Patch antenna and vehicle-mounted antenna device

Abstract

This patch antenna comprises a radiation element and n metal bodies (n is a natural number equal to or greater than 2) positioned above the radiation element. The area of at least one of the n metal bodies differs from the areas of the other metal bodies. In addition, the number n is 2 or 3 and at least two of the metal bodies among the n metal bodies in the patch antenna are a first metal body and a second metal body, the first metal body is provided at a distance of 1 / 10th or less the wavelength of a desired frequency band from the radiation element in a direction perpendicular to the upper surface of the radiation element, and the second metal body is arranged in a position closest to the first metal body in the direction perpendicular to the upper surface of the radiation element.

Description

[Technical Field]

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

[0002] A patch antenna is an example of a planar antenna having a radiating element on a dielectric member (for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2017-191961 Summary of the Invention [Problem to be solved by the invention]

[0004] Depending on the configuration of the patch antenna, the axial ratio may deteriorate at least at some elevation angles from low to high.

[0005] One object of the present invention is to improve the axial ratio of a patch antenna. Other objects of the present invention will become apparent from the description herein. [Means for solving the problem]

[0006] One aspect of the present invention is a patch antenna comprising a radiating element and n (where n is a natural number greater than or equal to 2) metal bodies positioned above the radiating element, wherein the area of ​​at least one of the n metal bodies is different from the areas of the others.

[0007] Another aspect of the present invention is an in-vehicle antenna device comprising the patch antenna of the above aspect and an antenna different from the patch antenna, wherein at least two of the n metal bodies are a first metal body and a second metal body, and a part of the antenna is the second metal body.

[0008] Yet another aspect of the present invention is an in-vehicle antenna device comprising the patch antenna of the above aspect and an antenna different from the patch antenna, wherein at least three of the n metal bodies are the first metal body, the second metal body, and a third metal body, and a part of the antenna is the third metal body. [Effects of the Invention]

[0009] According to one aspect of the present invention, the axial ratio of the elevation angle of a patch antenna can be improved. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a perspective view of an in-vehicle antenna device 10. [Figure 2] FIG. 2 is a diagram showing a patch antenna 31. [Figure 3] FIG. 2 is an exploded perspective view of the patch antenna 31. [Figure 4] FIG. 2 is a cross-sectional perspective view of a patch antenna 31. [Figure 5] FIG. 10 is a diagram showing the characteristics of a patch antenna X. [Figure 6] 10 is a diagram showing the characteristics of a patch antenna 31. FIG. [Figure 7] FIG. 10 is a diagram showing the relationship between the distance D1 and the axial ratio. [Figure 8] FIG. 10 is a diagram showing the relationship between the distance D2 and the axial ratio. [Figure 9] 10 is a diagram showing the relationship between the length L of a side of a metal body 55 and the axial ratio. FIG. [Figure 10] 10 is a diagram showing the relationship between the magnification and the axial ratio of metal bodies 55 and 57. FIG. [Figure 11] FIG. 4 is a schematic diagram showing an in-vehicle antenna device 11 according to a second embodiment. [Figure 12] FIG. 4 is a schematic diagram showing an in-vehicle antenna device 11 according to a second embodiment. [Figure 13] FIG. 10 is a schematic diagram showing an in-vehicle antenna device 12 according to a third embodiment. [Figure 14] FIG. 10 is a schematic diagram showing an in-vehicle antenna device 12 according to a third embodiment. [Figure 15] 10A and 10B are diagrams showing another embodiment of the metal body. [Figure 16] FIG. 2 is a diagram showing an example of a main body 300 of a patch antenna. [Figure 17] FIG. 3 is a diagram illustrating an example of a radiating element 350. [Figure 18] FIG. 2 is a schematic diagram showing the relationship between a patch antenna and a ground member. [Figure 19] FIG. 5 is a perspective view of a patch antenna 502. [Figure 20] 5 is a schematic diagram showing electric field lines around a patch antenna 502. FIG. [Figure 21] 10 is a schematic diagram for explaining the arrangement of power supply lines 510 and 511. FIG. [Figure 22] FIG. 20 is a cross-sectional perspective view taken along the line BB in FIG. 19. [Figure 23] 10 is a diagram illustrating a shield member 590. FIG. [Figure 24] 5 is a schematic diagram showing electric field lines around a patch antenna 502. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0011] At least the following matters will become clear from the description of this specification and the accompanying drawings.

[0012] Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. The same or equivalent components, members, etc. shown in each drawing are designated by the same reference numerals, and redundant explanations will be omitted where appropriate.

[0013] =====This embodiment===== <<<Outline of Vehicle-Mounted Antenna Device 10 (First Embodiment)>>> 1 is a diagram showing the configuration of an in-vehicle antenna device 10 according to a first embodiment of the present invention. The in-vehicle antenna device 10 is a device that is attached to the roof of a vehicle (not shown), and is configured to include an antenna base 20, metal bases 21 and 22, a case 23, patch antennas 30 and 31, and an antenna 32.

[0014] 1, the front-to-rear direction of the vehicle on which the in-vehicle antenna device 10 is mounted is defined as the x direction, the left-to-right direction perpendicular to the x direction is defined as the y direction, and the vertical direction perpendicular to the x and y directions is defined as the z direction. The front side from the driver's seat of the vehicle is defined as the +x direction, the right side is defined as the +y direction, and the zenith direction (upward) is defined as the +z direction. Hereinafter, in this embodiment, the front-to-rear, left-to-right, and up-to-down directions of the in-vehicle antenna device 10 will be described as being the same as the front-to-rear, left-to-right, and up-to-down directions of the vehicle.

[0015] The antenna base 20 is a plate-like member that forms the bottom surface of the in-vehicle antenna device 10, and is molded from, for example, insulating resin. Metal bases 21 and 22 are attached to the antenna base 20, in that order from the front, with multiple screws (not shown). The metal base 21 is a plate-like member on which the patch antenna 30 is mounted, and the metal base 22 is a plate-like member on which the patch antenna 31 and the antenna 32 are mounted.

[0016] The metal bases 21 and 22 are electrically connected by a metal plate (not shown). When the in-vehicle antenna device 10 is attached to the roof (not shown) of a vehicle, the metal bases 21 and 22 are electrically connected to the roof. Therefore, the metal bases 21 and 22 function as the ground of the in-vehicle antenna device 10. In this embodiment, the metal bases 21 and 22 are provided as separate bodies, but they may be a single metal base. Even when such a metal base is used, the metal base properly functions as the ground of the patch antennas 30 and 31, which will be described later.

[0017] Moreover, the antenna base 20 may be composed of only the metal bases 21 and 22, or may be composed of the metal bases 21 and 22 and an insulating base. The antenna base 20 may be composed of the insulating base and a metal plate that replaces the metal bases 21 and 22, or further, the antenna base 20 may be composed of the insulating base, the metal bases 21 and 22, and a metal plate.

[0018] The patch antenna 30 is an antenna for receiving, for example, radio waves in the 2.3 GHz band for the Satellite Digital Audio Radio Service (SDARS). The patch antenna 31 is an antenna for receiving, for example, radio waves in the 1.5 GHz band for the Global Navigation Satellite System (GNSS). Details of the patch antenna 31 will be described later.

[0019] Antenna 32 is an antenna for receiving, for example, AM / FM radio waves. Specifically, antenna 32 receives, for example, AM broadcast waves of 522 kHz to 1710 kHz and FM broadcast waves of 76 MHz to 108 MHz. Antenna 32 includes a helical element 80, a capacitive loading element 100, and a filter 110.

[0020] Helical element (hereinafter simply referred to as "coil") 80 is mounted on a columnar holder (not shown) and is provided on metal base 22. One end of coil 80 is electrically connected to metal base 22, and the other end of coil 80 is electrically connected to capacitance loading element 100. Capacitance loading element 100 is an element that resonates in a desired frequency band together with coil 80, and includes metal bodies 100a to 100d divided into four along the front-rear direction (longitudinal direction).

[0021] Here, the term "metal body" refers to a metal member formed by processing, and includes, for example, a plate-shaped metal member such as a metal plate, as well as a metal member having a three-dimensional shape other than a plate. Each of the metal bodies 100a to 100d in this embodiment is formed by bending both ends of the metal plate in the y-axis direction upward from a bottom surface that is substantially parallel to the central xy plane. Filters 110 are provided in the gap between the metal body 100a and the metal body 100b on the left side, the gap between the metal body 100b and the metal body 100c on the right side, and the left gap between the metal body 100c and the metal body 100d on the left side. The filter 110 is, for example, a circuit that resonates in parallel in the frequency band of the patch antenna 31 and includes a capacitor and a coil (not shown). Therefore, the filter 110 electrically connects the four metal bodies 100a to 100d. The filter 110 exhibits high impedance in the frequency band of the patch antenna 31.

[0022] 1, the filter 110 of this embodiment is provided at the position shown in FIG. 1, but the installation position and number of the filter 110 are not limited thereto, and the filter 110 may be provided at a position connecting adjacent metal bodies among the metal bodies 100a to 100d. Therefore, the filter 110 may be provided, for example, at an upper position including the top of the metal bodies 100a to 100d, or at a lower position including the bottom. The filter 110 may also be provided on only one of the left and right sides of the capacitance loading element 100.

[0023] In this way, the four metal bodies 100a to 100d are electrically connected via the filter 110, which has high impedance in the frequency band of the patch antenna 31. The coil 80 is designed to have high impedance in the frequency band of the patch antenna 31. Because the filter 110 has low impedance in the AM / FM frequency band, all of the metal bodies 100a to 100d, together with the coil 80, operate as a single conductor in the AM / FM frequency band. In other words, the coil 80 and the capacitive loading element 100 operate as an antenna that resonates in the AM / FM frequency band.

[0024] In this embodiment, the capacitance loading element 100 is configured to include four metal bodies 100a to 100d, but this is not limited to this. For example, it may be formed of one metal body or multiple metal bodies. Furthermore, the capacitance loading element 100 has a shape in which both ends of the central bottom surface are bent upward, but the shape is not limited to this. For example, the capacitance loading element 100 may have both ends bent downward. Furthermore, the capacitance loading element 100 may have, for example, an inverted V shape, an inverted U shape, a mountain shape, or an arch shape.

[0025] In this embodiment, the four metal bodies 100a-100d have the same length in the front-rear direction, but this is not limited to this. For example, the four metal bodies 100a-100d may have different lengths in the front-rear direction, or some of them may have the same length. Furthermore, although each of the metal bodies 100a-100d has a shape with a bottom surface, some metal bodies may not have a bottom surface.

[0026] <<<Details of Patch Antenna 31>>> Here, the patch antenna 31 will be described in detail with reference to Figures 2 to 4. Figure 2 is a perspective view of the patch antenna 31, and Figure 3 is an exploded perspective view of the patch antenna 31. Also, Figure 4 is a cross-sectional perspective view of the patch antenna 31. As shown in Figures 3 and 4, the patch antenna 31 is configured to include a substrate 50, a dielectric member 52 on which a pattern 51 is formed, a radiating element 53, holding members 54 and 56, and metal bodies 55 and 57.

[0027] The substrate 50 is a circuit board on which a dielectric member 52 having a pattern 51 formed on its back surface is mounted. The pattern 51 on the back surface of the dielectric member 52 is a conductor that functions as a ground conductor film (or ground conductor plate). The back surface of the dielectric member 52 is attached to the substrate 50 by, for example, an adhesive (not shown). The dielectric member 52 is made of a dielectric material such as ceramic, and is a substantially square plate-like or box-like member in plan view on the xy plane seen from the +z direction.

[0028] A conductive radiating element 53 having a substantially square shape with equal length and width is formed on the front surface of the dielectric member 52. Here, "substantially square" includes a shape in which at least some of the corners are cut out obliquely relative to the sides, and a shape in which a notch (recess) or protrusion (protrusion) is provided on part of the side.

[0029] The radiating element 53 is a substantially square shape including two feed points as described below, but may include, for example, one feed point. In this case, the radiating element 53 has a substantially rectangular shape with different vertical and horizontal lengths. Note that, like the substantially square, the term "substantially rectangular" also includes shapes in which the corners are cut diagonally relative to the sides. In this embodiment, the term "substantially square" is used to refer to both the substantially square and the substantially rectangular shape as appropriate.

[0030] In this embodiment, as shown in Fig. 4, a through hole 60 is formed penetrating the substrate 50 and the dielectric member 52. Although only one through hole 60 is shown in Fig. 4, in reality, two through holes 60 are formed in the substrate 50 and the dielectric member 52 so that two feed lines 61 are connected to the feed points of the radiating element 53, respectively.

[0031] A resin holding member 54 is provided on the front surface of the dielectric member 52 so as to surround the radiating element 53. The holding member 54 is a frame-shaped member that holds the metal body 55. Specifically, the holding member 54 is composed of upper and lower frames, each having a substantially square opening with a predetermined area in plan view.

[0032] The width of one side constituting the upper frame of holding member 54 is wider than the width of one side constituting the lower frame. In this embodiment, the front surface of the wider upper frame of holding member 54 holds metal body 55, so metal body 55 is placed on holding member 54 in a stable state.

[0033] Furthermore, protrusions 62a and 62b extending in the z-axis direction are formed near the centers of two sides parallel to the y-axis of the upper frame of holding member 54. Each of protrusions 62a and 62b is a protrusion having a substantially rectangular parallelepiped shape, formed, for example, to determine the position of metal body 55 relative to holding member 54.

[0034] The "center of the side" is, for example, the position where the +x side (or the -x side) parallel to the y axis of the upper frame of the holding member 54 intersects with the x-axis passing through the geometric center of the holding member 54 (hereinafter simply referred to as the "center").

[0035] The metal body 55 is a substantially square zenith plate (or zenith capacitance plate) held by the holding member 54, and recesses 63a and 63b are formed near the center of each of the +x side and -x side parallel to the y axis. In this embodiment, the metal body 55 is placed on the front surface of the holding member 54 with the protrusions 62a and 62b of the holding member 54 fitted into the recesses 63a and 63b of the metal body 55, respectively.

[0036] As described above, the holding member 54 is a substantially square frame, and the metal body 55 is a plate-like member having a substantially square shape in a plan view. Therefore, when the metal body 55 is attached to the holding member 54 so that the protrusions 62a and 62b are aligned with the recesses 63a and 63b, the center of the holding member 54 and the center of the metal body 55 will be substantially aligned.

[0037] The holding member 56 is a frame-shaped member made of resin, and is provided on the front surface of the metal body 55. Specifically, the holding member 56 is composed of upper and lower frames, each of which has a substantially square opening with a predetermined area in a plan view. The width of one side of the lower frame of the holding member 56 is wider than the width of one side of the upper frame. In this embodiment, the front surface of the metal body 55 and the bottom surface of the wider lower frame of the holding member 56 overlap, and the holding member 56 is installed on the metal body 55. Therefore, the holding member 56 is installed on the metal body 55 in a stable state.

[0038] Recesses 64a and 64b are formed near the centers of two sides of the lower frame of holding member 56 that are parallel to the y-axis. In this embodiment, recesses 64a and 64b are designed so that, when holding member 56 is provided on the front surface of metal body 55, recesses 64a and 64b overlap recesses 63a and 63b, respectively, in a plan view. As a result, when holding member 54, metal body 55, and holding member 56 are stacked, recesses 63a and 64a fit into protrusion 62a, and recesses 63b and 64b fit into protrusion 62b.

[0039] Furthermore, protrusions 65a and 65b are formed near the centers of two sides of the upper frame of holding member 56 that are parallel to the y-axis. Like metal body 55, metal body 57 is a plate-shaped member (zenith plate) that is substantially square in plan view, and recesses 66a and 66b are formed near the centers of the +x-side side and the -x-side side that are parallel to the y-axis. In this embodiment, metal body 57 is disposed on the front surface of holding member 56 with protrusions 65a and 65b of holding member 56 fitted into recesses 66a and 66b of metal body 57, respectively. Therefore, the center of holding member 56 and the center of metal body 57 are substantially aligned.

[0040] Incidentally, the holding member 54 of this embodiment is provided on the dielectric member 52 so that the center of the holding member 54 coincides with the center of the radiating element 53. Therefore, the holding member 54 holds the metal body 55 so that the center of the radiating element 53 coincides with the center of the metal body 55.

[0041] The holding member 56 is also provided on the metal body 55 so that the center of the holding member 56 coincides with the center of the metal body 55. Therefore, the holding member 56 holds the metal body 57 so that the center of the metal body 55 coincides with the center of the metal body 57. In this way, the centers of the substantially square radiating element 53 and the metal bodies 55 and 57 all coincide with each other, so that the axial ratio (AR) of the patch antenna 31 can be further improved. Furthermore, with this configuration, the patch antenna 31 can be made smaller than when, for example, the centers of the radiating element 53 and the metal bodies 55 and 57 are misaligned.

[0042] Metal body 55 corresponds to the "first metal body" that is provided closest to radiating element 53 in the direction perpendicular to the top surface of radiating element 53. Metal body 57 corresponds to the "second metal body" that is provided closest to metal body 55 in the direction perpendicular to the top surface of radiating element 53. Metal bodies 55 and 57 correspond to "two metal bodies," holding member 54 corresponds to the "first holding member," and holding member 56 corresponds to the "second holding member."

[0043] Here, the minimum distance from the front surface of radiating element 53 to metal body 55 in the vertical direction (+z direction) is defined as distance D1 between radiating element 53 and metal body 55. In this embodiment, metal body 55 is a plate-shaped member, and has a surface facing the front surface of radiating element 53. Therefore, distance D1 is the distance from the front surface of radiating element 53 to the back surface of metal body 55 facing radiating element 53.

[0044] Furthermore, metal body 57 is provided so that at least the two face each other in the direction perpendicular to metal body 55 (+z direction) and in a planar view. In this embodiment, the distance between metal body 55 and metal body 57 is the minimum distance between the facing portions of the two, and is defined as distance D2 between metal body 55 and metal body 57. Note that the term "portion" here includes a flat surface, edge, or part of a side when the metal body is a plate-like member, and a surface, curved surface, edge, or part of a side when the metal body has a three-dimensional shape with irregularities. Therefore, the distance between metal body 55 and metal body 57 is the minimum distance between the two in the z-axis direction.

[0045] Here, since both metal bodies 55 and 57 are plate-shaped members, distance D2 is the distance from the front surface of metal body 55 to the back surface of metal body 57. In addition, in patch antenna 31, each component, such as dielectric member 52 and holding member 54, is adhered to each other with, for example, double-sided tape or adhesive (not shown).

[0046] <<<About the characteristics of patch antennas>>> The patch antenna 31 has two metal bodies 55, 57 provided above the radiating element 53. However, for comparison, the electrical characteristics of a patch antenna (hereinafter referred to as patch antenna X) that does not have the metal bodies 55, 57 will be described. Unless otherwise specified below, the patch antenna receives right-handed circularly polarized radio waves in the GNSS L1 band (center frequency 1575.42 MHz). In this embodiment, the "wavelength of the desired frequency band" refers to a wavelength corresponding to a desired frequency in the desired frequency band in which the patch antenna 31 is used. Specifically, the "wavelength of the desired frequency band" refers to, for example, a wavelength corresponding to the center frequency of the desired frequency band (hereinafter referred to as the "used wavelength") and is represented by λ. Hereinafter, for example, ½ of the used wavelength will be represented as λ / 2 (=(½)×λ).

[0047] ==Patch antenna configuration size etc== Furthermore, radiating element 53 is a substantially square with sides of 28 mm (approximately λ / 8). Furthermore, metal body 55 is a substantially square with sides of 35 mm (approximately λ / 6), and metal body 57 is a substantially square with sides of 27 mm (approximately λ / 8). Furthermore, distance D1 from radiating element 53 to metal body 55 is 3 mm (approximately λ / 80), and distance D2 from metal body 55 to metal body 57 is 8.5 mm (approximately λ / 23). Note that hereinafter in this embodiment, the above-described conditions of the sizes of radiating element 53 and metal bodies 55 and 57, and distances D1 and D2 are referred to as standard conditions.

[0048] == Characteristics of Batch Antenna X == Here, patch antenna X (not shown) does not include metal bodies 55 and 57, but is configured to include, for example, substrate 50, pattern 51, dielectric member 52, and radiating element 53 as shown in FIGS. 2 and 3. FIG. 5 is a diagram showing the axial ratio characteristics when patch antenna X receives a desired radio wave. In FIG. 5, the +x-axis direction corresponds to an azimuth angle of 180°, and the +y-axis direction corresponds to an azimuth angle of 270°. As is clear from FIG. 5, as the elevation angle decreases, the axial ratio deteriorates, particularly around azimuth angles of 135° and 270°.

[0049] ==Characteristics of Patch Antenna 31== 6 is a diagram showing the axial ratio characteristics when patch antenna 31 receives a desired radio wave. Comparing the axial ratio of patch antenna X with that of patch antenna 31, it is clear that patch antenna 31 has a smaller axial ratio value, particularly at low elevation angles (10° to 30°), and thus has an improved axial ratio. Therefore, as shown in FIG. 6, by providing metal bodies 55 and 57 in patch antenna 31, the axial ratio at low elevation angles can be improved.

[0050] <<<When the components of the patch antenna 31 are changed>>> As described above, the patch antenna 31 having the metal bodies 55 and 57 can improve the axial ratio. While the patch antenna 31 employs standard conditions in which the size of the metal body 55 is 35 mm square, the size of the metal body 57 is 27 mm square, the distance D1 is 3 mm, and the distance D2 is 8.5 mm, these four elements may be changed. Below, we will sequentially explain the case where the distances D1 and D2 are changed and the case where the sizes of the metal bodies 55 and 57 are changed. ==When distance D1 is changed==

[0051] FIG. 7 is a diagram showing the relationship between the distance D1 and the axial ratio. The axial ratio value in FIG. 7 is the largest value (worst value) among azimuth angles of 0 to 360° at an elevation angle of 30°. Note that standard conditions are adopted for elements other than the distance D1. As is clear from FIG. 7, when the distance D1 is changed from 0 mm to 20 mm (λ / 10), the axial ratio gradually decreases from 7.92 dB, and when the distance D1 reaches 20 mm, the axial ratio reaches its minimum value (7.22 dB). Then, when the distance D1 is increased from 20 mm, the axial ratio increases from the minimum value. Therefore, in the patch antenna 31, the axial ratio can be improved by setting the distance D1 in the range of 0 mm to 20 mm (λ / 10). ==When distance D2 is changed==

[0052] FIG. 8 is a diagram showing the relationship between the distance D2 and the axial ratio. The axial ratio in FIG. 8 is the same as that in FIG. 7, and standard conditions are used for the elements other than the distance D2. As is clear from FIG. 8, when the distance D2 is changed from 0 mm to 20 mm (λ / 10), the axial ratio gradually decreases from 7.4 dB, and when the distance D2 reaches 20 mm, the axial ratio reaches its minimum value (7.0 dB). When the distance D2 is increased from 20 mm, the axial ratio increases from the minimum value. Therefore, in the patch antenna 31, the axial ratio can be improved by setting the distance D2 in the range of 0 mm to 20 mm (λ / 10).

[0053] It is preferable that each of the distances D1 and D2 be set in the range of 0 mm to 20 mm (λ / 10), which is the range in which each component is capacitively coupled to improve the characteristics of the patch antenna 31. That is, in this embodiment, the axial ratio of the patch antenna 31 is improved by capacitively coupling the radiating element 53 and the metal body 55, and by capacitively coupling the metal body 55 and the metal body 57. ==When the size of the metal body 55 is changed==

[0054] FIG. 9 is a diagram showing the relationship between the size of metal body 55 and the axial ratio. Note that the axial ratio in FIG. 9 is the same as that in FIG. 7, and standard conditions are used for elements other than the size of metal body 55. Furthermore, because metal body 55 is approximately square, the size of metal body 55 is expressed by the length of one side of the approximately square (hereinafter referred to as length L). As is clear from FIG. 9, when length L is 0 mm, the axial ratio is 8.6 dB, but when length L is 20 mm (λ / 10), the axial ratio drops to 8.2 dB. Then, when length L is 50 mm (λ / 4), the axial ratio reaches its minimum value (7.2 dB).

[0055] Furthermore, when the length L is increased from 50 mm, the axial ratio increases from the minimum value. Therefore, in the patch antenna 31, the axial ratio can be improved by setting the length L of the metal body 55 closest to the radiating element 53 of the patch antenna 31 in the range of 20 mm (λ / 10) to 50 mm (λ / 4). ==When the size of metal body 57 is changed==

[0056] FIG. 10 is a diagram showing the relationship between the size ratio of the metal body 55 and the metal body 57 and the axial ratio. In FIG. 10, the largest value (worst value) among azimuth angles of 0 to 360° at elevation angles of 10°, 30°, and 90° is plotted as the axial ratio. Standard conditions are used for elements other than the size of the metal body 57. The magnification shown in FIG. 10 is a numerical representation of the area of ​​the approximately square metal body 57, assuming that the area of ​​the approximately square metal body 55 is 1.0. Therefore, for example, if the area of ​​the metal body 57 is half the area of ​​the metal body 55, the magnification is 0.5.

[0057] In the axial ratio of the elevation angle of 30° in Figure 10, when the magnification is greater than 0 and less than 0.5, the axial ratio remains unchanged at 8.2 dB, but when the magnification is increased to 0.5, the axial ratio drops to 8.1 dB. As the magnification increases from 0.5, the axial ratio gradually drops. When the magnification becomes 1.5, the axial ratio drops the most, reaching the minimum value (6.8 dB).

[0058] Furthermore, if the magnification is increased beyond 1.5, the axial ratio increases from the minimum value. Therefore, in the patch antenna 31, the axial ratio can be improved by setting the magnification somewhere in the range of 0.5 or more and 1.5 or less.

[0059] Furthermore, when the elevation angle is 10°, the axial ratio decreases significantly, particularly when the magnification is in the range of 0.5 to 1.0. When the elevation angle is 90°, the axial ratio decreases significantly, particularly when the magnification is in the range of 1.0 to 1.5. Therefore, in this embodiment, when the magnification is in the range of 0.5 to 1.0, the axial ratio can be improved particularly at low to medium elevation angles (e.g., 10° to 30°). Furthermore, when the magnification is in the range of 1.0 to 1.5, the axial ratio can be improved particularly at medium to high elevation angles (e.g., 30° to 90°). Therefore, in this embodiment, the axial ratio at a desired elevation angle can be adjusted by adjusting the magnification.

[0060] <<<Vehicle-Mounted Antenna Device 11 of Second Embodiment>>> Fig. 11 is a schematic perspective view of an in-vehicle antenna device 11 of the second embodiment, and Fig. 12 is a schematic side view of the in-vehicle antenna device 11. The in-vehicle antenna device 11 is similar to the in-vehicle antenna device 10 of Fig. 1, but here, for convenience, only a portion of the configuration is depicted, and the other configuration is omitted. Note that the in-vehicle antenna device 10 and the in-vehicle antenna device 11 have the same configurations assigned the same reference numerals.

[0061] In the in-vehicle antenna device 11, a patch antenna 33 is provided instead of the patch antenna 31. The patch antenna 33 is an antenna obtained by removing the holding member 56 and the metal body 57 from the patch antenna 31. In other words, in the patch antenna 33, only the holding member 54 and the metal body 55 are provided above the radiating element 53.

[0062] In addition, in the in-vehicle antenna device 11, the antenna 32 is attached to the antenna base 20 (not shown) so that the bottom surface of the metal body 100a of the antenna 32 is located at a distance D3 from the front surface of the metal body 55. Note that, like the above-mentioned distance D2, the distance D3 is the minimum distance between the opposing portions of the metal body 55 and the metal body 100a.

[0063] In this embodiment, the distance D3 from the metal body 55 to the bottom surface of the metal body 100a is set to a distance (for example, within λ / 10) at which the metal body 55 and the metal body 100a are capacitively coupled.

[0064] Here, for convenience, the size of the antenna 32 including the metal body 100a is drawn slightly smaller, but the area of ​​the actual bottom surface of the metal body 100a facing the metal body 55 is at least 0.5 times the area of ​​the metal body 55. With this configuration, the axial ratio at low elevation angles of the patch antenna 33 of the in-vehicle antenna device 11 can be improved. Note that here, the metal body 100a, which is part of the antenna 32, corresponds to the "second metal body."

[0065] Although the capacitance loading element 100 in the in-vehicle antenna device 11 has four metal bodies 100a-100d each having a bottom surface substantially parallel to the xy plane, this is not limiting. For example, each of the metal bodies 100a-100d may have an upwardly convex umbrella shape. Even in this case, the distance D3 (the minimum separation distance described above) between the radiating element 53 and the metal body 100a should be set to a distance (for example, within λ / 10) that allows capacitive coupling between the radiating element 53 and the metal body 100a.

[0066] Furthermore, the axial ratio can be further improved by making the area of ​​the surface of the metal body 100a facing the radiating element 53 at least 0.5 times the area of ​​the radiating element 53. Here, the "surface of the metal body facing the radiating element 53" does not necessarily have to be a surface parallel to the xy plane, but may also be a curved surface or a surface including irregularities.

[0067] <<<Third embodiment of the vehicle-mounted antenna device 12>>> Fig. 13 is a schematic perspective view of an in-vehicle antenna device 12 of the third embodiment, and Fig. 14 is a schematic side view of the in-vehicle antenna device 12. The in-vehicle antenna device 12 is similar to the in-vehicle antenna device 10 of Fig. 1, but here, for convenience, only a portion of the configuration is depicted, and the other configuration is omitted. Note that the configurations assigned the same reference numerals are the same in the in-vehicle antenna device 10 and the in-vehicle antenna device 12.

[0068] Like the in-vehicle antenna device 10, the in-vehicle antenna device 12 includes a patch antenna 31 and an antenna 32, but the antenna 32 is provided above the patch antenna 31. Specifically, the antenna 32 is attached to the antenna base 20 (not shown) so that the bottom surface of the metal body 100a of the antenna 32 is located at a distance D4 from the front surface of the metal body 57 of the patch antenna 31. Note that the distance D4, like the above-mentioned distance D2, is the minimum distance between the opposing portions of the metal body 57 and the metal body 100a.

[0069] In this embodiment, the distance D4 from the metal body 57 to the bottom surface of the metal body 100a is set to a distance (for example, within λ / 10) at which the metal body 57 and the metal body 100a are capacitively coupled. This configuration can improve the axial ratio at low elevation angles of the patch antenna 31 of the in-vehicle antenna device 12. Here, the metal body 100a, which is part of the antenna 32, corresponds to the "third metal body."

[0070] <<<Others>>> ==About radiating element 53== In the patch antenna 31, the radiating element 53 is substantially square, but is not limited to this and may be substantially polygonal other than a substantially quadrilateral, including a circle, an ellipse, a substantially square, or a substantially rectangle. Even when a radiating element of such a shape is used, the axial ratio of the patch antenna at low elevation angles can be improved, as in this embodiment.

[0071] ==Retaining members 54, 56== Furthermore, while the holding members 54, 56 are described as being frame-shaped members, they may have any shape (for example, supports supporting the four corners of the metal body) as long as they can hold the metal bodies 55, 57 at the desired positions. Furthermore, for example, the holding members may be solid bases made of resin, for example, to hold the metal bodies 55, 57.

[0072] Furthermore, the metal bodies 55, 57 may be attached to a part of the inside of the case 23, and the metal bodies 55, 57 may be positioned as desired. In such a case, the case 23 corresponds to the "holding member."

[0073] ==Positions of radiating element 53, metal bodies 55, 57== In addition, in the patch antenna 31, the metal body 55 is held so that the center of the radiating element 53 and the center of the metal body 55 coincide with each other, but even if the centers of the two are misaligned, the axial ratio of the patch antenna 31 at low elevation angles can be improved.

[0074] In addition, in patch antenna 31, metal body 57 is held so that the center of metal body 55 and the center of metal body 57 coincide with each other, but even if the centers of the two are misaligned, the axial ratio of patch antenna 31 at low elevation angles can be improved.

[0075] ==Metal body55,57== Although the metal bodies 55 and 57 are substantially square in shape, the shape is not limited thereto and may be, for example, a circle, an ellipse, or a polygon other than a substantially quadrilateral. Even when using metal bodies 55 and 57 of such shapes, the axial ratio of the patch antenna 31 at low elevation angles can be improved, as in this embodiment.

[0076] In the present embodiment, the metal bodies 55 and 57 are plate-like members parallel to the xy plane, but they may be bent at least partially to have a convex or concave shape. Also, the metal bodies 55 and 57 may have an asymmetric shape, for example.

[0077] Figure 15 shows another embodiment of the metal body. In the metal body 200 shown in Figure 15(a), both ends of the metal plate in the y-axis direction are bent downward from the center, forming a convex shape in the positive direction of the z-axis. In the metal body 201 shown in Figure 15(b), the metal plate is curved in an arch shape, forming a convex shape in the positive direction of the z-axis.

[0078] In the metal body 202 shown in Fig. 15(c), both ends of the metal plate in the y-axis direction are bent upward from the center, forming a convex shape in the positive axial direction. In the metal body 203 shown in Fig. 15(d), both ends of the metal plate in the y-axis direction are bent downward from the center to form bent portions, and then the ends of the bent portions are further bent to form flanges. Note that the two flanges at the ends formed on the metal body 203 and the center are both approximately parallel to the xy plane.

[0079] Even when such a metal body is used, as described above, the distance between the radiating element 53 and the metal body is determined by the distance D1, and the distance between the multiple metal bodies is determined by the distance D2.

[0080] ==Stacked patch antenna== In the present embodiment, the patch antenna 31 is provided with only one dielectric member 52 and one radiating element 53, but this is not limited to this. For example, if the dielectric member 52 is the first dielectric member and the radiating element 53 provided on the front surface of the first dielectric member is the first radiating element, the patch antenna 31 may include a second dielectric member provided above the first radiating element and a second radiating element provided on the front surface of the second dielectric member. Alternatively, the patch antenna 31 may have a structure including the dielectric member 52 and another dielectric member provided on the front surface of the dielectric member 52 and having radiating elements on its front and back surfaces. In other words, the number of dielectric members and radiating elements is not limited to one, but may be two or more, and may have a laminated or multi-layered configuration.

[0081] In a layered configuration including the first and second dielectric members and the first and second radiating elements, the plurality of metal bodies 55, 57 described in this embodiment may be provided above the uppermost second radiating element. In such a case, the configuration including the first and second dielectric members, the first and second radiating elements, and the plurality of metal bodies 55, 57 corresponds to a layered patch antenna.

[0082] In the laminated patch antenna, the first radiating element and the second radiating element may operate in different frequency bands. In this way, even in a laminated patch antenna having a plurality of dielectric members and a plurality of radiating elements, the same effects as those of this embodiment can be obtained.

[0083] 16 is a diagram showing an example of a stacked patch antenna main body 300. The stacked patch antenna is an antenna that supports, for example, radio waves in two different frequency bands for GNSS (for example, radio waves in the L1 and L2 bands).

[0084] As shown in the plan view of FIG. 16(a) and the side view of FIG. 16(b), the main body 300 includes dielectric members 310 and 311 and radiating elements 320 and 321.

[0085] The dielectric member 310 is, for example, the same member as the dielectric member 52 of the patch antenna 31 in Fig. 3, and is placed on a substrate 330. The substrate 330 is a circuit board having a pattern (not shown) formed on the back surface thereof.

[0086] Furthermore, a substantially square conductive radiating element 320 is formed on the front surface of the dielectric member 310. In the main body 300, the dielectric member 310 (first dielectric member) and the radiating element 320 (first radiating element) are configured to correspond to a first frequency (for example, a frequency in the L2 band).

[0087] Dielectric member 311 is provided on the front surface of radiating element 320, and radiating element 321 is provided on the front surface of dielectric member 311. Here, dielectric member 311 (second dielectric member) and radiating element 321 (second radiating element) are configured to correspond to a second frequency (for example, a frequency in the L1 band) of main body 300 that is different from the first frequency.

[0088] Then, two metal bodies may be provided above the radiating element 321 of such a main body 300, similar to the patch antenna 31. By providing such two metal bodies, the axial ratio of the stacked patch antenna including the main body 300 can be improved, similar to the patch antenna 31.

[0089] ==Radiating element with slots== Furthermore, although the radiating element 53 of the patch antenna 31 of this embodiment is, for example, an element that supports radio waves in a predetermined frequency band (for example, radio waves in the L1 band of GNSS), the present invention is not limited to this. For example, as shown in Fig. 17, a radiating element 350 that supports radio waves in multiple frequency bands (for example, the L1 and L2 bands) may be used.

[0090] Radiating element 350 has a substantially square shape, and is provided with slots 360 provided at positions corresponding to each of the four sides, and four feed points 361. Slot 360 is an opening formed in radiating element 350, and has a meandering shape as one means for adjusting the electrical length of slot 360. By providing such slot 360 in radiating element 350, radiating element 350 can emit (or reflect) radio waves in, for example, two frequency bands.

[0091] ==Relationship between patch antenna and ground member== Incidentally, if the patch antenna is placed approximately in the center of a ground member that functions as a ground, the axial ratio of the patch antenna is improved. Here, the "ground member" may be any member that functions as a ground, such as a metal base, a metal plate (a so-called flat metal plate), or a member that combines a metal base and a metal plate.

[0092] Furthermore, the "approximate center" of the ground member refers to, for example, a region that includes the geometric center of the ground member in a plan view and is smaller than the area of ​​the patch antenna to be placed thereon (for example, the area of ​​the patch antenna when viewed in a plan view). To further improve the axial ratio, it is preferable to place the patch antenna with respect to the ground member so that the geometric center of the patch antenna and the geometric center of the ground member overlap in a plan view.

[0093] Fig. 18 is a schematic diagram showing the relationship between the patch antenna and the ground member, in which the upper part of each of Fig. 18(a) to (e) is a plan view and the lower part is a cross-sectional view taken along line AA.

[0094] 18(a), a substrate 401 is provided on the front surface of a metal base 400, which serves as a ground member. A patch antenna 402 is provided on the front surface of the substrate 401. Here, the patch antenna 402 is provided so that the geometric center of the quadrilateral patch antenna 402 and the geometric center of the quadrilateral metal base 400 overlap in a plan view.

[0095] 18(b), a patch antenna 411 is provided on the front surface of a metal plate 410 serving as a ground member. In Fig. 18(b), the patch antenna 411 is also arranged so that the geometric center of the quadrilateral patch antenna 411 and the geometric center of the quadrilateral metal plate 410 overlap in a plan view.

[0096] 18(c), a metal base 420 and a metal plate 421 are connected to function as a single ground. A patch antenna 422 is provided on the front surface of the metal base 420. Again, the patch antenna 422 is arranged so that the geometric center of the quadrilateral patch antenna 422 coincides with the geometric center of the ground member (quadrilateral) formed by the metal base 420 and the metal plate 421 in plan view.

[0097] 18(d) shows a resin base 431 having a metal base 430 in the center. A patch antenna 432 is provided on the front surface of the metal base 430. Again, in a plan view, the patch antenna 432 is disposed on the metal base 430 such that the geometric center of the quadrilateral patch antenna 432 and the geometric center of the quadrilateral metal base 430 overlap.

[0098] 18(e), a resin base 441 having a metal base 440 is illustrated on the left side of the central part of the drawing. As in the case of FIG. 18(d), a patch antenna 442 is disposed on the metal base 440 so that the geometric center of the quadrilateral patch antenna 442 and the geometric center of the quadrilateral metal base 440 overlap.

[0099] By placing the patch antenna at the positions shown in Figures 18(a) to 18(e), distortion of the directivity of the patch antenna can be suppressed and the axial ratio can be improved. In Figure 18, the patch antenna and the ground member (e.g., a metal base) are each depicted as a quadrilateral for convenience, but this is not limiting and any shape may be used. Here, the patch antenna should be placed so that its geometric center in a plan view is "approximately the center" of the ground member, preferably so that it overlaps with the geometric center.

[0100] Furthermore, the patch antenna in Fig. 18 is not limited to a patch antenna configured from a general dielectric material and a radiating element, and may be, for example, patch antenna 31 in Fig. 2, a patch antenna having stacked main body 300 in Fig. 16, or a patch antenna using radiating element 350 in Fig. 17.

[0101] ==About power supply line placement== Fig. 19 is a perspective view of an example of a patch antenna. The patch antenna in Fig. 19 is included in, for example, an in-vehicle antenna device similar to that in Fig. 1, but for convenience, only the peripheral configuration of the patch antenna is shown here. Specifically, Fig. 19 depicts a metal base 500, a substrate 501, a patch antenna 502, feed lines 510 and 511, and screws 520 to 523.

[0102] 1, the metal base 500 is a plate-like member that functions as a ground, and the substrate 501 is attached to it with five screws (screws 520 to 523 and a screw 524 (described later)). The metal base 500 is also provided with an opening 530 that penetrates the metal base 500 so that feeder lines 510 and 511 (described later) can be connected to a device external to the vehicle-mounted antenna device.

[0103] 2, the substrate 501 is a circuit board on which a pattern (not shown) is formed on the back surface and on which a patch antenna 502 is disposed. The patch antenna 502 is an antenna compatible with, for example, the L1 band and L2 band of the GNSS, and includes a dielectric member 550 and the radiating element 350 of FIG.

[0104] The feeders 510 and 511 are coaxial cables that connect the patch antenna 502 to a device external to the in-vehicle antenna device. The inner conductors (not shown) of the feeders 510 and 511 are connected to the feed point 361 of the radiating element 350 via via holes (not shown) in the dielectric member 550 or conductors (not shown) that pass through through holes provided in the dielectric member 550, and the outer conductors (not shown) are connected to, for example, a ground portion on the back surface of the substrate 501.

[0105] Here, the two feed lines 510, 511 are connected to the four feed points 361, but this is not limiting. For example, if the radiating element has two feed points, the feed lines 510, 511 may be connected to the two feed points. In addition, in this embodiment, the ground portion of the substrate 501 is electrically connected to the metal base 500, as will be described in detail later.

[0106] Meanwhile, when the patch antenna 502 is operating, the electric field between the radiating element 350 of the patch antenna 502 and the metal base 500 changes. Fig. 20 is a schematic diagram showing the electric field lines between the patch antenna 502 and the metal base 500. As shown in Fig. 20, the feeder lines 510 and 511 connected to the patch antenna 502 are affected by the electric field. As a result, leakage current may occur in each of the feeder lines 510 and 511 due to the influence of the electric field.

[0107] If, of the feed lines 510 and 511, the feed line 510 is more affected by the electric field than the feed line 511, a large leakage current occurs in the feed line 510. As a result, the directivity of the patch antenna 502 may deteriorate.

[0108] Therefore, in this embodiment, the power feed lines 510 and 511 are arranged so that the power feed lines 510 and 511 are equally affected by the electric field.

[0109] Fig. 21 is a schematic diagram illustrating the arrangement of power feed lines on the back surface of the substrate 501. Fig. 21(a) is a schematic diagram of the metal base 500 in Fig. 19 viewed from the -z direction, so the arrangement of the power feed lines will be described first with reference to Fig. 21(a).

[0110] For convenience, the schematic diagram of FIG. 21 shows the geometric center of quadrilateral patch antenna 502 and the geometric center of quadrilateral substrate 501 overlapping in a plan view.

[0111] Each of the connection portions 560 and 561 is a conductive member to which the inner conductors of the feed lines 510 and 511 attached to the back surface of the substrate 501 are connected. Here, the connection portions 560 and 561 are arranged on the back surface of the substrate 501 at positions symmetrical with respect to the x-axis passing through the geometric center of the patch antenna 502.

[0112] 19 (FIG. 21(a)), the feed lines 510 and 511 are arranged symmetrically from the connection portions 560 and 561 to the opening 530 with respect to the x-axis passing through the geometric center of the patch antenna 502. By arranging them in this manner, the connection portions 560 and 561 can be affected by the electric field of the patch antenna 502 in a substantially equal manner.

[0113] Here, the arrangement of the feeder line 510 and the feeder line 511 is "symmetrical" with respect to the x-axis passing through the geometric center of the patch antenna 502, but it is sufficient if the influence of the electric field on each of the feeder lines 510 and 511 is approximately equal. Therefore, the feeder line 510 and the feeder line 511 may be approximately symmetrical with respect to the x-axis passing through the geometric center of the patch antenna 502 so that the influence of the electric field on each of the feeder lines 510 and 511 is approximately equal.

[0114] Furthermore, the electric field from patch antenna 502 becomes smaller depending on the distance from patch antenna 502. Therefore, it is sufficient that the lead-out portions of feeder lines 510 and 511, which are relatively heavily influenced by the electric field, are arranged approximately symmetrically. Here, the "lead-out portion of the feeder line" refers to the portion of the feeder line, for example, from the connection to the point where the feeder line is drawn out in a straight line (the point where the feeder line is bent).

[0115] 21(b) and 21(c) are diagrams showing other examples of the arrangement of the feeder lines 510 and 511. Even with such an arrangement, the influence of the electric field on the feeder lines 510 and 511 is approximately equal, and therefore the directivity of the patch antenna 502 can be improved.

[0116] ==Enhancing the ground function of board 501== Incidentally, in order to suppress the influence of the electric field on the power feed lines 510 and 511, it is effective to strengthen the ground function of the substrate 501 provided so as to cover part of the power feed lines 510 and 511. Therefore, in the embodiment of Fig. 19, in addition to the screws 520, 522 to 524 at the four corners of the substrate 501, a screw 521 is provided, thereby reducing the impedance between the metal base 500 and the ground part of the substrate 501.

[0117] Fig. 22 is a cross-sectional perspective view taken along line BB of the embodiment of Fig. 19. Here, various elements (e.g., capacitors and coils) not shown are mounted on the back surface of substrate 501. For this reason, a recessed space 570 having a substantially rectangular parallelepiped shape is formed in metal base 500 so that substrate 501 can be attached to metal base 500 with these elements mounted thereon.

[0118] Supporting portions 580, 582 to 584 that support the substrate 501 are formed at the four corners of the space 570. Furthermore, in this embodiment, a supporting portion 581 is formed between the supporting portion 580 and the supporting portion 582 to support the substrate 501 and to enhance the grounding function of the substrate 501.

[0119] Furthermore, screw holes corresponding to the conductive screws 520 to 524 are formed in the supporting portions 580 to 584, respectively. Therefore, when the screws 520 to 524 are attached while the supporting portions 580 to 584 are supporting the substrate 501, the substrate 501 is fixed to the metal base 500.

[0120] Here, conductive ground portions (not shown) are formed in the portions of the substrate 501 where the screws 520 to 524 are attached and in the portions supported by the supports 580 to 584. Therefore, when the conductive screws 520 to 524 are attached with the substrate 501 supported on the metal base 500, the metal base 500 and the substrate 501 are electrically connected.

[0121] In the embodiments of FIGS. 19 and 22, the power supply line 510 (first power supply line) is arranged in a region (first region) formed between the support portion 580 and the support portion 581, and the power supply line 511 (second power supply line) is arranged in a region (second region) formed between the support portion 581 and the support portion 582.

[0122] Therefore, both of the power feed lines 510 and 511 are partially covered by the substrate 501, whose grounding function is enhanced by the screws 521 and the support parts 581. As a result, in this embodiment, it is possible to suppress the influence of the electric field on the power feed lines 510 and 511. Furthermore, since the grounding function of the substrate 501 is enhanced, it is also possible to suppress the influence of noise (e.g., radiation noise) from the power feed lines 510 and 511.

[0123] In this embodiment, the substrate 501 is fixed to the metal base 500 by attaching the screws 520 to 524 to the screw holes of the support parts 580 to 584, but this is not limiting. For example, the substrate 501 may be directly fixed to the support parts 580 to 584 by soldering or the like. Even in this case, the same effect as when screws are used can be obtained.

[0124] ==About Shields== 22 and other drawings, the ground function of the substrate 501 is enhanced to suppress the influence on or from the power supply lines 510 and 511. However, for example, as shown in FIG. 23, a shielding member may be used.

[0125] Fig. 23 is a diagram for explaining the relationship between the patch antenna 502 and the shielding member. Fig. 23(a) illustrates a state without a shielding member, and Fig. 23(b) illustrates a state with a shielding member. Note that the configuration other than the shielding member in Fig. 23(b) is the same as, for example, Fig. 19, and therefore the explanation will focus on the shielding member.

[0126] The shielding member 590 is a metal plate provided on the front surface of the metal base 500 so as to cover the power supply lines 510 and 511 and the opening 530. The shielding member 590 is electrically connected to the metal base 500 by, for example, conductive screws (not shown).

[0127] 24, for example, it is possible to prevent the electric field from the patch antenna 502 from affecting the power feed lines 510 and 511. Furthermore, the shielding member 590 can suppress the noise generated by the power feed lines 510 and 511 from affecting the device (for example, the patch antenna 502) provided on the front surface of the metal base 500.

[0128] Here, the shielding member 590 is configured to cover all of the power supply lines 510, 511 drawn out from the substrate 501, but it may cover only a portion of them. Also, instead of the shielding member 590, ferrite cores may be attached to the power supply lines 510, 511. Even with this configuration, the same effects as those of the embodiment in FIG. 23(b) can be obtained.

[0129] <<<<Summary>>>> The above has described the in-vehicle antenna devices 10 to 12 of the present embodiment. For example, in patch antenna 31, two (n=2) metal bodies 55, 57 are provided above radiating element 53. The areas of metal bodies 55, 57 are different from each other. In patch antenna 31 configured in this way, the axial ratio of patch antenna 31 can be improved.

[0130] Furthermore, the number of metal bodies provided above the radiating element 53 may be any natural number equal to or greater than two, but by using two or three metal bodies in particular, it is possible to improve the axial ratio while reducing the height of the patch antenna 31. In other words, even in cases where there is a height restriction, such as in a shark-fin shaped vehicle antenna device or a roof-embedded vehicle antenna device, the patch antenna 31 can be arranged with an improved axial ratio.

[0131] Furthermore, in patch antenna 31, distance D1 between radiating element 53 and metal body 55 in the +z direction perpendicular to the top surface of radiating element 53 is equal to or less than λ / 10 of the operating frequency. Therefore, for example, as shown in FIG. 7, the axial ratio of patch antenna 31 at low elevation angles can be improved.

[0132] Furthermore, in the +z direction perpendicular to the top surface of radiating element 53, distance D2 between metal body 57 and metal body 55 is equal to or less than λ / 10 of the operating frequency. Therefore, for example, as shown in FIG. 8, the axial ratio of patch antenna 31 at low elevation angles can be further improved.

[0133] Furthermore, the area of ​​metal body 55 is equal to or greater than the area of ​​a square with a side length L of 20 mm (λ / 10). Therefore, for example, as shown in Fig. 9, the axial ratio of patch antenna 31 at low elevation angles can be improved. Note that, as long as the area of ​​metal body 55 is equal to or greater than the area of ​​a square with a side length L of 20 mm (λ / 10), metal body 55 may have any shape.

[0134] Furthermore, the area of ​​metal body 55 is equal to or less than the area of ​​a square with a side length L of 50 mm (λ / 4). Therefore, for example, as shown in Fig. 9, the axial ratio of patch antenna 31 at a low elevation angle can be improved. Note that, since the area of ​​metal body 55 only needs to be equal to or less than the area of ​​a square with a side length L of 50 mm (λ / 4), metal body 55 may have any shape.

[0135] The area of ​​the metal body 57 may be, for example, 0.5 to less than 1.0 times the area of ​​the metal body 55. In such a case, the axial ratio of the patch antenna 31 at low to medium elevation angles can be improved. Furthermore, the area of ​​the metal body 57 may be, for example, more than 1.0 to 1.5 times the area of ​​the metal body 55. In such a case, the axial ratio of the patch antenna 31 at medium to high elevation angles can be improved, for example, as shown in FIG. 10 .

[0136] Furthermore, the holding member 54 holds the metal body 55 so that the center of the radiating element 53 and the center of the metal body 55 are aligned. This allows the patch antenna 31 to be reduced in size and to have an improved axial ratio. Furthermore, the holding member 54 is provided on the front surface of the dielectric member 52. This allows the patch antenna 31 to be made even more compact than when the holding member 54 is provided on the substrate 50, for example.

[0137] Furthermore, the holding member 56 holds the metal body 57 so that the center of the metal body 55 and the center of the metal body 57 are aligned. This allows the patch antenna 31 to be reduced in size and to have an improved axial ratio. Furthermore, the holding member 56 is provided on the front surface of the metal body 55. This allows the patch antenna 31 to be made even more compact than when the holding member 56 is provided on the substrate 50, for example.

[0138] In addition, in the patch antenna 31, the radiating element 53 and the metal bodies 55 and 57 are each substantially square. Therefore, in the patch antenna 31, the centers of each can be easily aligned.

[0139] Furthermore, in the vehicle-mounted antenna device 11, the metal body 100a is used as the zenith plate instead of the metal body 57. Even with this configuration, the axial ratio of the patch antenna 33 can be improved.

[0140] Furthermore, in the in-vehicle antenna device 12, a metal body 100a corresponding to a third (n=3) zenith plate is provided above the metal bodies 55 and 57. Even with this configuration, the axial ratio of the patch antenna 33 can be improved.

[0141] In this embodiment, "on-board" means that it can be placed on a vehicle, and therefore includes not only those that are attached to a vehicle but also those that are brought into a vehicle and used within the vehicle. Furthermore, although the antenna device of this embodiment is used on a "vehicle" that is a vehicle with wheels, the present invention is not limited to this, and may also be used on moving objects such as drones and other flying objects, probes, construction machinery that does not have wheels, agricultural machinery, ships, and the like.

[0142] The above-described embodiments are intended to facilitate understanding of the present invention and are not intended to limit the present invention. Furthermore, the present invention may be modified or improved without departing from the spirit thereof, and the present invention includes equivalents thereof. [Explanation of symbols]

[0143] 10, 11, 12 Vehicle antenna device 20 Antenna base 21, 22, 400, 420, 430, 440, 500 Metal base 23 cases 30,31,402,411,422,432,442,502 Patch antenna 32 Antenna 50,330,401,501 board 51 patterns 52,310,311,550 Dielectric materials 53,320,321,350 Radiating elements 54,56 Retaining member 55, 57, 100a-100d, 200-203 Metal body 62,65 Convex part 63, 64, 66 Recess 80 helical element (coil) 100 Capacitive Loading Element 110 Filters 300 Main body 360 Slots 361 Power supply point 410,421 Metal plates 431,441 Resin-based 510,511 Power line 520~524 screws 530 Aperture 570 Space 580~584 Support part 590 Shielding material

Claims

1. a radiating element; n (where n is a natural number of 2 or more) metal bodies positioned above the radiating element; At least one of the n metal bodies has an area different from the other areas, At least two of the n metal bodies are a first metal body and a second metal body, the first metal body is provided at a distance of one-tenth or less of a wavelength of a desired frequency band from the radiating element in a direction perpendicular to an upper surface of the radiating element, the second metal body is disposed at a position closest to the first metal body in a direction perpendicular to an upper surface of the radiating element, The area of ​​the second metal body is in the range of 0.5 times or more and less than 1.0 times, or more than 1.0 times and less than 1.5 times, the area of ​​the first metal body. Patch antenna.

2. wherein n is 2 or 3; The patch antenna of claim 1 .

3. The second metal body is provided at a distance of 1 / 10 of the wavelength or less from the first metal body. The patch antenna of claim 1 .

4. The area of ​​the first metal body is equal to or greater than the area of ​​a square with one side being 1 / 10 of the wavelength. The patch antenna according to claim 3 .

5. The area of ​​the first metal body is equal to or less than the area of ​​a square with one side being a quarter of the wavelength. The patch antenna according to claim 4 .

6. a first holding member that holds the first metal body so that a center of the radiating element and a center of the first metal body coincide with each other; The patch antenna according to any one of claims 1 to 5.

7. a second holding member that holds the second metal body so that the center of the shape of the first metal body coincides with the center of the second metal body; The patch antenna according to any one of claims 1 to 6.

8. Each of the radiating element, the first metal body, and the second metal body is substantially square. The patch antenna according to any one of claims 1 to 7.

9. A patch antenna according to any one of claims 1 to 8; an antenna different from the patch antenna, At least two of the n metal bodies are the first metal body and the second metal body. is a genus, A part of the antenna is the second metal body. Vehicle antenna device.

10. A patch antenna according to any one of claims 1 to 8; an antenna different from the patch antenna, Among the n metal bodies, at least three metal bodies are the first metal body, the second metal body, and a third metal body, A part of the antenna is the third metal body. Vehicle antenna device.

11. A patch antenna including a radiating element and n (where n is a natural number greater than or equal to 2) metal bodies positioned above the radiating element; an antenna different from the patch antenna, At least two of the n metal bodies are a first metal body and a second metal body, A part of the antenna is the second metal body. Vehicle antenna device.

12. A patch antenna including a radiating element and n (where n is a natural number greater than or equal to 2) metal bodies positioned above the radiating element; an antenna different from the patch antenna, At least three of the n metal bodies are a first metal body, a second metal body, and a third metal body, A part of the antenna is the third metal body. Vehicle antenna device.

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