Antenna device

Abstract

This antenna device comprises: a planar antenna having a radiation element and a ground conductor positioned below the radiation element; and a ground element having at least a portion positioned below the ground conductor. The ground element has: a first portion including a surface substantially perpendicular to the vertical direction; and a second portion including a surface substantially perpendicular to a lateral direction which is a direction perpendicular to the vertical direction.

Description

Antenna apparatus

[0001] The present invention relates to an antenna apparatus.

[0002] Patent Document 1 describes an antenna apparatus including a planar antenna disposed inside a recess formed in a roof of a vehicle.

[0003] Japanese Unexamined Patent Application Publication No. 2022-099411

[0004] Incidentally, when a planar antenna is positioned inside a recess formed in a vehicle roof, the low-elevation gain of the planar antenna may deteriorate.

[0005] An example of an object of the present invention is to improve the low-elevation gain of a planar antenna. Other objects of the present invention will become apparent from the description of the present specification.

[0006] One aspect of the present invention is an antenna apparatus including: a planar antenna having a radiating element and a ground conductor positioned below the radiating element; and a ground element at least part of which is positioned lower than the ground conductor, the ground element having a first portion including a surface substantially perpendicular to a vertical direction, and a second portion including a surface substantially perpendicular to a lateral direction, where the lateral direction is a direction perpendicular to the vertical direction.

[0007] According to the above aspect of the present invention, the low-elevation gain of the planar antenna can be improved.

[0008] This is a side view (partial cross-sectional view) of a vehicle 1 on which the antenna device 100 of the first embodiment is installed. This is a plan view of the antenna device 100 of the first embodiment. This is a perspective view of the SXM antenna 30 in the antenna device 100 of the first embodiment. This is a diagram showing an example of the elevation angle characteristics of the SXM antenna 30. This is a diagram showing an example of the elevation angle characteristics of the SXM antenna 30 when the length GZ in the Z direction of the second portion 132 of the ground element 130 is changed. This is a perspective view of the SXM antenna 30A in the modified antenna device 100A of the first embodiment. This is a side view of the SXM antenna 70 in the antenna device 200 of the second embodiment. This is a perspective view of the SXM antenna 70A in the modified antenna device 200A of the second embodiment. This is a perspective view of the antenna device 300 of the third embodiment. This is a perspective view of the antenna device 300A of the reference example. This is a diagram showing an example of the elevation angle characteristics of the SXM antenna 80 in the third embodiment and the SXM antenna 80A of the reference example. This figure shows an example of the frequency characteristics of the GNSS antenna 90 in the third embodiment and the GNSS antenna 90A in the reference example. This is a plan view of the antenna device 300B, a modified example of the third embodiment. This is a plan view of the antenna device 400 in the fourth embodiment. This is a plan view of the antenna device 400X of the comparative example. This figure shows an example of the directivity of antenna 470 and antenna 470X. This figure shows an example of the directivity of antenna 470 when the length C1 of the circumference of the opening P1 is changed. This is a plan view of the antenna device 400A, a first modified example of the fourth embodiment. This is a perspective view of the antenna 470B, a second modified example of the fourth embodiment. This is a plan view of the antenna device 400C, a third modified example of the fourth embodiment. This figure shows an example of the gain of antenna 470C when the position of the conductor connection part 105F in the Y direction is changed. This figure shows an example of the gain of antenna 470C when the width YW of the conductor connection part 105F is changed. This figure shows an example of the gain of antenna 470C when the length YL of the protruding part at the end of the conductor base 104 is changed. This figure shows an example of the gain of antenna 470C when the end of the conductor base 104 is connected to the conductor portion of the recess 4. This figure shows an example of the gain of antenna 470C when it is positioned in the central part of the conductor base 104. This figure shows an example of the gain of antenna 470C when the conductor connection portion 105F or conductor connection portion 105R is omitted.This is a plan view of the antenna device 500 of the fifth embodiment. This is a side view of the antenna 510 of the antenna device 500. This is a plan view of the modified antenna 510A. This is an explanatory diagram showing the assembly procedure of the antenna device 500B. This is an explanatory diagram showing the assembly procedure of the antenna device 500C. This is an explanatory diagram showing the assembly procedure of the antenna device 500D. This is an explanatory diagram showing the assembly procedure of the antenna device 500E. This is an explanatory diagram showing how to fix the cable 106 to the base 101.

[0009] The following matters become clear from this specification and the accompanying drawings:

[0010] 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 denoted by the same reference numerals, and redundant explanations will be omitted as appropriate.

[0011] ==First Embodiment== Figure 1 is a side view (partial cross-sectional view) of a vehicle 1 in which the antenna device 100 of the first embodiment is arranged.

[0012] <<Definition of Direction, etc.>> First, with reference to Figure 1, we define the direction, etc. in the antenna device 100 of the first embodiment.

[0013] As shown in Figure 1, the direction forward as viewed from the driver's seat 2 of the vehicle 1 on which the antenna device 100 is located is defined as the +X direction (forward direction) of the antenna device 100, the direction left as viewed from the driver's seat 2 of the vehicle 1 is defined as the +Y direction (left direction) of the antenna device 100, and the direction upward as viewed from the driver's seat 2 of the vehicle 1 is defined as the +Z direction (upward direction) of the antenna device 100. The opposite directions of the +X direction, +Y direction, and +Z direction are defined as the -X direction (rear direction), -Y direction (right direction), and -Z direction (downward direction), respectively.

[0014] The +X, -X, +Y, -Y, +Z, and -Z directions are all unidirectional (directions with a fixed orientation). Furthermore, directions that are not unidirectional, such as both the +X and -X directions, are sometimes simply referred to as the "X direction." Similarly, directions that are both the +Y and -Y directions are sometimes simply referred to as the "Y direction." Also, directions that are both the +Z and -Z directions are sometimes simply referred to as the "Z direction."

[0015] Furthermore, in this embodiment, the +Z direction is sometimes referred to as "upward," the -Z direction as "downward," the Z direction as "up and down," and the direction perpendicular to the up and down direction as "horizontal."

[0016] In Figure 1, the +X, +Y, and +Z directions are represented by line segments with arrows to facilitate understanding of the direction of the antenna device 100. Note that the intersection of these line segments with arrows does not represent the coordinate origin.

[0017] Unless otherwise specified, the definitions of directions and other terms described above are common to other embodiments of this specification.

[0018] <<Overview of Antenna Device 100>> Next, referring again to Figure 1 described above, and then again to Figure 2, the overview of the antenna device 100 of this embodiment will be explained.

[0019] Figure 2 is a plan view of the antenna device 100 according to the first embodiment.

[0020] The antenna device 100 is an antenna device that is placed inside a recess formed of a conductor. In this embodiment, the antenna device 100 is placed on a vehicle 1, as shown in Figure 1. Here, the configuration in which the antenna device 100 is placed on a vehicle 1 is not limited to the configuration in which it is attached to the vehicle 1, but also includes the configuration in which it is brought into the vehicle 1 and used within the vehicle 1. Furthermore, "vehicle" means a vehicle with wheels, and examples include ordinary automobiles such as passenger cars, buses, and trucks, motorcycles and other two-wheeled vehicles, and special vehicles (industrial vehicles) such as tractors, bulldozers, and other special vehicles.

[0021] As shown in Figure 1, the antenna device 100 of this embodiment is positioned on the bottom surface of a recess 4 formed in the roof 3 of the vehicle 1. The body of the vehicle 1 has a frame 5 made of a conductor (for example, metal) as a structural element, and the frame 5 constitutes part of the recess 4. The antenna device 100 is positioned on the bottom surface of the recess 4 surrounded by the frame 5. In other words, the antenna device 100 is positioned inside the recess 4, which is at least partly made of a conductor.

[0022] The recess 4 is formed on the +Z-direction side (upper surface) of the roof 3 of the vehicle 1. The recess 4 extends along the Y-direction (i.e., the width direction of the vehicle 1) of the roof 3 of the vehicle 1. The upper part of the recess 4 is covered by, for example, a resin roof panel 6. Although not shown in Figure 1, when viewed from the +Z-direction side, the length of the recess 4 in the Y-direction is longer than the length in the X-direction. However, the shape of the recess 4 when viewed from the +Z-direction side is not limited to this example. Furthermore, the object on which the antenna device 100 is placed is not limited to the vehicle 1. That is, the antenna device 100 may be placed inside a recess formed of a different conductor than the roof 3 of the vehicle 1.

[0023] As shown in Figure 2, the antenna device 100 includes a base 101 and a case 102 (the case 102 is not shown in Figure 2; see Figure 1), and a plurality of antennas (here, a TEL antenna 10, a V2X antenna 20, an SXM antenna 30, an AM antenna 40, an FM antenna 50, and a GNSS antenna 60).

[0024] The base 101 and case 102 are formed from an insulating resin such as PC resin, ASA resin, PC / ASA resin composition, or ABS resin. However, the base 101 and case 102 may be formed from a material other than an insulating resin and that transmits radio waves. Furthermore, the base 101 and case 102 may consist of an insulating resin portion and a portion made of a material other than an insulating resin and that transmits radio waves. In addition, parts of the base 101 and case 102 may be made of a conductive material or a material that does not transmit radio waves. That is, the base 101 and case 102 may be formed by freely combining desired materials, and the base 101 and case 102 may be made of different materials from each other.

[0025] As shown in Figure 2, the base 101 has a roughly rectangular shape when viewed from the +Z direction, having a pair of short sides substantially parallel to the X direction and a pair of long sides substantially parallel to the Y direction. However, the shape of the base 101 when viewed from the +Z direction is not limited to this example.

[0026] Here, a roughly rectangular shape is included in a roughly quadrilateral shape. A "roughly quadrilateral shape" refers to a shape consisting of four sides, including, for example, a square or a rectangle, and may have at least some corners cut diagonally to the sides. In addition, a "roughly quadrilateral shape" may have notches (recesses) or protrusions (convex parts) formed on some of its sides.

[0027] The base 101 is located on the -Z side, and the case 102 is located on the +Z side. The base 101 and the case 102 form a housing space for accommodating the multiple antennas of the antenna device 100. The base 101 and the case 102 are attached to each other by a desired mounting means such as screw fastening, snap-fitting, welding, or adhesive. In the following description, the member that covers at least a portion of the upper part of the recess 4 may be referred to as the "cover." The "cover" may be the case 102, the roof panel 6 of the vehicle 1, or the glass roof.

[0028] As shown in Figure 1, the antenna device 100 is covered by the roof panel 6 of the vehicle 1 on the +Z side of the case 102. Since the multiple antennas of the antenna device 100 are arranged inside the recess 4 and the +Z side is covered by the roof panel 6, the multiple antennas of the antenna device 100 are not visible from the exterior of the vehicle 1. Therefore, compared to the case where each antenna is arranged on the upper surface (+Z side) of the roof 3, the design constraints of the vehicle 1 are reduced and the design freedom of the vehicle 1 is improved. In addition, compared to the case where each antenna is arranged on the upper surface (+Z side) of the roof 3, the aerodynamic influence of each antenna can be suppressed.

[0029] Furthermore, in this embodiment, since the multiple antennas of the antenna device 100 are arranged inside the recess 4, each antenna can be made less susceptible to noise from the vehicle 1. However, the antenna device 100 may also be arranged inside an exterior part such as a spoiler. In that case, each antenna should be configured to shield against noise from the vehicle 1.

[0030] The antennas of the antenna device 100 are, as described above, a TEL antenna 10, a V2X antenna 20, an SXM antenna 30, an AM antenna 40, an FM antenna 50, and a GNSS antenna 60.

[0031] The TEL antenna 10 is, for example, an antenna for mobile communications in the 699 MHz to 5000 MHz band for GSM, UMTS, LTE, and 5G. However, the TEL antenna 10 is not limited to this, and may support radio waves in some frequency bands of GSM, UMTS, LTE, and 5G (for example, only for 5G), or it may support radio waves in frequency bands other than the 699 MHz to 5000 MHz band.

[0032] The V2X antenna 20 is an antenna that corresponds to radio waves used in V2X (Vehicle to Everything: vehicle-to-vehicle communication, vehicle-to-infrastructure communication), and is formed as a monopole antenna. However, the V2X antenna 20 may be formed in other antenna forms such as a dipole antenna, loop antenna, collinear antenna, or bowtie antenna.

[0033] The SXM antenna 30 is a planar antenna (patch antenna) that corresponds to, for example, SXM (Sirius XM) radio waves for satellite radio broadcasting in the 2320 MHz to 2345 MHz band. However, the antenna device 100 may have a DAB antenna instead of the SXM antenna 30. Here, since the SXM antenna 30 is an antenna that corresponds to radio waves for satellite radio broadcasting in the US area, and the DAB antenna is an antenna that corresponds to radio waves for satellite radio broadcasting in the European area, generally both of these antennas are not mounted on the same vehicle 1. Therefore, in the antenna device 100, the space for arranging the SXM antenna 30 and the space for arranging the DAB antenna may be the same. In this case, the antenna device 100 can be made smaller compared to the case where the space for arranging the SXM antenna 30 and the space for arranging the DAB antenna are separate.

[0034] The AM antenna 40 has a capacitively charged element on the +Z direction side and is an antenna that corresponds to, for example, AM broadcasting radio waves in the 522 kHz to 1710 kHz band.

[0035] The FM antenna 50 has a capacitively charged element on the +Z direction side and is an antenna that corresponds to radio waves for FM broadcasting in the 76 MHz to 108 MHz band, for example.

[0036] The GNSS antenna 60 is a planar antenna (patch antenna) that corresponds to radio waves of the Global Navigation Satellite System (GNSS), and corresponds to radio waves in the L1 band (1559 MHz to 1610 MHz band), for example. However, the communication standards and frequency bands that the GNSS antenna 60 corresponds to are not limited to those described above, and may be other communication standards and frequency bands. The GNSS antenna 60 may also be a so-called multi-band antenna that corresponds to radio waves in multiple frequency bands. For example, the GNSS antenna 60 may correspond to radio waves in two frequency bands, the L2 band (1212 MHz to 1254 MHz band) and the L5 band (1164 MHz to 1214 MHz band).

[0037] Furthermore, the frequency bands of the radio waves that the GNSS antenna 60 supports may be other than the combination of the two frequency bands, the L2 band and the L5 band. For example, the frequency bands of the radio waves that the GNSS antenna 60 supports may be a combination of two frequency bands, the L1 band and the L2 band, or a combination of three frequency bands, the L1 band, the L2 band and the L5 band.

[0038] Furthermore, the frequency bands of the radio waves that the GNSS antenna 60 supports may also include the L6 band (1273 MHz to 1284 MHz band) and the L band (1525 MHz to 1559 MHz band), which are formed by further combining the L1 band, L2 band, and L5 band with correction satellite signals. The frequency bands of the radio waves that the GNSS antenna 60 supports are not limited to the specific combinations of multiple frequency bands described above, but may be any combination of multiple frequency bands.

[0039] The TEL antenna 10, V2X antenna 20, SXM antenna 30, AM antenna 40, FM antenna 50, and GNSS antenna 60 are arranged on the +Z side (top side) of the base 101. When viewed from the +Z side, the TEL antenna 10, V2X antenna 20, SXM antenna 30, AM antenna 40, FM antenna 50, and GNSS antenna 60 are arranged in this order from the +Y side to the -Y side. However, the arrangement of the TEL antenna 10, V2X antenna 20, SXM antenna 30, AM antenna 40, FM antenna 50, and GNSS antenna 60 is not limited to this example. Furthermore, the antenna device 100 may have only a portion of the multiple antennas shown in Figure 2, or it may have additional antennas other than the multiple antennas shown in Figure 2.

[0040] <<SXM Antenna 30>> As described above, in this embodiment, the multiple antennas of the antenna device 100 are arranged inside a recess 4 surrounded by a frame 5 made of a conductor. In this case, the low elevation angle gain of the planar antennas (in this case, the SXM antenna 30 and the GNSS antenna 60) may deteriorate. This is because, compared to when the planar antennas are arranged on the +Z side surface (top surface) of the roof 3 of the vehicle 1, when they are arranged inside the recess 4, they are shielded laterally by the conductor of the recess 4, causing the directivity of the planar antennas to tilt upward (shoot up).

[0041] Therefore, in the antenna device 100 of this embodiment, the ground elements of these planar antennas have a portion located below the ground conductor of the planar antenna, thereby improving the low elevation angle gain of the planar antenna. This point will be described in detail below, using the SXM antenna 30 of the antenna device 100 as an example, with reference to Figure 3. However, the following description can also be applied to the GNSS antenna 60.

[0042] Figure 3 is a perspective view of the SXM antenna 30 in the antenna device 100 of the first embodiment.

[0043] The SXM antenna 30 includes a radiating element 31, a dielectric 32, and a ground conductor 33.

[0044] The radiating element 31 is a conductive member formed to correspond to SXM radio waves. As shown in FIG. 3, the radiating element 31 is arranged on the surface of the dielectric 32 on the +Z direction side, and when viewed from the +Z direction side, it is formed in a substantially quadrilateral shape smaller than the size of the surface of the dielectric 32 on the +Z direction side. In addition, the normal direction of the radiation surface of the radiating element 31 is the +Z direction (zenith direction). The shape of the radiating element 31 is not limited to a substantially quadrilateral shape, and may be, for example, a circular shape or an elliptical shape. In other words, the radiating element 31 only needs to have a shape that can correspond to radio waves in a desired frequency band.

[0045] As shown in FIG. 3, the radiating element 31 has a feeding portion 34. The feeding portion 34 is a member including a feeding point where the feeding line of the SXM antenna 30 is electrically connected to the radiating element 31. In the present embodiment, a configuration in which there is only one feeding line connected to the radiating element 31, that is, a single feeding method is adopted. The radiating element 31 of the single feeding method is formed in a substantially rectangular shape with different vertical and horizontal lengths, for example, so as to correspond to a desired circularly polarized wave.

[0046] However, the feeding method adopted in the SXM antenna 30 is not limited to the single feeding method. For the SXM antenna 30, for example, a dual feeding method may be adopted. The radiating element 31 of the SXM antenna 30 adopting the dual feeding method has two feeding portions 34. In addition, for the SXM antenna 30, for example, a four feeding method may be adopted. The radiating element 31 of the SXM antenna 30 adopting the four feeding method has four feeding portions 34.

[0047] The dielectric 32 is a member formed of a dielectric material such as ceramic. As shown in FIG. 3, the dielectric 32 in the present embodiment is formed in a substantially quadrilateral plate shape, and the surface on the +Z direction side and the surface on the -Z direction side of the dielectric 32 are perpendicular to the Z direction as shown in FIG. 3. However, the dielectric 32 is not limited to the embodiment shown in FIG. 3. For example, the antenna device 100 may include a substrate and a resin member in addition to the members shown in FIG. 1, and at least a part of these substrate and resin member may be used as the dielectric 32.

[0048] The ground conductor 33 is a conductive member disposed on the surface of the dielectric 32 on the -Z direction side. The ground conductor 33 may be formed in a plate shape (that is, may function as a ground conductor plate), or may be formed in a film shape (that is, may function as a ground conductor film). Alternatively, it may be formed as a conductor pattern on the surface of the dielectric 32 on the -Z direction side.

[0049] As shown in FIG. 3, the antenna device 100 of the present embodiment further includes a ground element 130. The ground element 130 is a conductive member used as a ground for the SXM antenna 30. The ground element 130 may be used as a ground by being grounded, or may not be grounded.

[0050] The ground element 130 includes a first portion 131 and a second portion 132. The first portion 131 is a portion of the ground element 130 that includes a surface substantially perpendicular to the Z direction (vertical direction). The second portion 132 is a portion substantially perpendicular to the lateral direction (a direction perpendicular to the Z direction (vertical direction)).

[0051] Here, the term "substantially perpendicular" is not limited to being strictly perpendicular, and includes cases where the surface deviates from the perpendicular direction by a predetermined angle, and cases where the surface is slightly curved relative to the perpendicular direction. In addition, the "portion including a substantially perpendicular surface" is not limited to a case constituted only by a substantially perpendicular surface. The "portion including a substantially perpendicular surface" also includes, for example, a case where there is a slight step between a plurality of substantially perpendicular surfaces due to connection between the plurality of substantially perpendicular surfaces having different positions in the Z direction. It also includes cases where notches or holes such as slits and slots are formed in the substantially perpendicular surface. In addition, the second portion 132 is aligned with, for example, a rib formed on the case 102 that constitutes a part of the antenna device 100, thereby suppressing displacement of the ground element 130 in the lateral direction, and thus can stabilize the characteristics of the SXM antenna 30 against vibration and the like when the vehicle 1 is traveling.

[0052] When viewed from the +Z direction side, the first portion 131 is formed in a substantially rectangular shape having a pair of long sides substantially parallel to the X direction and a pair of short sides substantially parallel to the Y direction. However, the shape of the first portion 131 is not limited to a substantially rectangular shape, and may be, for example, a substantially quadrilateral shape other than a substantially rectangular shape, a circular shape, or an elliptical shape.

[0053] The second portion 132 extends downward from the end of the first portion 131. Specifically, the second portion 132 extends downward from both ends of the first portion 131 in the X direction. In other words, the ground element 130 has portions that are bent downward at both ends in the X direction. In the antenna device 100 of this embodiment, the presence of such a second portion 132 in the ground element 130 means that the ground element 130 has a portion that is located below the ground conductor 33. As a result, in the SXM antenna 30 of this embodiment, the electric field extends below the radiating element 31, and the radiation of radio waves at low elevation angles becomes stronger. Therefore, in the antenna device 100 of this embodiment, the gain of the SXM antenna 30 at low elevation angles can be improved by strengthening the radiation of radio waves at low elevation angles.

[0054] The second portion 132 may extend downward from both ends of the first portion 131 in the Y direction. However, as shown in Figure 2, the V2X antenna 20 (hereinafter sometimes referred to as the "first antenna") and the AM antenna 40 (hereinafter sometimes referred to as the "second antenna") are located at both ends of the SXM antenna 30 in the Y direction (hereinafter sometimes referred to as the "first transverse direction"). That is, the V2X antenna 20 and the AM antenna 40 are positioned so as to sandwich the SXM antenna 30. In this case, the SXM antenna 30 and the V2X antenna 20 and AM antenna 40 may mutually influence each other's characteristics. For this reason, in the antenna device 100 of this embodiment, these influences can be suppressed by making the second portion 132 extend downward from both ends of the first portion 131 in the X direction (hereinafter sometimes referred to as the "second transverse direction") which is perpendicular to the Y direction. Thus, in this embodiment, the SXM antenna 30 may determine from which position on the first part 131 the second part 132 extends below the ground conductor 33, depending on its positional relationship with other antennas arranged around it and the frame structure of the vehicle 1 to which it is mounted.

[0055] The configuration in which the second portion 132 is arranged is not limited to the above-described case. It may extend downward from one end of the first portion 131 in the X or Y direction, or it may extend downward from both ends of the first portion 131 in the X and Y directions. Furthermore, when viewed from the +Z direction, the second portion 132 may be formed in a surrounding shape that encloses the first portion 131. In this way, the position and number of second portions 132 extending from the first portion 131 can be appropriately changed according to the desired characteristics of the SXM antenna 30.

[0056] Furthermore, if the first portion 131 is formed in a substantially rectangular shape, the low-elevation gain of the SXM antenna 30 can be further improved by extending the second portion 132 from the long side end of the first portion 131 downwards to the ground conductor 33. The low-elevation gain of the SXM antenna 30 can be further improved by increasing the number of second portions 132 extending downwards to the ground conductor 33, thereby maximizing the size of the surface that is substantially perpendicular to the lateral direction in the second portion 132. Here, the low-elevation gain of the SXM antenna 30 can be adjusted while considering mutual interference due to the positional relationship with other antennas arranged around the SXM antenna 30, and the ease of assembly of the SXM antenna 30. Moreover, the ground element 130 is not limited to having both the first portion 131 and the second portion 132 as described above; it may have only the second portion 132.

[0057] Furthermore, the second portion 132 shown in Figure 3 and other figures does not have any notches such as slits or openings such as slots formed in its planar portion. This makes it possible to suppress the fact that the strength of the second portion 132 is inferior to, for example, the form in which notches or openings are formed. However, the second portion 132 shown in Figure 3 and other figures may have notches or openings formed in it, as long as it is within a range that can improve the low elevation angle gain of the SXM antenna 30 and can ensure the desired strength of the second portion 132.

[0058] <<Elevation Angle Characteristics of SXM Antenna 30>> Figure 4 shows an example of the elevation angle characteristics of the SXM antenna 30.

[0059] In Figure 4, the horizontal axis represents the elevation angle, and the vertical axis represents the gain. Also in Figure 4, the results for an SXM antenna placed on the roof 3 of vehicle 1 as a comparative example, an SXM antenna placed inside the recess 4 as a comparative example, and the SXM antenna 30 of this embodiment are shown by solid lines, dashed lines, and broken lines, respectively. Note that in the comparative example SXM antenna, the ground element does not have a portion located below the ground conductor (the second portion 132 in this embodiment).

[0060] As shown in Figure 4, the comparative example SXM antenna (dotted line) placed inside the recess 4 has worse gain in the low elevation angle range (~35 degrees) compared to the comparative example SXM antenna (solid line) placed on the roof 3. However, the SXM antenna 30 (dashed line) of this embodiment has improved gain in the low elevation angle range (~35 degrees) compared to the comparative example SXM antenna (dotted line) placed inside the recess 4, and is equivalent to the comparative example SXM antenna (solid line) placed on the roof 3. Therefore, in the antenna device 100 of this embodiment, the ground element 130 of the SXM antenna 30 has a second portion 132 located below the ground conductor 33, thereby improving the low elevation angle gain of the SXM antenna 30.

[0061] Figure 5 shows an example of the elevation angle characteristics of the SXM antenna 30 when the length GZ in the Z direction of the second portion 132 of the ground element 130 is changed.

[0062] In Figure 5, the horizontal axis represents the elevation angle, and the vertical axis represents the gain. The results when the length of the second part 132 of the ground element 130 in the Z direction (GZ in Figure 3) is 10 mm and 20 mm are shown by solid and dashed lines, respectively.

[0063] As shown in Figure 5, when the length (GZ) in the Z direction of the second portion 132 of the ground element 130 is changed from 20 mm to 10 mm, the gain at medium to high elevation angles (30 degrees and above) is improved, while the gain at low elevation angles (up to 30 degrees) is decreased. This makes it possible to arbitrarily adjust the elevation characteristics of the antenna device 100 of this embodiment in response to the influence of directivity when other antennas are placed, for example. For example, if there is a margin in the gain condition at low elevation angles (up to 30 degrees) of a certain planar antenna, and improvement in the gain at medium to high elevation angles (30 degrees and above) is necessary, the gain at medium to high elevation angles (30 degrees and above) can be improved by shortening the length (GZ) in the Z direction of the second portion 132 of the ground element 130.

[0064] <<Modified Antenna Device 100A>> Figure 6 is a perspective view of the SXM antenna 30A in the modified antenna device 100A of the first embodiment.

[0065] The modified antenna device 100A has a ground element 130A that is different from the ground element 130 of the antenna device 100 of the embodiment described above. In the antenna device 100 of the embodiment described above, the ground element 130 had a second portion 132 that extended downward from the end of the first portion 131, but in this modified antenna device, the ground element 130A has a first portion 131A, which is a portion that includes a plane substantially perpendicular to the Z direction (vertical direction), located below the ground conductor 33.

[0066] In the modified antenna device 100A, as shown in Figure 6, the first portion 131A of the ground element 130A is spaced a predetermined distance below the ground conductor 33 of the SXM antenna 30A, and the second portion 132A is located between the first portion 131A and the ground conductor 33. Specifically, the second portion 132A is the portion that bends upward (towards the ground conductor 33) from the first portion 131A.

[0067] Furthermore, the antenna device 100A of this modified example has a substrate 110 on which the SXM antenna 30A is arranged. The substrate 110 is positioned at the +Z direction end of the second portion 132A, so that the second portion 132A connects the first portion 131A and the substrate 110. Note that "connection" here means that the substrate 110 and the second portion 132A are physically connected, even if it is an insulating connection, and an electrical connection between the first portion 131A and the substrate 110 is not required.

[0068] In the modified antenna device 100A, the ground element 130A has a first portion 131A located below the ground conductor 33, so that in the SXM antenna 30A, the electric field extends below the radiating element 31. Therefore, the low-elevation radiation of the SXM antenna 30A is strengthened, which improves the low-elevation gain of the SXM antenna 30A.

[0069] Furthermore, in the modified antenna device 100A, the first portion 131A is spaced a predetermined distance below the ground conductor 33, thereby forming a space 130S between the first portion 131A and the substrate 110 in the Z direction. In addition, an opening 131P is formed in the first portion 131A of the ground element 130A below the space 130S. This allows another antenna to be placed in the space 130S. At this time, openings are formed between the second portions 132A on both sides of the space 130S in the X direction. Also, the second portions 132A are not formed on both sides of the space 130S in the Y direction, and openings are formed there. Through these openings formed on the sides of the space 130S, the radio waves corresponding to the other antenna can pass through. By placing another antenna in the space 130S, the antenna device 100A can be made more space-saving.

[0070] Furthermore, in the modified antenna device 100A, a shield cover may be placed on the -Z direction side of the SXM antenna 30A. When the ground element 130A is made of sheet metal, for example, it may be made by cutting out a portion corresponding to the opening 131P of the first portion 131A. In this case, the shield cover can be made using this portion corresponding to the opening 131P. In other words, the ground element 130A and the shield cover can be made from a single sheet of metal (the ground element 130A and the shield cover can be made integrally), so the number of parts when manufacturing the antenna device 100A can be reduced and the antenna device 100A can be easily assembled.

[0071] If another antenna is placed in space 130S, the cable connected to this other antenna can be passed through an opening on the side of space 130S (an opening formed on both sides in the X direction or on both sides in the Y direction). The cable connected to this other antenna can be fixed and held on the first portion 131A of the ground element 130A, and capacitively coupled with the first portion 131A, thereby suppressing the influence of the cable on the SXM antenna 30A and stabilizing the characteristics of the SXM antenna 30A. However, a portion of the opening on the side of space 130S may be filled in to ensure strength.

[0072] Furthermore, in the modified antenna device 100A, the ground element 130A and the circuit board 110 are fastened together with a screw 35 and fixed to, for example, the case 102 (not shown in Figure 6, see Figure 1). This reduces the number of screws required to assemble the antenna device 100A, thereby reducing costs and assembly man-hours. However, the ground element 130A and the circuit board 110 may also be fixed to a component other than the case 102, for example, the base 101.

[0073] Here, the opening 131P of the first part 131A is formed to be larger than the size of the substrate 110 when viewed from the +Z direction. Therefore, when the ground element 130A and the substrate 110 are fastened together with screws 35, only the unit consisting of the substrate 110 and the SXM antenna 30A (radiating element 31, dielectric 32, and ground conductor 33) can be easily removed from the ground element 130A. For example, when it is necessary to remove the SXM antenna 30A from the antenna device 100A, it is not necessary to disassemble the entire antenna device 100A. Therefore, for example, when the above-mentioned unit (substrate 110 and SXM antenna 30A) malfunctions, it becomes possible to repair and maintain it smoothly.

[0074] However, the ground element 130A and the circuit board 110 do not necessarily have to be fastened together with the screw 35; the ground element 130A and the circuit board 110 can each be fixed to other components (for example, the base 101 or the case 102) in different ways. In this case, only the SXM antenna 30A, which is most likely to fail due to static electricity or strong external radio waves, can be removed. In other words, if only the circuit board 110 is to be removed, there is no need to remove the SXM antenna 30A. Therefore, the work of attaching and detaching components that affect the performance of the SXM antenna 30A can be minimized.

[0075] Incidentally, the screw 35 that fixes the substrate 110 on which the SXM antenna 30A is placed to the ground element 130A is located around the SXM antenna 30A when viewed from the +Z direction. In this case, by making the electrical length of the screw 35 one-quarter of the wavelength of the radio wave that the SXM antenna 30A corresponds to, it is possible to make the screw 35 function as a director, and the low elevation angle characteristics of the SXM antenna 30A can be further improved. However, since the low elevation angle directivity of the SXM antenna 30A may change, in order to suppress this, the screw 35 may be made of resin, for example, and the substrate 110 on which the SXM antenna 30A is placed may be fixed to the base 101 side (-Z direction side) of the antenna device 100A with an insulating material or the like.

[0076] ==Second Embodiment== <<Antenna Device 200>> Next, the antenna device 200 of the second embodiment will be described with reference to Figure 7.

[0077] Figure 7 is a side view of the SXM antenna 70 in the antenna device 200 of the second embodiment.

[0078] In the antenna device 100 of the first embodiment described above, the ground element 130 has a portion located below the ground conductor 33 of the SXM antenna 30, thereby improving the low elevation angle gain of the SXM antenna 30. However, the method for improving the low elevation angle gain of a planar antenna is not limited to this.

[0079] The SXM antenna 70 in the second embodiment has a radiating element 71, a dielectric 72, and a ground conductor 73 (not shown in Figure 7), similar to the SXM antenna 30 in the first embodiment described above. The ground element 140 does not have a portion located below the ground conductor (the second portion 132 in the first embodiment). However, the antenna device 200 of the second embodiment has a parasitic element 150 that is positioned at a predetermined distance from the radiating element 71.

[0080] Specifically, as shown in Figure 7, the parasitic element 150 is positioned above the radiating element 71 at a predetermined distance. The parasitic element 150 is also positioned on the recessed surface 4 of the case 102 via a spacer 103. By positioning the parasitic element 150 on the case 102 via the spacer 103 in this way, the gain at low elevation angles can be arbitrarily adjusted by arbitrarily adjusting the distance between the parasitic element 150 and the radiating element 71 (the predetermined distance mentioned above). Alternatively, the parasitic element 150 may be positioned directly on the recessed surface 4 of the case 102 without the spacer 103. In this case, instead of being able to adjust the distance between the parasitic element 150 and the radiating element 71 using the spacer 103, the gain of the SXM antenna 70 at low elevation angles can be improved by pre-setting a predetermined distance between the bottom surface of the recess 4 and the recessed surface 4 of the case 102. However, the passive power element 150 may be placed on the resin roof of the vehicle 1 (the roof panel 6 in Figure 1 above) or the glass roof, rather than on the recessed surface 4 of the case 102. In other words, the passive power element 150 only needs to be placed on the recessed surface 4 of the cover.

[0081] Alternatively, a holder (not shown) may be positioned to extend in the +Z direction from the bottom surface of the recess 4 toward the case 102 to a position close to the surface of the case 102 on the recess 4 side, and the passive element 150 may be fixed to this close position of the holder. In this case, the close position of the holder (not shown) is above the radiating element 71, and the passive element 150 is fixed to such a position that it overlaps with the holder in a plan view. Therefore, for example, by making the holder extendable and retractable in the Z direction, the distance between the passive element 150 and the radiating element 71 (the predetermined distance mentioned above) can be arbitrarily adjusted.

[0082] Furthermore, in the antenna device 200 of this embodiment, the directivity of the SXM antenna 70 can be controlled, and the low-elevation gain of the SXM antenna 70 can be improved. In addition, in the antenna device 200 of this embodiment, the lateral size of the antenna device 200 can be suppressed compared to the case where components are arranged around the SXM antenna 70 in the lateral direction.

[0083] <<Modified Antenna Device 200A>> Next, with reference to Figure 8, a modified antenna device 200A of the second embodiment will be described.

[0084] Figure 8 is a perspective view of the SXM antenna 70A in the antenna device 200A of a modified example of the second embodiment.

[0085] In the modified antenna device 200A, multiple (in this case, four) parasitic elements 150A are arranged around the lateral periphery of the radiating element 71 at predetermined distances apart. In this modified antenna device 200A, the parasitic elements 150A act as radio wave directors for the SXM antenna 70A, thereby improving the low-elevation gain of the SXM antenna 70A.

[0086] ==Third Embodiment== <<Antenna Device 300>> Figure 9 is a perspective view of the antenna device 300 of the third embodiment.

[0087] In the antenna device 100 of the first embodiment described above, as shown in Figure 2, the SXM antenna 30 was positioned near the center, and the GNSS antenna 60 was positioned at the end on the -Y direction side. In the antenna device 300 of the third embodiment, as shown in Figure 9, the SXM antenna 80 and the GNSS antenna 90 are positioned next to each other.

[0088] In the antenna device 300 of the third embodiment, ground elements are separately arranged for the SXM antenna 80 and the GNSS antenna 90. Specifically, a ground element 160 is arranged for the SXM antenna 80, and a ground element 170, located below the ground element 160, is arranged for the GNSS antenna 90. The ground element 160 also has a connection portion 163. The connection portion 163 is the connection portion with the ground element 170 and is the portion that extends downward from the -Y direction end of the first portion 161 of the ground element 160. As a result, in the SXM antenna 80 of this embodiment, the radiation of radio waves at low elevation angles is strengthened, thereby improving the low elevation angle gain of the SXM antenna 80.

[0089] In the antenna device 300 of this embodiment, the ground element 170 and the connecting portion 163 are arranged on the -Y direction side of the ground element 160. However, the positional relationship between the ground element 160 and the ground element 170 and the connecting portion 163 in a plan view (when viewed in the Z direction) is not limited to the case shown in Figure 9. For example, the ground element 170 and the connecting portion 163 may be arranged on the +Y direction side of the ground element 160, or the ground element 170 and the connecting portion 163 may be arranged on the +X direction side or the -X direction side of the ground element 160. In this case as well, the SXM antenna 80 arranged on the ground element 160 will have stronger radiation of radio waves at low elevation angles, thereby improving the low elevation angle gain of the SXM antenna 80.

[0090] Furthermore, in addition to the ground element 170 and connection portion 163 located on the -Y side of the ground element 160, the antenna device 300 may also have another ground element on which another antenna is located, and a connection portion (another connection portion) between the ground element 160 and the other ground element. In this case, the other ground element is located below the ground element 160, similar to the ground element 170, and the other connection portion is a portion that extends downward from the end of the ground element 160. This also improves the low-elevation gain of the SXM antenna 80 by increasing the radiation of radio waves at low elevation angles in the SXM antenna 80 located on the ground element 160. Even in this case, the positional relationship in plan view between the ground element 160 and the other ground element and the other connection portion is not limited to the above case. For example, the other ground element and the other connection portion may be located on the +X side or the -X side of the ground element 160.

[0091] Figure 10 is a perspective view of an example antenna device 300A.

[0092] In the reference example antenna device 300A, similar to the antenna device 300 of the third embodiment, the SXM antenna 80A and the GNSS antenna 90A are arranged adjacent to each other, as shown in Figure 10. Furthermore, a ground element 160A is provided for the SXM antenna 80A, and a ground element 170A is provided for the GNSS antenna 90A, which is located below the ground element 160. However, the ground element 160A does not have a connection portion with the ground element 170A.

[0093] <<Elevation Angle Characteristics of SXM Antenna 80>> Figure 11 shows an example of the elevation angle characteristics of the SXM antenna 80 in the third embodiment and the SXM antenna 80A in the reference example.

[0094] In Figure 11, the horizontal axis represents the elevation angle, and the vertical axis represents the gain. Also in Figure 11, the results for the SXM antenna 80 in the third embodiment and the SXM antenna 80A in the reference example are shown by solid and dashed lines, respectively.

[0095] As shown in Figure 11, the SXM antenna 80 (solid line) of this embodiment has improved gain in the low elevation angle range (~35 degrees) compared to the SXM antenna 80A (dashed line) in the reference example. Therefore, in the antenna device 300 of this embodiment, the ground element 160 of the SXM antenna 80 has an additional connection portion 163 located below the ground conductor 33, thereby improving the low elevation angle gain of the SXM antenna 80.

[0096] <<Frequency Characteristics of GNSS Antenna 90>> Figure 12 shows an example of the frequency characteristics of the GNSS antenna 90 in the third embodiment and the GNSS antenna 90A in the reference example.

[0097] In Figure 12, the horizontal axis represents frequency and the vertical axis represents gain. Also in Figure 12, the results for the GNSS antenna 90 in the third embodiment and the GNSS antenna 90A in the reference example are shown by solid and dashed lines, respectively. As shown in Figure 12, the GNSS antenna 90 of this embodiment (solid line) has improved gain in the range of 1100 MHz to 1400 MHz compared to the GNSS antenna 90A in the reference example (dashed line).

[0098] <<Modified Antenna Device 300B>> Figure 13 is a plan view of the modified antenna device 300B of the third embodiment.

[0099] In the antenna device 300 of this embodiment, as shown in Figure 9 above, the ground element 160 on which the SXM antenna 80 is located and the ground element 170 on which the GNSS antenna 90 is located do not overlap in a plan view (when viewed in the Z direction). However, as in the modified antenna device 300B, the ground element 160B on which the SXM antenna 80B is located and the ground element 170B on which the GNSS antenna 90B is located may overlap in a plan view. Specifically, in the modified antenna device 300B, as shown in Figure 13, all of the ground elements 160B overlap with the ground elements 170B in a plan view.

[0100] However, the positional relationship between the ground element 160B and the ground element 170B in a plan view is not limited to the case shown in Figure 13. In the antenna device 300B, it is sufficient that at least a part of the ground element 160B and at least a part of the ground element 170B overlap. In the overlapping portion of the ground elements 160B and 170B, a connecting portion 163B is arranged to connect the ground elements 160B and 170B.

[0101] The connection portions 163B are arranged in four places at the corners of the ground element 160B in a plan view (specifically, at the four corners of the quadrilateral-shaped ground element 160B). The connection portions 163B are the parts that extend downward from the ends of the ground element 160B. This also increases the low-elevation angle radiation of the SXM antenna 80B placed on the ground element 160B, thereby improving the low-elevation angle gain of the SXM antenna 80B.

[0102] Furthermore, in the modified antenna device 300B, each of the four connection portions 163B is formed in a cylindrical shape. However, the shape of the connection portions 163B is not limited to that shown in Figure 13. Each of the four connection portions 163B may be formed in a prismatic shape such as a triangular prism or a rectangular prism, or it may be of another shape. Moreover, the number of connection portions 163B arranged in the antenna device 300B is not limited to four, but may be any other number. For example, in a plan view, one connection portion 163B may be arranged that overlaps with at least a part of the end of the ground element 160B. In this case, the single connection portion 163B may be of various shapes such as a cylindrical shape or a prismatic shape. As a result, the connection portion 163B extends downward from the end of the ground element 160B, and the low-elevation radiation of the SXM antenna 80B placed on the ground element 160B is strengthened, thereby improving the low-elevation gain of the SXM antenna 80B.

[0103] ==Fourth Embodiment== Figure 14 is a plan view of the antenna device 400 of the fourth embodiment.

[0104] The antenna device 100 of the first embodiment shown in Figure 1 above is positioned on the bottom surface of a recess 4, part of which is composed of a frame 5 made of a conductor (for example, metal). In addition to being composed of the frame 5, the recess may also be formed by recessing it from a conductor part of the vehicle body (for example, the metal part of the roof or hood). In other words, the recess in which the antenna device is positioned may be configured as a so-called bathtub-shaped section.

[0105] Incidentally, in order to reduce the weight and cost of the vehicle body, for example, an opening region is sometimes formed on the bottom surface of a recess, thereby reducing a portion of the conductive part that forms the recess. In antennas that have antenna devices placed in such recesses, the conductive part that forms the recess is used as part of the ground. As a result, when an opening region is formed in the recess, the current flows along the edge of the opening region. Consequently, the path of the current flowing through the conductive part of the recess becomes longer than when no opening region is formed in the recess, and if the current path satisfies certain conditions, unwanted resonance may occur, degrading the performance of the antenna. In this invention, "unwanted resonance" refers to resonances that occur in an antenna other than resonances in the desired operating frequency band, and which adversely affect the radiation characteristics, impedance matching, or gain characteristics of the antenna.

[0106] Therefore, in the antenna device 400 of this embodiment, the conductive portion of the recess where the antenna is placed can be reduced, and the deterioration of antenna performance due to the occurrence of unwanted resonance can be suppressed. The details of such an antenna device 400 will be described below.

[0107] The antenna device 400 includes a conductor base 104 and an antenna 470.

[0108] As shown in the plan view of Figure 14, the conductor base 104 is located inside the overall opening region EP formed on the bottom surface of the recess 4. In the antenna device 400 of this embodiment, the recess 4 is formed by recessing it from the conductor portion of the vehicle body (for example, the metal portion of the roof or hood). The conductor base 104 has conductor connection portions 105. The conductor connection portions 105 are the parts of the conductor base 104 that are electrically connected to the conductor portion of the recess 4. In the antenna device 400 of this embodiment, the conductor base 104 has a total of six conductor connection portions 105, three on the +X side and three on the -X side.

[0109] However, the conductor base 104 does not have to have multiple conductor connection parts 105, but may have only one conductor connection part 105. Also, the conductor connection part 105 may be formed integrally with the parts of the conductor base 104 other than the conductor connection part 105, or it may be formed as a separate component from the parts of the conductor base 104 other than the conductor connection part 105. In this case, the conductor connection part 105 may be a separate part (bracket) from the parts of the conductor base 104 other than the conductor connection part 105. When the conductor connection part 105 is formed integrally with the parts of the conductor base 104 other than the conductor connection part 105, the number of parts can be reduced, thereby improving the ease of assembly of the antenna device 400. Also, when the conductor connection part 105 is formed as a separate component from the parts of the conductor base 104 other than the conductor connection part 105, it becomes possible to flexibly adjust the position and shape of the conductor base 104 according to the mounting state of each vehicle 1 on which the antenna device 400 is mounted, and according to the shape of the vehicle body 1.

[0110] Antenna 470 is, for example, a DAB antenna and is positioned in the central part of the conductor base 104. However, antenna 470 may be other antennas such as a TEL antenna, a V2X antenna, or an SXM antenna. In addition, in the antenna device 400 of this embodiment, only one antenna (antenna 470) is positioned on the conductor base 104. However, the antenna device 400 may have other antennas besides antenna 470. That is, multiple antennas may be positioned on the conductor base 104.

[0111] Antenna 470 is an antenna that operates on the principle of utilizing the current flowing through the ground (hereinafter sometimes referred to as "ground current") as part of the antenna's radiation, such as a monopole antenna, slot antenna, or patch antenna. For this reason, antenna 470 is susceptible to the influence of the shape of the surrounding conductor (here, the conductor base 104) on which it is placed. In particular, if an opening is formed in the conductor portion of the recess 4 where the antenna device 400, as in this embodiment, is placed, a change in the path of the ground current flowing along the edge of the opening can easily cause unwanted resonances depending on the length of the ground current path, potentially significantly degrading the characteristics of antenna 470 of the antenna device 400. For this reason, in antennas that utilize ground current as part of their radiation, appropriately controlling the shape of the opening and the length of the perimeter of the opening is especially important from the viewpoint of stabilizing the antenna's performance.

[0112] The overall aperture region EP has multiple openings because it is demarcated by the conductor connection portion 105. In other words, the overall aperture region EP has multiple openings defined by the conductor portion of the recess 4 and the conductor base 104. However, the conductor base 104 may have only one opening because it has only one conductor connection portion 105. In the antenna device 400 of this embodiment, the overall aperture region EP has six openings P1, P2, P3, P4, P5 and P6 because it has the six conductor connection portions 105 described above. Also, in the antenna device 400 of this embodiment, the overall aperture region EP is formed on the bottom surface of the recess 4, and the six openings P1, P2, P3, P4, P5 and P6 are located on the bottom surface of the recess 4. However, at least a part of the overall aperture region EP may be formed on the side surface of the recess 4. In this case, at least a portion of the six openings P1, P2, P3, P4, P5, and P6 may be located on the side surface of the recess 4.

[0113] Unwanted resonance may occur if the current path flowing along the edges of each of these openings (P1, P2, P3, P4, P5, and P6) satisfies certain conditions. Specifically, the lengths of the perimeters of each of the openings P1, P2, P3, P4, P5, and P6 are C1, C2, C3, C4, C5, and C6, respectively. When the lengths of the perimeters of each of these openings (C1, C2, C3, C4, C5, and C6) are near integer multiples of the wavelength of the frequency to which the antenna 470 corresponds, unwanted resonance may occur, and the performance of the antenna 470 may deteriorate.

[0114] Therefore, in the antenna device 400 of this embodiment, when the circumference of the aperture is C, the wavelength of the frequency to which the antenna 470 corresponds is λ, and n is an integer, the following equation (1) or equation (2) can be satisfied to suppress the deterioration of the performance of the antenna 470 due to unwanted resonance. C < nλ - 1 / 4λ ... Equation (1) C > nλ + 1 / 4λ ... Equation (2)

[0115] By the way, the antenna device 400 of this embodiment has a plurality of openings (P1, P2, P3, P4, P5, and P6). In this case, the circumference of the opening with the largest circumference among the circumferences of each of the plurality of openings (C1, C2, C3, C4, C5, and C6) (here, the circumference C1 of opening P1) should satisfy the above formula (1) or formula (2).

[0116] Furthermore, if the antenna device 400 has other antennas besides antenna 470 (i.e., multiple antennas), the following equation (3) can be satisfied by setting the wavelength of the lowest frequency among the frequencies corresponding to each of the multiple antennas to λm, and the length of the largest circumference among the circumferences of each of the multiple apertures to Cm, thereby suppressing the deterioration of the antenna performance of each of the multiple antennas due to unwanted resonance: Cm < nλm - 1 / 4λm ... Equation (3)

[0117] Figure 15 is a plan view of the comparative antenna device 400X.

[0118] The comparative example antenna device 400X has a conductor base 104X that is different from the conductor base 104 of the antenna device 400 of this embodiment described above. The conductor base 104X has a total of four conductor connection parts 105, two on the +X side and two on the -X side. In other words, the comparative example conductor base 104X has one less conductor connection part 105 on the +X side and one less conductor connection part 105 on the -X side compared to the conductor base 104 of this embodiment. For this reason, the circumference length C2X of the opening P2X in the comparative example is different from the circumference length C2 of the opening P2 in this embodiment, and the circumference length C3X of the opening P3X in the comparative example is different from the circumference length C3 of the opening P3 in this embodiment. In addition, in the comparative example antenna device 400X, the same antenna 470X as the antenna 470 of this embodiment is located in the central part of the conductor base 104X.

[0119] Figure 16 shows an example of the directivity of antenna 470 and antenna 470X.

[0120] Figure 16 shows the directivity results for antenna 470 of this embodiment and antenna 470X of the comparative example in vertical polarization, indicated by solid and dashed lines, respectively. In Figure 16, the gain around 90°, which represents the gain at low elevation angles, is better for antenna 470 of this embodiment compared to antenna 470X of the comparative example. This is thought to be because the circumference lengths C2X of aperture P2X and C3X of aperture P3X in the comparative example are close to integer multiples of the wavelength of the frequency corresponding to antenna 470X, causing unwanted resonance and degrading the performance of antenna 470X.

[0121] To elaborate on this point, the following can be said: In antenna 470X, when unwanted resonance occurs, the current flowing along the edges of each aperture (P2X, P3X) increases locally, and the component of current that does not contribute to the radiation of antenna 470X increases. As a result, the ground current that should be used for the radiation of antenna 470X is consumed by the unwanted resonance, and the radiation efficiency of antenna 470X decreases. In addition, the current distribution around antenna 470X is disturbed by the unwanted resonance, causing distortion of the directivity, and it is thought that the radiation in the direction of its apertures (P2X, P3X) (in this case, radiation at low elevation angles) weakens, resulting in a decrease in the gain of antenna 470X.

[0122] In contrast, in the antenna 470 of this embodiment, the length of the circumference of each of the multiple apertures (P1, P2, P3, P4, P5, and P6) satisfies the above formula (1) or formula (2), thereby suppressing a decrease in the radiation efficiency of the antenna 470 due to unwanted resonance and distortion of directivity. As a result, the weakening of radiation in the direction of the apertures (P1, P2, P3, P4, P5, and P6) (here, radiation at low elevation angles) is suppressed, and the deterioration of the performance of the antenna 470 is suppressed.

[0123] Figure 17 shows an example of the directivity of the antenna 470 when the circumference C1 of the aperture P1 is changed.

[0124] Figure 17 shows the directivity results for vertical polarization when the circumference C1 of the aperture P1 shown in Figure 14 is changed to 900 mm, 1300 mm, and 1700 mm, represented by solid, dashed, and dotted lines, respectively. In Figure 16, the gain around 90°, which represents the gain at low elevation angles, is better for C1 = 900 mm and C1 = 1700 mm compared to the case where C1 = 1300 mm. This is thought to be because when the circumference C1 of the aperture P1 is 1300 mm, the antenna 470 approaches an integer multiple of the wavelength of the corresponding frequency, causing unwanted resonance and degrading the performance of the antenna 470.

[0125] The antenna 470 used here as an example of directivity corresponds to a frequency of 240 MHz. Therefore, the wavelength λ of the frequency corresponding to antenna 470 is approximately 1250 mm, and 1 / 4λ is approximately 312 mm. Substituting these into the above equations (1) and (2), in the case of n=1, if the circumference C1 of the aperture P1 is less than 938 mm or greater than 1562 mm, the degradation of antenna 470's performance due to unwanted resonance can be suppressed. Accordingly, the results for C1 = 900 mm (<938 mm) and C1 = 1700 mm (>1562 mm) are good, while the result for the case where the circumference C1 of the aperture P1 is 1300 mm is poor.

[0126] Figure 18 is a plan view of the antenna device 400A of the first modified example of the fourth embodiment.

[0127] In the first modified antenna device 400A, the position of the antenna 470A arranged on the conductor base 104 is different from the position of the antenna 470 in the embodiment shown in Figure 14 above. Specifically, the antenna 470A in this modified example is positioned at the +Y end of the conductor base 104, compared to the antenna 470 described above which is positioned in the central part of the conductor base 104. Even in this case, by making the length of the perimeter of the opening satisfy the above formula (1) or formula (2), the deterioration of the performance of the antenna 470A due to the occurrence of unwanted resonance can be suppressed.

[0128] However, in this modified example, current flows more easily through the conductor connection parts 105 located around the apertures P4 and P5 that are close to the antenna 470A, and less easily through the conductor connection parts 105 located around the aperture P1 that is farther from the antenna 470A. For this reason, the circumference length C1 of the aperture P1 has less influence on the occurrence of unwanted resonance. In the antenna device 400A of this modified example, there are multiple current paths from the element (radiating element) including the feed point electrically connected to the feed point of the antenna 470A, through the conductor connection parts 105 of the conductor base 104, to the vehicle body of the vehicle 1 having the conductor part of the recess 4. Of these multiple current paths, if the antenna 470A is, for example, a monopole antenna, then, due to its characteristics, the paths where the wavelength of the frequency to which the antenna 470A corresponds is about one-quarter or less will have an electrical length that allows current to flow strongly. In this modified antenna device 400A, the shape of the conductor base 104X and the arrangement of the conductor connection part 105 are set so that a path with an electrical length that allows this current to flow strongly does not come into contact with an opening whose circumference is near an integer multiple of the wavelength of the frequency to which the antenna 470A corresponds, thereby preventing the formation of a path that is prone to unwanted resonance.

[0129] Figure 19 is a perspective view of the second modified antenna 470B.

[0130] As explained above, in antennas that utilize ground current as part of their radiation, appropriately controlling the shape of the aperture where the antenna is placed and the length of the circumference of the aperture is particularly important from the viewpoint of stabilizing the antenna's performance. Even when the antenna 470B is placed on a substrate 110 attached to the ground element 130A, as in this modified example, the aperture formed by the ground element 130A and the substrate 110 can cause unwanted resonance.

[0131] The antenna 470B shown in Figure 19 is the same as the SXM antenna 30A in the antenna device 100A shown in Figure 6 described above. In this modified example, as described above, a space 130S is formed between the first portion 131A of the ground element 130A and the substrate 110 in the Z direction. As a result, an opening 131C is formed in the first portion 131A of the ground element 130A below the space 130S. Even in this case, by ensuring that the length of the circumference of the opening 131C satisfies the above formula (1) or formula (2), the deterioration of the antenna performance of the antenna 470B due to unwanted resonance can be suppressed.

[0132] Figure 20 is a plan view of the antenna device 400C, a third modified example of the fourth embodiment.

[0133] In the first modified antenna device 400A described above, the antenna 470A was positioned at the +Y direction end of the conductor base 104, whereas in this modified antenna device 400C, the antenna 470C is positioned at the -Y direction end of the conductor base 104. Furthermore, the antenna 470C is a GNSS antenna that corresponds to radio waves in the frequency band of, for example, 1571 MHz to 1608 MHz.

[0134] In the following, we will describe the results of our investigation into the gain of antenna 470C when the shape of the conductor base 104 (particularly the position and width of the conductor connection portion 105) and the position of antenna 470C on the conductor base 104 are varied in this modified antenna device 400C. In this modified antenna device 400C, similar to the antenna device 400 described above, the conductor base 104 has a total of six conductor connection portions 105, three on the +X side and three on the -X side. In the following, as shown in Figure 20, the three conductor connection portions 105 on the +X side may be referred to as conductor connection portion 105F, and the three conductor connection portions 105 on the -X side may be referred to as conductor connection portion 105R to distinguish them.

[0135] Figure 21 shows an example of the gain of the antenna 470C when the position of the conductor connection part 105F in the Y direction is changed.

[0136] In Figure 21, the gain results for antenna 470C are shown by solid, dashed, and dotted lines, respectively, for the following cases: when the position of the conductor connection 105F closest to antenna 470C in the -Y direction, of the three conductor connection 105F shown in Figure 20, overlaps with the position of the antenna 470C element in the Y direction; when it does not overlap with the position of the antenna 470C element on the +Y direction side; and when it does not overlap with the position of the antenna 470C element on the -Y direction side.

[0137] As shown in Figure 21, in the frequency band (GNSS) that antenna 470C operates in, the peak gain of antenna 470C (around 1500 MHz) is highest when the Y-direction position of the conductor connection 105F overlaps with the Y-direction position of the antenna 470C element (solid line). The next highest peak gain of antenna 470C is when the Y-direction position of the conductor connection 105F does not overlap with the antenna 470C element position on the -Y side (dotted line). Furthermore, when the Y-direction position of the conductor connection 105F does not overlap with the antenna 470C element position on the +Y side (dashed line), the peak gain of antenna 470C is lower than the previous two cases.

[0138] From the above, the gain of antenna 470C can be maximized by having the position of the conductor connection part 105F in the Y direction overlap with the position of the antenna element 470C in the Y direction. In antenna 470C, which is a GNSS antenna, radio waves tend to radiate in the zenith direction (in this case, the +Z direction). Therefore, even if the position of the conductor connection part 105F in the Y direction does not overlap with the position of the antenna element 470C, if it can be positioned on the -Y direction side (towards the end of the conductor base 104) of antenna 470C, the impedance at the end of the conductor base 104 can be lowered, and it is thought that the gain result of antenna 470C will be good.

[0139] Figure 22 shows an example of the gain of antenna 470C when the width YW of the conductor connection part 105F is changed.

[0140] Figure 22 shows the gain results for antenna 470C when the width YW of the conductor connection part 105F closest to antenna 470C in the -Y direction, of the three conductor connection parts 105F shown in Figure 20, is set to 17 mm, 27 mm, 37 mm, 47 mm, 57 mm, 67 mm, and 77 mm.

[0141] As shown in Figure 22, across almost the entire frequency band (GNSS) that antenna 470C operates in, the gain of antenna 470C is highest when the width YW of the conductor connection part 105F is largest at 77 mm, and lowest when the width YW of the conductor connection part 105F is smallest at 17 mm. It can also be seen that the gain of antenna 470C decreases as the width YW of the conductor connection part 105F decreases.

[0142] This is because, when the width of the conductor connection part 105F is small, current does not flow sufficiently to the ground, and the effective impedance at the end of the conductor base 104 increases. In contrast, by ensuring a sufficient width for the conductor connection part 105F, current flows stably to the ground, and the radiation efficiency of the antenna 470C saturates. Therefore, in the frequency band (GNSS) that the antenna 470C corresponds to, when the width YW of the conductor connection part 105F is 47 mm or more (47 mm, 57 mm, 67 mm, 77 mm), the gain of the antenna 470C is constant, and the results are considered stable. When the frequency that the antenna 470C corresponds to is, for example, 1.5 GHz, by making the width YW of the conductor connection part 105F at least one-quarter (1 / 4λ) of the wavelength of the frequency that the antenna 470C corresponds to, the gain of the antenna 470C is constant, and the results are considered stable.

[0143] Figure 23 shows an example of the gain of antenna 470C when the length YL of the protruding portion at the end of the conductor base 104 is changed.

[0144] Figure 23 shows the gain results for antenna 470C when the length YL of the portion protruding beyond the conductor connection portion 105F (or conductor connection portion 105R) at the -Y direction end of the conductor base 104 shown in Figure 20 is 15 mm, 25 mm, 35 mm, and 45 mm.

[0145] As shown in Figure 23, across almost the entire frequency band (GNSS) that antenna 470C operates in, the gain of antenna 470C is highest when the length YL of the protruding portion at the end of the conductor base 104 is smallest at 15 mm, and lowest when the length YL of the protruding portion at the end of the conductor base 104 is largest at 45 mm. It can also be seen that the gain of antenna 470C decreases as the length YL of the protruding portion at the end of the conductor base 104 increases.

[0146] From the above results, by setting the length YL of the protruding portion at the end of the conductor base 104 to an appropriate range, for example, to about one-eighth or less of the wavelength of the frequency corresponding to the antenna 470C, the effective impedance of the ground as seen from the antenna 470C can be kept low. As a result, it becomes possible to efficiently pass current through the wide surface of the conductor portion of the recess 4 (in this case, the part with low ground impedance, and the surface of the conductor portion of the recess 4 that is on the +X side from the conductor base 104), improving the radiation efficiency of the antenna 470C and ensuring a good gain for the antenna 470C.

[0147] Figure 24 shows an example of the gain of antenna 470C when the end of the conductor base 104 is connected to the conductor portion of the recess 4.

[0148] Figure 24 shows the gain results for antenna 470C shown in Figure 20 with a solid line, and also shows the gain results for antenna 470C when the -Y-direction end of the conductor base 104 is connected to the conductor portion of the recess 4 (outline shown as a dashed line in Figure 20) with a dashed line. As shown in Figure 24, it can be seen that when the -Y-direction end of the conductor base 104 is connected to the conductor portion of the recess 4, the gain of antenna 470C decreases in the vicinity of the frequency band (GNSS) to which antenna 470C operates.

[0149] This is because, in order to achieve good gain for antenna 470C, it is important that current flows through the wide surface of the conductor portion of recess 4 (in this case, the part with low ground impedance, and the surface of the conductor portion of recess 4 that is on the +X side of the conductor base 104). However, since the -Y side end of the conductor base 104 is connected to the conductor portion of recess 4, the current flow is dispersed in the Y direction, which is thought to reduce the gain of antenna 470C.

[0150] Figure 25 shows an example of the gain of antenna 470C when it is positioned in the central part of the conductor base 104.

[0151] Figure 25 shows the gain results for antenna 470C shown in Figure 20 with a solid line, and also shows the gain results for antenna 470C when antenna 470C is positioned in the central part of the conductor base 104 (outline shown as a dashed line in Figure 20) with a dashed line. As shown in Figure 25, it can be seen that the gain of antenna 470C deteriorates when antenna 470C is positioned in the central part of the conductor base 104.

[0152] This is because, in order to achieve good gain for antenna 470C, it is important that current flows through the part of the conductor in recess 4 where the ground impedance is low (in this case, the surface of the conductor in recess 4 that is on the +X side of the conductor base 104). However, because antenna 470C is positioned in the central part of the conductor base 104, the current flow is dispersed in the Y direction, which is thought to reduce the gain of antenna 470C.

[0153] Furthermore, by positioning the patch antenna antenna 470C towards the end of the conductor base 104, it becomes easier to secure spatial space in the central part of the conductor base 104, making it easier to position an antenna, such as one for receiving terrestrial radio waves, near the center, separate from antenna 470C. In addition, with antenna 470C as a GNSS antenna, multipath caused by reflected waves from low elevation angles may be suppressed, resulting in the secondary effect of improving the reception quality of antenna 470C.

[0154] Figure 26 shows an example of the gain of antenna 470C when the conductor connection part 105F or conductor connection part 105R is omitted.

[0155] In Figure 26, the gain results for antenna 470C shown in Figure 20 are shown with a solid line, the gain results for antenna 470C when the three conductor connection parts 105R are omitted (when only the three conductor connection parts 105F are present) are shown with a dashed line, and the gain results for antenna 470C when the three conductor connection parts 105F are omitted (when only the three conductor connection parts 105R are present) are shown with a dotted line.

[0156] As shown in Figure 26, the gain of antenna 470C is highest when it has conductor connection parts 105 on both the +X and -X sides (when the conductor base 104 is arranged to straddle the entire aperture region EP). In contrast, the gain of antenna 470C decreases when the conductor connection part 105F or conductor connection part 105R is omitted (when only the conductor connection part 105R or conductor connection part 105F is present). However, the decrease in the gain of antenna 470C is greater when the conductor connection part 105F is omitted (when only the conductor connection part 105R is present).

[0157] This is because, in order to achieve good gain for antenna 470C, it is important that current flows through the part of the conductor in recess 4 where the ground impedance is low (in this case, the surface of the conductor in recess 4 that is on the +X side of the conductor base 104). By omitting the conductor connection part 105F (only the conductor connection part 105R exists), it becomes difficult for current to flow through the wider surface of the conductor in recess 4, which is thought to worsen the gain of antenna 470C.

[0158] Further consideration of the results shown in Figure 26 suggests that the gain of antenna 470C largely depends on the area and extent of the ground-side conductor portion to which the current is connected via the conductor connection portion 105. In other words, to ensure the gain of antenna 470C, it is important to flow the ground current through a wider conductor surface of the recess 4, and by placing the conductor connection portion 105 on such a wide conductor surface side, the impedance of the ground as seen from antenna 470C can be kept low. For this reason, for example, if the overall opening region EP of the recess 4 is formed off-center in the front-rear direction of the vehicle, it may be advantageous from the viewpoint of antenna characteristics to place the conductor connection portion 105 on the opposite side of the opening region EP from antenna 470C, i.e., on the side where a relatively wide conductor surface remains. Furthermore, as shown in Figure 26, by providing conductor connection portions 105 on both the +X and -X sides and arranging the conductor base 104 to straddle the overall opening region EP, it becomes possible to utilize the wide conductor surfaces on both sides of the conductor portion of the recess 4 as ground. This allows the impedance of the ground as seen from the antenna 470C to be kept as low as possible, and thus the gain of the antenna 470C is expected to be the best.

[0159] ==Fifth Embodiment== <<Arrangement of each antenna of the antenna device 500>> Figure 27 is a plan view of the antenna device 500 of the fifth embodiment. Figure 28 is a side view of the antenna 510 of the antenna device 500.

[0160] In the antenna device 100 of the first embodiment described above, only one TEL antenna 10 was provided. However, in the antenna device 500 of this embodiment, instead of the TEL antenna 10, there may be multiple TEL antennas having similar element shapes. The antenna device 500 has antennas 510, 520, 530 and 540 instead of the TEL antenna 10 of the antenna device 100.

[0161] Antenna 510 comprises an element 511, a power supply unit 512 that supplies power to element 511, and a substrate 513 to which element 511 is connected. Element 511 is an element corresponding to the frequency band of the radio waves that antenna 510 supports. Antenna 510, like TEL antenna 10, is an element for a TEL antenna that supports the 699 MHz to 5000 MHz band for GSM, UMTS, LTE, and 5G, for example. Substrate 513 is a plate-shaped member to which element 511 is electrically connected.

[0162] As shown in Figure 28, element 511 has an upright portion 514, an extended portion 515, and a short-circuit portion 516.

[0163] The upright portion 514 is a part of the element 511 that is formed to rise up relative to the substrate 513. In this embodiment, the upright portion 514 is formed to rise up in the +Z direction relative to the substrate 513. However, the direction of the upright portion 514 relative to the substrate 513 is not limited to the +Z direction, and it may be inclined at a predetermined angle relative to the substrate 513. In this embodiment, the upright portion 514 has a self-similar shape, as shown in Figure 28. This makes it possible to broaden the bandwidth. Here, a self-similar shape is a shape that remains similar even when the scale (size ratio) is changed. However, the upright portion 514 does not have to have a self-similar shape.

[0164] The extended portion 515 is a part formed to extend from the upright portion 514. Furthermore, the extended portion 515 is a part formed to face the surface of the substrate 513 in the +Z direction. In this embodiment, as shown in Figure 28, the extended portion 515 is formed to extend in the -Y direction from the +Z end of the upright portion 514. However, the upright portion 514 may be formed to extend from a point other than the +Z end. That is, the extended portion 515 may be formed to extend from a point in the Z direction of the upright portion 514. Here, the direction in which the extended portion 515 extends is not limited to a direction parallel to the surface of the substrate 513 in the +Z direction, but may also be a direction inclined at a predetermined angle from a direction parallel to the surface of the substrate 513 in the +Z direction.

[0165] The short-circuit portion 516 branches off from the extended portion 515 and is electrically connected to the substrate 513. The short-circuit portion 516 is also electrically connected to the base 101 (not shown in Figure 28, see Figure 27) via the substrate 513. The presence of the short-circuit portion 17A in the first element 11A makes it easier to achieve impedance matching in the frequency band of the radio waves that the antenna 510 corresponds to. Furthermore, by connecting the element 511 to the same substrate 513 on which the feed portion 512 is located, soldering and detaching the antenna 510 (the set of element 511 and substrate 513) becomes easier. In this embodiment, the short-circuit portion 516 is electrically connected to the +Y direction end of the substrate 513, but it may be electrically connected to an end other than the +Y direction end of the substrate 513. Also, the element 511 does not have to have the short-circuit portion 516 (the antenna 510 may be an inverted L antenna).

[0166] Antenna 520 comprises an element 521, a power supply unit 522 that supplies power to element 521, and a circuit board 523 to which element 521 is connected. Since element 521 is the same as element 511 of antenna 510, and circuit board 523 is the same as circuit board 513 of antenna 510, a detailed explanation is omitted.

[0167] Antenna 510 is located on the +X side of a predetermined axis A, and antenna 520 is located on the -X side of a predetermined axis A. Furthermore, as shown in Figure 27, antennas 510 and 520 are arranged point-symmetrically with respect to a predetermined point S located on the predetermined axis A. As a result, the feed point 512 of antenna 510 and the feed point 522 of antenna 520 are arranged as follows: In the plan view shown in Figure 27, the feed point 512 of antenna 510 is located at the end of element 511 on the predetermined axis A side, and the feed point 522 of antenna 520 is located at the end of element 521 on the side facing the predetermined axis A (closer to axis A).

[0168] By arranging antennas 510 and 520 symmetrically (alternating) with respect to a predetermined point S, a space is formed between the positions of antenna 510 and antenna 520. The cables for supplying power to antennas 510 and 520 can then be placed within this space, eliminating the need to place the cables below elements 511 and 521. As a result, in a plan view, the cables can be positioned in a location that does not overlap with elements 511 and 521, suppressing unwanted electromagnetic coupling between the cables and elements 511 and 521. Furthermore, variations in the characteristics of antennas 510 and 520 due to cable movement can be suppressed.

[0169] Furthermore, in the antenna device 500 of this embodiment, as shown in Figure 27, the position of the feed point 512 of antenna 510 and the position of the feed point 522 of antenna 520 are spaced apart in the direction along a predetermined axis A (here, the Y direction). This ensures isolation between antenna 510 and antenna 520. Alternatively, in this case, the feed points 512 and 522 may be placed at the ends of the base 101 to further improve the isolation between antenna 510 and antenna 520.

[0170] Furthermore, the direction in which the extension portion 515 of element 511 extends and the direction in which the extension portion 525 of element 521 extends are different from each other. Specifically, in the plan view shown in Figure 27, the extension portion 515 of element 511 has an end 517 that is furthest from the position of the power supply unit 512, and the extension portion 525 of element 521 has an end 527 that is furthest from the position of the power supply unit 522. In a direction along a predetermined axis A (here, the Y direction), the D1 direction (-Y direction) in which the extension portion 515 extends from the position of the power supply unit 512 toward the end 517 and the D2 direction (+Y direction) in which the extension portion 525 extends from the position of the power supply unit 522 toward the end 527 are opposite directions. As a result, the D1 direction of the extension portion 515 and the D2 direction of the extension portion 525 are parallel to each other, while the directions of the currents that mainly flow in the extension portion 515 and the extension portion 525 are opposite to each other. Therefore, when elements 511 and 521 are placed in close proximity, the magnetic field coupling between them can be reduced. Furthermore, the ends 517 and 527 are areas where the voltage tends to be high in elements 511 and 521, respectively. In this embodiment, these areas where the voltage tends to be high are spaced apart at an angle in a plan view. As a result, the electric field coupling between elements 511 and 521 can be reduced, and combined with the magnetic field coupling reduction effect described above, the mutual impedance between elements 511 and 521 is reduced. As a result, even when antennas 510 and 520 are placed in close proximity, the isolation between the two antennas can be improved.

[0171] However, the direction in which the extension portion 515 of element 511 extends and the direction in which the extension portion 525 of element 521 extends may be the same. In this case, antenna 510 and antenna 520 may be arranged symmetrically with respect to a predetermined axis A.

[0172] Antennas 530 and 540 are positioned adjacent to antennas 510 and 520 in a direction along a predetermined axis A (Y direction). The above-described explanation of the positional relationship between antennas 510 and 520 can be similarly applied to the explanation of the positional relationship between antennas 530 and 540. Antennas 530 and 540 are positioned based on the positional relationship between antennas 510 and 520, but shifted parallel to them in a predetermined direction (here, the -Y direction). By arranging antennas 530 and 540 in this way, it is possible to avoid having parts of antennas 530 and 540 that tend to have high voltages in a plan view (ends 517 and 527 of antennas 510 and 520) being close to or facing each other. As a result, electric field coupling between antennas 530 and 540 and antennas 510 and 520 is reduced, and even when multiple antennas are arranged in close proximity, the effects of coupling between antennas can be suppressed.

[0173] Figure 29 is a plan view of a modified antenna 510A.

[0174] In the modified antenna 510A, as shown in the plan view in Figure 29, the element 511 is arranged so as not to overlap with the fixing portion 518 of the substrate 513 to the base 101. This makes it easy to tighten screws from the +X direction (upward direction), and thus makes it easy to assemble the antenna 510A.

[0175] <<Assembly Procedure for Antenna Devices 500B to 500E>> The assembly procedure for antenna devices 500B to 500E will be described below. To simplify the explanation, the assembly procedure will be described as the procedure for fixing the antenna 510 (element 511) of each antenna device 500B to 500E to the base 101 and case 102, and the procedure for connecting the cable 106 to the antenna 510.

[0176] Figure 30 is an explanatory diagram showing the assembly procedure for the antenna device 500B. The antenna device 500B is assembled according to the following steps (1) to (4).

[0177] (1) Fix element 511 to case 102. (2) Fix circuit board 513 to case 102. (3) Fix base 101 to case 102 and circuit board 513. (4) Connect cable 106 to circuit board 513 by soldering.

[0178] In the antenna device 500B, the cable 106 is positioned on the -Z side (bottom side) of the base 101, allowing the connection of the cable 106 to the substrate 513 to be the last step in the assembly procedure (step (4) above), thus simplifying steps (1) to (3). However, in the antenna device 500B, another base 108 may be positioned on the -Z side (bottom side) to protect the cable 106. Also, in the antenna device 500B, since the cable 106 is positioned on the -Z side of the base 101, the cable 106 can avoid passing near the element 511, suppressing unnecessary electromagnetic coupling between the cable 106 and the element 511, which contributes to stabilizing the antenna characteristics.

[0179] Figure 31 is an explanatory diagram showing the assembly procedure for the antenna device 500C. The antenna device 500C is assembled according to the following steps (1) to (4).

[0180] (1) Fix element 511 to case 102. (2) Fix circuit board 513 to case 102. (3) Connect cable 106 to circuit board 513 by soldering. (4) Fix base 101 to circuit board 513.

[0181] In the antenna device 500C, as shown in Figure 31, the cable 106 is arranged within the housing space between the base 101 and the case 102, so the overall height of the antenna device 500C can be reduced.

[0182] Figure 32 is an explanatory diagram showing the assembly procedure for the antenna device 500D. The antenna device 500C has a holder 109 for fixing the antenna 510 and is assembled in the following steps (1) to (5).

[0183] (1) Fix element 511 to holder 109. (2) Fix circuit board 513 to holder 109. (3) Fix element 511 and circuit board 513, which are fixed to holder 109, to base 101. (4) Fix case 102 to base 101. (5) Connect cable 106 to circuit board 513 by soldering.

[0184] In the antenna device 500D, the cable 106 is positioned on the -Z side (bottom side) of the base 101, allowing the connection of the cable 106 to the circuit board 513 to be the last step in the assembly procedure (step (5) above), thus simplifying steps (1) to (4). However, in the antenna device 500D, another base (not shown) may be positioned on the -Z side (bottom side) to protect the cable 106.

[0185] Figure 33 is an explanatory diagram showing the assembly procedure of the antenna device 500E. The antenna device 500E has a holder 109 for fixing the antenna 510 and is assembled in the following steps (1) to (5). By fixing the antenna 510 using the holder 109, the element 511 and the substrate 513 can be assembled in an integral position, and the relative positional relationship of the antenna 510 with other antennas can be reproduced with high precision. As a result, when mass-producing the antenna device 500E, variations in coupling and directivity between antennas can be suppressed.

[0186] (1) Fix element 511 to holder 109. (2) Fix circuit board 513 to holder 109. (3) Connect cable 106 to circuit board 513 by soldering. (4) Fix element 511 and circuit board 513, which are fixed to holder 109, to base 101. (5) Fix case 102 to base 101.

[0187] In the antenna device 500E, the cable 106 is located within the space between the base 101 and the case 102, which allows the entire antenna device 500E to be made lower in profile.

[0188] Figure 34 is an explanatory diagram showing how to fix the cable 106 to the base 101.

[0189] As shown in Figure 34, a resin part 7 may be used to fix the cable 106 to the base 101. By using a separate resin part 7 to fix the cable 106 to the base 101, the cable 106 can be easily fixed from the back side of the base 101 (in this case, the -Z direction side). This suppresses the movement of the cable 106 due to vibrations during transportation (for example, when a vehicle is running), and suppresses changes in the antenna characteristics caused by fluctuations in the position of the cable 106.

[0190] The resin part 7 has a cable holding portion 8 for holding the cable 106 and a fixing portion 9 for fixing the cable holding portion 8 to the base 101. If the cable 106 has ferrite for leakage current countermeasures, the cable holding portion 8 may hold the cable 106 and the ferrite together. The fixing portion 9 has a structure that clamps the cable 106, but it may also be a snap-fit ​​structure using a claw structure.

[0191] However, the cable 106 may be fixed to the base 101 without using the resin part 7. For example, the cable 106 may be fixed by forming a rib on the base 101 and holding it in place. Alternatively, if the base 101 is made of sheet metal, the rib portion that holds the cable 106 may be cut and bent, and then crimped together with the cable 106, or the cable 106 may be sandwiched between them. In this case, the outer sheath of the cable 106 may be stripped to provide a midpoint ground.

[0192] ==Summary== According to this specification, antenna devices in the following embodiments are provided.

[0193] (Aspect 1) Aspect 1 is an antenna device comprising a planar antenna having a radiating element and a ground conductor located below the radiating element, and a ground element in which at least a portion is located below the ground conductor.

[0194] According to the above-described embodiment, the gain of a planar antenna at low elevation angles can be improved.

[0195] (Aspect 2) In aspect 2, the ground element has a first portion including a plane substantially perpendicular to the vertical direction, and a second portion including a plane substantially perpendicular to the horizontal direction when the direction perpendicular to the vertical direction is taken as the horizontal direction.

[0196] According to the above-described embodiment, it is possible to improve the gain at low elevation angles while ensuring the gain at medium to high elevation angles of the planar antenna.

[0197] (Aspect 3) In aspect 3, the second portion extends downward from the end of the first portion.

[0198] According to the above-described embodiment, the gain of the planar antenna at low elevation angles can be further improved.

[0199] (Aspect 4) In aspect 4, a first antenna is provided which is located next to the planar antenna in a predetermined first lateral direction among the lateral directions, and the second portion extends downward from the end of the first portion in a direction different from the first lateral direction.

[0200] According to the above-described embodiment, it is possible to suppress the mutual influence on the characteristics of the first antenna located next to the planar antenna, and to improve the low elevation angle gain of the planar antenna.

[0201] (Aspect 5) In aspect 5, in the vertical direction, the first portion is spaced a predetermined distance below the ground conductor, and the second portion is located between the first portion and the ground conductor.

[0202] According to the above-described embodiment, it is possible to improve the gain at low elevation angles while ensuring the gain at medium to high elevation angles of the planar antenna.

[0203] (Aspect 6) In aspect 6, the second part further comprises a substrate on which the planar antenna is arranged, and the second part connects the first part and the substrate.

[0204] According to the above-described embodiment, it is possible to support the substrate on which the planar antenna is placed and to improve the low elevation gain of the planar antenna.

[0205] According to this specification, antenna devices in the following embodiments are provided.

[0206] (Aspect 7) Aspect 7 is an antenna device disposed inside a recess formed at least partly of a conductor, wherein the recess in which the antenna device is disposed is covered with a cover, and comprises a planar antenna having a radiating element disposed on the cover side, and a parasitic element disposed at a predetermined distance from the radiating element on the cover side.

[0207] According to the above-described embodiment, the gain of a planar antenna at low elevation angles can be improved.

[0208] (Aspect 8) In aspect 8, the passive element is arranged on the side of the cover where the planar antenna is located.

[0209] According to the above-described embodiment, compared to the case in which members are arranged around the planar antenna in a horizontal direction perpendicular to the vertical direction, the size in the horizontal direction can be suppressed, and the gain of the planar antenna at low elevation angles can be improved.

[0210] According to this specification, antenna devices in the following embodiments are provided.

[0211] (Aspect 9) Aspect 9 is an antenna device comprising, in a plan view, a conductor base located inside an overall aperture region formed in a conductor portion and having a conductor connection portion connected to the conductor portion, and at least one antenna disposed on the conductor base, wherein the overall aperture region has at least one opening defined by the conductor portion and the conductor base, and when the circumference length of the opening is C, the wavelength of the frequency to which the antenna corresponds is λ, and n is an integer, C < nλ - 1 / 4λ or C > nλ + 1 / 4λ.

[0212] According to the above-described embodiment, it is possible to suppress the deterioration of antenna performance due to the occurrence of unwanted resonance.

[0213] (Aspect 10) In aspect 10, a plurality of antennas are provided, the overall aperture region has a plurality of apertures, and when the wavelength of the lowest frequency among the frequencies corresponding to each of the plurality of antennas is λm, and the length of the largest circumference among the circumferences of each of the plurality of apertures is Cm, then Cm < nλm - 1 / 4λm.

[0214] According to the above embodiment, it is possible to suppress the degradation of the performance of multiple antennas due to the occurrence of unwanted resonance.

[0215] (Aspect 11) In aspect 11, the antenna has an element, and in a plan view, at least a part of the conductor connection is located in the region between the element and the conductor.

[0216] According to the above-described embodiment, it is possible to suppress the deterioration of antenna performance due to the occurrence of unwanted resonance.

[0217] According to this specification, antenna devices in the following embodiments are provided.

[0218] (Aspect 12) Aspect 12 comprises a first antenna having a first element, a first power supply unit for supplying power to the first element, and a first substrate to which the first element is connected, and a second antenna having a second element, a second power supply unit for supplying power to the second element, and a second substrate to which the second element is connected, wherein the first element has a first erected portion rising from the first power supply unit relative to the first substrate, and a first extended portion extending from the first erected portion and facing the first substrate, and the second element has the second power supply unit The antenna device has a second erected portion that rises from the second substrate and a second extended portion that extends from the second erected portion and faces the second substrate, and in a plan view, the first antenna and the second antenna are arranged point-symmetrically with respect to a predetermined point located on a predetermined axis, the first feeding portion is located at the predetermined axis-side end of the first element and the second feeding portion is located at the predetermined axis-side end of the second element, and the positions of the first feeding portion and the second feeding portion are spaced apart in the direction along the predetermined axis.

[0219] According to the above-described embodiment, when multiple antennas are placed in close proximity, variations in characteristics due to cable movement can be suppressed, and isolation of the multiple antennas can be ensured.

[0220] (Aspect 13) In aspect 13, in a plan view, the first extension has a first end furthest from the position of the first power supply unit, and the second extension has a second end furthest from the position of the second power supply unit, and of the directions along the predetermined axis, the first direction of the first extension extending from the position of the first power supply unit to the first end and the second direction of the second extension extending from the position of the second power supply unit to the second end are different.

[0221] According to the above-described embodiment, when multiple antennas are placed in close proximity, isolation between the multiple antennas can be ensured.

[0222] (Aspect 14) In aspect 14, the system comprises two first antennas and two second antennas arranged adjacent to each other in a direction along the predetermined axis.

[0223] According to the above-described embodiment, when multiple antennas are placed in close proximity, variations in characteristics due to cable movement can be suppressed, and isolation of the multiple antennas can be ensured.

[0224] The embodiments described above are provided to facilitate understanding of the present invention and are not intended to limit its interpretation. Furthermore, the present invention may be modified or improved without departing from its spirit, and it goes without saying that the present invention includes equivalents thereof.

[0225] 4 Recess, 5 Frame, 6 Roof panel, 7 Resin part, 8 Cable holder, 9 Fixing part, 30, 30A, 70, 70A, 80, 80A SXM antenna, 31, 71 Radiating element, 33, 73 Ground conductor, 60, 90, 90A GNSS antenna, 100, 100A, 200, 200A, 300, 300A Antenna device, 101 Base, 102 Case, 103 Spacer, 104, 104X Conductor base, 105 Conductor connection part, 106 Cable, 109 Holder, 110 Circuit board, 130, 130A, 140, 140A, 160, 160A, 170, 170A Ground element, 131, 131A, 141A, 161, 161A First part, 132, 132A, 142A, 162, 162A Second part, 150, 150A Unpowered element, 400, 400A, 400X Antenna device, 470, 470A, 470B, 470X, 510, 520, 530, 540 Antenna, 511, 521, 531, 541 Element, 512, 522, 532, 542 Power supply section, 513, 523, 533, 543 Substrate, 514 Upright section, 515 Extension section, 516 Short-circuit section, 517, 527 End section, 518 Fixing section, C1-C6, C2X, C3X Circumference length, P1 to P6, P2X, P3X opening, EP entire opening area

Claims

A planar antenna having a radiating element and a ground conductor located below the radiating element, The system comprises a ground element, at least a portion of which is located below the ground conductor, The aforementioned ground element is A first part including a plane that is substantially perpendicular in the vertical direction, When the direction perpendicular to the vertical direction is defined as the horizontal direction, the second portion includes a plane that is substantially perpendicular to the horizontal direction, Antenna device. 　 The second portion extends downward from the end of the first portion, The antenna device according to claim 1. 　 In the aforementioned lateral directions, a first antenna is provided which is located adjacent to the planar antenna in a predetermined first lateral direction, The second portion extends downward from the end of the first portion in a direction different from the first transverse direction. The antenna device according to claim 1. 　 In the vertical direction, The first portion is spaced a predetermined distance below the ground conductor, The second part is located between the first part and the ground conductor, The antenna device according to claim 1. 　 The substrate further comprises the aforementioned planar antenna on which the planar antenna is arranged. The second part connects the first part and the substrate. The antenna device according to claim 4. 　 An antenna device disposed inside a recess formed at least partly of a conductor, The recess in which the antenna device is arranged is covered with a cover. A planar antenna having a radiating element arranged on the cover side, A powerless element is positioned at a predetermined distance from the radiating element on the cover side, An antenna device equipped with the following features. 　 The powerless element is located on the side of the cover where the planar antenna is positioned. The antenna device according to claim 6.

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