the dielectric cover, the center frequency, and the total radiation efficiency. As shown in FIG. 19, when the relative dielectric constant εr of the dielectric cover 30 is greater than 1 and equal to or less than 11, the decrease in the total radiation efficiency η at the operating frequency (center frequency fc) is suppressed.

17, 18, and 19 show an example of results of simulating the operation of an antenna comprising substrate 10D (FIG. 13). εr=1 indicates the case without the dielectric cover 30 . 17, 18, and 19, the dimensions and characteristics of each part shown in FIG. 10 are the same as those in the simulation of FIG. Same conditions as above.

FIG. 20 is a diagram showing an example of the relationship between total radiation efficiency and dielectric loss tangent at operating frequencies. As shown in FIG. 20, when the dielectric loss tangent of the dielectric cover at the operating frequency of the antenna was 0.13 or less, a decrease in the total radiation efficiency η at the operating frequency was suppressed.

FIG. 20 shows an example of the result of simulating the operation of an antenna comprising the substrate 10D (FIG. 13). In the simulation of FIG. 20, the dimensions and characteristics of each part shown in FIG. 10 are the same as the above conditions during the simulation of FIG. 14 except that the dielectric loss tangent tan δ is changed and the thickness t is fixed at 1.0 mm. and

FIG. 21 is a diagram showing an example of the result of simulating the directivity of the antenna provided with the substrate 10B (FIG. 11) of the first configuration example. 4 shows the antenna gain in the ZX plane. In FIG. 21, 0° represents the positive side in the Z-axis direction, and 90° represents the negative side in the X-axis direction. FIG. 22 is a diagram showing an example of the result of simulating the directivity of the antenna provided with the substrate 10B (FIG. 11) of the first configuration example. Antenna gain in the YZ plane is shown. In FIG. 22, 0° represents the positive side in the Z-axis direction, and 90° represents the positive side in the Y-axis direction. As shown in FIGS. 21 and 22, the antenna provided with the substrate 10B (FIG. 11) of the first configuration example operates as a directional antenna in which the main radiation direction is directed to the positive side of the Z-axis direction with respect to the XY plane. The result was obtained.

In the simulations of FIGS. 21 and 22, the dimensions and characteristics of each part shown in FIG.
L1: about 30mm
L2: 407.99mm
L3: about 30mm
L4: 407.99mm
L5: 16.46mm
Number of antenna elements 20: 8 (= 1 horizontal x 8 vertical)
Relative permittivity of dielectric cover 30: 4
Thickness of dielectric cover 30: 0.5 mm
Dielectric loss tangent of dielectric cover 30: 0.004
and

FIG. 23 is a diagram showing an example of simulation results of the frequency characteristics of the reflection intensity |S11| of the antenna provided with the substrate 10C (FIG. 12) of the second configuration example. As shown in FIG. 23, the antenna resonates in the frequency band 4.75 GHz to 4.95 GHz in the Sub6 region. By changing at least one characteristic of the relative permittivity and thickness of the dielectric cover, the frequency range in which the antenna resonates moves left and right on the frequency axis, and the frequency band of the Sub6 range (4.1 to 5.0 GHz, For example, 3GPP n79 band (4.4 GHz to 5.0 GHz) can be covered. FIG. 24 is a diagram showing an example of the result of simulating the directivity of the antenna provided with the substrate 10C (FIG. 12) of the second configuration example. 4 shows the antenna gain in the ZX plane. In FIG. 24, 0° represents the positive side in the Z-axis direction, and 90° represents the negative side in the X-axis direction. FIG. 25 is a diagram showing an example of the result of simulating the directivity of the antenna provided with the substrate 10C (FIG. 12) of the second configuration example. Antenna gain in the YZ plane is shown. In FIG. 25, 0° represents the positive side in the Z-axis direction, and 90° represents the positive side in the Y-axis direction. As shown in FIGS. 24 and 25, the antenna provided with the substrate 10C (FIG. 12) of the second configuration example operates as a directional antenna in which the main radiation direction is directed to the positive side of the Z-axis direction with respect to the XY plane. The result was obtained.

In the simulations of FIGS. 23, 24, and 25, the dimensions and characteristics of each part shown in FIG.
L1: 245.71mm
L2: 407.99mm
L3: 245.71mm
L4: 407.99mm
L5: 16.46mm
Number of antenna elements 20: 64 (=8 horizontal×8 vertical)
Relative permittivity of dielectric cover 30: 3.63
Thickness of dielectric cover 30: 0.2 mm
Dielectric loss tangent of dielectric cover 30: 0.004
and

Although the embodiments have been described above, the technology of the present disclosure is not limited to the above embodiments. Various modifications and improvements such as combination or replacement with part or all of other embodiments are possible.

For example, antennas are not limited to base stations, and may be used in wireless communication devices other than base stations (for example, roadside units used for road-to-vehicle communication, etc.).

Also, the antenna need not be used fixed to the surface it faces. The antenna is suspended from the ceiling so that the antenna faces the surface of an object (e.g., a building or part thereof), or a frame that holds projections that exist around the surface (e.g., the outer edge of a wall). etc.). The antennas may be placed in contact with the facing surfaces, or may be placed in close proximity without contacting the facing surfaces.

10, 10B, 10C, 10D Substrate 11 Rear surface 12 Front surface 13, 14, 19 Lines 15, 16, 17, 18 Feeder lines 20, 21, 22 Antenna element 30 Dielectric cover 40 Fixtures 51, 52, 58 Connectors 53, 54 Feeder wiring 55, 56, 57 Terminals 61, 64, 65, 68, 70, 73, 75 Dielectric substrates 62, 67, 71, 76 Ground layers 63, 66, 69, 72, 74 Adhesive layers 100, 100A Antenna 200 Wall 201, 202 wall surface 203 ceiling 300 communication control unit 400 base station

Claims (23)

a substrate having a front surface and a back surface;
at least one antenna element provided on the front surface or inside the substrate and having a main radiation direction opposite to the back surface;
a dielectric cover that overlaps the antenna element in a front view of the substrate and is detachably attached to the front surface;
An antenna whose operating frequency is changed by attachment and detachment of the dielectric cover. 2. The antenna according to claim 1, wherein said substrate has a connector used for connection with a feed wiring outside the antenna, and a feed line connecting said connector and said antenna element. 3. An antenna according to claim 2, wherein the substrate has a first dielectric layer between the front face and the feed line. 4. An antenna according to claim 3, wherein said substrate has a second dielectric layer between said first dielectric layer and said feeder line in contact with said feeder line. 5. Antenna according to claim 3 or 4, wherein the substrate has a ground layer between the first dielectric layer and the feed line. 6. An antenna according to claim 5, wherein said substrate has a third dielectric layer between said ground layer and said feeder line in contact with said feeder line. The connector has a plurality of terminals,
7. The feed line according to any one of claims 2 to 6, wherein the feed line has a plurality of lines connecting between corresponding antenna elements among the plurality of antenna elements and corresponding terminals among the plurality of terminals. antenna. 8. An antenna according to claim 7, wherein said plurality of lines have the same electrical length as each other. 9. The antenna according to any one of claims 2 to 8, wherein said connector is provided on an outer peripheral edge of said substrate. 10. The antenna according to claim 9, wherein said connector is provided only on one side of a pair of opposing sides forming part of said outer periphery. 10. The antenna according to claim 9, wherein said connector is provided on each of a pair of opposite sides forming part of said outer periphery. The antenna according to any one of claims 2 to 8, wherein the connector is provided on the back surface. 13. Antenna according to any one of claims 1 to 12, wherein the dielectric cover has a thickness of 4.5 mm or less. 14. The antenna according to any one of claims 1 to 13, wherein the dielectric cover has a dielectric constant greater than 1 and equal to or less than 11. 15. The antenna according to any one of claims 1 to 14, wherein the dielectric cover has a dielectric loss tangent of 0.13 or less at the operating frequency of the antenna. 16. Antenna according to any one of the preceding claims, wherein the dielectric cover is fixed to the front face by at least one fixture for fixing the antenna. 17. Antenna according to any one of claims 1 to 16, wherein the dielectric cover has a light shielding area facing the antenna element. 18. Antenna according to any one of the preceding claims, wherein the antenna element is a patch element. 19. Antenna according to any one of claims 1 to 18, for a base station. 20. The antenna according to any one of claims 1 to 19, wherein the antenna is used with the back surface facing the surface of an object. 21. Antenna according to claim 20, wherein the object is a building or part thereof. A radio communication apparatus comprising: the antenna according to any one of claims 1 to 21; and a communication control section that controls radio communication by the antenna. An antenna according to claim 20 or 21, and a communication control unit that controls wireless communication by the antenna,
The wireless communication device, wherein the communication control unit is installed on the back side of the surface of the object.

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