Antenna device

Abstract

To provide an antenna device which has two different radiation characteristics and can be miniaturized.SOLUTION: The antenna device includes a patch conductor 1 configured to operate as a patch antenna, a ground plane 2, and a first feeding point 11 that is a feeding point, wherein the antenna device includes a slit pattern 21 provided along a current direction Di1 when operating as a patch antenna in a region E of the ground plane overlapping the patch conductor, and a second feeding point 12 provided at a position different from the first feeding point in the patch conductor, and the second feeding point is provided at a position where the slit pattern operates as a slot antenna.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The disclosure herein relates to an antenna device. [Background technology]

[0002] Patent Document 1 discloses an antenna device that has two directivities by including two patch antennas. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-91665 Summary of the Invention [Problem to be solved by the invention]

[0004] As disclosed in Patent Document 1, there is a demand for antenna devices with different radiation characteristics. On the other hand, there is also a demand for antenna devices that are compact.

[0005] An object of the present disclosure is to provide an antenna device that has two different radiation characteristics and can be made smaller. [Means for solving the problem]

[0006] The antenna device disclosed herein comprises: An antenna device configured to operate as a patch antenna, the antenna device comprising a patch conductor (1), a ground plane (2), and a feed point (11), In the region (E) overlapping with the patch conductor of the ground plane, a slit pattern (21) is provided along the current direction (Di1) when operating as a patch antenna; a second feed point (12) provided in the patch conductor at a position different from the first feed point, which is a feed point; The antenna device has a second feed point located at a position that allows the slit pattern to function as a slot antenna.

[0007] The slit pattern is arranged along the direction of the current when the antenna operates as a patch antenna. Therefore, even with the slit pattern, the antenna can still function as a patch antenna, and a predetermined radiation characteristic is formed.

[0008] Furthermore, the second feed point is formed at a position where the slit pattern operates as a slot antenna. Therefore, when power is fed to the second feed point, the antenna device mainly operates as a slot antenna. In other words, the above antenna device has a mode in which it operates as a patch antenna using the first feed point, and a mode in which it operates as a slot antenna using the second feed point. This allows the antenna device to have two different radiation characteristics.

[0009] In the above configuration, a slit pattern is provided in the ground plane to form another antenna element (slot antenna), making it possible to realize an antenna device with two radiation characteristics in a size equivalent to that of a single patch antenna. Therefore, with the above configuration, it is possible to provide an antenna device that has two different radiation characteristics and can be made compact.

[0010] The various aspects disclosed in this specification employ different technical means to achieve their respective objectives. The reference numerals in parentheses in the claims and in this section are intended to exemplify correspondences with the following embodiments and are not intended to limit the technical scope. The objectives, features, and advantages disclosed in this specification will become more apparent by reference to the following detailed description and the accompanying drawings. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 2 is a top view of the antenna device. [Figure 2]FIG. 2 is a cross-sectional view taken along line II-II in FIG. [Figure 3] FIG. 2 is a bottom view of the antenna device. [Figure 4] FIG. 10 is a top view of a single patch conductor. [Figure 5] 10A and 10B are diagrams illustrating the directivity in the xz plane when the antenna device is activated. [Figure 6] 10A and 10B are diagrams illustrating the directivity in the xz plane when the antenna device is activated. [Figure 7] FIG. 10 is a bottom view of the antenna device of the first modified example. [Figure 8] FIG. 10 is a bottom view of the antenna device of the second modified example. [Figure 9] FIG. 10 is a top view of an antenna device according to a second embodiment. [Figure 10] FIG. 10 is a cross-sectional view taken along line XX in FIG. 9. [Figure 11] 10A and 10B are diagrams illustrating the directivity in the xz plane when the antenna device is activated. [Figure 12] FIG. 10 is a top view of an antenna device according to a third embodiment. [Figure 13] 10A and 10B are diagrams illustrating the directivity in the xz plane when the antenna device is activated. [Figure 14] 10A and 10B are diagrams illustrating the directivity in the xz plane when the antenna device is activated. [Figure 15] FIG. 10 is a cross-sectional view of an antenna device according to a third embodiment. [Figure 16] 10A and 10B are diagrams illustrating the directivity in the xz plane when the antenna device is activated. [Figure 17] 10A and 10B are diagrams illustrating the directivity in the xz plane when the antenna device is activated. [Figure 18] FIG. 10 is a top view of an antenna device according to a fourth embodiment. [Figure 19] FIG. 19 is a cross-sectional view taken along line XIX-XIX in FIG. 18. [Figure 20] 10A and 10B are diagrams illustrating the directivity in the xz plane when the antenna device is activated. [Figure 21] 10A and 10B are diagrams illustrating the directivity in the xz plane when the antenna device is activated. [Figure 22] FIG. 11 is a cross-sectional view of an antenna device according to a fifth embodiment. [Figure 23] FIG. 11 is a bottom view of the antenna device according to the fifth embodiment. [Figure 24] 10A and 10B are diagrams illustrating the directivity in the xz plane when the antenna device is activated. [Figure 25] 10A and 10B are diagrams illustrating the directivity in the xz plane when the antenna device is activated. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. The present disclosure is not limited to the following embodiments, and various modifications described below are also included within the technical scope of the present disclosure. Furthermore, various modifications other than those described below can be implemented without departing from the gist of the present disclosure. Various supplements and modifications can be implemented in appropriate combinations as long as no technical contradictions arise. Components having the same function are given the same reference numerals, and their description may be omitted. Furthermore, when only a portion of a configuration is mentioned, the description given elsewhere can be applied to the other portions.

[0013] In the present disclosure, "parallel" is not limited to a completely parallel state. The "parallel" state also includes a state inclined by several degrees to approximately 15 degrees. In other words, the expression "parallel" can include a state in which the two are roughly parallel (a so-called substantially parallel state). The expression "perpendicular" in the present disclosure is also not limited to a completely perpendicular state, but also includes a state inclined by several degrees to approximately 15 degrees. In the present disclosure, "opposed" refers to a state in which the two components face each other with a predetermined distance between them. The opposed state also includes a state in which the two components face each other roughly, such as a state in which the two components face each other at an angle of approximately 15 degrees.

[0014] The antenna device 100 of the present disclosure is used by being attached to a moving body such as a vehicle. The antenna device 100 may be attached to the roof of the vehicle, the upper edge of the windshield, the dashboard, a pillar, a door panel, a bumper, or the like. The antenna device 100 may be used by being connected to an ECU (Electronic Control Unit) for communication mounted on the vehicle. The ECU may use signals received by the antenna device 100 and input transmission signals to the antenna device 100. The antenna device 100 may also be used by being attached to a body other than a moving body.

[0015] As will be described later, the antenna device 100 has a mode in which it operates as a patch antenna and a mode in which it operates as a slot antenna. Here, the antenna device 100 is configured to operate at the same frequency in both modes. The antenna device 100 may be used for only either transmission or reception. Because radio wave transmission and reception are reciprocal, a configuration capable of transmitting radio waves of a certain frequency is also a configuration capable of receiving radio waves of that frequency. In the following description, the term "transmission and reception" refers to at least one of transmission and reception.

[0016] Hereinafter, the frequency that the antenna device 100 targets for transmission or reception will be referred to as the target frequency. The target frequency may also be referred to as the operating frequency. The antenna device 100 may be capable of transmitting and receiving radio waves not only at the target frequency but also at frequencies within a predetermined range determined based on the target frequency.

[0017] The antenna device 100 of this embodiment is configured to be capable of transmitting and receiving radio waves in the frequency band used in cellular communication. In other words, the antenna device 100 is configured as an antenna for performing data communication with a wireless base station that constitutes a 4G or 5G mobile communication system. The target frequency here is assumed to be 3.75 GHz, as an example.

[0018] In another embodiment, the antenna device 100 may be configured to transmit and receive radio waves in a frequency band used in short-range wireless communication, such as Bluetooth Low Energy (Bluetooth is a registered trademark), Wi-Fi (registered trademark), ZigBee (registered trademark), and UWB (Ultra Wide Band). Of course, the target frequency may be designed appropriately, and in other embodiments, it may be, for example, 300 MHz, 760 MHz, 850 MHz, 900 MHz, 1.17 GHz, 1.28 GHz, 1.55 GHz, 2.45 GHz, 5.9 GHz, etc. The antenna device 100 of the present disclosure may be used for various wireless communication. The uses of the antenna device 100 are not limited to those exemplified in the present disclosure.

[0019] Hereinafter, "λ" represents the wavelength of a radio wave of a target frequency (hereinafter also referred to as the target wavelength). For example, "λ / 2" and "0.5λ" mean half the target wavelength, and "λ / 4" and "0.25λ" mean one-quarter the target wavelength. In the examples of dimensions of components constituting the antenna device 100, expressions using λ can be interpreted as the electrical length. Here, the electrical length refers to the effective length taking into account factors such as fringing electric fields and wavelength shortening effects due to dielectrics. The electrical length is sometimes also referred to as the effective length. Of course, for portions not affected by wavelength shortening effects, λ may be interpreted as the length in a vacuum or in air. In this disclosure, the term "approximately λ / 2" may be interpreted as a length within λ / 2 ± 20%. The term "approximately λ / 4" may be interpreted as a length within λ / 4 ± 20%. The simple descriptions of λ / 2 and λ / 4 may also be interpreted as meaning approximately λ / 2 and approximately λ / 4 unless otherwise specified, such as "exactly."

[0020] First Embodiment The schematic configuration of the antenna device 100 will be described using Figures 1 and 2. In Figure 1, the substrate 3 is not shown. The antenna device 100 includes a patch conductor 1, a ground plane 2, and a first feed point 11. The antenna device 100 also includes a substrate 3 and a second feed point 12. The first feed point 11 and the second feed point 12 are feed points located at different positions. As will be described later, the antenna device 100 is configured to operate as a patch antenna when power is fed to the first feed point 11. The antenna device 100 is also configured to operate as a slot antenna when power is fed to the second feed point 12.

[0021] The substrate 3 is a member for supporting the patch conductor 1 and the ground plane 2 so that they face each other with a predetermined distance h between them. The substrate 3 is made of an electrically insulating material such as resin. The substrate 3 is a plate-like member with a predetermined thickness. The shape of the substrate 3 is not limited to a plate, and other shapes are also possible. The substrate 3 may be hollow, such as a honeycomb shape. The substrate 3 may be any element.

[0022] The substrate 3 has a first surface 3a and a second surface 3b. The first surface 3a is the surface to which the patch conductor 1 is attached. The second surface 3b is the surface to which the ground plane 2 is attached.

[0023] The patch conductor 1 is a component made of a conductor such as copper. The patch conductor 1 is a rectangular plate (including foil). The patch conductor 1 is arranged to face the ground plane 2 across the substrate 3. Here, the shape of the patch conductor 1 is assumed to be square. In other embodiments, the planar shape of the patch conductor 1 may be circular, regular octagonal, regular hexagonal, or the like. The patch conductor 1 may also be rectangular, elongated, or the like.

[0024] Hereinafter, the configuration of the antenna device 100 will be described by introducing the concept of a right-handed three-dimensional coordinate system having x-, y-, and z-axes as appropriate. The x-axis is defined along one side of the patch conductor 1. The y-axis is defined along another side of the patch conductor 1 that is perpendicular to the x-axis. The z-axis is defined to be perpendicular to an imaginary plane including the x- and y-axes. The up-down direction of the antenna device 100 is defined along the z-axis. The up-down direction is the direction from the second surface 3b to the first surface 3a, or from another perspective, the direction from the ground plane 2 to the patch conductor 1. The down-down direction is the opposite direction to the up-down direction, specifically, the direction from the patch conductor 1 to the ground plane 2.

[0025] The patch conductor 1 has four sides: patch sides 111, 112, 113, and 114. The first patch side 111 and the third patch side 113 are sides that extend along the y-axis. The second patch side 112 and the fourth patch side 114 are sides that extend along the x-axis. The second patch side 112 and the fourth patch side 114 are sides that are perpendicular to the first patch side 111 and the third patch side 113.

[0026] A first patch length L1, which is the length of the first patch side 111 and the third patch side 113, is λ / 2 of the target frequency. A second patch length L2, which is the length of the second patch side 112 and the fourth patch side 114, is λ / 2 of the target frequency.

[0027] The patch conductor 1 is formed with a first feed point 11 and a second feed point 12. The first feed point 11 and the second feed point 12 are portions where the inner conductor of the coaxial cable and the patch conductor 1 are electrically connected.

[0028] Note that various methods can be used to feed power to the patch conductor 1, such as a direct feeding method or an electromagnetic coupling method. The direct feeding method is a method in which a feed line is directly connected to the patch conductor 1. The feed line refers to a conductive member that is electrically connected to the inner conductor of a coaxial cable or the signal input / output terminal of a transmitting / receiving circuit. The feed line may be a microstrip line. The feed line may also include a conductor pin, a via, etc. In the direct feeding method, the connection point between the feed line and the patch conductor 1 corresponds to the first feed point 11 or the second feed point 12. The electromagnetic coupling method is a feed method that utilizes electromagnetic coupling between the patch conductor 1 and a microstrip line or the like used for feeding power.

[0029] The first feed point 11 is provided at a position offset from the center Cn of the patch conductor 1 toward either the second patch side 112 or the fourth patch side 114. The center Cn is a point on the patch conductor. Here, the first feed point 11 is provided at a position offset from the center Cn toward the second patch side 112. From another perspective, the first feed point 11 is arranged on an axis (hereinafter also referred to as the first axis A1) that is parallel to the first patch side 111 and passes through the center Cn (see FIG. 4). The distance from the center Cn to the first feed point 11 may be designed to ensure impedance matching. The first feed point 11 may be provided at a position offset from the first axis A1 in the x-axis direction by several millimeters.

[0030] The second feed point 12 is provided at a position on the patch conductor 1 that is different from the first feed point 11. In this embodiment, the second feed point 12 is provided at a position offset from the center Cn of the patch conductor 1 toward either the first patch side 111 or the third patch side 113. Specifically, the second feed point 12 is provided at a position offset from the center Cn of the patch conductor 1 toward the first patch side 111. In this manner, the second feed point 12 is arranged on an axis (also referred to as the second axis A2) that is parallel to the second patch side 112 and passes through the center Cn. The second feed point 12 may be provided at a position offset from the second axis A2 by several millimeters in the y-axis direction.

[0031] The ground plane 2 provides a ground potential (earth potential) for the patch conductor 1. The ground plane 2 is made of a conductor such as copper. The ground plane 2 is a rectangular plate (including foil). The ground plane 2 may be electrically connected to a ground pattern (not shown) on a printed circuit board that supplies a ground potential. Note that the ground plane 2 need only be larger than the patch conductor 1, and its shape is not limited to a rectangular shape. Here, the shape of the ground plane 2 is assumed to be square. The planar shape of the ground plane 2 may be a circle, a regular octagon, a regular hexagon, or the like. The ground plane 2 may also be a rectangle, an oblong, or the like. The patch conductor 1 may be disposed a predetermined distance above the ground plane 2 so that its center Cn roughly coincides with the center of the ground plane 2.

[0032] The ground plane 2 has four sides: ground plane sides 211, 212, 213, and 214. The first ground plane side 211 and the third ground plane side 213 are sides that extend along the y-axis. The second ground plane side 212 and the fourth ground plane side 214 are sides that extend along the x-axis. The first ground plane side 211 and the third ground plane side 213 are sides that are parallel to the first patch side 111. The second ground plane side 212 and the fourth ground plane side 214 are sides that are parallel to the second patch side 112. The second ground plane side 212 corresponds to the first ground plane parallel side. The fourth ground plane side 214 corresponds to the second ground plane parallel side. The length L3 of the first ground plane side 211 is set to be a predetermined amount longer than λ / 2 of the target frequency. The length L3 of the first ground plane side 211 is also the length of the third ground plane side 213. In this embodiment, the length L3 of the first ground plane side 211 is set to λ (one wavelength). In other embodiments, the length L3 of the first ground plane side 211 may be 0.5λ, 0.75λ, 1.5λ, or the like.

[0033] The ground plane 2 has a slit pattern 21 provided in a portion facing the patch conductor 1 so as to extend along a patch current direction Di1, which will be described later. For example, the slit pattern 21 is provided so as to cross the region overlapping with the patch conductor 1 (hereinafter also referred to as the facing region E) in top view. In other words, the slit pattern 21 is provided so as to traverse (longitudinal) the facing region E. In Fig. 3, the area inside the dashed line indicating the outline of the patch conductor 1 is the facing region E. The slit pattern 21 divides the facing region E into two regions in the x-axis direction.

[0034] The slit pattern 21 is a linear cutout having a predetermined length. The slit pattern 21 does not have to be linear. In other embodiments, the slit pattern 21 may be L-shaped or serpentine-shaped. The slit pattern 21 is a strip-like shape having a predetermined width.

[0035] The patch current direction Di1 is the direction in which a current flows when the antenna device 100 operates as a patch antenna, and is roughly determined by the shape of the patch conductor 1 and the position of the first feed point 11 in the patch conductor 1. The patch current direction Di1 corresponds to the current direction. In this embodiment, the patch current direction Di1 is parallel to the first patch side 111 and the third patch side 113 (i.e., the x-axis). The slit pattern 21 may be interpreted as a slit formed parallel to the first patch side 111 (and the third patch side 113) in one aspect. The slit pattern 21 is formed closer to the third patch side 113 than to the first patch side 111. For example, the slit pattern 21 may be formed at a position 0.05λ to 0.2λ away from the third patch side 113.

[0036] The ground plane 2 has a first cut surface 21a and a cut surface 21b that define the slit pattern 21. The first cut surface 21a and the second cut surface 21b face each other. The first cut surface 21a and the second cut surface 21b extend parallel to the first patch side 111. The expression "cut surface" may be replaced with "cut edge." Of the two cut edges that are parallel to the y-axis that form the slit pattern 21, the first cut surface 21a corresponds to the cut edge on which the first ground plane side 211 is located. Of the two cut edges that are parallel to the y-axis that form the ground plane 21, the second cut surface 21b corresponds to the cut edge on which the third ground plane side 213 is located.

[0037] The slit pattern 21 extends from the second ground plane side 212 to the fourth ground plane side 214. The cut surfaces 21a and 21b extend from the second ground plane side 212 to the fourth ground plane side 214. In other words, the ground plane 2 is completely divided by the slit pattern 21. For convenience, of the two ground plane components divided by the slit pattern 21, the one including the first ground plane side 211 will be referred to as the first ground plane portion 2a, and the other will be referred to as the second ground plane portion 2b. In addition, the slit pattern 21 extends so as to cross the opposing region E.

[0038] The slit length L4, which is the length of the slit pattern 21, is set to be equal to or longer than the first patch length L1. In this embodiment, the slit length L4 is set to be the same as the length L3 of the first base plate side 211. That is, the slit length L4 is set to λ. However, the slit length L4 is not limited to this. The slit length L4 may be set arbitrarily. The slit length L4 may be an integer multiple of 0.5λ, such as 0.5λ or 1.5λ. The dimensions of the base plate 2 may be determined according to the required slit length L4. The slit pattern 21 may be set to be longer than the first patch length L1 so as to cross (longitudinal in the drawing) the facing region E. This is also the length of the cut surface 21a and the cut surface 21b.

[0039] The width W1 of the slit pattern 21 may be set arbitrarily. The width W1 of the slit pattern 21 is also the distance between the cut surfaces 21a and 21b. Here, the width W1 of the slit pattern 21 is set to λ / 30.

[0040] <Patch antenna operation mode> The length of the patch conductor 1 in the y-axis direction is set to λ / 2. The first feed point 11 is located at a position offset from the center Cn toward the second patch edge 112 (i.e., in the negative y-axis direction). Therefore, when power is fed to the first feed point 11, current flows along the y-axis direction on the patch conductor 1 and the ground plane 2, and the current resonates mainly in the y-axis direction at the patch edge, radiating radio waves, and the antenna device 100 attempts to function as a patch antenna. Here, the patch edge refers to the area around the first patch edge 111 and the third patch edge 113 on the patch conductor 1.

[0041] For convenience, the direction of the current excited in the patch conductor 1 using the first feed point 11 is also referred to as the patch current direction Di1. The patch current direction Di1 is determined by the directions in which the first patch edge 111 and the third patch edge 113 extend. In other words, the patch current direction Di1 is parallel to the y-axis. From another perspective, the first patch edge 111 and the third patch edge 113 can also be considered as edges extending along the patch current direction Di1.

[0042] A slit pattern 21 is provided on the ground plane 2, but the slit pattern 21 is arranged along the y-axis direction (in other words, the patch current direction Di1). Therefore, the slit pattern 21 does not affect the resonance of the current that resonates at the end of the patch antenna. In other words, the slit pattern 21 does not hinder operation as a patch antenna. Therefore, the antenna device 100 can operate as a patch antenna even with the slit pattern 21. Note that the expression "does not hinder operation as a patch antenna" may allow for cases where the gain is slightly reduced. "Does not hinder" may be interpreted as meaning that the effect on gain is small or within an acceptable range and does not cause any practical problems.

[0043] 5 is a diagram showing the directivity when the antenna device 100 is operated by feeding power to the first feeding point 11. The antenna device 100 operates as a patch antenna. Therefore, the antenna device 100 radiates radio waves strongly upward.

[0044] <Slot antenna operation mode> In the antenna device 100 of this embodiment, the length of the patch conductor 1 in the y-axis direction is set to λ / 2. The second feed point 12 is disposed at a position offset from the center Cn toward the direction in which the first patch edge 111 exists (i.e., the positive direction of the x-axis). Due to this relationship between the shape of the patch conductor 1 and the position of the second feed point 12, when power is fed to the second feed point 12, a current tries to flow through the patch conductor 1 and the ground plane 2 along the x-axis direction.

[0045] However, as shown in Fig. 1, a slit pattern 21 is provided in parallel to the y-axis direction in the facing region E of the ground plate 2. In other words, the slit pattern 21 is provided so as to block the current excited using the second feeding point 12. As a result, the current concentrates in the slit pattern 21 of the ground plate 2. The slit length L4 is set to λ (an integer multiple of 0.5λ). Therefore, the antenna device 100 mainly operates as a slot antenna, not as a patch antenna.

[0046] 6 is a diagram showing the directivity when the antenna device 100 is operated by feeding power to the second feeding point 12. At this time, the antenna device 100 mainly operates as a slot antenna. Therefore, the antenna device 100 radiates radio waves strongly downward.

[0047] <Summary of the First Embodiment> According to this embodiment, the antenna device 100 has a mode in which it operates as a patch antenna using the first feed point 11, and a mode in which it operates as a slot antenna using the second feed point 12. This allows the antenna device 100 to have two different radiation characteristics. Furthermore, in the configuration of this embodiment, another antenna element (slot antenna) is formed by providing the slit pattern 21 in the base plate 2, so it is possible to realize an antenna device 100 that has two radiation characteristics with a size equivalent to that of a single patch antenna. Therefore, with the above configuration, it is possible to provide an antenna device 100 that has two directivities and can be miniaturized.

[0048] According to this embodiment, the second feed point 12 is provided at a position offset from the center Cn of the patch conductor 1 to either the first patch side 111 or the third patch side 113. This allows the antenna device 100 to function well as a slot antenna when power is fed to the second feed point 12. Furthermore, the slit pattern 21 is formed parallel to the first patch side 111. This improves the gain in the mode in which the antenna operates as a slot antenna.

[0049] According to this embodiment, the slit pattern 21 has a length equivalent to one wavelength of the target frequency, which allows the antenna device 100 to operate as a slot antenna at the target frequency.

[0050] According to this embodiment, the first feed point 11 is provided at a position offset from the center Cn to either the second patch side 112 or the fourth patch side 114. This allows the antenna device 100 to function well as a patch antenna when power is fed to the first feed point 11.

[0051] According to this embodiment, the first patch length L1 is half the wavelength of the target frequency, which allows the antenna device 100 to operate as a patch antenna at the target frequency.

[0052] In the above embodiment, the second feed point 12 is provided on the second axis A2, but the position of the second feed point 12 is not limited to the second axis A2. The second feed point 12 may be provided at a position where current concentrates in the slit pattern 21 when power is fed to the second feed point 12, in other words, at a position where the slit pattern 21 operates as a slot antenna.

[0053] The position at which the slit pattern 21 can function as a slot antenna may be at least a position that is offset from the first axis A1 by a predetermined amount or more. If the second feed point 12 is provided on the first axis A1, the second feed point 12 also becomes a feed point that causes the antenna device 100 to function as a patch antenna. In that case, current does not concentrate in the slit pattern 21, and the antenna device 100 does not function as a slot antenna. For this reason, the position of the second feed point 12 that can cause the slit pattern 21 to function as a slot antenna may be a position that is offset from the first axis A1 by a predetermined distance (for example, 2 mm) or more.

[0054] Furthermore, the farther second feed point 12 is from second axis A2, the more easily the current flowing from second feed point 12 flows in the y-axis direction. As a result, the current component flowing in the x-axis direction weakens, and the current is less likely to concentrate in slit pattern 21.

[0055] For this reason, when the second feed point 12 is located in a region that is at least a predetermined first distance from the first axis A1 and within a predetermined second distance from the second axis A2, current may concentrate in the slit pattern 21. That is, the position of the second feed point 12 that allows the slit pattern 21 to function as a slot antenna may be a location that is at least a predetermined first distance from the first axis A1 and within a predetermined second distance from the second axis A2. The first distance may be any value that satisfies the above-described technical concept, such as 0.02λ. The second distance may be any value that satisfies the above-described technical concept, such as 0.1λ. Thus, the second feed point 12 may be located at a position offset by a predetermined amount from the second axis A2 in the direction toward the second patch side 112 or the fourth patch side 114.

[0056] The position of the second feed point 12 at which the slit pattern 21 can function as a slot antenna may be affected by the position and shape of the slit pattern 21. Therefore, it is difficult to uniquely define the range of feed point positions at which the slit pattern 21 can function as a slot antenna solely from the shape of the patch conductor 1. However, it is expected that a person skilled in the art would be able to identify the position at which the slit pattern 21 can function as a slot antenna by performing a feed simulation at several points on the second axis A2. In other words, it should be noted that a person skilled in the art would be able to understand, to some extent, the position of the second feed point 12 at which the slit pattern 21 can function as a slot antenna without excessive trial and error.

[0057] <Modification> In the first embodiment, the antenna device 100 is configured to operate at the same frequency in the two modes, but this is not limiting. The antenna device 100 may be configured to operate at different frequencies in the two modes. For convenience, the target frequency in the mode in which the antenna operates as a patch antenna is referred to as the first frequency, and its wavelength is denoted as λ1. Furthermore, the target frequency in the mode in which the antenna operates as a slot antenna is referred to as the second frequency, and its wavelength is denoted as λ2. The first frequency may be lower or higher than the second frequency. In this case, the first patch length L1 may be set to λ1 / 2. The slit length L4 may be set to λ2 / 2.

[0058] Although the slit pattern 21 has been shown to extend parallel to the first patch side 111, this is not necessarily the case. The slit pattern 21 may extend obliquely relative to the first patch side 111.

[0059] Although the configuration has been shown in which the slit length L4 is set to be the same as the length L3 of the first ground plate side 211, this is not limiting. As shown in Fig. 7, the slit pattern 21 may be formed to be equal to or less than the length L3 of the first ground plate side 211 so as not to completely divide the ground plate 2. Fig. 7 shows a configuration in which the slit length L4 is set to be longer than the first patch length L1 and shorter by a predetermined amount than the length L3 of the first ground plate side 211.

[0060] 7 will be referred to as the first modified example below. In the first modified example, the first ground plate portion 2a and the second ground plate portion 2b are connected near the second patch side 112 and the fourth patch side 114. In the first modified example, the first ground plate portion 2a and the second ground plate portion 2b are connected near the second ground plate side 212 and the fourth ground plate side 214. In the first modified example, the slit pattern 21 divides the opposing region E, but does not completely divide the ground plate 2 itself.

[0061] Hereinafter, the portions on the extension line of the slit pattern 21 that connect the first base plate portion 2a and the second base plate portion 2b are also referred to as the first joint portion 231 and the second joint portion 232. The first joint portion 231 is the portion between the slit pattern 21 and the fourth base plate side 214, and the second joint portion 232 is the portion between the slit pattern 21 and the second base plate side 212. In FIG. 7, portions that correspond to the joints are indicated by hatching with a dot pattern. Hereinafter, the end of the slit pattern 21 on the positive side of the y-axis will also be referred to as the first slit end 21c. The end of the slit pattern 21 on the negative side of the y-axis will also be referred to as the second slit end 21d.

[0062] Even in this first modified example, the antenna device 100 can operate as a slot antenna by using the second feed point 12. However, in the first modified example, when power is fed from the second feed point 12, current may flow from the first ground plate portion 2a to the second ground plate portion 2b via the first joint 231 and the second joint 232. Therefore, in the first modified example, the radiation gain from the slot antenna may be lower than in the configuration of the embodiment. Paradoxically, in the configuration of the above embodiment, the slit pattern 21 extends from the first ground plate side 211 to the fourth ground plate side 214, completely dividing the ground plate 2. Therefore, the current does not flow around as described above, and the current concentrates in the slit pattern 21. Therefore, the configuration of the above embodiment may achieve a higher gain than the first modified example.

[0063] As a further modified example (hereinafter referred to as the second modified example), the slit pattern 21 of the antenna device 100 may be formed so as not to completely divide the facing region E, as shown in Fig. 8. In other words, the slit length L4 may be shorter than the first patch length L1. The second modified example corresponds to a configuration in which a connection portion between the first ground plate portion 2a and the second ground plate portion 2b exists inside the facing region E.

[0064] In the second modified example, current also flows from the first ground plate portion 2a to the second ground plate portion 2b via the first joint 231 and the second joint 232. Furthermore, current may be distributed primarily in the facing region E of the ground plate 2. If the connection between the first ground plate portion 2a and the second ground plate portion 2b is located inside the facing region E, current is more likely to sneak from the first ground plate portion 2a to the second ground plate portion 2b. In other words, in the second modified example, current is less likely to concentrate in the slit pattern 21 than in the first modified example or the embodiment. In the second modified example, the antenna device 100 can also function as a slot antenna using the second feed point 12, but its gain may be lower than that of the first modified example or the embodiment. Paradoxically, in the embodiment and the first modified example, the slit pattern 21 is formed to cross the facing region E. Furthermore, in the embodiment and the first modified example, the number of joints is smaller (or nonexistent) than in the second modified example. Therefore, the amount of sneak current is smaller, and the gain may be increased.

[0065] As described above, the slit length L4 may be shorter than the length L3 of the first base plate side 211. In that case, the slit pattern 21 may be formed so that its center is located on the second axis A2. In other words, the slit pattern 21 may be formed line-symmetrically with respect to the second axis A2.

[0066] Second Embodiment This embodiment is a modification of the preceding embodiment as a basic form, and the description of the preceding embodiment can be used. In this embodiment, as shown in Figures 9 and 10, sub-slits 22 are provided in the base plate 2. The sub-slits 22 are slit patterns that are shorter in length than the slit pattern 21. The base plate 2 has an inner surface 22a that defines the sub-slits 22. The inner surface 22a is rectangular in top view.

[0067] The sub-slit 22 is provided between the slit pattern 21 and the second feed point 12 in a top view. For convenience, in this disclosure, the point located directly below the second feed point 12 is also referred to as the corresponding point 12g. The sub-slit 22 is provided along the patch current direction Di1. In other words, the sub-slit 22 is formed parallel to the slit pattern 21. The sub-slit 22 is provided within the facing region E of the ground plane 2. The length L5 of the sub-slit 22 is set to be shorter than the first patch length L1. Here, the width W2 of the sub-slit 22 is set to λ / 30, similar to the width W1 of the slit pattern 21. The width W2 of the sub-slit 22 may be set arbitrarily. The sub-slit 22 may have an axisymmetric shape with respect to the second axis A2.

[0068] In the second embodiment, a sub-slit 22 is provided between the slit pattern 21 and the second feed point 12. Furthermore, the sub-slit 22 is provided along the patch current direction Di1. Therefore, the current excited in the ground plate 2 by feeding power to the second feed point 12 flows in a detour around the sub-slit 22. Then, as in the previous embodiment, the current concentrates in the slit pattern 21 of the ground plate 2. Therefore, the antenna device 100 mainly operates as a slot antenna, as in the previous embodiment.

[0069] 11 is a diagram showing the directivity when the antenna device 100 is operated by feeding power to the second feeding point 12. Since the antenna device 100 mainly operates as a slot antenna, the antenna device 100 radiates radio waves strongly downward.

[0070] The sub-slit 22 introduced in the second embodiment acts to change the path length of the current from the corresponding point 12g to the slit pattern 21 on the ground plate 2. By changing the path length, the phase of the radio wave radiated as the slot pattern can fluctuate. In this way, the antenna device 100 may be provided with the sub-slit 22 that functions as a phase adjuster.

[0071] <Effects of the second embodiment> When power is fed to the second feed point 12, the antenna device 100 mainly functions as a slot antenna. However, the developers of the present disclosure and others have conducted a detailed study of its operation and found that radio waves can also be radiated from the patch conductor 1 even when the second feed point 12 is in use. In other words, the radiation characteristics of the antenna device 100 when the second feed point 12 is in use are a combination of the radio waves radiated from the patch conductor 1 and the radio waves radiated from the slot antenna. Depending on the relationship between the phase of the radio waves radiated from the patch conductor 1 and the phase of the radio waves radiated from the slot antenna, the two waves may weaken each other.

[0072] In response to such circumstances, the antenna device 100 of the second embodiment has a sub-slit 22 provided between the slit pattern 21 and the second feed point 12. This sub-slit 22 lengthens the current path from the corresponding point 12g to the slit pattern 21. The phase of the current is delayed by the amount of the lengthened current path. Therefore, the sub-slit 22 can adjust the phase of the radio wave radiated from the slot antenna.

[0073] That is, by introducing the sub-slit 22, it becomes possible to adjust the phase of the radio wave radiated from the slot antenna to match the phase of the radio wave radiated from the patch conductor 1. This can improve the gain of the antenna device 100.

[0074] Although the above description shows a configuration in which the sub-slits 22 are arranged along the patch current direction Di1, the orientation of the sub-slits 22 is not limited to this. The sub-slits 22 may be arranged to extend in any direction.

[0075] <Third embodiment> This embodiment is a modification of the preceding embodiment as a basic form, and the description of the preceding embodiment can be used. In this embodiment, as shown in FIG. 12, the antenna device 100 includes a metal plate 4. As an example, the metal plate 4 is the body of a vehicle on which the antenna device 100 is mounted. Here, the metal plate 4 is flat. The metal plate 4 is disposed below the base plate 2 with a predetermined distance K therebetween. Here, the predetermined distance K is λ / 4. The predetermined distance K may be set arbitrarily.

[0076] Fig. 13 is a diagram showing the directivity of antenna device 100 in a mode in which it operates as a patch antenna. Because metal plate 4 is disposed below base plate 2, radiation downward from antenna device 100 is suppressed compared to the case in Fig. 5. Fig. 14 is a diagram showing the directivity of antenna device 100 in a mode in which it operates as a slot antenna. In this case as well, radiation downward from antenna device 100 is suppressed compared to the case in Fig. 6. As shown in Figs. 13 and 14, antenna device 100 has two different radiation characteristics in the upward direction.

[0077] The antenna device 100 itself may be integrally provided with the metal plate 4, but the antenna device 100 may also be used by being attached to a position on a vehicle body or the like where the distance between the metal plate 4 and the base plate 2 is K. The metal plate 4 may be attached later.

[0078] According to this embodiment, as in the previous embodiment, the antenna device 100 can have two different radiation characteristics. Furthermore, it is possible to provide an antenna device 100 that has two directivities and can be miniaturized.

[0079] In this embodiment, the metal plate 4 is disposed at a λ / 4 interval from the ground plate 2. This allows the radio waves radiated from the patch conductor 1 and the ground plate 2 to be in phase with the radio waves reflected from the metal plate 4. This makes it possible to increase the gain of the antenna device 100.

[0080] Although the above description has shown a configuration in which the metal plate 4 is flat, the present invention is not limited to this. The shape of the metal plate 4 may be set arbitrarily. As shown in FIG. 15, the metal plate 4 may be triangular prism-shaped. Here, the predetermined distance K is the distance between the center of the base plate 2 and the metal plate 4. Here, as before, the predetermined distance K is set to λ / 4.

[0081] Fig. 16 is a diagram showing the directivity of antenna device 100 in a mode in which it operates as a patch antenna. Fig. 17 is a diagram showing the directivity of antenna device 100 in a mode in which it operates as a slot antenna. It can be seen that in this modification as well, antenna device 100 has two different radiation characteristics in the upward direction.

[0082] <Fourth embodiment> This embodiment is a modification of the preceding embodiment as a basic form, and the description of the preceding embodiment can be used. In this embodiment, as shown in Figures 18 and 19, the patch conductor 1 is provided at a position offset from the center of the ground plane 2 toward the first ground plane side 211. The second feed point 12 is provided at a position offset from the center Cn of the patch conductor 1 toward the third patch side 113. The second feed point 12 is located on an axis passing through the second axis A2. The slit pattern 21 is formed closer to the first patch side 111 than to the third patch side 113.

[0083] Fig. 20 is a diagram showing the directivity of the antenna device 100 in a mode in which it operates as a patch antenna. Fig. 21 is a diagram showing the directivity of the antenna device 100 in a mode in which it operates as a slot antenna. In this embodiment, the patch conductor 1 is provided at a position offset from the center of the ground plate 2 toward the first ground plate side 211. Therefore, in both cases, the directivity of the antenna device 100 is offset in the positive direction of the x-axis compared to Figs. 5 and 6.

[0084] According to this embodiment, as in the previous embodiment, the antenna device 100 can have two different radiation characteristics. Furthermore, it is possible to provide an antenna device 100 that has two directivities and can be miniaturized.

[0085] In this embodiment, the patch conductor 1 is provided at a position offset from the center of the ground plane 2 toward the first ground plane side 211. Therefore, the directivity of the antenna device 100 is offset in the positive direction of the x-axis. In this way, by adjusting the position of the patch conductor 1 with respect to the ground plane 2, it is possible to adjust the direction of the directivity to any direction.

[0086] The patch conductor 1 may be positioned arbitrarily relative to the ground plane 2. The patch conductor 1 may be provided at a position offset from the center of the ground plane 2 toward any of the ground plane sides 211, 212, 213, and 214.

[0087] Fifth Embodiment This embodiment is a modification based on the preceding embodiment, and the description of the preceding embodiment can be used. In this embodiment, as shown in Figures 22 and 23, the substrate 3 has at least one dielectric layer 31 and a conductive reflecting member 32 on the side (lower side) of the ground plane 2 different from the side on which the patch conductor 1 is located. The reflecting member 32 is disposed opposite the ground plane 2.

[0088] The reflecting member 32 is made of a conductor such as copper. The reflecting member 32 has a configuration in which a plurality of linear conductor patterns extending perpendicular to the slit pattern 21 are periodically arranged. The direction in which the conductor patterns extend is referred to as the pattern direction Pd. The conductor patterns are parallel to the second ground plane side 212 and the fourth ground plane side 214. The width of the conductor patterns may be 1 mm or 2 mm, for example. The linear shape may include a shape having a width of 1 mm or more. The spacing between the conductor patterns is 2 mm. The spacing between the conductor patterns may be set arbitrarily.

[0089] 24 is a diagram showing the directivity of the antenna device 100 in a mode in which it operates as a patch antenna. Because the reflecting member 32 is disposed below the base plate 2, radiation downward from the antenna device 100 is suppressed compared to the case of FIG.

[0090] FIG. 25 is a diagram showing the directivity of the antenna device 100 in a mode in which it operates as a slot antenna. Because the antenna device 100 operates as a slot antenna, the direction perpendicular to the longitudinal direction of the slit pattern 21 is the vibration direction of the electric field. In other words, the vibration direction of the electric field and the pattern direction Pd are parallel. Therefore, radio waves radiated in the direction (downward) from the patch conductor 1 toward the reflecting member 32 are suppressed. As a result, as shown in FIG. 25, downward radiation of the antenna device 100 is suppressed compared to the case of FIG. 6. As shown in FIGS. 24 and 25, the antenna device 100 has two different radiation characteristics in the upward direction.

[0091] According to this embodiment, as in the previous embodiment, the antenna device 100 can have two different radiation characteristics. Furthermore, it is possible to provide an antenna device 100 that has two directivities and can be miniaturized.

[0092] In this embodiment, a reflective member 32, which is a conductor, is provided on a side of the ground plane 2 that is different from the side where the patch conductor 1 is present, thereby making it possible to suppress radio waves from being radiated downward.

[0093] In this embodiment, the reflecting member 32 is formed by periodically arranging a plurality of linear conductor patterns that extend perpendicular to the slit pattern 21. Here, consider a case where the reflecting member 32 is a one-surface conductor. In this case, the reflecting member 32 may function as a GND, and the antenna device 100 may not function as a slot antenna.

[0094] Furthermore, consider a case where the reflecting member 32 is formed by periodically arranging multiple linear conductor patterns that extend parallel to the slit pattern 21. In this case, when the antenna device 100 operates as a slot antenna, the direction of propagation of the electric field and the pattern direction Pd become perpendicular. In other words, it is considered that the effect of the reflecting member 32 in reflecting radio waves radiated downward from the slit pattern 21 will be weakened.

[0095] In this embodiment, the reflecting member 32 is formed by periodically arranging a plurality of linear conductor patterns that extend perpendicular to the slit pattern 21. This allows the antenna device 100 to function as a slot antenna, and also makes it possible to suppress radio waves radiated downward.

[0096] In other embodiments, the conductor pattern may be formed obliquely or parallel to the slit pattern 21. The pattern direction Pd may be any other direction.

[0097] <Other embodiments> The disclosure in this specification and drawings, etc. is not limited to the above-exemplified embodiments and variations. The disclosure encompasses the exemplified embodiments and variations thereon 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 disclosure can be implemented in various combinations. The disclosure can have additional parts that can be added to the embodiments. The disclosure encompasses the omission of parts and / or elements from the embodiments. The disclosure encompasses the substitution or combination of parts and / or elements between one embodiment and another. The technical idea described as a variation of the first embodiment may also be applied to the second to fifth embodiments. Configurations in which the technical idea described as a variation of the first embodiment is applied to the second to fifth embodiments are also included within the scope of this disclosure. The disclosed technical scope is not limited to the description of the embodiments. Some disclosed technical scopes are defined by the claims, and should be interpreted as including all modifications within the meaning and scope of the claims.

[0098] The disclosure in the specification, drawings, etc. is not limited by the claims. The disclosure in the specification, drawings, etc. encompasses the technical ideas described in the claims, and extends to more diverse and broader technical ideas than the technical ideas described in the claims. Therefore, various technical ideas can be extracted from the disclosure in the specification, drawings, etc. without being bound by the claims. [Explanation of symbols]

[0099] 1 patch conductor, 1 wavelength, 11 first feed point, 111 first patch edge, 112 second patch edge, 113 third patch edge, 114 fourth patch edge, 12 second feed point, 2 ground plane, 21 slit pattern, 212 first ground plane parallel edge, 214 second ground plane parallel edge, 22 sub-slit, 3 substrate, 31 dielectric layer, 32 reflective member, Cn center, Di1 current direction, E area, h spacing, 12g corresponding point.

Claims

1. An antenna device configured to operate as a patch antenna, the antenna device comprising a patch conductor (1), a ground plane (2), and a feed point (11), A slit pattern (21) is provided in a region (E) of the ground plane that overlaps with the patch conductor, along a current direction (Di1) when the antenna operates as the patch antenna; a second feed point (12) provided in the patch conductor at a position different from the first feed point, which is the feed point; The antenna device, wherein the second feeding point is provided at a position that causes the slit pattern to function as a slot antenna.

2. The patch conductor is It is rectangular, The patch patch has a first patch side (111) and a third patch side (113) which are sides extending along the current direction, and a second patch side (112) and a fourth patch side (114) which are sides perpendicular to the first patch side, the slit pattern is formed parallel to the first patch side, 2. The antenna device according to claim 1, wherein the second feed point is provided at a position offset from a center (Cn) of the patch conductor toward either the first patch side or the third patch side.

3. 3. The antenna device according to claim 1, wherein the slit pattern has a length corresponding to one wavelength of a target frequency.

4. 3. The antenna device according to claim 1, wherein a sub-slit (22) which is a slit pattern having a length shorter than that of the slit pattern is provided between the slit pattern and a corresponding point (12g) which is a point on the ground plane that overlaps with the second feed point.

5. 3. The antenna device according to claim 1, further comprising a reflecting member (32) made of a conductor and arranged below said ground plane to face said ground plane at a predetermined distance.

6. A reflecting member (32) is provided below the base plate and is arranged opposite the base plate at a predetermined distance, 3. The antenna device according to claim 1, wherein the reflecting member has a structure in which a plurality of linear conductor patterns extending perpendicular to the slit pattern are periodically arranged.

7. The antenna device according to claim 2 , wherein the first feed point is provided at a position offset from the center toward either the second patch side or the fourth patch side.

8. The ground plane is rectangular and has a first ground plane parallel side (212) and a second ground plane parallel side (214) that are parallel to the second patch side, The antenna device according to claim 2 , wherein the slit pattern extends from the first parallel side of the ground plane to the second parallel side of the ground plane.

9. the length of the slit pattern is set to be equal to or greater than the length of the first patch side, The antenna device according to claim 2 , wherein the slit pattern is formed so as to cross a region overlapping with the patch conductor.

10. The antenna device according to claim 2 , wherein the length of the first patch side is half the wavelength of the target frequency.

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