Antenna unit

Abstract

To provide an antenna unit that can be miniaturized.SOLUTION: An antenna unit 1 includes an antenna 10 capable of transmitting and receiving radio waves in a predetermined frequency band, the antenna 10 is formed on a conductor layer of a substrate 2 extending along a first direction, and includes a first antenna 11 and a second antenna 12 capable of transmitting and receiving different polarized waves, the first antenna 11 is powered from one end and has an open other end, the second antenna 12 is powered from one end and has an electrically connected other end to a ground region G, and the first antenna 11 and the second antenna 12 are formed in a central region along the first direction on the substrate 2.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an antenna unit having an antenna capable of transmitting and receiving radio waves in a predetermined frequency band. [Background technology]

[0002] 2. Description of the Related Art Conventionally, antennas are used for transmitting and receiving radio waves. As a technology relating to such antennas, for example, there is an antenna module described in Patent Document 1.

[0003] The antenna module described in Patent Document 1 (corresponding to the "antenna unit" of the present application) has a first antenna and a second antenna as antennas. These antennas are configured in a so-called inverted F shape, and the power supply part is electrically connected to the power supply part by capacitive coupling. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2023-104765 A Summary of the Invention [Problem to be solved by the invention]

[0005] In the antenna module described in Patent Document 1, the first antenna and the second antenna are disposed with their attitudes tilted by 90 degrees from each other. In this case, in order to transmit and receive differently polarized waves, it is necessary to use a substrate with an aspect ratio close to 1. For this reason, the substrate of the antenna module described in Patent Document 1 is square, and there is room for improvement in miniaturizing the substrate.

[0006] Therefore, there is a demand for an antenna unit that can be made smaller. [Means for solving the problem]

[0007] A characteristic configuration of the antenna unit of the present invention is an antenna unit equipped with an antenna capable of transmitting and receiving radio waves in a predetermined frequency band, the antenna being formed on a conductor layer of a substrate extending along a first direction, and having a first antenna and a second antenna capable of transmitting and receiving different polarized waves, the first antenna being powered from one end and having an open other end, the second antenna being powered from one end and having an electrically connected other end to a ground region, and the first antenna and the second antenna being formed in a central region along the first direction on the substrate.

[0008] With this characteristic configuration, the first antenna is formed in a central region along the first direction of the substrate, is powered from one end, and has the other end open, so that it can transmit and receive polarized waves in a direction perpendicular to the first direction. The second antenna is formed in a central region along the first direction of the substrate, is powered from one end, and has the other end electrically connected to the ground region, so that it can transmit and receive polarized waves in the first direction. In addition, with this configuration, the length of the substrate in the direction perpendicular to the first direction is not particularly limited, so that it is possible to miniaturize the substrate. [Brief description of the drawings]

[0009] [Figure 1] FIG. 2 is a plan view of the antenna unit. [Diagram 2] FIG. 2 is an enlarged view of the first antenna. [Diagram 3] FIG. 4 is an enlarged view of the second antenna. [Figure 4] 13 is a plan view of the antenna unit when the position of the antenna is changed. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] The antenna unit according to the present invention includes an antenna capable of transmitting and receiving radio waves in a predetermined frequency band, and is capable of transmitting and receiving different polarized waves. The antenna unit 1 according to the present embodiment will be described below. However, the antenna unit 1 is not limited to the following embodiment, and various modifications are possible within the scope of the gist of the invention.

[0011] Fig. 1 is a plan view of the antenna unit 1. Fig. 2 is an enlarged view of the first antenna 11, and Fig. 3 is an enlarged view of the second antenna 12. As shown in Fig. 1, the antenna unit 1 has an antenna 10, a cut-out portion 20, an impedance adjustment portion 30, and a control portion 40.

[0012] The antenna 10 has a first antenna 11 and a second antenna 12. The antenna 10 is capable of receiving radio waves propagating through the air, converting the radio waves into electrical signals, and transmitting the electrical signals to the control unit 40, and is also capable of propagating through the air the radio waves on which the electrical signals output from the control unit 40 are superimposed.

[0013] The antenna 10 is formed on a conductor layer of a substrate 2 extending along a first direction. The substrate 2 of this embodiment is configured in a rectangular shape having a long side along the first direction and a short side along a second direction perpendicular to the first direction as shown in FIG. 1 in a plan view. The antenna 10 is formed by patterning the conductor layer on the surface of the substrate 2 having such a rectangular shape. The substrate 2 corresponds to a printed circuit board in which a conductor layer made of a conductor such as copper foil and an insulating layer made of an insulating material are alternately laminated. In this embodiment, for example, a two-layer substrate is used. The two-layer substrate is a substrate formed by laminating two conductor layers with an insulating layer interposed therebetween. The surface layer of the substrate 2 means the conductor layer on one side of the substrate 2, and an insulating layer may be provided on the surface. The substrate 2 may be a four-layer substrate, a six-layer substrate, or a substrate with more layers.

[0014] As shown in FIG. 2, the first antenna 11 is configured with a power feeder 11A formed of a straight conductor except for the conductor constituting the conductive layer (by etching). The first antenna 11 is fed from one end 11B and the other end 11C is open. Power is supplied to the one end 11B of the power feeder 11A from the control unit 40 via a wiring pattern 71. The other end 11C of the power feeder 11A is configured in a state where the surrounding conductor except for the power feeder 11A is etched and separated from the surrounding conductor. As a result, a current flows from the one end 11B to the other end 11C in the power feeder 11A, and it is possible to transmit and receive polarized waves in a second direction perpendicular to the first direction.

[0015] As shown in FIG. 3, the second antenna 12 is configured with a power feeder 12A formed of a linear conductor by etching a conductor constituting a conductive layer. The second antenna 12 is fed from one end 12B, and the other end 12C is electrically connected to the ground area G. The one end 12B of the power feeder 12A is supplied with power from the control unit 40 via a wiring pattern 72. The other end 12C of the power feeder 12A is configured in a state in which the surrounding conductors other than the power feeder 12A are etched and separated from the surrounding conductors. Furthermore, this other end 12C is connected to the ground area G via a chip component mounted on the land L10. For example, a capacitor or a coil can be used as this chip component. It is also possible to use a chip jumper. When a capacitor or a coil is used, the power feeder 12A is electromagnetically connected to the ground area G. When a chip jumper is used, the power feeder 12A is connected by ohmic contact. In either case, a current flows through the feeder line 12A from one end 12B to the other end 12C, and a polarized wave in the first direction can be transmitted and received. Note that, in FIG. 1, the aspect ratio of the ground area G on the substrate 2 with respect to the antenna 10 is shown as 3:1, but is not limited thereto and may be, for example, about 3:2.

[0016] The first antenna 11 and the second antenna 12 are configured to have approximately the same antenna length, which enables the first antenna 11 and the second antenna 12 to receive radio waves in the same frequency band.

[0017] The first antenna 11 and the second antenna 12 are formed in a central region along the first direction of the substrate 2. The central region along the first direction of the substrate 2 refers to a region spaced apart from both ends of the substrate 2 in the first direction, and is not necessarily limited to only the center in the first direction. Therefore, the first antenna 11 and the second antenna 12 are formed in a central region spaced apart from both ends of the substrate 2 in the first direction.

[0018] Here, as described above, the first antenna 11 is capable of transmitting and receiving polarized waves in the second direction, and the second antenna 12 is capable of transmitting and receiving polarized waves in the first direction on the substrate 2. In this way, the first antenna 11 and the second antenna 12 are configured to be capable of transmitting and receiving polarized waves different from each other.

[0019] In this embodiment, the antenna 10 is provided at a distance of 1 / 10 or more of the wavelength of the radio wave from both ends of the ground area G along the first direction. As described above, the antenna 10 can transmit and receive radio waves in a predetermined frequency band, and in this embodiment, this frequency band is in the range of 2.4 GHz to 2.5 GHz. Since the wavelength of radio waves in this frequency band is 12 cm to 12.5 cm, 1 / 10 of the wavelength corresponds to 1.2 cm to 1.25 cm. Therefore, the antenna 10 is provided at a distance of 1.25 cm or more from both ends of the ground area G along the first direction. In other words, the antenna 10 is provided at least 1.25 cm from both ends of the ground area G along the first direction on the substrate 2 toward the center along the first direction.

[0020] The cut-out portion 20 is provided in the entire area of ​​the layer below each of the first antenna 11 and the second antenna 12 in the substrate 2, and is formed by cutting out the conductive layer. In this embodiment, the substrate 2 is a two-layer substrate, and the first antenna 11 and the second antenna 12 are formed in the first layer, which is the surface layer of the substrate 2. The substrate 2 also has a conductive layer in the second layer, which is the back layer on the opposite side of the first layer.

[0021] As shown in Figs. 2 and 3, in the first layer in which the first antenna 11 and the second antenna 12 are formed, the conductor layer around the first antenna 11 and the second antenna 12 is cut out over a predetermined range R. In addition, in a plan view of the substrate 2, the conductor layer is also cut out in a portion that overlaps with the range R in the second layer. Therefore, the cut-out portion 20 corresponds to a region in which the conductor layer is cut out over the range R in a plan view of the substrate 2. Note that "formed by cutting out the conductor layer" means that the conductor layer is formed by etching. Therefore, the cut-out portion 20 is in a state in which no conductor layer is present.

[0022] In this embodiment, the cutout portion 20 is formed in a rectangular shape in a plan view. The cutout portion 20 is provided in a state in which at least a part of the outer edge is in contact with the outer edge portion 2A of the substrate 2 along the first direction of the substrate 2. At least a part of the outer edge is at least one of the four sides constituting the rectangle. If the four sides are respectively designated as sides 20A, 20B, 20C, and 20D, the sides 20A, 20B, and 20C are in contact with the ground region G, but the side 20D coincides with the outer edge portion 2A. Therefore, as shown in FIG. 2-FIG. 3, the side 20D is not in contact with the ground region G. In this way, the cutout portion 20 of this embodiment is in contact with the ground region G in three of the four directions around the circumference, and in contact with the outer edge portion 2A in the remaining one direction.

[0023] The first antenna 11 is fed with power from the side 20A of the cutout portion 20. In this embodiment, the first antenna 11 extends from the side 20A along the sides 20B and 20D toward the side 20C. The tip (the other end 11C) of the first antenna 11 is electrically open as described above.

[0024] The second antenna 12 is fed from the side 20A of the cutout portion 20. In this embodiment, the second antenna 12 extends from the side 20A along the sides 20B and 20D toward the side 20C. The tip (other end 12C) of the second antenna 12 is electromagnetically connected to the ground region G as described above.

[0025] The impedance adjustment unit 30 is provided in the antenna 10 and is capable of adjusting the impedance of the antenna 10. In this embodiment, the impedance is adjusted by a chip component mounted on the substrate 2. In this embodiment, two impedance adjustment units 30 are provided in series with the power feeder 11A in the first antenna 11. One impedance adjustment unit 30 is provided in series with the wiring pattern 71, and one is provided across the ground region G. Instead of providing the chip components in series with the wiring pattern 71 in series, a land pattern is provided so that they can be provided across the wiring pattern 71 and the ground region G.

[0026] On the other hand, two impedance adjustment units 30 are provided in series with the power feeder 12A in the second antenna 12. Here, as described above, the tip (other end 12C) of the second antenna 12 is electrically connected to the ground region G, and the land L10 at this tip can also be used as the impedance adjustment unit 30. In addition, one impedance adjustment unit 30 is provided for the wiring pattern 72 across the ground region G.

[0027] In this embodiment, the first antenna 11 has lands L1 and L2 provided on the power supply line 11A. Furthermore, lands L3 and L4 are provided on the wiring pattern 71. A chip component can be mounted between the land L3 on the side of the land L4 closer to the land L3 and the land L31 provided in the ground region G. Since the land L4 is provided across the wiring pattern 71 and the ground region G, it is also possible to leave it unmounted. Furthermore, the lands L1, L2, and L3 may each have a jumper component (e.g., a 0 Ω resistor) mounted thereon.

[0028] As described above, when adjusting impedance by providing components on the land L1, the land L2, the land L3, and the land L4, it is possible to mount an inductor (for example, a chip inductor) or a capacitor (for example, a ceramic capacitor).

[0029] In this embodiment, the second antenna 12 is provided with a land L5 and a land L10 on the power supply line 12A. A land L6 is provided on the wiring pattern 72. The land L6 is provided across the wiring pattern 72 and the ground region G, and therefore may be left unmounted. The land L5 and the land L10 may each be mounted with a jumper component (e.g., a 0 Ω resistor).

[0030] As described above, when adjusting impedance by providing components on the land L5, the land L6, or the land L10, it is possible to mount an inductor (for example, a chip inductor) or a capacitor (for example, a ceramic capacitor).

[0031] In this embodiment, the length of the substrate 2 along the second direction perpendicular to the first direction is 1 / 3 or less of the wavelength of the radio wave. Since the frequency band in this embodiment is 2.4 GHz to 2.5 GHz, 1 / 3 of the wavelength is 4 cm. Therefore, the length of the substrate 2 along the second direction in this embodiment is 4 cm or less. It is preferable that the length of the substrate 2 along the second direction perpendicular to the first direction is 1 / 4 or less of the wavelength of the radio wave (i.e., 3 cm or less).

[0032] The control unit 40 supplies power to the first antenna 11 and the second antenna 12, and performs predetermined signal processing on signals transmitted from the first antenna 11 and the second antenna 12.

[0033] Other embodiments Next, other embodiments of the antenna unit 1 will be described.

[0034] In the above embodiment, the first antenna 11 and the second antenna 12 have been described as being provided on two opposing outer edge portions 2A of the substrate 2 along the first direction. However, as shown in Fig. 4, the first antenna 11 and the second antenna 12 may both be provided on one of the two opposing outer edge portions 2A of the substrate 2 along the first direction.

[0035] In the above embodiment, an example has been described in which the first antenna 11 and the second antenna 12 are configured in a straight line. However, at least one of the first antenna 11 and the second antenna 12 may be configured in an L-shape. In addition, when configured in an L-shape, the angle of the bent portion is not limited to 90 degrees, and may be less than 90 degrees or greater than 90 degrees.

[0036] In the above embodiment, the antenna 10 is described as being spaced 1 / 10 or more of the wavelength of the radio wave from both ends along the first direction of the ground area G. However, the antenna 10 may be provided at a location that is less than 1 / 10 of the wavelength of the radio wave from both ends along the first direction of the ground area G, for example.

[0037] In the above embodiment, the substrate 2 is provided in the entire area below each of the first antenna 11 and the second antenna 12, and has the cut-out portion 20 where the conductor layer is cut out. However, the substrate 2 may be configured without the cut-out portion 20.

[0038] In the above embodiment, the cutout 20 is provided at the outer edge 2A of the conductor layer. However, the cutout 20 may be provided away from the outer edge 2A of the substrate 2.

[0039] In the above embodiment, the antenna 10 has been described as being provided with the impedance adjustment unit 30 that adjusts the impedance. However, the antenna 10 can also be configured without providing the impedance adjustment unit 30. In this case, it is possible to configure the inductance component and the capacitance component by patterning, for example.

[0040] In the above embodiment, the length of the substrate 2 along the second direction perpendicular to the first direction is described as being equal to or less than 1 / 3 of the wavelength of the radio wave. However, the length of the substrate 2 along the second direction perpendicular to the first direction may be longer than 1 / 3 of the wavelength of the radio wave.

[0041] In the above embodiment, the frequency band has been described as being in the range of 2.4 GHz to 2.5 GHz. However, the frequency band may be a frequency band including frequencies smaller than 2.4 GHz, or may be a frequency band including frequencies larger than 2.5 GHz.

[0042] In the above embodiment, a jumper component is mounted on the land L10 at the other end 12C of the second antenna 12. However, instead of the land L10, the power supply line 12A and the ground area G may be electrically connected by patterning.

[0043] [Summary of the above embodiment] The above-described antenna unit 1 will now be outlined.

[0044] (1) The antenna unit 1 has an antenna 10 capable of transmitting and receiving radio waves in a predetermined frequency band, the antenna 10 is formed on a conductor layer of a substrate 2 extending along a first direction, and has a first antenna 11 and a second antenna 12 capable of transmitting and receiving different polarized waves, the first antenna 11 is powered from one end 11B and the other end 11C is open, the second antenna 12 is powered from one end 12B and the other end 12C is electrically connected to a ground area G, and the first antenna 11 and the second antenna 12 are formed in a central area along the first direction on the substrate 2.

[0045] According to this configuration, the first antenna 11 is formed in a central area along the first direction on the substrate 2, is fed from one end 11B, and has the other end 11C open, so that it can transmit and receive polarized waves in a direction perpendicular to the first direction. The second antenna 12 is formed in a central area along the first direction on the substrate 2, is fed from one end 12B, and has the other end 12C electrically connected to the ground area G, so that it can transmit and receive polarized waves in the first direction. In addition, in this configuration, the length of the substrate 2 in the direction perpendicular to the first direction is not particularly limited, so that it is possible to reduce the size of the substrate 2.

[0046] (2) In the antenna unit 1 described in (1), the antenna 10 is configured to be spaced apart from both ends of the ground contact area G along the first direction by 1 / 10 or more of the wavelength of the radio wave.

[0047] According to this configuration, a ground pattern (ground potential) can be secured for each of the first antenna 11 and the second antenna 12, so that the antenna characteristics of the first antenna 11 and the second antenna 12 can be improved.

[0048] (3) In the antenna unit 1 described in (1) or (2), the substrate 2 is preferably provided over the entire area of ​​the lower layer of each of the first antenna 11 and the second antenna 12, has a cut-out portion 20 where the conductor layer is cut out, and the cut-out portion 20 is preferably provided on the outer edge portion 2A of the substrate 2.

[0049] According to this configuration, by forming the cutout portion 20, it is possible to prevent electromagnetic coupling between the conductor layer of the first antenna 11 and the second antenna 12. Furthermore, since the cutout portion 20 is provided in the outer edge portion 2A, it is possible to prevent the conductor layer from being present in at least a part of the periphery of the first antenna 11 and the second antenna 12. Therefore, it is possible for the first antenna 11 and the second antenna 12 to have the desired performance.

[0050] (4) In the antenna unit 1 described in (1) or (2), it is preferable that the antenna 10 is provided with an impedance adjustment section 30 that adjusts the impedance.

[0051] According to this configuration, even if the sizes of the first antenna 11 and the second antenna 12 are reduced, the impedance adjustment section 30 can match the impedance of the first antenna 11 and the second antenna 12. Therefore, even if the antenna unit 1 is miniaturized, it is possible to maintain the desired characteristics.

[0052] (5) In the antenna unit 1 described in (1) or (2), it is preferable that the length of the substrate 2 along a second direction perpendicular to the first direction is equal to or less than 1 / 3 of the wavelength of the radio wave.

[0053] According to this configuration, since the length of the substrate 2 along the second direction can be shortened, it becomes possible to incorporate the antenna unit 1 into, for example, a housing having an elongated shape. In this way, it becomes possible to increase the degree of freedom in installing the antenna unit 1.

[0054] (6) The antenna unit 1 described in (1) or (2) preferably has a frequency band in the range of 2.4 GHz to 2.5 GHz.

[0055] According to this configuration, the antenna unit 1 can be used for communication such as Bluetooth (registered trademark). [Industrial Applicability]

[0056] The technology disclosed herein can be used in an antenna unit equipped with an antenna that transmits and receives radio waves at a predetermined frequency. [Explanation of symbols]

[0057] 1: antenna unit, 2: substrate, 2A: outer edge, 10: antenna, 11: first antenna, 11B: one end, 11C: other end, 12: second antenna, 12B: one end, 12C: other end, 20: cutout, 30: impedance adjustment section, G: ground area

Claims

1. An antenna unit having an antenna capable of transmitting and receiving radio waves in a predetermined frequency band, The antenna includes a first antenna and a second antenna formed on a conductor layer of a substrate extending along a first direction and capable of transmitting and receiving waves of different polarizations, The first antenna is powered from one end and has the other end open, the second antenna is powered from one end and is electrically connected to a ground region at the other end; The first antenna and the second antenna are formed in a central region of the substrate along the first direction.

2. The antenna unit according to claim 1 , wherein the antenna is spaced apart from both ends of the ground region along the first direction by at least 1 / 10 of the wavelength of the radio wave.

3. the substrate is provided under the first antenna and the second antenna, and has a cutout portion where the conductor layer is cut out; 3. The antenna unit according to claim 1, wherein the cutout portion is provided on an outer edge portion of the substrate.

4. 3. The antenna unit according to claim 1, wherein the antenna is provided with an impedance adjustment section for adjusting impedance.

5. 3. The antenna unit according to claim 1, wherein a length of the substrate along a second direction perpendicular to the first direction is equal to or less than 1 / 3 of the wavelength of the radio wave.

6. 3. The antenna unit according to claim 1 or 2, wherein the frequency band is in the range of 2.4 GHz to 2.5 GHz.

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