Antenna and vehicle antenna device

Abstract

The present invention provides an antenna and a vehicle antenna device that enable size reduction. An antenna (10) comprises: a dielectric body (13); a radiation conductor (11) that is disposed on the first main surface side of the dielectric body (13); and a ground conductor (14) that is disposed on the second main surface side of the dielectric body (13). The ground conductor (14) is a planar conductor that is disposed in a rectangular region which has a length in a first direction LG1 and a length in a second direction LG2. When the ground conductor (14) is divided into a first region and a second region, the ground conductor (14) has a slit (15) that extends from the outer edge of the ground conductor in the first region towards the internal side of the ground conductor (14).

Description

[Technical Field]

[0001] The present invention relates to an antenna and a vehicle antenna device. [Background technology]

[0002] In recent years, vehicle antenna devices such as flat-type patch antennas that transmit and receive radio waves in the GHz band have been introduced into automobiles and other vehicles. One example of the patch antenna is a patch antenna that receives signals transmitted from artificial satellites. For example, Patent Documents 1 and 2 disclose patch antennas that can receive GNSS (Global Navigation Satellite System) signals, including GPS (Global Positioning System) signals in a predetermined frequency band. Patent Document 2 discloses an example in which the patch antenna is mounted on the roof of an automobile and covered by an antenna case. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-048145 [Patent Document 2] Japanese Patent Application Publication No. 2019-193167 Summary of the Invention [Problem to be solved by the invention]

[0004] Here, the patch antennas disclosed in Patent Documents 1 and 2 require the area of ​​the ground conductor facing the radiating conductor via the dielectric substrate to be larger than the area of ​​the radiating conductor that transmits and receives radio waves of a predetermined frequency. Therefore, when installing a patch antenna in a vehicle, the patch antenna must be installed taking into account the area of ​​the ground conductor, which imposes a constraint that a certain amount of installation space must be secured. Therefore, it is desirable to realize an antenna that allows a patch antenna to be installed in a vehicle without considering the area of ​​the ground conductor of the patch antenna.

[0005] An object of the present invention is to provide an antenna and a vehicle antenna device that can be made smaller. [Means for solving the problem]

[0006] An antenna according to one aspect of the present invention includes a dielectric, a radiation conductor disposed on a first principal surface side of the dielectric, and a ground conductor disposed on a second principal surface side of the dielectric, the ground conductor having a length L in a first direction. G1 , and the length in the second direction L G2 When the wavelength in air of the radio wave transmitted and received by the radiation conductor is λ, G1 is 0.7×(λ / 2)≦L G1 ≦1.4×(λ / 2), and G2 is 0.7×(λ / 2)≦L G2 ≦1.4×(λ / 2), and when the ground conductor is divided into a first region and a second region by a virtual line connecting a virtual feed point, which is a projection of a feed point that feeds power to the radiation conductor in the thickness direction of the dielectric, and the center of gravity of the ground conductor in a planar view, the ground conductor has a first slit that starts from the outer edge of the ground conductor in the first region and extends toward the inside of the ground conductor, and an end of the first slit is located inside the outer edge of the ground conductor.

[0007] In the above antenna, the radiation conductor has a length L in the first direction. R1 , and the length L in the second direction R2 and the length L R1and the length L R2 That is, L R1 =L R2 may be satisfied.

[0008] In the above-described antenna, the ground conductor may have a quadrangular shape when viewed from above the dielectric.

[0009] In the above-described antenna, in a plan view of the dielectric, of the four sides constituting the ground conductor, the side closest to the virtual feed point is defined as a nearest side, and the side adjacent to the nearest side and including the outer edge of the first region is defined as a first side, and the length of the first side is defined as L G1 When this is the case, the first slit is located at the midpoint of the first side ±0.4×L G11 A position within the range may be used as the starting point.

[0010] In the above-described antenna, the outer periphery of the first slit is defined as D in a plan view of the ground conductor. S1 , where λ is the wavelength in air of the radio waves transmitted and received by the radiation conductor, 0.13×λ≦D S1 ≦0.45×λ may be satisfied.

[0011] In the above-described antenna, the ground conductor may have a second slit that starts from an outer edge of the ground conductor in the second region and extends toward an inside of the ground conductor.

[0012] In the above-described antenna, the ground conductor has a quadrangular shape in a plan view of the dielectric, and among the four sides constituting the ground conductor in the plan view of the dielectric, the side closest to the virtual feed point is defined as a nearest side, and the side adjacent to the nearest side and including the outer edge of the second region is defined as a second side, and the length of the second side is L G12 When this is the case, the second slit is located at the midpoint of the second side ±0.4×L G12 A position within the range may be used as the starting point.

[0013] In the above-described antenna, the outer periphery of the second slit is defined as D in a plan view of the ground conductor. S2, where λ is the wavelength in air of the radio waves transmitted and received by the radiation conductor, 0.13×λ≦D S2 The condition ≦0.45×λ may be satisfied.

[0014] In the above antenna, the outer periphery length D of the second slit S2 is the outer circumferential length D of the first slit S1 It may be approximately equal to

[0015] In the above-mentioned antenna, the ground conductor may have a third slit that extends toward the inside of the ground conductor, starting from a position between the starting point of the first slit and the starting point of the second slit, when viewed in a plane of the ground conductor.

[0016] In the above-described antenna, the ground conductor has a quadrangular shape in a plan view of the dielectric. Of the four sides constituting the ground conductor in the plan view of the dielectric, the side closest to the virtual feed point is defined as a nearest side, the side opposite to the nearest side is defined as a third side, and the length of the third side is L. G13 When this is the case, the third slit is located at the midpoint of the third side ±0.4×L G13 A position within the range may be used as the starting point.

[0017] In the above-described antenna, the outer periphery of the third slit is defined as D in a plan view of the ground conductor. S3 , where λ is the wavelength in air of the radio waves transmitted and received by the radiation conductor, 0.13×λ≦D S3 The condition ≦0.45×λ may be satisfied.

[0018] In the above antenna, the outer periphery length D of the third slit S3 is the outer circumferential length D of the first slit S1 and the outer circumferential length D of the second slit S2 It may be approximately equal to

[0019] In the above antenna, the radiation conductor may have a quadrangular shape when viewed from above the dielectric, and may have a first notch and a second notch at two diagonal corners of the four corners.

[0020] In the above antenna, the radiation conductor may be capable of transmitting and receiving linearly polarized waves.

[0021] In the above antenna, the radiation conductor may be capable of transmitting and receiving circularly polarized waves.

[0022] A vehicle antenna device according to a first aspect of the present invention comprises the above-described antenna in which a radiating conductor is capable of transmitting and receiving linearly polarized waves, the antenna being attached to a vehicle, and the radiating conductor being installed so that its normal direction is at an angle of 30° or less with respect to the direction of travel of the vehicle.

[0023] In the above-described vehicle antenna device, the antenna may be installed on the passenger compartment side, facing the windshield.

[0024] A second aspect of the present invention provides a vehicle antenna device comprising the above-described antenna in which a radiating conductor is capable of transmitting and receiving circularly polarized waves, the antenna being mounted on a vehicle, and the radiating conductor being installed such that its normal direction is at an angle of 30° or less with respect to the vertical direction.

[0025] In the above-described vehicle antenna device, the antenna may be installed on the passenger compartment side, facing the roof glass. [Effects of the Invention]

[0026] According to one aspect of the present invention, it is possible to provide an antenna and a vehicle antenna device that can be made smaller. [Brief explanation of the drawings]

[0027] [Figure 1] FIG. 2 is a plan view of the antenna according to Example 1. [Figure 2] FIG. 2 is a cross-sectional view of an antenna according to Example 1. [Figure 3] FIG. 2 is a bottom view of the antenna according to Example 1. [Figure 4] 10 is a diagram showing the relationship between the outer periphery of a slit, the wavelength of radio waves transmitted and received by a radiation conductor, and the FB ratio. FIG. [Figure 5]FIG. 10 is a plan view of an antenna according to Example 2. [Figure 6] FIG. 10 is a cross-sectional view of an antenna according to Example 2. [Figure 7] FIG. 10 is a bottom view of the antenna according to Example 2. [Figure 8] FIG. 10 is a bottom view of the antenna according to Example 3. [Figure 9] FIG. 10 is a cross-sectional view of an antenna according to Example 4. [Figure 10] FIG. 10 is a bottom view of the antenna according to Example 4. [Figure 11] FIG. 2 is a top view of the vehicle. [Figure 12] FIG. 10 is a front view of an antenna according to Example 5. [Figure 13] FIG. 10 is a cross-sectional view of an antenna according to Example 5. [Figure 14] FIG. 10 is a cross-sectional view of an antenna according to Example 6. [Figure 15] FIG. 10 is a cross-sectional view of an antenna according to Example 7. [Figure 16] FIG. 10 is a diagram for explaining the effect of a slit. [Figure 17] FIG. 2 is a top view of the vehicle. [Figure 18] FIG. 10 is a bottom view of the antenna according to Example 2A. DETAILED DESCRIPTION OF THE INVENTION

[0028] Specific embodiments to which the present invention is applied will be described in detail below with reference to the drawings. For clarity of explanation, the following description and drawings have been omitted and simplified as appropriate. In each drawing, the same elements are given the same reference numerals, and duplicate explanations are omitted as necessary. In each embodiment, deviations in directions such as parallel, horizontal, and vertical are permitted to the extent that they do not impair the effects of the present invention. Furthermore, in drawings used to explain the embodiments, unless otherwise specified, directions refer to directions on the drawings.

[0029] (First embodiment) [Example 1] A configuration example of an antenna 10 according to Example 1 of the first embodiment will be described with reference to Figures 1 to 3. Figure 1 is a plan view of the antenna 10 according to Example 1. Figure 2 is a cross-sectional view of the antenna 10 according to Example 1, taken along the cutting line II-II in Figure 1. Figure 3 is a bottom view of the antenna 10 according to Example 1. As shown in Figures 1 to 3, the antenna 10 includes a radiation conductor 11, a connecting conductor 12, a dielectric 13, and a ground conductor 14.

[0030] First, referring to FIG. 2, an example configuration of the antenna 10 will be described. The radiating conductor 11 is provided on a first principal surface, which is the principal surface (xy plane) on the positive side of the z-axis of the dielectric 13. The radiating conductor 11 is capable of transmitting and receiving radio waves in a predetermined frequency band. The predetermined frequency band may be a frequency band from 4G LTE (Long Term Evolution) to 5G, for example, a frequency band from 700 MHz to 6 GHz (so-called sub6), but is not limited thereto. That is, the predetermined frequency band may be a frequency band less than 700 MHz or a frequency band above 6 GHz, such as the 28 GHz band or a frequency band above 30 GHz known as a millimeter wave, such as the 79 GHz band. Furthermore, the radiating conductor 11 of the antenna 10 according to Example 1 is capable of transmitting and receiving linearly polarized waves, including vertically polarized waves and horizontally polarized waves. In particular, the antenna 10 is applicable to dedicated narrowband communications known as DSRC (Dedicated Short Range Communications).

[0031] The radiation conductor 11 is connected to a connecting conductor 12 arranged in the thickness direction of the dielectric 13. The radiation conductor 11 is provided with a feeding point 12a for feeding power to the radiation conductor 11. The radiation conductor 11 is connected at the feeding point 12a to a transmission line (not shown) for feeding power to the radiation conductor 11 via the connecting conductor 12 extending in the thickness direction. The transmission line is typically a coaxial cable, but is not limited to a coaxial cable and may be a microstrip line, a strip line, a coplanar waveguide, a GCPW (coplanar waveguide with ground plane), a coplanar strip, a slot line, a waveguide, or the like.

[0032] The dielectric 13 may be made of ceramic, resin, glass, or air. As described above, the radiating conductor 11 is provided on the first main surface of the dielectric 13. The ground conductor 14 is provided on the second main surface (xy plane) of the dielectric 13, which is the main surface opposite to the first main surface. When the dielectric 13 is air, the first main surface of the dielectric 13 refers to the xy plane that is flush with the radiating conductor 11, and the second main surface of the dielectric 13 refers to the xy plane that is flush with the ground conductor 14. When the dielectric 13 is air, the radiating conductor 11 and the ground conductor 14 may be fixed by a support (not shown). Furthermore, when the dielectric 13 is air, it is sufficient that a transmission line (not shown) is connected to the feed point 12a. Therefore, for example, the core wire of a coaxial cable may be directly connected to the feed point 12a, and the connecting conductor 12 may not be provided.

[0033] Furthermore, in this specification, when the dielectric 13 does not contain air, it can be visualized as a substrate, and therefore it is referred to as a "dielectric substrate 13" in addition to the "dielectric 13." Furthermore, the relationship between the "dielectric 23" and the "dielectric substrate 23," which will be described later, is similar. In this manner, the ground conductor 14 is disposed opposite the radiating conductor 11 via the dielectric 13. Inside the dielectric 13, the connecting conductor 12 is provided in the thickness direction corresponding to the feeding point 12a of the radiating conductor 11. Note that the dielectric 13 may have the same shape as or a different shape from the radiating conductor 11 in a planar view. Furthermore, the dielectric 13 may have the same shape as or a different shape from the ground conductor 14 in a planar view.

[0034] The ground conductor 14 is a conductor that forms a ground plane. The ground conductor 14 is configured to be connectable to a transmission line (not shown) that feeds power to the radiating conductor 11 at point 12b, which is a position facing the feed point 12a across the dielectric 13. Point 12b is a point facing the feed point 12a provided on the radiating conductor 11 across the dielectric 13, and is a point obtained by projecting the feed point 12a that feeds power to the radiating conductor 11 in the thickness direction of the dielectric 13. In the following description, point 12b will be referred to as a virtual feed point 12b.

[0035] Next, the radiating conductor 11 will be described with reference to FIG. 1. The radiating conductor 11 may be a planar conductor, or may be a substantially planar conductor having at least one of a convex portion and a concave portion including a component in the z-axis direction in a part of the radiating conductor 11, or may be a substantially planar conductor having a bent portion including a component in the z-axis direction. The radiating conductor 11 may be quadrangular in plan view, for example, rectangular or trapezoidal. The radiating conductor 11 may also be polygonal in plan view, or may be any shape having a curved outer edge, such as a circle or an ellipse. The radiating conductor 11 has a length L in the positive x-axis direction, which is a first direction, in plan view of the dielectric 13. R1 [mm], the length in the negative y-axis direction, which is the second direction perpendicular to the first direction, is length L R2 In the following description, unless otherwise specified, the radiating conductor 11 will be described as a planar conductor having the same shape as the rectangular area in which it is arranged. Specifically, the radiating conductor 11 has two sides each having a length L R1 and the lengths of the other two sides are length L R2 The following description will be given assuming that the conductor is a rectangular plane conductor.

[0036] Next, the ground conductor 14 will be described with reference to Fig. 3. The ground conductor 14 has a virtual feed point 12b formed at a position opposite the feed point 12a. A hole having an area larger than the area of ​​the connecting conductor 12 is formed in the ground conductor 14 in a plan view of the ground conductor 14 so that the ground conductor 14 does not come into contact with the connecting conductor 12. The ground conductor 14 also has a slit 15 extending toward the inside of the ground conductor 14. The slit 15 corresponds to a region that does not include a conductor in a plan view of the ground conductor 14. In other words, the interior of the slit 15 is a region that does not include a conductor in a plan view of the ground conductor 14.

[0037] The ground conductor 14 may be a planar conductor, or may be a substantially planar conductor having at least one of a convex portion and a concave portion including a component in the z-axis direction in a part of the ground conductor 14, or may be a substantially planar conductor having a bent portion including a component in the z-axis direction. The ground conductor 14 may be quadrangular in plan view, for example, rectangular or trapezoidal. The ground conductor 14 may also be polygonal in plan view, or may have any shape with a curved outer edge, such as a circle or an ellipse. The shape of the ground conductor 14 may be the same as or different from the shape of the radiating conductor 11 in plan view of the dielectric 13. The ground conductor 14 has a length L in the positive x-axis direction, which is the first direction. G1 [mm], and the length in the negative y-axis direction, which is the second direction perpendicular to the first direction, is L G2 In the following description, unless otherwise specified, the ground conductor 14 will be described as a planar conductor having the same shape as the rectangular area in which it is placed. Specifically, the ground conductor 14 has two sides with lengths L G1 and the lengths of the other two sides are L G2 The following description will be given assuming that the conductor is a rectangular plane conductor.

[0038] The ground conductor 14 has a wavelength in the air of the radio wave transmitted and received by the radiation conductor 11 (antenna 10) of 0.7×(λ / 2)≦L G1 ≦1.4×(λ / 2), and 0.7×(λ / 2)≦L G2 It is recommended that the value satisfy the following: L ≦1.4×(λ / 2) G1 is 0.8×(λ / 2)≦L G1 ≦1.3×(λ / 2), and 0.9×(λ / 2)≦L G1 It is more preferable that the value satisfies the condition L≦1.2×(λ / 2). G2 is 0.8×(λ / 2)≦L G2 ≦1.3×(λ / 2), and 0.9×(λ / 2)≦L G2 It is more preferable that the relationship be ≦1.2×(λ / 2).

[0039] The ground conductor 14 is 0.7 x L R1 ≦L G1 ≦1.4×L R1 and 0.7 x LR2 ≦L G2 ≦1.4×L R2 It is advisable to place it in a rectangular area that satisfies the following. R1 and length L R2 That is, L R1 =L R2 In general patch antennas such as those disclosed in Patent Documents 1 and 2, the area of ​​the ground conductor 14 is more than 1.3 times the area of ​​the radiating conductor 11. In contrast, in the antenna 10 according to Example 1, the ground conductor 14 is provided with the slit 15, so that the area of ​​the ground conductor 14 can be made smaller than that of the patch antennas disclosed in Patent Documents 1 and 2.

[0040] Also, L R1 =L R2 Under the condition that the relationship is satisfied, the ground conductor 14 is 0.8×L R1 ≦L G1 ≦1.3×L R1 and 0.8 x L R2 ≦L G2 ≦1.3×L R2 It is preferable that the pixel is arranged in a rectangular area that satisfies L R1 =L R2 Under the condition that the relationship is satisfied, the ground conductor 14 is 0.9××L R1 ≦L G1 ≦1.2×L R1 and 0.9 x L R2 ≦L G2 ≦1.2×L R2 It is more preferable that the image is arranged in a rectangular area that satisfies the following formula.

[0041] Before describing the slit 15 in detail, the terminology used below will be explained. First, in order to explain the position of the slit 15, virtual regions are defined by virtually dividing the area of ​​the ground conductor 14. Specifically, the ground conductor 14 is virtually divided by a virtual line L1 connecting (the center of) the virtual feed point 12b and the center of gravity C1 of the ground conductor 14 in a planar view, and the divided regions are defined as a first region and a second region, respectively. Explaining this with reference to FIG. 3, the region of the ground conductor 14 located in the positive y-axis direction from the virtual line L1 is defined as the first region, and the region located in the negative y-axis direction from the virtual line L1 is defined as the second region. Note that the region located in the negative y-axis direction from the virtual line L1 may be defined as the first region, and the region located in the positive y-axis direction from the virtual line L1 may be defined as the second region.

[0042] Next, of the four sides constituting the ground conductor 14, the side closest to the virtual feed point 12b is defined as the nearest side. Also, the side adjacent to the nearest side and including the outer edge of the first region is defined as the first side, the side adjacent to the nearest side and including the outer edge of the second region is defined as the second side, and the side opposite to the nearest side is defined as the third side. In the following description, the length of the first side is defined as L G11 [mm], and the length of the second side is L G12 [mm], and the length of the third side is L G13 3, of the four sides S1 to S4 that make up the ground conductor 14, the side closest to the virtual feed point 12b is side S4, and therefore side S4 is the nearest side. The first side is side S1, which is adjacent to side S4 and includes the outer edge of the first region. The second side is side S2, which is adjacent to side S4 and includes the outer edge of the second region. The third side is side S3, which is opposite to nearest side S4. Furthermore, when the ground conductor 14 has the same shape as the rectangular region described above, the length L G11 is the length L G1 and the length L G12 is the length L G1 and the length L G13 is the length L G2 is.

[0043] The slit 15 is formed in the ground conductor 14 so as to start from the outer edge of the ground conductor 14 in the first region and extend toward the inside of the ground conductor 14. The slit 15 is also formed in the ground conductor 14 so that the end of the slit 15 opposite the start point is located inside the outer edge of the ground conductor 14. The end of the slit 15 opposite the start point may be located in the first region, the second region, or the boundary between the first and second regions. For example, when the end of the slit 15 opposite the start point is located in the second region, the length of the slit 15 is set to L S1 [mm], the length L S1 is the length L G2 The starting point of the slit 15 may be formed in the ground conductor 14 so that the length is shorter than the midpoint of the first side S1 ±0.4×L G11 It can be anywhere within the range, and is the midpoint of side S1 ±0.1 × L G11 The shape of the slit 15 may be a triangle, a square, or any other shape including a polygon. Furthermore, each side of the slit 15 may be straight, curved, or wavy, and may have a meander shape including a bent portion. In the following description, the slit 15 will be described as having a rectangular shape.

[0044] The slit 15 has a circumferential length D in a plan view of the ground conductor 14. S1 [mm] and the wavelength in air of the radio waves transmitted and received by the radiation conductor 11 is λ [mm], the radiation conductor 11 is formed on the ground conductor 14 so as to satisfy the following formula (1a). 0.13×λ≦D S1 ≦0.45×λ (1a)

[0045] Also, length D S1 [mm] preferably satisfies the following formula (1b), and more preferably satisfies formula (1c). 0.19×λ≦D S1 ≦0.39×λ (1b) 0.24×λ≦D S1 ≦0.34×λ (1c)

[0046] The outer circumferential length of the slit 15 is the length indicated by the thick arrow in FIG. For example, as shown in FIG. 3, when the shape of the slit 15 is rectangular, the width of the slit 15 is W S1 [mm], the outer perimeter D S1 2 x L S1 +2×W S1 It is calculated as follows.

[0047] Next, the peak antenna gain of the antenna 10 according to Example 1 will be described. The peak antenna gain of the antenna 10 according to Example 1 and the peak antenna gain of a configuration in which the slit 15 is not provided in the antenna 10 according to Example 1 were obtained by simulation. Note that the configuration in which the slit 15 is not provided in the ground conductor 14 of the antenna 10 according to Example 1 will be described as "default configuration 1." Furthermore, in the simulation, calculations are performed assuming that the dielectric 13 is air, and in other simulations described later, calculations are also performed assuming that the dielectric 13 (dielectric 23) is air unless otherwise specified.

[0048] In order to calculate the peak antenna gain, the wavelength λ in air of the radio waves transmitted and received by the antenna 10 and the default configuration 1 was set to 190 mm (frequency: 1.575 GHz). The length L of the radiation conductor 11 of the antenna 10 and the default configuration 1 was set to R1 and length L R2 was set to 74 mm, and the length of each side of the ground conductor 14 of the antenna 10 and the default configuration 1 was set to 74 mm. S1 Set to 24.6mm and width W S1 was set to 1.5 mm. The thickness of the dielectric 13 (air) was set to 1 mm.

[0049] In this case, the peak antenna gain of the antenna 10 was 7.5 dBi, while the peak antenna gain of the default configuration 1 was 4.0 dBi. If the ground conductor 14 is configured so that its area is approximately equal to that of the radiating conductor 11, as in the default configuration 1, the peak antenna gain will be reduced. In other words, if the area of ​​the ground conductor of the patch antennas disclosed in Patent Documents 1 and 2 is reduced and configured as in the default configuration 1, the peak antenna gain will be reduced. In contrast, the peak antenna gain of the antenna 10 does not decrease, as in the case of conventional patch antennas. In other words, because the ground conductor 14 of the antenna 10 has the slit 15, the reduction in peak antenna gain can be suppressed even if the area of ​​the ground conductor 14 is reduced.

[0050] Next, the transmission and reception performance of the antenna 10 according to Example 1 will be described. In this specification, the transmission and reception performance of the antenna 10 will be described using the FB (Front-Back) ratio of the antenna 10. The FB ratio is an index value indicating the radiation power ratio [dB] between the radio wave radiation direction (Front direction) of the antenna 10 and the direction opposite to the radio wave radiation direction of the antenna 10 (Back direction). The FB ratio of the antenna 10 was obtained by simulating the gain [dBi] in the radio wave radiation direction (Front direction) of the antenna 10 and the gain [dBi] in the direction opposite to the radio wave radiation direction of the antenna 10 (Back direction). In the following description, the FB ratio will also be referred to as the FB ratio.

[0051] Here, the FB ratio of the antenna 10 was 9.4 dB, while the FB ratio of the default configuration 1 was 0 dB. If the ground conductor 14 is configured so that its area is approximately equal to that of the radiation conductor 11, as in the default configuration 1, radio waves are radiated in the back direction with approximately the same power as in the front direction. In other words, in the case of a conventional patch antenna, if the area of ​​the ground conductor is reduced and default configuration 1 is used, radio waves are radiated in the back direction with approximately the same power as in the front direction. In contrast, the FB ratio of the antenna 10 is greater than that of the default configuration 1, and therefore radio waves can be radiated in the front direction with higher power than in the default configuration 1. That is, since the ground conductor 14 of the antenna 10 includes the slit 15, a high FB ratio can be achieved even if the area of ​​the ground conductor 14 is reduced, and radio waves can be radiated in the front direction with high power. This is because the ground conductor 14 has the slit 15, and the path through which current flows is lengthened by approximately the outer periphery of the slit 15.

[0052] Next, the relationship between the perimeter of the slit 15 of the antenna 10, the wavelength of the radio wave transmitted and received by the radiation conductor 11 of the antenna 10, and the FB ratio of the antenna 10 will be described with reference to Fig. 4. The horizontal axis of Fig. 4 is the perimeter D of the slit 15. S1 is normalized by the wavelength λ (in air) of the radio wave transmitted and received by the radiation conductor 11, and the vertical axis represents the FB ratio of the antenna 10. S1 When the value normalized by the wavelength λ is in the range of 0.13 to 0.45, the FB ratio is 1 or more. S1 However, by satisfying the formula (1a) in relation to the wavelength λ, radio waves can be emitted with higher power in the front direction than in the back direction. S1 However, the FB ratio is improved by satisfying formula (1b), and the FB ratio is improved even more by satisfying formula (1c).

[0053] As described above, by providing the ground conductor 14 with the slit 15, it is possible to suppress a decrease in peak antenna gain and achieve a high FB ratio, compared to conventional patch antennas, even if the area of ​​the ground conductor 14 is reduced. In other words, by providing the ground conductor 14 with the slit 15, it is possible to achieve a peak antenna gain and a high FB ratio equivalent to those of conventional patch antennas that do not have the slit 15, and it is also possible to reduce the area of ​​the ground conductor 14. Therefore, the antenna 10 of Example 1 can be made smaller.

[0054] [Example 2] Next, Example 2, which is a modification of Example 1, will be described with reference to FIGS. 5 to 7. FIG. 5 is a plan view of antenna 20 according to Example 2. FIG. 6 is a cross-sectional view of antenna 20 according to Example 2, taken along line VI-VI in FIG. 5. FIG. 7 is a bottom view of antenna 20 according to Example 2. As shown in FIGS. 5 to 7, antenna 20 includes a radiation conductor 21, a connecting conductor 12, a dielectric 23, and a ground conductor 24. Note that antenna 20 has a configuration basically similar to that of antenna 10 according to Example 1, and therefore will not be described further as appropriate.

[0055] First, a configuration example of the antenna 20 will be described with reference to Fig. 6. The radiating conductor 21 is disposed on a first main surface of the dielectric 23. The ground conductor 24 is disposed on a second main surface of the dielectric 23. As shown in Fig. 5, the radiating conductor 21 is a planar conductor with a circular shape.

[0056] Next, the ground conductor 24 will be described with reference to FIG. 7 . The ground conductor 24 is a circular planar conductor. Like the ground conductor 14, the ground conductor 24 may be a substantially planar conductor having at least one of a convex portion and a concave portion including a z-axis component in a portion of the ground conductor 24, or a substantially planar conductor having a bent portion including a z-axis component in a portion of the ground conductor 24. The ground conductor 24 has a slit 25 extending toward the inside of the ground conductor 24. The concept of dividing the first region and the second region is the same as in Example 1. The slit 25 is formed in the ground conductor 24 so as to start from the outer edge of the ground conductor 24 in the first region and extend toward the inside of the ground conductor 24. The end of the slit 25 opposite the starting point of the slit 25 is located inside the outer edge of the ground conductor 24. The end of the slit 25 opposite the starting point of the slit 25 may be located within either the first region or the second region.

[0057] In the antenna 20 of Example 2, the ground conductor 24 has a slit 25, similar to the antenna 10 of Example 1. Therefore, similar to the antenna 10 of Example 1, the antenna 20 of Example 2 can suppress a decrease in peak antenna gain, achieve a high FB ratio, and further reduce the area of ​​the ground conductor 24. In other words, similar to the antenna 10 of Example 1, the use of the antenna 20 of Example 2 allows miniaturization to be achieved.

[0058] [Example 2A] Next, an antenna 20A of Example 2A, which corresponds to a modified example of Example 2, will be described using Fig. 5 and Fig. 6, which are common to Example 2, and Fig. 18 of Example 2A. Note that Fig. 5 and Fig. 6 are similar to those of Example 2 and have basically the same configuration as the antenna 20 according to Example 2, so they will be omitted as appropriate and described with reference to Fig. 18.

[0059] The ground conductor 54 is a circular planar conductor. Similar to the ground conductor 14, the ground conductor 54 may be a substantially planar conductor having at least one of a convex portion and a concave portion including a z-axis component, or a substantially planar conductor having a bent portion including a z-axis component. The ground conductor 54 has slits 55 and 65 extending toward the inside of the ground conductor 54. The concept of dividing the first and second regions is the same as in Example 1. The slits 55 are formed in the ground conductor 54 so as to start from the outer edge of the ground conductor 54 in the first region and extend toward the inside of the ground conductor 54. The slits 65 are formed in the ground conductor 54 so as to start from the outer edge of the ground conductor 54 in the second region and extend toward the inside of the ground conductor 54. The longitudinal extension directions of the slits 55 and 65 are perpendicular to the virtual line L1 and are aligned along a line passing through the center of gravity C1.

[0060] To calculate the peak antenna gain, the wavelength (in air) of the radio waves transmitted and received by antenna 20A was set to 176 mm (frequency: 1.7 GHz). The peak antenna gain of antenna 20A according to Example 2A and the peak antenna gain of a configuration in which slits 55 and slits 65 are not provided in antenna 20A according to Example 2A were determined by simulation. Note that the configuration in which slits 55 and slits 65 are not provided in ground conductor 54 in antenna 20A according to Example 2A will be referred to as "default configuration 1A" in the following description.

[0061] In Example 2A, the length L of the antenna 20A and the radiating conductor 21 of the default configuration 1A R1 and length L R2 The length of each side of the ground conductor 54 of the antenna 20A and the default configuration 1A was also set to 90 mm. S1 24.6mm, width W S1 is set to 1.48 mm, and the length of slit 65, L S2 24.6mm, width W S2 was set to 1.48 mm, and the thickness of the dielectric 13 (air) was set to 6.5 mm.

[0062] Here, the FB ratio of the antenna 20A was 8.5 dB, while the FB ratio of the default configuration 1A was 0 dB. If the ground conductor 54 is configured so that its area is approximately equal to that of the radiation conductor 11, as in the default configuration 1A, radio waves are radiated in the back direction with approximately the same power as in the front direction. In the case of a conventional patch antenna, if the area of ​​the ground conductor is reduced to be as in the default configuration 1A, radio waves are radiated in the back direction with approximately the same power as in the front direction. In contrast, the FB ratio of the antenna 20A is greater than that of the default configuration 1A, and therefore radio waves can be radiated in the front direction with higher power than in the default configuration 1A. That is, since the ground conductor 54 of the antenna 20A includes the slits 55 and 65, a high FB ratio can be achieved and radio waves can be radiated in the front direction with high power even if the area of ​​the ground conductor 54 is reduced.

[0063] [Example 3] Next, Example 3 will be described. Example 3 is an example of an antenna different from Examples 1 and 2, and a configuration example of an antenna 30 according to Example 3 will be described using FIG. 8. FIG. 8 is a bottom view of the antenna 30 according to Example 3. The antenna 30 according to Example 3 has a configuration in which the ground conductor 14 of the antenna 10 according to Example 1 is replaced with a ground conductor 34. The antenna 30 according to Example 3 includes, in addition to the ground conductor 34, a radiating conductor 11, a connecting conductor 12, and a dielectric 13, similar to the antenna 10 according to Example 1. Note that the front view and cross-sectional view of the antenna 30 are the same as those in FIGS. 1 and 2, and the radiating conductor 11 and the dielectric 13 are similar to those in the antenna 10 according to Example 1, and therefore their description will be omitted. Furthermore, the ground conductor 34 basically has the same configuration as the ground conductor 14, and therefore, description of parts common to the ground conductor 14 will be omitted as appropriate.

[0064] The ground conductor 34 includes a slit 15 and a slit 35. The slit 35 may be referred to as a second slit. The slit 15 (first slit) is similar to that of the antenna 10 according to Example 1, and therefore a description thereof will be omitted.

[0065] The slit 35 is formed in the ground conductor 34 so as to start from the outer edge of the ground conductor 34 in the second region and extend toward the inside of the ground conductor 34. The slit 35 is also formed in the ground conductor 34 so that the end opposite to the starting point of the slit 35 is located inside the outer edge of the ground conductor 34. Here, the length of the (rectangular) slit 35 is L S2 [mm], the slit 35 has a length L S2 But the length L G2 The starting point of the slit 35 may be formed in the ground conductor 34 so that the starting point is shorter than the midpoint of the side S2, which is the second side, ±0.4×L G12 It can be anywhere within the range, and is the midpoint of side S2 ±0.1 × L G12 The position within the range is also acceptable. Length L G12 is the length of side S2, which is the second side. The shape of slit 35 may be a rectangle or any other shape. Furthermore, each side of slit 35 may be a straight line, or may include a curved or wavy line in part, and may be, for example, a meander shape including a bent portion. In the following description, slit 35 will be described as being rectangular.

[0066] Length of slit 35 L S2 is the length L of the slit 15 S1 The length L may be approximately equal to or different from the length L. S2 But 0.95 x L S1 ≦L S2 ≦1.05×L S1 The width W of the slit 35 may be satisfied. S2 [mm] is the width W of slit 15 S1 The width W may be approximately equal to or different from the width W. S2 But 0.95 x W S1 ≦W S2 ≦1.05×W S1 The outer circumferential length D of the slit 35 may be S2 [mm] is the outer periphery length D of the slit 15 S1 The term "approximately equal" means that the outer circumferential length D of the slit 35 is equal to or different from the outer circumferential length D of the slit 35. S2 But 0.9 x D S1 ≦D S2≦1.1×D S1 The outer periphery of the slit 35 is the length indicated by the thick dashed arrow in Fig. 7. For example, as shown in Fig. 7, when the shape of the slit 35 is rectangular, the width of the slit 35 is set to W S2 Then, the perimeter D S2 2 x L S2 +2×W S2 It is calculated as follows.

[0067] The slit 35 has a circumferential length D in plan view of the ground conductor 34. S2 [mm] and the wavelength in air of the radio waves transmitted and received by the radiation conductor 11 is λ [mm], the radiation conductor 11 is formed on the ground conductor 34 so as to satisfy the following formula (2a). 0.13×λ≦D S2 ≦0.45×λ (2a)

[0068] Also, length D S2 [mm] preferably satisfies the following formula (2b), and more preferably satisfies formula (2c). 0.19×λ≦D S2 ≦0.39×λ (2b) 0.24×λ≦D S2 ≦0.34×λ (2c)

[0069] Next, we will explain the peak antenna gain of the antenna 30 according to Example 3. The peak antenna gain of the antenna 30 according to Example 3 was evaluated by comparing it with the peak antenna gain of the default configuration 1. The peak antenna gains of the antenna 30 according to Example 3 and the default configuration 1 were obtained by simulation.

[0070] The simulation conditions were the same as in Example 1, and in order to calculate the peak antenna gain, the wavelength λ (in air) of the radio waves transmitted and received by the antenna 30 and the default configuration 1 was set to 190 mm (frequency: 1.575 GHz). The length L of the radiation conductor 11 of the antenna 30 and the default configuration 1 was set to R1 and length L R2was set to 74 mm, and the length of each side of the antenna 30 and the ground conductor 14 of the default configuration 1 was set to 74 mm. S1 Set to 24.6mm and width W S1 The length L of the slit 35 of the antenna 30 was set to 1.5 mm. S2 Set to 24.6mm and width W S2 was set to 1.5 mm. The thickness of the dielectric 13 (air) was set to 1 mm.

[0071] The peak antenna gain of the antenna 30 was 7.5 dBi, and the peak antenna gain of the default configuration 1 was 4.0 dBi. As with the antenna 10 according to Example 1, the antenna 30 can suppress a decrease in peak antenna gain.

[0072] Next, the transmission and reception performance of the antenna 30 according to Example 3 will be described using the FB ratio. The FB ratios of the antenna 30 and default configuration 1 were determined by simulation. The simulation conditions for the antenna 30 and default configuration 1 were the same as those used to determine the peak antenna gain. The FB ratio of the antenna 30 was 21.1 dB, and the FB ratio of the default configuration 1 was 0 dB. Since the FB ratio of the antenna 30 is greater than that of the default configuration 1, it can radiate radio waves with higher power in the front direction than the default configuration 1. Furthermore, since the FB ratio of the antenna 10 according to Example 1 is 9.4 dB, the antenna 30 can radiate radio waves with higher power in the front direction than the antenna 10 according to Example 1. This is because the ground conductor 34 has not only the slit 15 but also the slit 35, and therefore the path through which current flows is longer than that of the antenna 10 according to Example 1 by approximately the outer periphery of the slit 35. That is, the ground conductor 34 has the slit 15 and the slit 35, which makes it possible to achieve a peak antenna gain and a high F-to-B ratio equivalent to those of the patch antennas disclosed in Patent Documents 1 and 2, and furthermore, to reduce the area of ​​the ground conductor 34. Furthermore, the ground conductor 34 has the slit 15 and the slit 35, which makes it possible to radiate radio waves in the front direction with higher power than the antenna 10 according to Example 1. Therefore, the antenna 30 according to Example 3 can be miniaturized and can radiate radio waves with high power in the desired radio wave radiation direction.

[0073] [Example 4] Next, Example 4 will be described. Example 4 is an example of an antenna different from Examples 1 to 3, and a configuration example of antenna 40 according to Example 4 will be described with reference to Fig. 9. Fig. 9 is a cross-sectional view taken along the boundary (imaginary line L1) between the first and second regions of antenna 40 according to Example 4. FIG. 10 is a bottom view of the antenna 40 according to Example 4. The antenna 40 according to Example 4 has a configuration in which the ground conductor 34 of the antenna 30 according to Example 3 is replaced with a ground conductor 44. As shown in FIG. 9, the antenna 40 according to Example 4 includes, in addition to the ground conductor 44, a radiation conductor 11, a connecting conductor 12, and a dielectric 13, similar to the antenna 30 according to Example 3. The front view of the antenna 40 is the same as FIG. 1, and the radiation conductor 11 and the dielectric 13 are similar to those of the antenna 10 according to Example 1 and the antenna 30 according to Example 3, and therefore their explanations will be omitted. Furthermore, the ground conductor 44 basically has the same configuration as the ground conductor 34, and therefore explanations common to the ground conductor 34 will be omitted as appropriate.

[0074] As shown in Fig. 10, the ground conductor 44 has a slit 15, a slit 35, and a slit 45. The slit 45 may be referred to as a third slit. The slit 15 (first slit) and the slit 35 (second slit) are similar to those in the antenna 10 according to Example 1 and the antenna 30 according to Example 3, respectively, and therefore a description thereof will be omitted. In the example shown in Fig. 10, the ground conductor 44 has the slit 45 formed on the imaginary straight line L1. Therefore, as shown in Fig. 9, the length of the ground conductor 44 along the imaginary straight line L1 is shorter than the length of the radiation conductor 11.

[0075] The slit 45 is formed in the ground conductor 44 so as to extend from the third side as a starting point toward the inside of the ground conductor 44. The slit 45 is also formed in the ground conductor 44 so that the end of the slit 45 opposite to the starting point is located inside the outer edge of the ground conductor 44 (in this case, the nearest side). In other words, the length of the slit 45 is set to L S3 [mm], the slit 45 has a length L S3 But the length L G1 The starting point of the slit 45 is located at the midpoint of the third side S3 ±0.4×L G13 It can be anywhere within the range, and is the midpoint of side S3 ±0.1 × L G13 The position within the range is also acceptable. Length L G13 is the length of the side S3, which is the third side. The shape of the slit 45 may be a rectangle or any other shape. Furthermore, each side of the slit 45 may be a straight line, or may include a curved or wavy line in part, and may be, for example, a meander shape including a bent portion. In the following description, the slit 45 will be described as being rectangular.

[0076] Length of slit 45 L S3 is the length L of the slit 15 S1 and the length L of the slit 35 S2 The length L may be approximately equal to or different from the length L. S3 But 0.95 x L S1 ≦L S3 ≦1.05×L S1 It is also possible to satisfy 0.95 x LS2 ≦L S3 ≦1.05×L S2 The width W of the slit 45 may be satisfied. S3 [mm] is the width W of slit 15 S1 and the width W of the slit 35 S2 The width W may be approximately equal to or different from the width W. S3 But 0.95 x W S1 ≦W S3 ≦1.05×W S1 It is also possible to satisfy 0.95 × W S2 ≦W S3 ≦1.05×W S2 The outer circumferential length D of the slit 45 may be S3 [mm] is the outer periphery length D of the slit 15 S1 and the outer circumferential length D of the slit 35 S2 The term "approximately equal" means that the outer circumferential length D of the slit 45 is equal to or different from the outer circumferential length D of the slit 45. S3 But 0.9 x D S1 ≦D S3 ≦1.1×D S1 It is also possible to satisfy 0.9 × D S2 ≦D S3 ≦1.1×D S2 The circumferential length of the slit 45 is the length indicated by the thick dashed double-dashed arrow in Fig. 10. When the shape of the slit 45 is rectangular as shown in Fig. 10, the circumferential length D of the slit 45 is S3 2 x L S3 +2×W S3 It is calculated as follows.

[0077] The slit 45 has a circumferential length D S3 When the wavelength in the air of the radio waves transmitted and received by the radiation conductor 11 is λ [mm], the radiation conductor 11 is formed on the ground conductor 44 so as to satisfy the following formula (3a). 0.13×λ≦D S3 ≦0.45×λ (3a)

[0078] Also, length D S3 [mm] preferably satisfies the following formula (3b), and more preferably satisfies formula (3c). 0.19×λ≦D S3 ≦0.39×λ (3b) 0.24×λ≦D S3 ≦0.34×λ (3c)

[0079] Next, we will explain the peak antenna gain of antenna 40 according to Example 4. The peak antenna gain of antenna 40 according to Example 4 was evaluated by comparing it with the peak antenna gain of default configuration 1. The peak antenna gains of antenna 40 according to Example 4 and default configuration 1 were obtained by simulation.

[0080] In order to calculate the peak antenna gain, the wavelength λ (in air) of the radio waves transmitted and received by the antenna 40 and the default configuration 1 was set to 190 mm (frequency: 1.575 GHz). The length L of the radiation conductor 11 of the antenna 40 and the default configuration 1 was set to R1 and length L R2 was set to 74 mm, and the length of each side of the antenna 40 and the ground conductor 14 of the default configuration 1 was set to 74 mm. S1 Set to 24.6mm and width W S1 was set to 1.5 mm. The length L of the slit 35 of the antenna 40 S2 Set to 24.6mm and width W S2 The length L of the slit 45 of the antenna 40 was set to 1.5 mm. S3 Set to 24.6mm and width W S3 was set to 1.5 mm. The thickness of the dielectric 13 (air) was set to 1 mm.

[0081] The peak antenna gain of antenna 40 was 7.5 dBi, and the peak antenna gain of antenna 30 was 7.5 dBi. Thus, the peak antenna gain of antenna 40 is equivalent to that of antenna 30 in Example 3, and a decrease in the peak antenna gain can be suppressed.

[0082] Next, the transmission and reception performance of the antenna 40 according to Example 4 will be described using the FB ratio. The FB ratios of the antenna 40 and the default configuration 1 were calculated by simulation. The simulation conditions for the antenna 40 and the default configuration 1 were the same as those used to calculate the peak antenna gain. The FB ratio of the antenna 40 was 21.1 dB, and the FB ratio of the antenna 30 was 21.1 dB. Since the FB ratio of the antenna 40 is the same as that of the antenna 30, the antenna 40 can radiate radio waves with high power in the front direction, similar to the antenna 30. Furthermore, since the FB ratio of the default configuration 1 is 0 dB, the antenna 40 can radiate radio waves with higher power in the front direction than the antenna of the default configuration 1. As described above, the antenna 40 according to Example 4, because the ground conductor 44 has the slits 15, 35, and 45, can radiate radio waves with high power in the front direction, similar to the antenna 30 according to Example 3. Therefore, the antenna 40 according to Example 4 can be miniaturized and can radiate radio waves with high power in the desired radio wave radiation direction.

[0083] [Antenna installation example] Next, an example of mounting the antenna 40 according to Example 4 on the vehicle 110 will be described with reference to Fig. 11. Fig. 11 is a diagram showing the vehicle 110 as viewed from above. Note that Fig. 11 illustrates the antenna 40 according to Example 4, but the same mounting example may also be used when mounting the antennas 10 to 30 according to Examples 1 to 3 on the vehicle 110.

[0084] 11, vehicle 110 includes a metal body 111, a windshield 112, and a rear window 113. Vehicle 110 may be any vehicle of any shape. Vehicle 110 may also include at least one of fixed windows, such as side windows, front bench windows, rear quarter windows, and roof windows.

[0085] The antenna 40 is attached to the vehicle 110. When attached to the vehicle 110, the antenna 40 may be referred to as a vehicle antenna device. The antenna 40 is installed so that the normal direction of the radiation conductor 11 is at an angle of 30° or less with respect to the traveling direction of the vehicle 110. The normal direction of the radiation conductor 11 is the direction indicated by a line perpendicular to the plane of the radiation conductor 11, and is the radio wave radiation direction. When the plane of the radiation conductor 11 is the xy plane, the normal direction of the radiation conductor 11 is the positive direction of the z axis. Also, in FIG. 11 , the antenna 40 is installed on the passenger compartment side of the vehicle 110, facing the windshield 112. It is preferable that the antenna 40 be installed so that the normal direction of the radiating conductor 11 is at an angle of 15° or less relative to the direction of travel of the vehicle 110, more preferably at an angle of 10° or less, even more preferably at an angle of 5° or less, particularly preferably at an angle of 3° or less, and most preferably at an angle of 0°.

[0086] The antenna 40 is disposed near the windshield 112 located in front of the vehicle 110 in the traveling direction, and is installed so that the normal direction of the radiation conductor 11 is at an angle of 30° or less with respect to the traveling direction of the vehicle 110. Therefore, if the antenna 40 is, for example, a V2X antenna using the 5.9 GHz band, it can receive many radio waves from a communication device (not shown) that is facing the vehicle 110. Also, if the antenna 40 is, for example, a Wi-Fi antenna using the 2.4 GHz band or the 5 GHz band, radio waves transmitted from the communication device are reflected by the ground, buildings, etc., and reach the antenna 40 as multiple radio waves due to multipath. By disposing the antenna 40 on the passenger compartment side facing the windshield 112 located in front of the vehicle 110 in the traveling direction, it may be possible to receive more radio waves than if the antenna 40 were disposed on the rear window 113. Also, as described above, the antenna 40 can be made smaller than conventional patch antennas by providing the slits 15, 35, and 45. In particular, even when the antenna 40 (vehicle antenna device) is attached to the vehicle 110, the degree of freedom in placement can be increased in a position on the windshield 112 that does not obstruct the field of view of the occupants. The antenna 40 is not limited to being placed only near the windshield 112, but may also be placed only near the rear window 113, or multiple antennas may be placed near both. Furthermore, when the antenna 40 is provided near the windshield 112 or the rear window 113, the antenna's miniaturization makes it easier to conceal it within an area of ​​a visible light blocking film coated with black ceramics or the like (not shown).

[0087] 11, only the antenna 40 according to Example 4 is attached to the vehicle 110, but the antennas 10 to 30 according to Examples 1 to 3 may be attached to the vehicle 110 instead of the antenna 40 according to Example 4. Alternatively, in addition to the antenna 40 according to Example 4, at least one of the antennas 10 to 30 according to Examples 1 to 3 may be further attached to the vehicle 110.

[0088] (Second embodiment) Next, a second embodiment will be described. In the first embodiment, the antennas 10 to 40 are antennas capable of transmitting and receiving linearly polarized waves due to the shape of the radiation conductor 11. The antenna according to the second embodiment is an antenna capable of transmitting and receiving circularly polarized waves.

[0089] [Example 5] An example of the configuration of an antenna 50 according to Example 5 will be described with reference to FIGS. 12 and 13. FIG. 12 is a front view of the antenna 50 according to Example 5. FIG. 13 is a cross-sectional view of the antenna 50 according to Example 5, taken along the section line XIII-XIII in FIG. 12. The antenna 50 according to Example 5 has a configuration in which the radiating conductor 11 of the antenna 10 according to Example 1 is replaced with a radiating conductor 51. As shown in FIG. 13, the antenna 50 according to Example 5 includes, in addition to the radiating conductor 51, a connecting conductor 12, a dielectric 13, and a ground conductor 14. The configurations of the connecting conductor 12, the dielectric 13, and the ground conductor 14 are basically the same as those of Example 1, and therefore descriptions thereof will be omitted as appropriate. Furthermore, the radiating conductor 51 has a configuration basically the same as that of the radiating conductor 11, and therefore descriptions of parts common to the radiating conductor 11 will be omitted as appropriate.

[0090] Next, the radiating conductor 51 will be described with reference to FIG. 12. The radiating conductor 51 is capable of transmitting and receiving circularly polarized signals in a predetermined frequency band. Specifically, the radiating conductor 51 may be capable of transmitting and receiving GNSS signals in a predetermined frequency band that are transmitted as circularly polarized waves from the zenith direction. The predetermined frequency band may be the 1.2 GHz band or the 1.6 GHz band. The 1.2 GHz band may be, for example, 1.226 GHz to 1.228 GHz, and the 1.6 GHz band may be, for example, 1.559 GHz to 1.606 GHz. Furthermore, the radiating conductor 51 may be capable of transmitting and receiving SDARS (Satellite Digital Audio Radio Service) signals in the S-band (2.320 GHz to 2.345 GHz) of the 2.3 GHz band. Note that the frequency band of signals that the radiating conductor 51 can transmit and receive is not limited to the above and may be another frequency band. The frequency band of signals that the radiating conductor 51 can transmit and receive may be, for example, the 5 GHz to 6 GHz band.

[0091] As shown in FIG. 12, the radiation conductor 51 has a cutout portion 51a and a cutout portion 51b at two diagonal corners of the four corners of the rectangular shape. The cutout portion 51a may be referred to as a first cutout (first cutout portion), and the cutout portion 51b may be referred to as a second cutout (second cutout portion). The radiation conductor 51 is configured to be able to receive circularly polarized signals by having the cutout portion 51a and the cutout portion 51b. The cutout portion 51a and the cutout portion 51b correspond to known degenerate separation elements and perturbation elements, and the area of ​​the portion removed from the rectangle when the cutout portion 51a and the cutout portion 51b are not present is an area determined by the degenerate separation method. Note that the shape of the radiation conductor 51 is not limited to a rectangle, and it may be a quadrangular shape other than a rectangle.

[0092] Next, the transmission and reception performance of the antenna 50 according to Example 5 will be described. The FB ratio of the antenna 50 according to Example 5 and the FB ratio of a configuration in which the slit 15 is not provided for the antenna 50 according to Example 5 were obtained by simulation. Note that the configuration in which the slit 15 is not provided for the antenna 50 according to Example 5 will be described as "default configuration 2."

[0093] In order to calculate the FB ratio of the antenna 50 and the default configuration 2, the wavelength λ (in air) of the radio waves transmitted and received by the antenna 50 and the default configuration 2 was set to 190 mm (frequency: 1.575 GHz). R1 and length L R2 was set to 74 mm, and the length of each side of the ground conductor 14 of the antenna 10 and the default configuration 2 was set to 74 mm. S1 Set to 24.6mm and width W S1 was set to 1.5 mm. The thickness of the dielectric 13 (air) was set to 1 mm.

[0094] The FB ratio of the antenna 50 was 9.4 dB, while the FB ratio of the default configuration 2 was 0 dB. As such, the antenna 50 of Example 5, like the antenna 10 of Example 1, can also radiate radio waves with higher power in the front direction than the default configuration 2. The peak antenna gain of the antenna 50 is 7.5 dBi, and a decrease in the peak antenna gain can be suppressed.

[0095] As described above, even if the polarization and wavelength of the radio waves transmitted and received by the radiating conductor 51 are different from those in Example 1, the ground conductor 14 has the slit 15, so that the area of ​​the ground conductor 14 can be reduced, a reduction in peak antenna gain can be suppressed, and a high FB ratio can be achieved, as in Example 1. In other words, by having the ground conductor 14 have the slit 15, it is possible to achieve a peak antenna gain and a high FB ratio equivalent to those of a conventional patch antenna, and furthermore, it is possible to reduce the area of ​​the ground conductor 14. Therefore, the antenna 50 according to Example 5 can be made smaller.

[0096] [Example 6] Next, an antenna 60 according to Example 6 will be described with reference to Fig. 14. Fig. 14 is a cross-sectional view of the antenna 60 according to Example 6. The antenna 60 according to Example 6 has a configuration in which the radiating conductor 11 of the antenna 30 according to Example 3 is replaced with the radiating conductor 51 of the antenna 50 according to Example 5. As shown in Fig. 14, the antenna 60 according to Example 6 includes the radiating conductor 51, a connecting conductor 12, a dielectric 13, and a ground conductor 34. The configurations of the radiating conductor 51, the connecting conductor 12, the dielectric 13, and the ground conductor 34 are similar to those of Examples 5, 1, 1, and 3, respectively, and therefore will not be described again.

[0097] As shown in Example 5, the polarization of the radiating conductor 51 according to Example 5 and the frequency (wavelength) of the radio waves transmitted and received by the radiating conductor 51 are different from those of the radiating conductor 11 according to Example 1, but the peak antenna gain and the FB ratio characteristics are similar. The antenna 60 according to Example 6 has a configuration in which the radiating conductor 11 of the antenna 30 according to Example 3 is replaced with the radiating conductor 51 according to Example 5, and therefore the peak antenna gain and the FB ratio characteristics can be made similar to those of Example 3. That is, since the ground conductor 34 has the slits 15 and 35, it is possible to radiate radio waves in the front direction with higher power than the antenna 50 according to Example 5. Therefore, the antenna 60 according to Example 6 can be made smaller and can radiate radio waves with high power in the desired radio wave radiation direction.

[0098] [Example 7] Next, an antenna 70 according to Example 7 will be described with reference to Fig. 15. Fig. 15 is a cross-sectional view of the antenna 70 according to Example 7. The antenna 70 according to Example 7 has a configuration in which the radiating conductor 11 of the antenna 40 according to Example 4 is replaced with the radiating conductor 51 of the antenna 50 according to Example 5. As shown in Fig. 15, the antenna 70 according to Example 7 includes the radiating conductor 51, a connecting conductor 12, a dielectric 13, and a ground conductor 44. The configurations of the radiating conductor 51, the connecting conductor 12, the dielectric 13, and the ground conductor 44 are the same as those of Examples 5, 1, 1, and 4, respectively, and therefore will not be described here.

[0099] As shown in Example 5, the polarization of the radiating conductor 51 according to Example 5 and the wavelength of the radio waves transmitted and received by the radiating conductor 51 are different from those of the radiating conductor 11 according to Example 1, but the peak antenna gain and the FB ratio characteristics are similar. The antenna 70 according to Example 7 has a configuration in which the radiating conductor 11 of the antenna 40 according to Example 4 is replaced with the radiating conductor 51 according to Example 5, and therefore the peak antenna gain and the FB ratio characteristics can be made similar to those of Example 4. In other words, the ground conductor 44 has the slits 15, 35, and 45, so that the peak antenna gain and the FB ratio can be made equivalent to those of the antenna 60 according to Example 6.

[0100] Next, the effect of the slit 45 when the radiation conductor 51 receives a circularly polarized signal will be described using Fig. 16. Fig. 16 is a diagram for explaining the effect of the slit 45. In order to explain the effect of the slit 45, the relationship between the frequency of the radio waves transmitted and received by the antenna 70 and the zenith axial ratio (AR) of the radio waves (circularly polarized waves) transmitted and received by the antenna 70 will be explained by comparing it with the relationship between the frequency and axial ratio of an antenna 60 that does not have the slit 45.

[0101] The horizontal axis of FIG. 16 represents the value (hereinafter referred to as the normalized frequency) obtained by normalizing the frequency by the resonant frequency f0, and the vertical axis represents the axial ratio. The solid line in FIG. 16 represents the relationship (characteristics) between the normalized frequency and the axial ratio of the antenna 70 having three slits (slits 15, 35, and 45). The dotted line represents the relationship (characteristics) between the normalized frequency and the axial ratio of the antenna 60 having two slits (slits 15 and 35). As shown in FIG. 16, the normalized frequency at which the axial ratio is smallest is 1.069 for the antenna 60, while it is close to 1.0 for the antenna 70. That is, the slit 45 in the ground conductor 44 of the antenna 70 can shift the frequency characteristics of the axial ratio of the antenna 60. In other words, because the ground conductor 44 of the antenna 70 has the third slit, the axial ratio (=1.0) approaching circular polarization can be adjusted to a desired frequency by adjusting the outer circumferential length of the slit 45.

[0102] As described above, the antenna 70 according to Example 7 has the ground conductor 44 with the slits 15, 35, and 45, and therefore can radiate radio waves with high power in the front direction, similar to the antenna 60 according to Example 6. Therefore, the antenna 70 according to Example 7 can be made smaller and can radiate radio waves with high power in the desired radio wave radiation direction. Furthermore, the antenna 70 according to Example 7 transmits and receives circularly polarized waves, and the ground conductor 44 has the slit 45, which is the third slit, so that the frequency characteristics of the axial ratio (approaching circular polarization) can be adjusted.

[0103] [Antenna installation example] Next, an example of mounting the antenna 70 according to Example 7 on the vehicle 120 will be described with reference to Fig. 17. Fig. 17 is a diagram showing the vehicle 120 as viewed from above. Note that Fig. 17 illustrates the antenna 70 according to Example 7, but the same mounting example may also be used when mounting the antennas 50 and 60 according to Examples 5 and 6 on the vehicle 120.

[0104] As shown in Fig. 17, vehicle 120 includes a metal body 111, a windshield 112, a rear window 113, and roof glass 121. Vehicle 120 has a configuration in which roof glass 121 is added to vehicle 110 shown in Fig. 11. Vehicle 120 may be any vehicle of any shape. Vehicle 120 may also include at least one of side glass, front bench glass, and rear quarter glass, which serve as fixed windows.

[0105] The antenna 70 is attached to the vehicle 120. When attached to the vehicle 120, the antenna 70 may be referred to as a vehicle antenna device. The antenna 70 is installed such that the normal direction of the radiation conductor 51 is at an angle of 30° or less with respect to the vertical direction of the vehicle 120. The normal direction of the radiation conductor 51 is the direction indicated by a line perpendicular to the plane of the radiation conductor 51, and is the radio wave radiation direction. When the plane of the radiation conductor 51 is the xy plane, the normal direction of the radiation conductor 51 is the positive direction of the z axis. Furthermore, the antenna 70 may be installed on the passenger compartment side of the vehicle 120 facing the roof glass 121, or may be installed inside a plastic aerodynamic part such as a rear spoiler, or may be installed inside a plastic cover as a protruding antenna on the roof (a so-called shark fin). The antenna 70 may be installed so that the normal direction of the radiating conductor 51 is at an angle of 15° or less, 10° or less, 5° or less, 3° or less, or 0° relative to the vertical direction of the vehicle 120.

[0106] The antenna 70 is positioned opposite the roof glass 121, which is in the vertical direction of the vehicle 120, and the normal direction of the radiation conductor 51 is installed at an angle of 30° or less with respect to the vertical direction of the vehicle 120, so that more (circularly polarized) signals such as GNSS transmitted from the zenith direction can be received. Depending on the traveling direction of the radio waves to be transmitted and received, the angle at which antenna 70 is installed may be set appropriately in accordance with specifications. As described above, by providing antenna 70 with slits 15, 35, and 45, it is possible to make it smaller than conventional patch antennas. Therefore, even when antenna 70 (vehicle antenna device) is attached to vehicle 120, it can be attached to the roof glass 121 in a position that does not obstruct the view of the occupants, with fewer restrictions on placement. Furthermore, when antenna 70 is provided near roof glass 121, its small size makes it easier to conceal it within an area of ​​a visible light blocking film coated with black ceramics or the like (not shown).

[0107] 17, only the antenna 70 according to Example 7 is attached to the vehicle 120, but the antenna 50 according to Example 5 or the antenna 6 according to Example 6 may be attached to the vehicle 120 instead of the antenna 70 according to Example 7. Alternatively, in addition to the antenna 70 according to Example 7, at least one of the antenna 50 according to Example 5 and the antenna 60 according to Example 6 may be further attached to the vehicle 120.

[0108] The present invention has been described above in accordance with the above-described embodiments, but the present invention is not limited to the configurations of the above-described embodiments, and naturally includes various modifications, alterations, and combinations that can be made by a person skilled in the art within the scope of the invention claimed in the claims of this application.

[0109] This application claims priority based on Japanese Patent Application No. 2021-117657, filed on July 16, 2021, the disclosure of which is incorporated herein in its entirety. [Explanation of symbols]

[0110] 10, 20, 20A, 30, 50, 60, 70 Antenna 11, 21, 51 Radiating conductor 12 Connecting conductor 12a power supply point Point 12b (virtual power supply point) 13, 23 Dielectrics 14, 24, 34, 44, 54 Ground conductors 15, 25, 35, 45, 55, 65 slits 51a, 51b Notch 110, 120 vehicles 111 Metal Body 112 Windshield 113 Rear window 121 Roof Glass S1, S2, S3, S4 sides C1 Center of gravity L1 Virtual line

Claims

1. a dielectric; a radiation conductor disposed on a first principal surface side of the dielectric; a ground conductor disposed on a second principal surface side of the dielectric, The ground conductor has a length L in a first direction in a plan view of the dielectric. Ｇ１ , and a length L in a second direction perpendicular to the first direction Ｇ２ is placed within a rectangular area of When the wavelength in air of the radio waves transmitted and received by the radiation conductor is λ, Said L Ｇ１ is 0.7 × (λ / 2) ≦ L Ｇ１ ≦1.4×(λ / 2), Said L Ｇ２ is 0.7 × (λ / 2) ≦ L Ｇ２ ≦1.4×(λ / 2), When the ground conductor is divided into a first region and a second region by a virtual line connecting a virtual feed point, which is a projected feed point for feeding power to the radiation conductor in the thickness direction of the dielectric, and the center of gravity of the ground conductor in a plan view, the ground conductor has a first slit that starts at an outer edge of the ground conductor in the first region and extends toward an inside of the ground conductor; an end of the first slit is located inside an outer edge of the ground conductor; When the circumferential length of the first slit in a plan view of the ground conductor is D S1 and the wavelength in air of the radio waves transmitted and received by the radiation conductor is λ, 0.13×λ≦D S1 ≦0.45×λ Meet the antenna.

2. The radiation conductor has a length L Ｒ１ , and the length L in the second direction Ｒ２ is placed within a rectangular area of The length L Ｒ１ and the length L Ｒ２ That is, L Ｒ１ =L Ｒ２ The antenna according to claim 1 , wherein

3. The antenna according to claim 1 , wherein the ground conductor has a rectangular shape when viewed from above the dielectric.

4. In a plan view of the dielectric, of four sides constituting the ground conductor, the side closest to the virtual feed point is defined as a nearest side, The side adjacent to the nearest side and including the outer edge of the first region is defined as a first side, and the length of the first side is L Ｇ１１ When The first slit is located at the midpoint of the first side ±0.4×L Ｇ１１ The antenna of claim 3 originating from a location within the range.

5. 3. The antenna according to claim 1, wherein the ground conductor has a second slit that starts at an outer edge of the ground conductor in the second region and extends toward an inside of the ground conductor.

6. the ground conductor has a quadrangular shape in a plan view of the dielectric, In a plan view of the dielectric, of four sides constituting the ground conductor, the side closest to the virtual feed point is defined as a nearest side, The side adjacent to the nearest side and including the outer edge of the second region is defined as a second side, and the length of the second side is L Ｇ１２ When you say, when you say, The second slit is located at the midpoint of the second side ±0.4×L Ｇ１２ The antenna of claim 5, originating from a location within the range.

7. A dielectric material; a radiation conductor disposed on a first principal surface side of the dielectric; a ground conductor disposed on a second principal surface side of the dielectric, the ground conductor is disposed within a rectangular region having a length L G1 in a first direction and a length L G2 in a second direction perpendicular to the first direction in a plan view of the dielectric; When the wavelength in air of the radio waves transmitted and received by the radiation conductor is λ, The L G1 satisfies 0.7×(λ / 2)≦L G1 ≦1.4×(λ / 2), The L G2 satisfies 0.7×(λ / 2)≦L G2 ≦1.4×(λ / 2), When the ground conductor is divided into a first region and a second region by a virtual line connecting a virtual feed point, which is a projected feed point for feeding power to the radiation conductor in the thickness direction of the dielectric, and the center of gravity of the ground conductor in a plan view, the ground conductor has a first slit that starts at an outer edge of the ground conductor in the first region and extends toward an inside of the ground conductor; an end of the first slit is located inside an outer edge of the ground conductor; the ground conductor has a second slit that starts at an outer edge of the ground conductor in the second region and extends toward an inside of the ground conductor; In a plan view of the ground conductor, the outer circumferential length of the second slit is D Ｓ２ When the wavelength in air of the radio waves transmitted and received by the radiation conductor is λ, 0.13×λ≦D Ｓ２ ≦0.45×λ An antenna that satisfies your needs.

8. The outer circumferential length D of the second slit Ｓ２ is the outer circumferential length D of the first slit Ｓ１ 8. The antenna of claim 7, wherein:

9. 6. The antenna according to claim 5, wherein the ground conductor has a third slit that, in a plan view of the ground conductor, has a start point at a position between a start point of the first slit and a start point of the second slit and extends toward an inside of the ground conductor.

10. the ground conductor has a quadrangular shape in a plan view of the dielectric, In a plan view of the dielectric, of four sides constituting the ground conductor, the side closest to the virtual feed point is defined as a nearest side, The side opposite to the nearest side is defined as a third side, and the length of the third side is L Ｇ１３ When The third slit is located at the midpoint of the third side ±0.4×L Ｇ１３ 10. The antenna of claim 9, originating from a location within the range.

11. A dielectric material; a radiation conductor disposed on a first principal surface side of the dielectric; a ground conductor disposed on a second principal surface side of the dielectric, the ground conductor is disposed within a rectangular region having a length L G1 in a first direction and a length L G2 in a second direction perpendicular to the first direction in a plan view of the dielectric; When the wavelength in air of the radio waves transmitted and received by the radiation conductor is λ, The L G1 satisfies 0.7×(λ / 2)≦L G1 ≦1.4×(λ / 2), The L G2 satisfies 0.7×(λ / 2)≦L G2 ≦1.4×(λ / 2), When the ground conductor is divided into a first region and a second region by a virtual line connecting a virtual feed point, which is a projected feed point for feeding power to the radiation conductor in the thickness direction of the dielectric, and the center of gravity of the ground conductor in a plan view, the ground conductor has a first slit that starts at an outer edge of the ground conductor in the first region and extends toward an inside of the ground conductor; an end of the first slit is located inside an outer edge of the ground conductor; the ground conductor has a second slit that starts at an outer edge of the ground conductor in the second region and extends toward an inside of the ground conductor; the ground conductor has a third slit that extends from a position between a starting point of the first slit and a starting point of the second slit toward an inside of the ground conductor in a plan view of the ground conductor, In a plan view of the ground conductor, the outer periphery of the third slit is D Ｓ３ When the wavelength in air of the radio waves transmitted and received by the radiation conductor is λ, 0.13×λ≦D Ｓ３ ≦0.45×λ An antenna that satisfies your needs.

12. The outer circumferential length D of the third slit Ｓ３ is the outer circumferential length D of the first slit Ｓ１ and the outer circumferential length D of the second slit Ｓ２ 12. The antenna of claim 11, wherein:

13. 3. The antenna according to claim 1, wherein the radiation conductor has a quadrangular shape in a plan view of the dielectric, and has a first notch and a second notch at two diagonal corners of the four corners.

14. 3. The antenna according to claim 1, wherein the radiation conductor is capable of transmitting and receiving linearly polarized waves.

15. The antenna according to claim 13, wherein the radiating conductor is capable of transmitting and receiving circularly polarized waves.

16. 15. An antenna according to claim 14, The antenna is mounted on a vehicle; The radiating conductor is installed such that its normal direction is at an angle of 30° or less with respect to the traveling direction of the vehicle.

17. 17. The vehicle antenna device according to claim 16, wherein the antenna is installed on the passenger compartment side facing a windshield.

18. 16. An antenna according to claim 15, The antenna is mounted on a vehicle; The radiating conductor is installed such that its normal direction is at an angle of 30° or less with respect to the vertical direction.

19. 19. The vehicle antenna device according to claim 18, wherein the antenna is installed on the passenger compartment side facing a roof glass.

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