Antenna device

Abstract

An antenna device comprising: an antenna that has a ground part, a body part opposed to the ground part and having an open end that is opened, and a feeding part extending from the body part toward the ground part and having a feeding point; and a parasitic element that has a first end spaced from the open end and that is used for impedance adjustment of the antenna.

Description

[Technical Field]

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

[0002] Patent Document 1 discloses an integrated antenna. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-81500 Summary of the Invention [Problem to be solved by the invention]

[0004] The antenna for the first telephone and the antenna for the second telephone in the integrated antenna disclosed in Patent Document 1 each support a limited frequency band and are not capable of supporting a wide band of radio waves.

[0005] In view of the above-mentioned problems, an example of an object of the present invention is to realize an antenna device that can handle radio waves in a wide frequency band. [Means for solving the problem]

[0006] One aspect of the present invention is an antenna device comprising an antenna having a ground section, a main body section having an open end facing the ground section and open, a power supply section extending from the main body section toward the ground section and having a power supply point, and a parasitic element for adjusting the impedance of the antenna, the parasitic element having a first end spaced apart from the open end.

[0007] According to one aspect of the present invention, an antenna device that can handle radio waves in a wide frequency band can be realized. [Brief explanation of the drawings]

[0008] [Figure 1] 1A and 1B are perspective views of the antenna device 1 of the first embodiment as seen from the rear left, front right, and rear right, respectively. [Figure 2] This is a schematic diagram of antenna 2, showing (a) the case where the length of antenna 20 is half the radio wave length of the corresponding frequency band, and (b) the case where the length of antenna 20 is one-quarter the radio wave length of the corresponding frequency band. [Figure 3] 10 is a Smith chart showing the impedance characteristics of the antenna 10 when (a) there is no parasitic element 30 and when (b) there is a parasitic element 30. FIG. [Figure 4] 10 is a Smith chart showing the impedance characteristics of the antenna 10 when the parasitic element 30 is not present. [Figure 5] 1 is a Smith chart showing the impedance characteristics of the antenna 10 when a parasitic element 30 is present. [Figure 6] 1 is a Smith chart showing the impedance characteristics of an antenna 10 when a parasitic element 30 is present and a capacitor is connected in series to the antenna 10. [Figure 7] 1 is a graph showing the relationship between VSWR and frequency in the antenna device 1. [Figure 8] 1A is a diagram showing an example of an antenna device 1, and FIG. 1B is a Smith chart showing the impedance characteristics of the antenna 10 when the distance between the parasitic element 30 and the antenna 10 is changed. [Figure 9] 1A is a diagram showing an example of an antenna device 1, and FIG. 1B is a Smith chart showing the impedance characteristics of the antenna 10 when the front-to-rear length of the parasitic element 30 is changed. [Figure 10] 1A is a diagram showing an example of an antenna device 1, and FIG. 1B is a Smith chart showing the impedance characteristics of the antenna 10 when the front-to-rear length of the parasitic element 30 is changed. [Figure 11] 1A is a diagram showing an example of an antenna device 1, and FIG. 1B is a Smith chart showing the impedance characteristics of the antenna 10 when the width of the parasitic element 30 is changed. [Figure 12] 1A is a diagram showing an example of an antenna device 1, and FIG. 1B is a Smith chart showing the impedance characteristics of the antenna 10 when the width of the parasitic element 30 is changed. [Figure 13] 1A is a diagram showing an example of an antenna device 1, and FIG. 1B is a Smith chart showing the impedance characteristics of an antenna 10. FIG. [Figure 14] 1A is a diagram showing an example of an antenna device 1, and FIG. 1B is a Smith chart showing the impedance characteristics of an antenna 10. FIG. [Figure 15] 1A is a diagram showing an example of an antenna device 1, and FIG. 1B is a Smith chart showing the impedance characteristics of an antenna 10. FIG. [Figure 16] FIG. 10 is an exploded perspective view of the antenna device 100 according to the second embodiment. [Figure 17] 10A and 10B are perspective views of an antenna device 100 according to a second embodiment, showing (a) a view from the front left and (b) a view from the front right. DETAILED DESCRIPTION OF THE INVENTION

[0009] At least the following matters will become clear from the description of 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 designated by the same reference numerals, and redundant explanations will be omitted where appropriate. ==First Embodiment== <<Outline of Antenna Device 1>> An overview of an antenna device 1 according to this embodiment will be described with reference to FIGS.

[0011] The antenna device 1 is a vehicle antenna device used in a vehicle (wheeled vehicle) not shown. In this embodiment, the antenna device 1 is mounted, for example, on the top surface (including the roof and back door) of the vehicle, below the top surface, or inside the instrument panel. However, the antenna device 1 may also be located in a part of the vehicle other than the roof or inside the instrument panel, such as the vehicle spoiler or overhead console. Furthermore, the antenna device 1 may be an antenna device for a vehicle other than that used in a vehicle.

[0012] Antenna device 1 includes antenna 2, ground section 3, parasitic element 30, circuit board 50, and holding member 60. Antenna 2 functions as two antennas, each capable of supporting a different frequency band. These two antennas will be referred to below as antenna 10 and antenna 20. Additionally, antenna 2 includes power supply section 12 (described below) that functions as a third antenna.

[0013] In the following description, the direction from the ground portion 3 toward the antenna 2 as shown in Fig. 1 is referred to as the upward direction, and the opposite direction is referred to as the downward direction. The direction in which the upper part of the parasitic element 30 (first extension portion 31 described later) extends toward the second extension portion 11B of the element 11 described later is referred to as the forward direction, and the opposite direction is referred to as the backward direction. Furthermore, the direction perpendicular to the up-down direction and the front-back direction is referred to as the left-right direction.

[0014] As shown in Figure 1, the front-to-back direction is sometimes called the "X direction," the left-to-right direction is sometimes called the "Y direction," and the up-to-down direction is sometimes called the "Z direction." The rearward direction is sometimes called the +X direction, the leftward direction is sometimes called the +Y direction, and the up-to-down direction is sometimes called the +Z direction. The left-to-right direction is sometimes called the "horizontal direction" or "width direction," and the up-to-down direction is sometimes called the "vertical direction" or "height direction."

[0015] The above definitions of directions and the like are common to other embodiments in this specification unless otherwise specified. <Ground section 3> The ground section 3 functions as a ground for the antenna 2 and the parasitic element 30 of the antenna device 1. However, the ground section 3 may also function as a ground for some of the antennas in the antenna 2. For example, the ground section 3 may function as a ground for the antenna 10, and another ground section may function as a ground for the antenna 20.

[0016] In this embodiment, the ground section 3 is formed as a single metal plate (sheet metal) as shown in Fig. 1. However, the ground section 3 may be made up of multiple separate metal plates. For example, the ground section 3 may be configured such that a metal plate on which the antenna 10 is provided and another metal plate on which the antenna 20 is provided are electrically connected.

[0017] The ground section 3 may be formed in a shape other than a plate, as long as it functions as the ground for the antenna of the antenna device 1. Furthermore, the ground section 3 may be formed by freely combining metal and non-metallic members, as long as it functions as the ground for the antenna of the antenna device 1. For example, the ground section 3 may be formed including a metal plate and a resin insulator. Furthermore, the ground section 3 may be formed by a single board on which a conductor pattern is formed, such as a printed circuit board (PCB).

[0018] 1, the ground portion 3 is formed of a substantially quadrilateral member when viewed from above. In the following description, "substantially quadrilateral" or "rectangle" refers to a shape consisting of four sides, including, for example, a square or a rectangle, and may have at least some corners cut out at an angle to the sides, or may have at least some corners that include curves. Furthermore, the "substantially quadrilateral" or "rectangle" shape may have cutouts (recesses) or protrusions (protrusions) on some of the sides. <Antenna 10> The antenna 10 is a wideband antenna for mobile communications based on an inverted-L antenna (see FIGS. 1 and 2). In this embodiment, the antenna 10 is compatible with radio waves in the 699 MHz to 894 MHz band (corresponding to the "first frequency band") for GSM, UMTS, and LTE, for example. However, the antenna 10 is not limited to this, and may be compatible with radio waves in some (for example, only 5G) frequency bands among GSM, UMTS, LTE, and 5G.

[0019] The antenna 10 may also be compatible with radio waves in frequency bands other than those for GSM, UMTS, and LTE. For example, the antenna 10 may be an antenna compatible with radio waves in frequency bands used for telematics, V2X (Vehicle to Everything: vehicle-to-vehicle communication, road-to-vehicle communication), Wi-Fi, Bluetooth, etc. Note that Wi-Fi and Bluetooth are registered trademarks.

[0020] Antenna 10 has an element 11 and a power supply section 12. Element 11 is an element that resonates together with power supply section 12 in the frequency band of radio waves corresponding to antenna 10. As shown in FIG. 1, element 11 is connected to the upper end of power supply section 12.

[0021] Note that "connected" is not limited to being physically connected, but also includes being electrically connected. Furthermore, electrical connection is not limited to being connected by a conductor, but includes being connected by an electronic circuit, electronic component, etc.

[0022] The element 11 is a horizontally extending plate-like member that faces the ground portion 3 via the holding member 60 and has an L-shaped bent shape at the front when viewed from above. The element 11 has a first extending portion 11A and a second extending portion 11B.

[0023] First extension portion 11A is a portion formed to extend forward from power supply portion 12. In addition, first extension portion 11A is formed to face ground portion 3 in the up-down direction.

[0024] The second extension portion 11B is a portion that extends rightward from the front portion of the first extension portion 11A. In this embodiment, the first extension portion 11A and the second extension portion 11B form a shape in which the element 11 is bent rightward in top view. An end portion 11C of the second extension portion 11B forms an open end portion, and faces the front end portion of the parasitic element 30 in the front-to-rear direction with a gap therebetween, as shown in FIG. 1(a). Note that the "end portion" does not mean the strict end, as indicated by the dotted line in FIG. 1(a), but rather means a certain region that includes the end.

[0025] Power supply unit 12 is a flat plate-like member formed to extend upward from circuit board 50. A power supply point 12A electrically connected to circuit board 50 is provided at the lower end of power supply unit 12.

[0026] Power supply unit 12 has a generally semicircular shape with an arc extending downward when viewed from the left to the right. Therefore, the upper end of power supply unit 12 has a longer length in the front-to-rear direction (hereinafter sometimes referred to as width) than the lower end. Note that power supply unit 12 is not limited to a semicircular shape and may have another shape, such as a polygonal shape, in which the length in the front-to-rear direction of the upper end of power supply unit 12 is longer than the lower end.

[0027] By increasing the length of the upper end of power supply unit 12 in the front-to-back direction (the width of power supply unit 12 when viewed in the left-to-right direction), power supply unit 12 functions as an antenna compatible with the 3.3 to 5 GHz frequency band (corresponding to the "second frequency band").

[0028] The length of antenna 10 along its shape from feed point 12A to end 11C is equal to approximately one-fourth the wavelength of radio waves in the 699 MHz to 894 MHz band (for example, the center frequency, 699 MHz in the example of FIG. 3) (indicated by the arrow with the circled number 1 in FIG. 2). By making the length of antenna 10 approximately one-fourth the length of radio waves in the supported frequency band, the sensitivity of antenna 10 in the supported frequency band can be improved.

[0029] <Antenna 20> Antenna 20 is a wideband antenna for mobile communications based on a bent monopole antenna (see FIGS. 1 and 2). In this embodiment, antenna 20, together with power supply unit 12, supports radio waves in the 2 GHz band (e.g., 1710 to 2170 MHz, corresponding to the "third frequency band"). However, antenna 20 is not limited to this, and may also support radio waves in a part of the 2 GHz frequency band.

[0030] The antenna 20 may also be compatible with radio waves in frequency bands for GSM, UMTS, LTE, and 5G. The antenna 20 may also be an antenna compatible with radio waves in frequency bands used for, for example, telematics, V2X (Vehicle to Everything: vehicle-to-vehicle communication, road-to-vehicle communication), Wi-Fi, Bluetooth, etc. Furthermore, the antenna 20 may be compatible with communication using MIMO (Multiple-Input Multiple-Output), as will be described later.

[0031] The antenna 20 has an element 21 and shares the feed portion 12 with the antenna 10 .

[0032] Element 21 is a flat plate-shaped conductive member, and is formed so as to extend rearward from the upper end of power supply portion 12. Element 21 has first extending portion 21A and second extending portion 21B.

[0033] First extension 21A is a portion that extends horizontally and rearward from the upper end of power supply unit 12. Second extension 21B is a portion that extends downward from the rear end of first extension 21A. The lower end of second extension 21B is connected to ground unit 3 using a connector such as a screw, and is also electrically connected to ground unit 3. Note that second extension 21B and ground unit 3 may be connected by soldering, welding, or other methods.

[0034] The length of antenna 20 along the shape of the connection portion between feed point 12A and ground portion 3, i.e., from feed point 12A to the short-circuited end, is approximately equal to half the wavelength of radio waves in the 2 GHz band (for example, the center frequency) (indicated by the arrow with the circled number 3 in FIG. 2(a)). By setting the length of antenna 20 to half the length of radio waves in the corresponding frequency band, the sensitivity of antenna 20 in the corresponding frequency band can be improved.

[0035] As shown in Figure 2(b), the end of the antenna 20 can be open. In this case, the sensitivity of the antenna 20 in the corresponding frequency band can be improved by making the length of the antenna 20 approximately one-fourth the wavelength of the radio wave in the corresponding frequency band (for example, the center frequency) (indicated by the arrow with the circled number 3 in Figure 2(b)). The wavelength of the corresponding frequency band indicated by the arrow with the circled number 1 in Figure 2(b) is the same as in Figure 2(a).

[0036] <Parasite element 30> The parasitic element 30 is a flat conductive member mechanically and electrically connected to the ground portion 3, and has the function of adjusting the impedance of the antenna 10. The parasitic element 30 includes a first extension portion 31 extending in the front-rear direction, and a second extension portion 32 extending downward from the rear end of the first extension portion 31 (see FIGS. 1 and 2).

[0037] The first extension portion 31 is a portion formed in a substantially rectangular shape in top view. The first extension portion 31 extends in the front-rear direction and faces the ground portion 3 in the up-down direction via the holding member 60. The distance (height in the up-down direction) of the first extension portion 31 from the ground portion 3 is shorter than the wavelength of the frequency band (699 MHz to 894 MHz) supported by the antenna 10 and is substantially equal to the distances of the first extension portion 11A, the second extension portion 11B, and the first extension portion 21A from the ground portion 3. As shown in FIG. 1, the front end portion of the first extension portion 31 faces the end portion 11C in the front-rear direction.

[0038] The distance (D1 in FIG. 2(a)) from the ground portion 3 to the first extension portion 31 does not necessarily have to be equal to the distance (D2 in FIG. 2(a)) from the ground portion 3 to the first extension portion 11A and the second extension portion 11B. Therefore, the front end of the first extension portion 31 may be located lower or higher than the end of the second extension portion 11B.

[0039] The second extension portion 32 is a rectangular portion when viewed from the left to right, extending vertically to connect the rear end of the first extension portion 31 and the ground portion 3. The lower end of the second extension portion 32 is connected to the ground portion 3 using a connector such as a screw, and is also electrically connected to the ground portion 3. The length from the front end of the first extension portion 31 to the short-circuit end, following the shapes of the first extension portion 31 and the second extension portion 32, is indicated by the number 2 in a circle with an arrow in FIGS. 2(a) and 2(b). Note that the second extension portion 32 and the ground portion 3 may be connected by a method such as soldering or welding.

[0040] The extending directions of the first extension portion 11A, the second extension portion 11B, and the first extension portion 21A, and the extending direction of the first extension portion 31 are not limited to a direction parallel to the surface of the ground portion 3, but may be a direction inclined at a predetermined angle from a direction parallel to the surface of the ground portion 3. The first extension portion 11A and the second extension portion 11B (element 11), and the first extension portion 21A correspond to the "main body portion" in this disclosure.

[0041] <Circuit board 50> The circuit board 50 is a rectangular member attached to the upper surface of the ground section 3 and is electrically connected to the feeding point 12A. The circuit board 50 is provided with a capacitor (not shown) which is connected in series to the antennas 10 and 20 via the feeding point 12A. The capacitance of the capacitor is set appropriately according to the characteristics of the antenna 10.

[0042] <Holding member 60> The holding member 60 is a member formed from an insulating material such as resin, and has the function of supporting the antennas 10, 20 and the parasitic element 30. In detail, the holding member 60 has the antennas 10, 20 and the parasitic element 30 mounted on its upper surface, and maintains the shapes of the antennas 10, 20 and the parasitic element 30. The holding member 60 also supports the first extension portion 11A, the second extension portion 11B, and the first extension portion 21A so that the distance from the ground portion 3 is constant.

[0043] The holding member 60 has two locking portions 61 with L-shaped upper ends on planes facing the first extension portion 11A of the element 11 of the antenna 10 and the first extension portion 31 of the parasitic element 30. The locking portions 61 are inserted into the hole 11D of the first extension portion 11A of the element 11 of the antenna 10 and the hole 31A formed in the first extension portion 31 of the parasitic element 30, and are slid back and forth to hold the element 11. This makes it easy to position the element 11 of the antenna 10 and the parasitic element 30 relative to the holding member 60, and furthermore, the distance between the element 11 (21) of the antenna 10 (20) and the parasitic element 30 is kept constant, thereby maintaining stable antenna performance.

[0044] It is also possible to provide a rib near the edge of the holding member 60 to position the element 11 (21) of the antenna 10 (20) and the parasitic element 30 relative to the holding member 60.

[0045] Naturally, the element 11 (element 21) of the antenna 10 (20) may be fixed and held to the holding member 60 by integral molding, welding, or screwing, without providing such locking portions 61 or holes (notches). In this case, equipment for integral molding or welding, and jigs for screwing are required. On the other hand, holding by the locking portions 61 and holes (notches) has the advantage of facilitating assembly, since such equipment and jigs are not required.

[0046] <Arrangement of parasitic element 30> As will be explained below, the impedance characteristics of the antenna 10 are adjusted by the size or position of the parasitic element 30.

[0047] The impedance characteristics of antenna 10 without parasitic element 30 are shown in Figures 3(a) and 4. Figure 3(a) shows the impedance of antenna 10 as a dotted line on a Smith chart normalized to 50 ohms, with the start and end points of the graph being 600 MHz and 1000 MHz. Markers numbered 1 and 2 on the graph correspond to the minimum (699 MHz) and maximum (894 MHz) values ​​in the frequency band supported by antenna 10. Figure 4 shows only the distribution in the frequency band supported by antenna 10 as shown in Figure 3(a) using a solid line.

[0048] As shown in the figure, the impedance of the antenna 10 is distributed along equal resistance circles (shown by solid lines) on the Smith chart. In this embodiment, the installation of the parasitic element 30 adjusts the impedance of the antenna 10 so that it is distributed above the real axis of the Smith chart. As will be described in detail later, this is because, in order to perform impedance matching and adjust the impedance to a constant value (e.g., 50 ohms) between 699 MHz and 894 MHz, it is preferable that the impedance be in the upper half of the Smith chart.

[0049] The impedance characteristics of the antenna 10 when the parasitic element 30 is installed are shown in Figures 3(b) and 5. Figure 3(b) shows the impedance characteristics (dotted line) and the distribution of a VSWR (Voltage Standing Wave Ratio) of 3.5 (solid line). The range and normalization method of the impedance characteristics are the same as those in Figure 3(a). Figure 5 shows only the distribution in the frequency band supported by the antenna 10 from Figure 3(b). As shown, most of the impedance of the antenna 10 is distributed above the real axis of the Smith chart. Comparing Figures 4 and 5, the impedance distribution shape changes and moves into or near the shaded area in Figure 4, as indicated by the dotted arrow. Furthermore, unlike Figure 3(a), the impedance distribution shape in Figure 3(b) forms an arc with a large curvature and falls within a certain range on the Smith chart.

[0050] Figure 6 is a Smith chart showing the impedance characteristics of antenna 10 when a 3.5 pF capacitor is added in series to antenna 10 in the presence of parasitic element 30. The capacitance component of the impedance increases due to the capacitor, causing the impedance graph to slide downward, as indicated by the "Series C" arrow in Figure 3(b). As a result, as shown in Figures 3(b) and 6, the impedance is distributed in an arc around VSWR 3.5, centered on 1.0 (50 Ω) on the real axis, and remains within a certain range.

[0051] 7, the VSWR of the antenna 10 with a 3.5 pF capacitor added is 3.5 or less in the frequency band of 699 MHz to 894 MHz. In this way, the parasitic element 30 contributes to adjusting the impedance characteristics of the antenna 10, and exhibits good VSWR characteristics over a wide band. The pF capacitor is provided on the circuit board 50 shown in FIG. 1(a), and a current that contributes to adjusting the impedance characteristics of the antenna 10 is supplied via the feeding point 12A in FIG.

[0052] As described above, the position and shape of the parasitic element 30 can adjust the impedance characteristics of the antenna 10. Therefore, in order to make the impedance characteristics of the antenna 10 match the design conditions, etc., the parasitic element 30 can be positioned in various shapes and positions other than those shown in Fig. 1 etc. The relationship between the position and shape of the parasitic element 30 and the impedance characteristics of the antenna 10 will be described below.

[0053] (Distance between parasitic element 30 and antenna 10) As an example, it is possible to adjust the impedance characteristics of the antenna 10 by changing the distance between the parasitic element 30 and the antenna 10. Fig. 8 shows the relationship between the configuration of the antenna 10 and the distance between the front end of the first extension 31 and the end of the second extension 11B, and the impedance of the antenna 10 (without a capacitor connected).

[0054] 8(a), the distance (distance) between the front end of the first extension 31 and the end of the second extension 11B is changed in 1 mm increments within a range of 1 mm to 4 mm. The distance d is changed by shifting the parasitic element 30 forward or backward while maintaining the shape of the parasitic element 30.

[0055] As shown in the Smith chart of Figure 8(b), it can be seen that adjusting the distance d changes the impedance distribution of the antenna 10. Increasing the distance d reduces the parasitic capacitance between the antenna 10 and the parasitic element 30, increasing the inductance component and shifting the impedance upward across a wide bandwidth. By changing the impedance distribution in this way, it is possible to distribute the impedance above the real axis on the Smith chart, preferably within a certain range such as the shaded area in Figure 4.

[0056] (Length of parasitic element 30) As an example, the impedance characteristics of the antenna 10 can be adjusted by changing the length of the parasitic element 30. FIGS. 9(a) and 10(a) show the configuration of the length of the first extension 31 in the front-rear direction and the relationship between the length of the first extension 31 and the impedance of the antenna 10 (without a capacitor connected). In FIGS. 9(a) and 10(a), the length L of the first extension 31 is changed in 5 mm increments within a range of 47 mm to 82 mm. The distance between the front end of the first extension 31 and the end 11C is maintained at 1 mm. In FIG. 9(a), the front-rear direction length L of the first extension 31 of the parasitic element 30 is longer than the front-rear direction length of the first extension 11A of the antenna 10 that is positioned opposite it. In FIG. 10(a), the length L is shorter than the front-rear direction length of the first extension 11A of the antenna 10 that is positioned opposite it.

[0057] 9(b) and 10(b), it can be seen that the impedance distribution of the antenna 10 changes by adjusting the length of the first extension portion 31 in the front-to-rear direction. In this way, it is possible to distribute the impedance above the real axis on the Smith chart, preferably near or within a certain range as shown in the shaded area in FIG.

[0058] (Width of parasitic element 30) The impedance characteristics of the antenna 10 can also be adjusted by changing the width of the parasitic element 30. FIGS. 11(a) and 12(a) show the configuration of the width of the first extension 31 and the relationship between that width, i.e., the left-right length, and the impedance of the antenna 10 (without a capacitor connected). In FIGS. 11(a) and 12(a), the width W of the first extension 31 is varied in 5-mm increments within a range of 10 mm to 30 mm. The distance between the front end of the first extension 31 and the end 11C is 1 mm, and the length in the front-to-back direction is 67 mm. In FIG. 11(a), the width W of the first extension 31 of the parasitic element 30 is narrower than the width of the first extension 31 shown in FIG. 1, while in FIG. 12(a), it is wider than the width of the first extension 31 shown in FIG. 1.

[0059] 11(b) and 12(b), it can be seen that the impedance distribution of the antenna 10 changes by changing the width of the first extension portion 31. In this way, it is possible to distribute the impedance above the real axis on the Smith chart, preferably near or within a certain range as shown in the shaded area in FIG.

[0060] (Variations of parasitic element 30) 13 to 15 show examples of parasitic element 30 designed based on the above considerations, showing the width and length of first extension 31 and the distance from the end of second extension 11B. In all of the examples shown in the figures, the impedance of antenna 10 is generally distributed above the real axis of the Smith chart. As can be seen, there are many variations in the width and length of first extension 31 and the distance from end 11C, which contribute to impedance adjustment.

[0061] ==Second Embodiment== An antenna device 100 according to the second embodiment is shown in FIGS.

[0062] The antenna device 100 includes a ground section 103, an antenna 102 (antennas 110 and 120), a parasitic element 130, a circuit board 150, a holding member (not shown) that holds the antenna 102, and a housing 101 that covers these members from above. The antenna device 100 also includes a flat patch antenna 170 (used for GNSS (Global Navigation Satellite System)) mounted on the circuit board 150, two bent rod-shaped Wi-Fi / Bluetooth antennas 140 (compatible with the 2.4 / 5 GHz bands), and two bent plate-shaped Sub6 antennas 175 (compatible with frequency bands below 6 GHz). The Wi-Fi / Bluetooth antennas 140 are not limited to being rod-shaped, and may be formed by punching a plate or conductive plate, or by forming a conductive pattern on a PCB. Additionally, the antenna device 100 is provided with a rod-shaped V2X monopole antenna 180 extending upward from the circuit board 150, and a V2X antenna 190 having a parasitic element 192 and a radiating element 191.

[0063] The patch antenna 170 arranged on the circuit board 150 is disposed approximately in the center of the circuit board 150. The V2X monopole antenna 180 and the radiating element 191 of the V2X antenna 190 are disposed on a line that passes through approximately the center of the patch antenna 170 in the left-right direction, with the patch antenna 170 sandwiched between them. Parasitic elements 192 are disposed at a predetermined interval on both sides of the radiating element 191 of the V2X antenna 190 in the front-to-back direction. In Fig. 16, a parasitic element is disposed only on the V2X antenna 190 on the left side of the patch antenna 170, but a parasitic element may also be disposed on the V2X monopole antenna 180 on the right side.

[0064] The V2X antenna 190 has a directivity characteristic in the forward direction, and the V2X monopole antenna 180 has a directivity characteristic in the rightward direction. The antenna device 100 can improve the directivity gain in the leftward direction by providing the parasitic element 192 to the V2X antenna 190 in the leftward direction in particular.

[0065] The two Wi-Fi / Bluetooth antennas 140 are arranged at positions separated in the left-right direction across the patch antenna 170, on a line passing through approximately the center of the patch antenna 170. Furthermore, each of the two Wi-Fi / Bluetooth antennas 140 is arranged between the antenna 120 and the parasitic element 130 in the front-to-rear direction, resulting in an arrangement that suppresses interference and is also compact.

[0066] Patch antenna 170 is applied to an antenna for a satellite positioning system that can receive circularly polarized signals using various feeding methods, such as a two-point feeding method, a four-point feeding method, etc. The patch antenna structure may be a stacked antenna, a multi-resonance antenna, or an antenna with a parasitic element added, as long as it is compatible with satellite wave signals.

[0067] The antenna device 100 includes an antenna 110, an antenna 120, a parasitic element 130, and a holding member (not shown), one on each of the left and right sides. These members are arranged approximately symmetrically on the left and right sides. Below, the antenna 110, antenna 120, and parasitic element 130 arranged on the left side will be mainly described with reference to FIG. 17. The antenna 110, antenna 120, and parasitic element 130 arranged on the right side have the same configuration as those on the left side, so their description will be omitted.

[0068] The ground section 103 is a rectangular member extending horizontally and has the same function as the ground section 3. That is, the ground section 103 functions as a ground for the antennas 110 and 120 and the parasitic element 130 of the antenna device 100. Like the ground section 3, the ground section 103 functions as a common ground for the antennas 110 and 120. As shown in Fig. 16, the ground section 103 is formed as an integrated metal plate (sheet metal). However, the ground section 103 may be made up of multiple separate metal plates.

[0069] Antenna 110 is a wideband antenna for mobile communications based on an inverted L antenna, and has the same functions as antenna 10. Antenna 110 also has element 111 and feeding section 112.

[0070] Element 111 is a plate-like member extending horizontally. Element 111 is formed to extend rearward from feeding section 112 and faces ground section 103 in the vertical direction. End section 111C, which is an open end, is formed at the rear end of element 111 and faces parasitic element 130 in the longitudinal direction.

[0071] Power supply section 112 is formed to extend upward from the upper surface of circuit board 150. Power supply section 112 contacts circuit board 150 at its lower end, and has power supply point 112A to which it is electrically connected. The upper end (element 111 side) of power supply section 112 has a shape in which the width in the front-to-rear direction is longer than the lower end (circuit board 150 side).

[0072] 17(b), the length of antenna 110 from feed point 112A to end 111C along its shape is equal to one-fourth the wavelength of radio waves in the 699 MHz to 894 MHz band. By making the length of antenna 110 one-fourth the wavelength of the corresponding frequency band, the sensitivity of antenna 110 in the corresponding frequency band can be improved.

[0073] Antenna 120 is a wideband antenna for mobile communications based on a bent monopole antenna. Like antenna 20, antenna 120 supports radio waves in the 2 GHz band (for example, 1710 to 2170 MHz). Antenna 120 may also support radio waves in frequency bands for GSM, UMTS, LTE, and 5G. Antenna 120 may also be an antenna that supports radio waves in frequency bands used for, for example, telematics, V2X (Vehicle to Everything: vehicle-to-vehicle communication, road-to-vehicle communication), Wi-Fi, Bluetooth, etc.

[0074] Antenna 120 has element 121 and shares feed section 112 with antenna 110 .

[0075] Element 121 is a flat conductive member, and is formed so as to extend rightward from the upper end of power supply portion 112 (FIG. 17(b)). Element 121 has first extending portion 121A and second extending portion 121B.

[0076] First extension 121A is a portion extending rightward from the upper end of power supply unit 112. Second extension 121B is a portion extending downward from the right end of first extension 121A. The lower end of second extension 121B is mechanically and electrically connected to ground unit 103. Note that second extension 121B and ground unit 103 can be connected to each other by a joining method using a joining tool such as a screw, or by soldering or welding.

[0077] 17(b), the electrical length along the shape of antenna 120 from feed point 112A to the lower end of second extension portion 121B is approximately equal to half the wavelength of radio waves in the 2 GHz band (for example, radio waves at the center frequency). By setting the electrical length of antenna 120 to half the wavelength of radio waves in the corresponding frequency band, the sensitivity of antenna 120 in the corresponding frequency band can be improved.

[0078] Parasitic element 130 is a flat conductive member mechanically and electrically connected to ground portion 103, and like parasitic element 30, has the function of adjusting the impedance of antenna 110 (FIG. 17(a)). Parasitic element 130 includes a first extension portion 131 extending in the left-right and front-rear directions, and a second extension portion 132 extending downward from the right end of first extension portion 131.

[0079] The first extension portion 131 is a portion formed so as to be bent in an L shape when viewed from above. The first extension portion 131 faces the ground portion 103 in the up-down direction. The height of the first extension portion 131 from the ground portion 103 is approximately equal to the height of the element 111 from the ground portion 103.

[0080] The first extending portion 131 extends leftward from the upper end of the second extending portion 132 and bends forward at the left end. The front end of the first extending portion 131 forms an open end and faces the end 111C of the element 111 with a gap therebetween.

[0081] The second extension portion 132 is a portion formed in a rectangular shape when viewed in the front-to-rear direction, and extends vertically to connect the right end of the first extension portion 131 and the ground portion 103. The lower end of the second extension portion 132 is mechanically and electrically connected to the ground portion 103 using a connector such as a screw. Note that the connection between the second extension portion 132 and the ground portion 103 can be achieved by a joining method using a connector such as a screw, or by a method such as soldering or welding.

[0082] Circuit board 150 is a rectangular member disposed above ground portion 103 and is electrically connected to feed point 112A. Circuit board 150 is provided with a capacitor (not shown), which is connected in series to antennas 110 and 120 via feed point 112A.

[0083] In the above configuration, as in the first embodiment, the impedance characteristics of antenna 110 are adjusted by the length (indicated by the number 2 with a circled arrow in FIG. 17(a)) of parasitic element 130 along its shape, its width, or the distance from antenna 10. As a result of designing parasitic element 130 through such adjustments, antenna 110 exhibits desired impedance characteristics. In addition, by connecting antenna 110 to a capacitor on circuit board 150, antenna 110 can exhibit good VSWR characteristics in the corresponding frequency band.

[0084] <Effects> In each of the above embodiments, the antenna device 1, 100 has a ground section 3, 103, an antenna 2, 102, and a parasitic element 30, 130. The antenna 2, 102 has an element 11, 111 (corresponding to a "main body") that faces the ground section 3, 103 and has an open end that is open, and a feed section 12, 112 that extends from the element 11, 111 in the direction of the ground section 3, 103 and has a feed point 12A, 112A. The parasitic element 30, 130 has a first end that is spaced apart from the open end of the element 11, 111, and is used to adjust the impedance of the antenna 10, 110.

[0085] According to the above configuration, the provision of the parasitic elements 30 and 130 adjusts the impedance characteristics of the antennas 10 and 110, thereby improving the performance of the antennas 10 and 110 over a wide band.

[0086] In addition to the above configuration, the length from the feeding point 12A, 112A through the antenna 10, 110 to the open end corresponds to the frequency band supported by the antenna 10, 110.

[0087] With this configuration, radio waves in the corresponding frequency band can be transmitted and received satisfactorily.

[0088] In addition to the above configuration, the distance between the elements 11 and 111 and the ground portions 3 and 103 is shorter than the wavelength of the frequency band that the antennas 10 and 110 support.

[0089] By configuring as described above, the antenna devices 1, 100 can be made low-profile, i.e., their vertical height can be reduced, making them more compact. The parasitic elements 30, 130 contribute to achieving this compact size. More specifically, as shown in FIGS. 3 and 7, the parasitic elements 30, 130 adjust the impedance of the antennas 10, 110, improving the VSWR characteristics over a wide band. For this reason, in the above-described embodiments, the elements 11, 111 are arranged at a low position, thereby achieving a compact overall device. This compact size allows the antenna devices 1, 100 to be placed in a narrow space.

[0090] In addition to the above configuration, the parasitic elements 30 and 130 are arranged so as to increase the inductance component of the impedance in the corresponding frequency band.

[0091] With the above configuration, the impedance can be distributed upward on the Smith chart as shown in Figure 5, making it easier to adjust the impedance using elements such as capacitors (Figure 6). If the impedance of the corresponding frequency band is located above the real axis on the Smith chart, the impedance distribution can be slid downward on the Smith chart by increasing the conductance component using a capacitor, making it easier to adjust the impedance.

[0092] In each of the above embodiments, a capacitor that increases the capacitance component of the impedance in the corresponding frequency band is connected to the antenna 10, 110, so that the impedance is adjusted to fall within a certain range centered around 50 Ω on the Smith chart (FIG. 6), thereby achieving good VSWR characteristics.

[0093] The feeding section 12 has a width (length from front to back) greater than that of feeding point 12A at the connection portion with element 11. This allows it to support a higher frequency band than the corresponding frequency band, and high performance can be obtained over a wide band.

[0094] The antennas 2 and 102 include second extensions 21B and 121B (corresponding to a "connection portion") that connect the first extensions 21A and 121A (corresponding to a "main body portion") and the ground portions 3 and 103.

[0095] With this configuration, the antennas 2 and 102 have the functions of the antennas 20 and 120 that support a frequency band different from both the frequency band supported by the antennas 10 and 110 and the frequency band supported by the power supply unit 12 .

[0096] The vertical distance D2 (corresponding to the "first distance") from the end of the second extension 11B to the ground portion 3 is the same as the vertical distance D1 (corresponding to the "second distance") from the front end of the first extension 31 to the ground portion 3. In addition, the vertical distance from the front end of the element 111 to the ground portion 103 is the same as the vertical distance from the front end of the first extension 131 to the ground portion 103.

[0097] In this way, by aligning the ends of elements 11, 111 and the ends of the opposing parasitic elements 130, 130 at the same height and making them flush, the antenna devices 1, 100 can be made low-profile, i.e., their vertical height can be reduced, and they can be made smaller. [Explanation of symbols]

[0098] 1, 100 Antenna equipment 2, 102 antenna 3, 103 Ground Section 12, 112 Power supply unit 12A, 112A power supply point 30, 130 Parasitic element 50 Circuit Board 60 Retaining member

Claims

1. The ground section and an antenna including: a main body portion having an open end portion facing the ground portion and open; and a feed portion extending from the main body portion toward the ground portion and having a feed point; a parasitic element for adjusting the impedance of the antenna, the parasitic element having a first end spaced apart from the open end; Equipped with The antenna device, wherein the main body portion has, in a plan view, a first extension portion extending from the power supply portion and a second extension portion bent from a portion of the first extension portion different from the power supply portion.

2. a length from the feed point through the antenna to the open end corresponds to a first frequency band; The antenna device according to claim 1 .

3. The length is approximately one-quarter of the wavelength of the first frequency band; The antenna device according to claim 2 .

4. The antenna device according to claim 2 , wherein a distance between the main body and the ground portion is shorter than a wavelength of the first frequency band.

5. The parasitic element is arranged to increase the inductance component of the impedance of the antenna in the first frequency band; 5. The antenna device according to claim 2, wherein the antenna device is a semiconductor integrated circuit.

6. a capacitor connected to the antenna to increase a capacitance component of the impedance of the antenna in the first frequency band; The antenna device according to any one of claims 2 to 5.

7. The power supply unit is The width of the connection portion with the main body is greater than the width of the feeding point portion so as to correspond to a second frequency band higher than the first frequency band.

7. The antenna device according to claim 2.

8. The antenna is a connection portion that connects the main body portion and the ground portion so as to support a third frequency band that is different from both the first frequency band and the second frequency band; The antenna device according to claim 7.

9. a first distance from the first end to the ground portion in a vertical direction of the ground portion is equal to a second distance from the open end to the ground portion; 9. The antenna device according to claim 1.

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