antenna device

Abstract

Antenna device with: a grounding plate that provides a grounding potential a counter conductor (50) which is separated at a specified distance from the earthing plate in a plate thickness direction of the earthing plate, wherein the counter conductor is configured for connection to a feed line (60); a short-circuit section (70) that electrically connects the counter conductor and the grounding plate, wherein the antenna device operates in an 0th-order resonant mode through LC parallel resonance of a capacitance formed between the grounding plate and the counter conductor and an inductance provided in the short-circuit section; and an intermediate conductor (80) which has the same potential as the earthing plate and is placed between the earthing plate and the counter-conductor in the plate thickness direction, wherein the intermediate conductor defines at least partially a penetration part (81) that penetrates the intermediate conductor and contains the counter conductor in a top view in the plate thickness direction.

Description

[0001] The present invention generally relates to an antenna device.

[0002] The antenna device of JP 2020-10135 A has a third-order resonant antenna using metamaterial technology. The third-order resonant antenna has a narrow band (i.e., a narrow frequency bandwidth). Further improvements to the antenna device are required from the aforementioned perspective or from other unmentioned perspectives.

[0003] A phased array antenna with two frequencies and two polarizations is also known from US 2017 / 0 352 960 A1.

[0004] Furthermore, EP 0 407 145 A1 discloses a broadband mobile phone antenna which has a planar antenna.

[0005] US 2012 / 0 229 343 A1 discloses a horizontal radiation antenna.

[0006] It is an object of the present disclosure to provide a broadband antenna device. This object is achieved by the features of independent claim 1. Advantageous further developments are disclosed in the subclaims.

[0007] The antenna device disclosed herein includes: a ground plate providing a ground potential; a counter conductor arranged to have a predetermined distance from the ground plate in a plate thickness direction of the ground plate and having a feeding point; a short-circuiting part electrically connecting the counter conductor and the ground plate; and an intermediate conductor having the same potential as the ground plate and placed between the ground plate and the counter conductor in the plate thickness direction.

[0008] The intermediate conductor has a penetration part that penetrates the intermediate conductor in the plate thickness direction and has the counter conductor in a plan view in the plate thickness direction.

[0009] In the disclosed antenna device, a capacitor is also formed between the intermediate conductor and the counter conductor by providing the intermediate conductor with the penetrating portion. As a result, a resonance point is additionally formed. Thus, it is possible to provide a broad-band antenna device.

[0010] The aspects disclosed in this specification adopt different technical solutions from each other to achieve their respective objects. The claims described in this section and reference numerals in parentheses illustrate the correspondence to the parts of the later-described embodiments and are not intended to limit the technical scope. The objects, features, and effects disclosed herein will become clearer with reference to the following detailed description and the accompanying drawings.

[0011] Objects, features and advantages of the present disclosure will become more apparent from the following detailed description with reference to the accompanying drawings, in which: Fig. 1 is a perspective view showing an electronic device to which an antenna device is applied; Fig. 2 is an exploded perspective view showing the antenna device according to the first embodiment; Fig. 3 is an enlarged plan view of a close-up portion of a counter conductor; Fig. 4 is a cross-sectional view along a line IV-IV of Fig. 3; Fig. 5 is a diagram showing reflection characteristics; Fig. 6 is a diagram showing an inductor and a capacitor of the antenna device; Fig. 7 is a plan view showing a modification example; Fig. 8 is a diagram showing a distribution of an electric field; Fig. 9 is a plan view showing the antenna device according to a second embodiment; Fig. 10 is a plan view showing the antenna device according to a third embodiment; Fig. 11 is an equivalent circuit diagram of the antenna device; Fig. 12 is a diagram showing reflection characteristics; Fig. 13 is a plan view showing an antenna device according to a fourth embodiment; Fig. 14 is a cross-sectional view taken along a line XIV-XIV of Fig. 13; Fig. 15 is a plan view showing a modification example; Fig. 16 is a cross-sectional view taken along a line XVI-XVI of Fig. 15; Fig. 17 is a plan view showing a modification example; and Fig. 18 is a cross-sectional view taken along a line XVIII-XVIII of Fig. 17.

[0012] Embodiments are described below with reference to the drawings.

[0013] In each of the embodiments, parts that correspond functionally and / or structurally to one another are given the same reference numerals. (First embodiment)

[0014] First, a schematic configuration of an electronic device to which the antenna device is applied is described with respect to Fig. 1. The electronic device is, for example, an electronic control unit (ECU) mounted on a moving body such as a vehicle. ECU is an abbreviation for Electronic Control Unit. <Elektronische Steuereinheit>

[0015] As in Fig. 1, an electronic device 10 includes a printed circuit board 11. The printed circuit board 11 has a wiring board in which the wiring is arranged on an insulating base plate material, and an electronic component mounted on the wiring board to form a circuit together with the wiring. The printed circuit board 11 is housed in, for example, a case or a box (not shown). Hereinafter, the thickness direction of the printed circuit board 11 (i.e., the wiring board) is defined as the Z direction. Further, a direction perpendicular to the Z direction is defined as the X direction, and the Z direction and the direction perpendicular to the X direction are defined as the Y direction.

[0016] A region R1, which is part of the circuit board 11, provides a wireless communication function. A wireless communication unit 12 is formed in the region R1. The region R1 is a part surrounded by an alternating long and short dash line (or a dotted line) in a plan view in the Z direction. The region R1 is a region including a corner of the circuit board 11 having a substantially rectangular shape in a plan view in the Z direction. The region R1 comprises a part of a side surface 11a of the circuit board 11 in the Y direction. Hereinafter, the side surface 11a may also be referred to as a board end part 11a. The wireless communication unit 12 includes an antenna device 20 described later and a power supply circuit (i.e., a communication circuit).

[0017] As described above, the electronic device 10 has a built-in wireless communication unit 12. For example, the electronic device 10 can perform wireless communication with other electronic devices arranged in the vehicle. The other electronic device can be arranged outside a housing that houses the circuit board 11, or it can be housed in the same housing as the electronic device 10. The electronic device 10 can be configured to perform wireless communication with the exterior of the vehicle.

[0018] In the circuit board 11, an electronic component 13 is mounted in an area R2, which is the remaining part excluding the area R1, to form a circuit. The area R2 provides the ability to perform the control operation of the vehicle. The area R2 is larger than the area R1 in the plan view in the Z direction. A processor, a memory, and the like (not shown) are mounted in the area R2. The memory here is a storage device or is, for example, at least one type of non-transitory, tangible storage medium, such as a semiconductor memory, a magnetic medium, an optical medium, or the like, for storing or memorizing a computer-readable program, data, or the like.The processor includes, for example, at least a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), a RISC (Reduced Instruction Set Computer) CPU, and the like as a core.

[0019] The processor executes various processes to realize the function according to the program stored in the memory. For example, at least one of the processing results is transmitted to another electronic device through wireless communication. For example, the processor uses information acquired from another electronic device through wireless communication and executes processing according to the previous program. The processor and the memory are provided, for example, as a microcomputer / microcontroller, which is an electronic component. A power supply circuit and the like are also formed in the area R2 of the circuit board 11. <Struktur der Antennenvorrichtung>

[0020] Next, the structure of the antenna device is described in relation to the Fig. 2, Fig. 3 and Fig. 4 described. Fig. 2 is an exploded perspective view of the antenna device. Fig. 3 is an enlarged plan view of a near portion of the counter conductor as seen from one side of the counter conductor. Fig. 4 is a cross-sectional view along a line IV-IV of Fig. 3.

[0021] The antenna device 20 is configured to transmit and / or receive radio waves at a predetermined operating frequency. An example of the operating frequency is 2.44 GHz. The antenna device 20 is configured to be capable of transmitting and / or receiving radio waves in a frequency band used in short-range wireless communication. The operating frequency can be suitably configured and can be a frequency other than 2.44 GHz (for example, 5 GHz).

[0022] The antenna device 20 of the present embodiment is formed on the circuit board 11. In other words, the antenna device 20 is realized by using the circuit board 11. The antenna device 20 is arranged near a side surface in the Y direction (right in the Fig. 1, Fig. 2 and Fig. 3) of the circuit board 11.

[0023] As in the Fig. 2 to 4, the antenna device 20 includes a base material 30, a ground plate 40, a counter conductor 50, a feed line 60, a short-circuiting part 70, and an intermediate conductor 80. Hereinafter, for simplicity, the direction from the ground plate 40 to the counter conductor 50 is defined as "upward" (in a positive Z direction) and the direction from the counter conductor 50 to the ground plate 40 is defined as "downward" (in a negative Z direction). Fig. 3 is a top view (a bird's eye view in a negative Z direction), with the Z direction extending out of the plane of the paper. Fig. 4 is a side view in a positive Y direction (equivalent to “left-to-right” in Fig. 3).

[0024] The base material 30 corresponds to an insulating base plate material that forms the circuit board 11 (i.e., the wiring board). The antenna device 20 is configured in the region R1 of the base material 30. The base material 30 is made of a dielectric material such as resin. By using the base material 30, the wavelength shortening effect of the dielectric material can be expected. For example, a material consisting of only resin or a combination of resin and glass cloth, nonwoven fabric, or the like can be used as the base material 30.

[0025] The facing distance between the grounding plate 40 and the counter conductor 50 and the length of the short-circuiting part 70 can be adjusted by adjusting the thickness of the base material 30. The base material 30 functions as a holding part that holds the grounding plate 40 and the counter conductor 50 in a predetermined positional relationship (i.e., separated from each other). The base material 30 has a multi-layer structure. The base material 30 of the present embodiment is a laminated body formed by laminating three thin plates 30A provided as a dielectric material. The thin plate 30A is not limited to a sheet shape but may be a film shape.

[0026] The grounding plate 40 is a flat, plate-shaped conductor made of copper or the like. The plate thickness direction of the grounding plate 40 is substantially parallel to the Z direction, which is the plate thickness direction of the printed circuit board 11. The direction perpendicular (normal to) the plate surface of the grounding plate 40 is also substantially parallel to the Z direction. Hereinafter, the shape of the grounding plate 40 is viewed in a plane from the plate thickness direction; that is, the Z direction is simply referred to as a plane shape.

[0027] The ground plate 40 has a size including the entire counter conductor 50 and a penetrating portion 81 (or penetrating cutout) described later in a plan view. The ground plate 40 has, for example, a substantially rectangular shape in a plane. The ground plate 40 of the present embodiment is arranged on the bottom surface of the base material 30. The ground plate 40 is formed by patterning a metal foil arranged on one surface of a thin plate 30A forming the bottom surface of the base material 30. The ground plate 40 is connected to a feed circuit (not shown) to provide a ground potential in the antenna device 20.

[0028] The counter conductor 50 is a plate-shaped conductor made of copper or the like. The counter conductor 50 is a conductor arranged to face / oppose the ground plate 40 at a predetermined distance from the ground plate 40 in the Z direction. The counter conductor 50 may be referred to as a patch part or a radiating element. In a plan view, the entire counter conductor 50 overlaps the ground plate 40. That is, the entire plate surface (bottom surface) of the counter conductor 50 faces the ground plate 40 in the Z direction. The counter conductor 50 is arranged substantially parallel to the ground plate 40. The counter conductor 50 of the present embodiment is arranged on the upper surface of the base material 30. The counter conductor 50 is formed by patterning a metal foil arranged on one surface of a thin plate 30A forming the upper surface of the base material 30.The counter conductor 50 has a flat square shape. As the side portion defining the square, the counter conductor 50 has one side portion substantially parallel to the X direction and one side portion substantially parallel to the Y direction.

[0029] The counter conductor 50 is electrically connected to the feeder circuit via the feeder line 60. The feeder line 60 of the present embodiment includes a conductor arranged on the upper surface of the base material 30. Such a conductor may also be referred to as a microstrip line. One end of the feeder line 60 is connected to one of the four sides of the counter conductor 50. A connecting part of the feeder line 60 at the counter conductor 50 corresponds to a feed point. The current input to the feeder line 60 from the feeder circuit propagates to the counter conductor 50 and excites the counter conductor 50. The power supply method is not limited to the direct power supply method. A feed method in which the feeder line 60 and the counter conductor 50 are electromagnetically coupled can also be adopted.

[0030] The short-circuiting part 70 electrically connects the grounding plate 40 and the counter conductor 50, that is, short-circuits the two. The short-circuiting part 70 is a columnar conductor, one end of which is connected to the grounding plate 40 and the other end to the counter conductor 50. The short-circuiting part 70 of the present embodiment consists of a through conductor formed on the printed circuit board 11 (i.e., the wiring board). As described above, the base material 30 (thin plate 30A) has a through hole 31. Then, the short-circuiting part 70 is formed by a conductor disposed in the through hole 31.

[0031] The short-circuit part 70 is substantially connected to the center of the counter conductor 50 in a plan view. The center of the counter conductor 50 corresponds to the center of gravity of the counter conductor 50. Since the counter conductor 50 of the present embodiment has a flat square shape, the center corresponds to the intersection point of the two diagonal lines of the counter conductor 50. The number of conductors constituting the short-circuit part 70 is not specifically limited. The short-circuit part 70 may be provided as a plurality of conductors connecting the substantial center (ie, the central region) of the counter conductor 50 and the grounding plate 40.

[0032] The intermediate conductor 80 is a conductor having the same potential (i.e., ground potential) as the ground plate 40, and is arranged in the Z direction between the ground plate 40 and the counter conductor 50. The intermediate conductor 80 of the present embodiment is an inner ground layer arranged within the base material of the circuit board 11. The intermediate conductor 80 is electrically connected to the ground plate 40 on the circuit board 11. The connection part between the intermediate conductor 80 and the ground plate 40 is provided in at least one of the regions R1 and R2. The intermediate conductor 80 is also formed by patterning a metal foil arranged on the base material 30 (i.e., the thin plate 30A).

[0033] The intermediate conductor 80 has a penetration part 81 that penetrates the intermediate conductor 80 in the Z-direction. The penetration part 81 is provided to overlap the counter conductor 50 in a plan view (see dashed lines in Fig. 3). The penetration part 81 may have two parts, i.e., a part directly under the counter conductor 50 and a peripheral part surrounding the part directly under the counter conductor 50. In a plan view, the intermediate conductor 80 has a predetermined gap between the intermediate conductor 80 and the counter conductor 50 (see L1, L2 and L3 in Fig. 3). The intermediate conductor 80 is arranged around or in the vicinity of the counter conductor 50 so as not to overlap the counter conductor 50 in a plan view. Fig. 2 and Fig. 3 show the intermediate conductor 80 around three sides of the counter conductor 50 separated by distances of L1, L2 and L3.

[0034] The penetration part 81 is formed as a notch (in Fig. 2) or as a through hole (not shown). The penetrating part 81 of the present embodiment is a notch. The penetrating part 81 has a substantially rectangular shape in a plane. Specifically, the penetrating part 81 has a rectangular shape with the X direction as the longitudinal direction and the Y direction as the transverse direction. Three sides of the rectangular penetrating part 81 are defined by the intermediate conductor 80 (specifically, defined by three vertical inner surfaces of each intermediate conductor 80), and the remaining one side is defined by the plate end part (side surface) 11a. The intermediate conductor 80 has a substantially C-shaped plane (or a substantially U-shaped plane).

[0035] The number of intermediate conductors 80 arranged between the grounding plate 40 and the counter conductor 50 is not specifically limited. At least one conductor 80 may be arranged therein. The intermediate conductor 80 may be arranged in multiple stages / layers in the Z direction. The intermediate conductor 80 of the present embodiment is arranged in two stages (ie, in two layers). The configurations of the two intermediate conductors 80 are common to each other. The intermediate conductors 80 may be substantially coincident / matched with each other in a plan view. <Betriebsweise der Antennenvorrichtung>

[0036] Next, the operation of the antenna device 20 will be described. As described above, the antenna device 20 has a structure in which the grounding plate 40 and the opposing conductor 50, which face each other, are connected by the short-circuit part 70. Such a structure is a so-called mushroom structure, which corresponds to the basic structure of metamaterials. Since the antenna device 20 is an antenna to which metamaterial technology is applied, it is sometimes referred to as a metamaterial antenna.

[0037] Since the antenna device 20 is designed to operate in a 0th-order resonance mode at a desired operating frequency, it is sometimes referred to as a 0th-order resonance antenna. Among the dispersion properties of the metamaterial, the phenomenon of resonance at a frequency where a phase constant β becomes zero (0) is 0th-order resonance. The phase constant β is an imaginary part of a propagation coefficient γ of the wave propagating on the transmission line. The antenna device 20 can satisfactorily transmit and / or receive radio waves in a predetermined band, including a frequency where 0th-order resonance occurs.

[0038] The antenna device 20 operates by LC parallel resonance of the capacitance formed between the ground plate 40 and the counter conductor 50 and the inductance provided in the short-circuiting part 70. In the antenna device 20, the counter conductor 50 is short-circuited to the ground plate 40 by the short-circuiting part 70 provided in its central region. The area of ​​the counter conductor 50 is an area that forms a capacitance that resonates parallel to the inductance of the short-circuiting part 70 at a desired frequency (i.e., the operating frequency). Note that the inductance is determined according to the dimensions of each part of the short-circuiting part 70, for example, the diameter and the length in the Z direction.

[0039] Therefore, when an electric current of the operating frequency is supplied, a parallel resonance occurs due to the energy exchange between the inductance and the capacitance, generating an electric field between the ground plate 40 and the counter conductor 50 perpendicular to the ground plate 40 (and to the counter conductor 50). That is, an electric field in the Z direction is generated. The vertical electric field (perpendicular to the ground plate 40) propagates from the short-circuit part 70 toward the edge of the counter conductor 50, is vertically polarized at the edge of the counter conductor 50, and propagates in space. Note that the vertically polarized wave here refers to a radio wave in which the oscillation direction of the electric field is perpendicular to the ground plate 40 and the counter conductor 50.Furthermore, the antenna device 20 receives vertically polarized waves arriving from the outside of the antenna device 20 through LC parallel resonance.

[0040] The resonant frequency of the 0th-order resonance does not depend on the antenna size. Therefore, the length of one side of the counter conductor 50 can be designed to be shorter than half a wavelength of the 0th-order resonance frequency. Even if, for example, one side has a length corresponding to 1 / 4 wavelength, a 0th-order resonance can be created. It is possible to make the wavelength shorter than 1 / 4, but in this case, for example, the gain will be reduced. < Summary of the first embodiment>

[0041] Fig. Figure 5 shows the results of performing an electromagnetic field simulation (reflection characteristics) at the same operating frequency in a reference example and the present embodiment. The operating frequency is 2.44 GHz. Fig. In Fig. 5, the dashed line indicates the result of the reference example, and the solid line indicates the result of the present embodiment, that is, the antenna device 20 having the above-described configuration. The antenna device of the reference example is a third-order resonant antenna without an intermediate conductor. In the reference example and the present embodiment, the composition (i.e., the dielectric constant and the thickness) of the base material and the diameter of the short-circuit part are the same. Then, the optimization design was performed according to the size (i.e., area size) of the counter conductor. Specifically, the counter conductor of the reference example has a square shape with a side of 15.64 mm, and the counter conductor of the present embodiment has a square shape with a side of 14.9 mm.

[0042] In a third-order resonant antenna that does not have an intermediate conductor, as in the reference example, operation becomes unstable if the area of ​​the ground plate is small. For example, in the third-order resonant antenna, it is ideal for the ground plate to have an infinite size to improve reflection characteristics. Therefore, it is preferable to set the length of each side of the flat rectangular ground plate to a length of one wavelength or more. In the reference example, the length of each side is longer than one wavelength. Even if the size of the ground plate is taken into account, the frequency bandwidth, which is the return loss bandwidth S11 = -10 dB, is narrow in the antenna device that does not have the intermediate conductor, as shown by the dashed line in Fig. 5. It should be noted that if the length of each side of the ground plate is designed to be shorter than one wavelength, the reflection properties will be reduced compared to that shown in Fig. 5, and the frequency bandwidth is further reduced.

[0043] In contrast, according to the present embodiment, as shown by the solid line in Fig. 5, the reflection characteristics can be improved compared to the reference example. The provision of the intermediate conductor 80 increases the frequency bandwidth. According to the antenna device 20 of the present embodiment, as shown in Fig. 6, a capacitor C2 is additionally formed in the parallel resonance structure of an inductor L1 by means of the short-circuit part 70, and a capacitor C1 is formed between the grounding plate 40 and the counter conductor 50. The capacitor C2 is formed between the intermediate conductor 80, which has a ground potential together with the grounding plate 40, and the counter conductor 50. That is, a parallel resonance structure of the inductor L1 and the capacitor C2 is added. Since a resonance point is formed by the capacitor C2, the frequency bandwidth becomes wide, as shown in Fig. 5 shown.

[0044] As described above, according to the present embodiment, it is possible to provide the antenna device 20 with a wide band (ie, frequency bandwidth). Since the band is wide, it is not easily affected by, for example, reflection from the metal of the casing and switching noise from the power supply circuit formed on the circuit board 11.

[0045] The size of the penetrating portion 81, that is, the length in the direction parallel to each side of the counter conductor 50, is not particularly limited. The penetrating portion 81 may be provided to include the counter conductor 50 at least in a plan view. The capacitor C2 is formed by providing a gap between the intermediate conductor 80 and the counter conductor 50 in a plan view. Since the intermediate conductor 80 includes the penetrating portion 81 including the counter conductor 50, the antenna device 20 can have a wide band.

[0046] In the above-described configuration, a part of the ground plate 40 that overlaps the penetrating portion 81 in a plan view essentially functions as the ground plate (i.e., ground). Therefore, the ground plate 40 can be made smaller according to the size of the penetrating portion 81. By reducing the size of the ground plate 40, the physical size / dimension of the antenna device 20 can be made smaller. Therefore, it is preferable to set the size of the penetrating portion 81 within a range where the physical size / dimension of the antenna device 20 can be reduced, in other words, within a range where the length of each side of the ground plate 40 can be made shorter than one wavelength of the operating frequency. Furthermore, the size of the penetrating portion 81 can be set so that the frequency bandwidth at the 0th-order resonance frequency (i.e., the operating frequency) becomes wider.

[0047] When performing the previously described simulation of an electromagnetic field, as in Fig. 3, the length of the penetrating part 81 in the X direction is defined as LX, and the length of the penetrating part 81 in the Y direction is defined as LY. Further, a distance between the counter conductor 50 and the intermediate conductor 80 in a plan view in the X direction is defined as L1 and L2, and a distance between the counter conductor 50 and the intermediate conductor 80 in a plan view is defined as L3 in the Y direction. Also, a distance between an end surface of the plate (i.e., an end of the penetrating part 81) and the counter conductor 50 is defined as L4 in the Y direction. Then, the distances L1 and L2 are set to 6 mm, the distance L3 is set to 2.5 mm, and the distance L4 is set to 3.2 mm.

[0048] The length of each side of the (substantially square) counter conductor 50 in the present embodiment is 14.9 mm, which corresponds approximately to 1 / 4 wavelength of the operating frequency (i.e., the 0th-order resonance frequency). Therefore, the length LX of the penetrating part 81 in the X direction is 26.9 mm, and its length LY in the Y direction is 20.6 mm. The size of the penetrating part 81 is shorter than half the wavelength of the operating frequency in both the X and Y directions. Even if the size of the penetrating part 81 is designed to be shorter than half the wavelength of the operating frequency in this way, the band can be broadened, as shown by the solid line in Fig. 5. Note that a wavelength λε of the radio wave of the operating frequency (ie, the 0th-order resonance frequency) can be obtained by (300 [mm / s] / 2.44 [GHz]) / square root of the primitive of the base material 30. In the present embodiment, the dielectric constant of the base material 30 is 4.4. In the configuration with the base material 30, all wavelengths shown in the embodiment are the aforementioned wavelength λε. (First variation)

[0049] Fig. 7 shows a first modified example of the antenna device 20. Fig. 7 corresponds to Fig. 3. In the antenna device 20 of Fig. 7, the distances L1 to L4 and the lengths LX and LY defined in the simulation of the electromagnetic field are applied. Since the intermediate conductor 80 only needs to have a size and a shape that are capable of defining the penetration part 81, Fig. 7 a frame body is used which is narrower than the one in Fig. 3. The width of the intermediate conductor 80 is, for example, shorter than 1 / 4 wavelength. The width is, for example, shorter than each of the distances L1 to L4. The grounding plate 40 may be arranged at least in a part / position that overlaps the penetrating part 81. When the grounding plate 40 coincides with the penetrating part 81, the length of the grounding plate 40 in the X direction is 26.9 mm and its length in the Y direction is 20.6 mm. The grounding plate 40 may be aligned with (parallel to) the penetrating part 81 and the frame body.

[0050] In this way, the size of the ground plate 40 can be designed to be smaller than or approximately equal to half a wavelength in both the X-direction and the Y-direction. Even if the size of the ground plate 40 is designed to be smaller than or equal to half a wavelength, it is possible to prevent the narrowing of the frequency bandwidth. Even in the Fig. 7, the same effects as those of the present embodiment are shown by the solid line in Fig. 5. Therefore, the physical dimensions can be reduced while the frequency bandwidth is broadened.

[0051] The relationship between the distances L3 and L4 is not limited to the previous example. In the present embodiment, the antenna device 20 is provided in the area including the plate end portion 11a (i.e., the side surface). That is, the counter conductor 50 is arranged near the plate end portion 11a. Due to such an arrangement, the length of the ground plate 40 placed on one side of the plate end portion 11a of the counter conductor 50a and the length of the ground plate 40 placed on an opposite side of the plate end portion 11a are different along the Y direction. In other words, the arrangement of the ground plate 40 is uneven and biased in the Y direction with respect to the center of the counter conductor 50.Since the grounding plate 40 is short on the plate end part 11a side, the intermediate conductor 80 is not arranged on the plate end part 11a side with respect to the counter conductor 50, and the penetration part 81 is cut out as a notch.

[0052] In such a configuration as in Fig. As shown in Fig. 8, a discontinuous surface 41 is formed at an interface between the plate end part 11a (i.e., the circuit board 11) and the outside (i.e., air) in the Y direction. Further, a discontinuous surface 42 formed by the penetration part 81 of the intermediate conductor 80 is formed on a side opposite to the discontinuous surface 41. Since the difference in dielectric constant is large, the discontinuous surface 41 is more likely to reflect the electric field than the discontinuous surface 42. If the distance L4 on the plate end part 11a side is made longer than the distance L3 on the opposite side, as shown in the present embodiment, the bias of the electric field with respect to the X-axis can be inhibited, or the electric field can be made substantially symmetrical thereto.By adjusting the distance from the counter conductor 50 to the end part of the penetrating part 81 in this way, it is possible to suppress deterioration of the reflection characteristics otherwise caused by the asymmetric arrangement of the ground plate 40 with respect to the counter conductor 50.

[0053] The relationship between the lengths L1 and L2 is not limited to the previous example. In the X-direction, discontinuous surfaces are formed on both sides of the counter conductor 50, which are formed by the penetrating portions 81 of the intermediate conductor 80. Since the reflections on the discontinuous surfaces are substantially equal, the electric fields can be designed to be substantially symmetrical with respect to the Y-axis by making the distances L1 and L2 substantially equal to each other, as described above.

[0054] The thickness of the base material 30 and the number of layers are not limited to the previous examples. The capacitance of the capacitors C1 and C2 and the inductance of the inductor L1 can be adjusted by adjusting the thickness of the base material 30 (i.e., the thin plate 30A). (Second embodiment)

[0055] The second embodiment is a modification of a previous embodiment, serving as a basic configuration, and may include a description of the previous embodiment. In the previous embodiment, a notch is used as the penetration part 81. A through hole may also be used instead.

[0056] Fig. 9 shows the antenna device 20 of the present embodiment. Fig. 9 corresponds to Fig. 3. The antenna device 20 is formed away from the plate end portion 11a (ie, the side surface). The intermediate conductor 80 has a through-hole (a rectangular hole) as the penetrating portion 81. The penetrating portion 81 overlaps at least the counter conductor 50. The intermediate conductor 80 has a closed rectangular cutout near its center. The intermediate conductor 80 surrounds the counter conductor 50 in a plan view.

[0057] In the present embodiment, the penetrating portion 81 is formed as a substantially square plane. The lengths LX and LY of the penetrating portion 81 are substantially equal to each other. Regarding the distance between the counter conductor 50 and the intermediate conductor 80 in a plan view, the distances L1 and L2 in the X direction are substantially equal to each other. The distances L3 and L4 in the Y direction are also substantially equal to each other. In other words, the distances L1 to L4 are substantially equal to each other. Other configurations are the same as those described in the previous embodiments. Fig. 9 shows the bilateral symmetry with respect to a central axis in the X direction and also shows a bilateral symmetry with respect to a central axis in the Y direction (except for the feed line 60). <Zusammenfassung des zweiten Ausführungsbeispiels>

[0058] The antenna device 20 of the present embodiment also has the same effects as the configuration described in the previous embodiment. For example, even in a configuration in which a through-hole is used as the penetrating part 81, the capacitor C2 is formed between the counter conductor 50 and the intermediate conductor 80 (see Fig. 6). Therefore, it is possible to provide the antenna device 20 with a wide band (ie, a wide frequency bandwidth).

[0059] The size of the penetrating portion 81 is not particularly limited. Since a portion of the grounding plate 40 that overlaps the penetrating portion 81 in a plan view essentially functions as the grounding plate (i.e., ground), the size of the penetrating portion 81 can be set within a range where the physical size of the antenna device 20 can be reduced. Furthermore, the size of the penetrating portion 81 can be set so that the frequency bandwidth at the 0th-order resonant frequency (i.e., the operating frequency) becomes wider.

[0060] In the present embodiment, too, the band can be widened if the size of the penetrating part 81, that is, the lengths LX and LY of the penetrating part 81, are shorter than half the wavelength of the operating frequency. Even if the size of the ground plate 40 is reduced to about half a wavelength or less, it is possible to prevent the narrowing of the frequency bandwidth. Therefore, the physical size / dimension can be made smaller while widening the frequency bandwidth.

[0061] The relationship between the distances L1 and L2 and the relationship between the distances L3 and L4 are not limited to the previous examples. The discontinuous surfaces formed by the penetrating parts 81 of the intermediate conductor 80 are positioned / provided on both sides of the counter conductor 50 in the X direction. Since the reflections on the discontinuous surfaces are substantially equal, the electric fields can be designed to be substantially symmetrical with respect to the Y axis by making the distances L1 and L2 substantially equal to each other as described above. Similarly, the electric field can be designed to be substantially symmetrical with respect to the X axis by making the distances L3 and L4 substantially equal to each other.

[0062] The distance L1 (L2) and the distance L3 (L4) can be designed differently from each other. Since the distances L1 to L4 are substantially equal to each other in the present embodiment, the conductors 50 have a directivity in all directions from the central region toward the edge. (Third embodiment)

[0063] The third embodiment is a modification of a previous embodiment, serving as a basic configuration, and may include a description of the previous embodiment. In the previous embodiment, the counter conductor 50 has a flat square shape. Instead, a slot may be provided in the counter conductor 50, which otherwise has a flat square shape.

[0064] Fig. 10 shows the antenna device 20 of the present embodiment. Fig. 10 corresponds to Fig. 3. The antenna device 20 is formed in a region including the plate end portion 11a, as in the configuration described in the first embodiment. At least one slot 51 is formed in the counter conductor 50. The slot 51 has a predetermined depth in the Z direction and is open toward one of the end faces (side faces) of the counter conductor 50.

[0065] The slot 51 of the present embodiment penetrates the counter conductor 50 in the Z direction. The counter conductor 50 has two slots 51 (a left slot 51 open on a left side and a right slot 51 open on a right side). Fig. 10 is open). The two slots 51 are provided so that the counter conductor 50 has a two-fold symmetry about the Z axis. The two slots 51 are provided to enclose the short-circuit part 70, in other words, to bind the center of the counter conductor 50 in the Y direction in a plan view. One of the slots 51 opens its opening on the side surface of the counter conductor 50 on the plate end part 11a side, and the other of the slots 51 opens on the side surface on the opposite side. The slot 51 opens on two facing side surfaces to which the feeder line 60 is not connected.

[0066] The extension length and width of the two slots 51 are equal to each other. The slot 51 divides the mating conductor 50 into a first mating portion 50a and a second mating portion 50b. The first mating portion 50a and the second mating portion 50b have the same shape and area. A portion sandwiched between the two slots 51 forms a connecting portion 50c connecting the first mating portion 50a and the second mating portion 50b. In other words, the mating conductor 50 has the first mating portion 50a, the second mating portion 50b, and the connecting portion 50c. The extension length of the slot 51 is longer than the length of the connecting portion 50c in the Y direction, and the width of the slot 51 is shorter than those of the first mating portion 50a and the second mating portion 50b. The counter conductor 50 forms a flat, substantially square shape in which the slot 51 is cut and removed from the square shape.

[0067] Fig. 11 is an equivalent circuit diagram of the antenna device 20. In Fig. 11, some circuit elements, such as the inductor included in the counter conductor 50, are omitted for simplicity. By providing the slot 51, a capacitor C3 is formed between the first counter conductor 50a and the second counter conductor 50b. The capacitor C3 is a parallel circuit (an equivalent capacitor) of capacitors formed in each of the two slots 51. The capacitor C3 is connected in series with another parallel circuit consisting of the capacitors C1 and C2. <Zusammenfassung des dritten Ausführungsbeispiels>

[0068] Fig. 12 shows the results of the electromagnetic field simulation (reflection characteristics). The basic conditions of the electromagnetic field simulation are the same as those of the previous embodiment. Specifically, the operating frequency, the composition of the base material (dielectric constant and thickness), and the diameter of the short-circuit part are the same as those in the previous embodiments. Furthermore, the size of the penetrating part 81, that is, the lengths LX and LY, are also the same as in the previous embodiments. Then, the optimization design is performed based on the size of the counter conductor 50 and the size of the slot 51. The size of the counter conductor 50 means the size of the area facing the ground plate 40 and the counter conductor 50. The size of the slot 51 means the length and width of the slot.As previously discussed, the slot 51 in the third embodiment may be a pair of slots (left slot 51 and right slot 51).

[0069] Specifically, each side of the counter conductor 50 is set to 13 mm. Furthermore, the length of the left slot 51 in the extension direction is set to 5.6 mm, and its width is set to 1.75 mm. For comparison, Fig. 12 an example of the previous embodiment (ie without slots) shown in Fig. 5 is shown by the solid line. The example “without slot” is shown in Fig. 12 is shown by a two-dot chain line, and the example of the present embodiment (with a left slot and a right slot) is shown by a solid line.

[0070] The antenna device 20 of the present embodiment also includes an intermediate conductor 80 forming a capacitor C2. As a result, the frequency bandwidth can be broadened, as shown in Fig. 12 shown.

[0071] In the present embodiment, by providing slot 51 in counter conductor 50, the surface area of ​​counter conductor 50 is reduced, thereby reducing the capacitance of capacitor C1. Conversely, slot 51 connects capacitor C3 in series with capacitor C1. This increases the number of variables that determine the total capacitance. The capacitance of capacitor C3 can be determined, for example, by increasing the length and / or width of slot 51.

[0072] By providing the capacitor C3 in this way, the degree of freedom in designing the antenna device 20 (ie, a 0th-order resonant antenna) is improved. Therefore, as shown in Fig. As shown in Figure 12, the reflection properties are improved compared to the case without slits. It is also possible to adjust (i.e., shift) the frequency band.

[0073] Furthermore, the mating conductor 50 can have a smaller body size while maintaining characteristics equal to or superior to those of the configuration without the slot 51. By downsizing, for example, the printed circuit board 11, the degree of freedom in arranging the mating conductor 50 can be improved. In particular, it can fit into a narrower / smaller space.

[0074] The shape, size, arrangement, and number of the slits 51 are not limited to the previous examples. For example, the positions of the two slits 51 may be offset or staggered in the X direction (i.e., not on a virtual straight line). Furthermore, the slit 51 may be provided to open on the side surface in the X direction. Only one slit 51 may be provided, or three or more slits 51 may be provided. The slit 51 is not limited to a straight line shape. For example, a slit 51 having a substantially L-shaped, flat shape may be adopted. As described above, if the slit 51 is provided so that the counter conductor 50 has twofold symmetry, the bias of the electric field distribution can be inhibited.

[0075] Although an example is shown in which the slot 51 penetrates the mating conductor 50 in the Z direction, the present invention is not limited to such an example. The slot 51 in the mating conductor 50 may be half the depth of the conductor 50, that is, it may have a groove shape. Even in such a structure, the capacitor C3 is formed between the facing surfaces of the first mating conductor 50a and the second mating conductor 50b.

[0076] Although an example of combining the slot 51 with the configuration described in the first embodiment has been shown, the present invention is not limited to such an example. The configuration of the present embodiment can also be combined with the configuration described in the second embodiment. (Fourth embodiment)

[0077] The fourth embodiment is a modification of a previous embodiment, serving as a basic configuration, and may include a description of the previous embodiment. In addition to the configuration described in the previous embodiments, a shielding wall may be further provided.

[0078] The Fig. 13 and Fig. 14 show the antenna device 20 of the present embodiment. Fig. 13 corresponds to Fig. 10. Fig. 14 is a cross-sectional view taken along a line XIV-XIV of Fig. 13. The antenna device 20 further includes a shielding wall 90. The configuration other than the shielding wall 90 is a combination of the configuration described in the third embodiment (see Fig. 10) and the intermediate conductor 80 described in the modification example (see Fig. 7).

[0079] The shielding wall 90 consists of a plurality of columnar portions 91. The columnar portion 91 is connected to the intermediate conductor 80 and extends in the Z direction. The columnar portion 91 is a columnar conductor connected to the intermediate conductor 80 and set as a ground potential. The plurality of columnar portions 91 function as a wall for blocking / interrupting radio waves by being arranged at intervals of half a wavelength or less of the operating frequency, so that no radio waves leak between the columnar portions 91. The plurality of columnar portions 91 are arranged along an inner edge of the intermediate conductor 80, which defines the penetration portion 81. In the configuration in which the intermediate conductors 80 are arranged in multiple layers (multi-stage), the columnar portion 91 is connected to at least one intermediate conductor 80.

[0080] The columnar portion 91 has a conductor disposed in a through-hole 32 penetrating the thin plate 30A of at least one layer. The columnar portion 91 is provided, for example, as a through-conductor or a through-hole conductor. The through-hole 32 may be formed in units of the thin plate 30A (i.e., may be formed plate 30A-to-plate 30A). The through-hole 32 may also be formed on the base material 30, which is fabricated as a layered thin plate 30A. In the present embodiment, the through-hole 32 penetrates the base material 30, and each of the columnar portions 91 extends from the grounding plate 40 to the upper surface of the base material 30. The columnar portion 91 is connected to the grounding plate 40.

[0081] As in Fig. As shown in Fig. 13, three sides of the rectangular penetrating part 81 are defined by the intermediate conductor 80, and the remaining one side is defined by the plate end part 11a. The intermediate conductor 80 is a narrow frame having a flat, substantially C-shape (i.e., substantially U-shape). The plurality of column parts 91 are arranged along the frame of the intermediate conductor 80. The column parts 91 are arranged on two sides of the intermediate conductor 80, other than a side to which the feeder line 60 extends. The shield wall 90 has a substantially L-shape in a plan view. The shield wall 90 is provided on a side opposite to the feeder line 60 in the X direction with respect to the counter conductor 50. Further, the shield wall 90 is provided on a side opposite to the plate end part 11a in the Y direction.

[0082] Note that in the present embodiment, the base material 30 is formed by laminating five thin plates 30A, and the intermediate conductor 80 is arranged in four layers. The intermediate conductors 80 of each layer have the same configuration. <Zusammenfassung des vierten Ausführungsbeispiels>

[0083] According to the present embodiment, the shielding wall 90 can block / interrupt the energy transmitted from the antenna device 20 to the region R2 of the circuit board 11. Furthermore, the shielding wall 90 can block / interrupt the energy entering the antenna device 20 from the circuit formed in the region R2 on the circuit board 11. Since the shielding wall 90 is provided outside the penetration part 81, the antenna device 20 can achieve the same effects as the configuration described in the previous embodiments even if it has the shielding wall 90. For example, the frequency bandwidth can be widened.

[0084] The arrangement of the shielding wall 90 is not limited to the previous example. For example, it can be arranged only between the two intermediate conductors 80. In the present embodiment, the shielding wall 90 extends from the grounding plate 40 to the upper surface of the base material 30. In other words, the shielding wall 90 is connected to the grounding plate 40, and all intermediate conductors 80 are arranged above it. Therefore, the energy transmitted through the circuit board 11 can be effectively interrupted.

[0085] Previously, an example was shown in which the shielding wall 90 is provided on two sides of the intermediate conductor 80, other than a side to which the feeder line 60 extends. However, the present invention is not limited to this. The shielding wall 90 may be provided on only one side thereof.

[0086] Previously, an example was shown in which the grounding plate 40 extends to the outside of the intermediate conductor 80. However, the present invention is not limited to this. The configuration may be the same as that of the modification example (see Fig. 7). The number of laminated thin plates 30A and the number of intermediate conductors 80 constituting the base material 30 are not limited to the previous examples.

[0087] The shielding wall 90 can be combined with any configuration described in the previous embodiments. An example was previously shown in which the shielding wall 90 is provided in the antenna device 20 in which the counter conductor 50 has a slot 51. However, the present invention is not limited to this. The shielding wall 90 can be provided in the antenna device 20 in which the counter conductor 50 is provided without a slot 51.

[0088] As in the modification examples shown in the Fig. 15 and Fig. 16, the shielding wall 90 may be provided on the antenna device 20 positioned away from the plate end part 11a. Fig. 15 corresponds to Fig. 9. Fig. 16 is a cross-sectional view taken along a line XVI-XVI of Fig. 15. The intermediate conductor 80 is a frame body forming a rectangular ring shape. The plurality of columnar parts 91 are arranged on three sides of the intermediate conductor 80, other than a side to which the feeder line 60 extends. The shielding wall 90 has a substantially C-shape (ie, a substantially U-shape) in a plan view.

[0089] As in a second variation example, which is shown in the Fig. 17 and Fig. 18, a part of the shielding wall 90 may be arranged on a placement surface of the counter conductor 50. Fig. 17 corresponds to Fig. 15. Fig. 18 is a cross-sectional view taken along a line XVIII-XVIII of Fig. 17. The shielding wall 90 has a surface conductor 92 arranged on the upper surface of the base material 30 in addition to the columnar part 91. Like the counter conductor 50, the surface conductor 92 is formed by patterning / cutting a metal foil. The different configuration of the surface conductor 92 is the same as that shown in Fig. 15 shown modification example.

[0090] The surface conductor 92 substantially corresponds to the intermediate conductor 80 in a plan view. The surface conductor 92 has a penetrating portion 93 that substantially corresponds to the penetrating portion 81 in a plan view. The penetrating portion 93 penetrates the surface conductor 92 in the Z direction. The penetrating portion 93 is a region without conductor arrangement defined by the surface conductor 92. The surface conductor 92 further has a penetrating groove 94. The penetrating groove 94 is provided to avoid / bypass the feed line 60 and penetrates the surface conductor 92 in the Z direction. The penetrating groove 94 may also be referred to as a gap between the surface conductors 92. The penetrating groove 94 is connected to the penetrating portion 93. The surface conductor 92 has a flat, substantially C-shape.The penetration groove 94 and the surface conductor 92 substantially coincide with the intermediate conductor 80 in a plan view.

[0091] The shielding wall 90 may be provided to surround the counter conductor 50. For example, in the Fig. 15 or Fig. 17, a plurality of columnar parts 91 may be provided on all sides of the intermediate conductor 80, including a side to which the feed line 60 extends. (Other embodiments)

[0092] The disclosure in the present description, drawings, and the like is not limited to the exemplary embodiments. The present disclosure includes the exemplary embodiments and their modifications based on the embodiments by those skilled in the art. For example, the disclosure is not limited to the combinations of parts and / or elements shown in the embodiments. The present disclosure can be implemented in various combinations. The disclosure may include additional parts that can be added to the embodiment. The disclosure covers omissions of parts and / or elements of the embodiment. The disclosure covers the exchange or combination of components and elements between one embodiment and another. The disclosed technical scope is not limited to the description of the embodiments.It should be noted that disclosed technical scopes of protection are shown by the description of the claims and further include meanings equivalent to the description of the claims and all modifications within the scope of protection.

[0093] The disclosure in the description, drawings, and the like is not limited by the description of the claims. The disclosures in the description, drawings, and the like include the technical ideas described in the claims and further extend to a wider variety of technical ideas than those in the claims. Therefore, various technical ideas can be extracted from the disclosure of the present description, drawings, and the like without being limited to the description of the claims.

[0094] Although an example in which the antenna device 20 is configured on the circuit board 11 was shown, the present invention is not limited thereto. Although an example in which the antenna device 20 includes the base material 30 is shown, the present invention is not limited thereto. The antenna device 20 may include at least the intermediate conductor 80 with the grounding plate 40, the counter conductor 50, the short-circuit part 70, and the penetration part 81.

[0095] The plan view shapes of the grounding plate 40 and the counter conductor 50 are not limited to the previously described examples. The shapes of the grounding plate 40 and the counter conductor 50 may have a substantially polygonal shape other than a rectangular shape or a substantially circular shape. The plan view shape of the intermediate conductor 80 is not limited to the previously described example. For example, the shape of the intermediate conductor 80 may be a substantially circular ring. The shape of the short-circuit part 70 is not limited to a circle / ring.

Claims

[1] Antenna device with: a grounding plate that provides a grounding potential a counter conductor (50) separated from the grounding plate by a predetermined distance in a plate thickness direction of the grounding plate, the counter conductor being configured for connection to a feed line (60); a short-circuit part (70) electrically connecting the counter conductor and the ground plate, wherein the antenna device operates in a third-order resonance mode by LC parallel resonance of a capacitance formed between the ground plate and the counter conductor and an inductance provided in the short-circuit part; and an intermediate conductor (80) having the same potential as the grounding plate and placed between the grounding plate and the counter conductor in the plate thickness direction, wherein the intermediate conductor at least partially defines a penetration part (81) which penetrates the intermediate conductor and which contains the counter conductor in a plan view in the plate thickness direction. [2] The antenna device according to claim 1, further comprising: a base material (30) containing a dielectric, wherein the earthing plate, the counter conductor and the intermediate conductor are arranged at different positions of the base material in elevations in the direction of the plate thickness. [3] Antenna device according to claim 2, wherein the grounding plate, the counter conductor, the short-circuit part and the intermediate conductor are part of the base material in plan view and are arranged in a region (R1) including a plate end part (11a), and the penetration part is a notch defined by the intermediate conductor and the plate end part. [4] The antenna device according to claim 1 or 2, wherein the penetrating part is a through hole surrounded by the intermediate conductor. [5] The antenna device according to any one of claims 1 to 3, wherein the penetrating part has a rectangular shape in plan view and the length in the direction along each side of the rectangle is half a wavelength or less of an operating frequency. [6] The antenna device according to claim 1, wherein a length of one side of the counter conductor (50) is shorter than a half wavelength of a 0th-order resonance frequency.

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