Antenna device

Abstract

The present invention provides an antenna device, which has multiple antennas in a common housing, can suppress the decrease of antenna gain and achieve miniaturization. The antenna device (1) has a TEL antenna (2) and a capacitive load element (3) in a common housing. The capacitive load element (3) is located above the TEL antenna (2). The length of the capacitive load element (3) is a natural number multiple of 1 / 2 of the wavelength of the PCS band. The TEL antenna (2) is arranged to avoid the maximum voltage point of the standing wave of the PCS band generated by the capacitive load element (3).

Description

[0001] This application is a divisional application of the application with application date of January 23, 2017, application number of 201780005280.7, and invention name of antenna device. Technical Field

[0002] The present invention relates to an antenna device including two or more antennas in a common housing. Background Art

[0003] In recent years, vehicle-mounted antenna devices called shark fin antennas have been developed. In addition to broadcast receiving antennas such as AM / FM antennas, there is also a trend of installing information communication antennas such as TEL antennas in vehicle-mounted antenna devices (for example, Patent Document 1 below).

[0004] Prior Art Literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Publication No. 2012-124714 Summary of the invention

[0007] Problems to be solved by the invention

[0008] If multiple antennas are arranged in a limited space in a housing, the distance between the antennas cannot be sufficiently obtained, resulting in a problem of reduced antenna gain. On the other hand, if the distance between the antennas is to be increased in the housing, the housing will become larger, resulting in a problem of not being able to be miniaturized.

[0009] The present invention has been made in recognition of such a situation, and an object of the present invention is to provide an antenna device that includes a plurality of antennas in a common housing and can suppress a decrease in antenna gain and achieve miniaturization.

[0010] Solutions to Solve Problems

[0011] One aspect of the present invention is an antenna device. The antenna device includes a first antenna and a second antenna disposed in a common housing, the second antenna being plate-shaped and located above the first antenna, and the first antenna being arranged to avoid a voltage maximum point of a standing wave in a frequency band of the first antenna generated by the second antenna.

[0012] Alternatively, the first antenna may be disposed or extended within a range where a horizontal distance from a point where a voltage of the standing wave generated by the second antenna is minimum is within 1 / 8 of a wavelength of the standing wave.

[0013] Alternatively, the second antenna may include a first plate-shaped portion located above the first antenna, the first antenna may be located below a central portion of the first plate-shaped portion, and a length of the first plate-shaped portion may be an odd multiple of 1 / 2 of a wavelength of a frequency band of the first antenna.

[0014] The second antenna may include a first plate-shaped portion and a second plate-shaped portion, the first plate-shaped portion being located above the first antenna, and the second plate-shaped portion being electrically connected to the first plate-shaped portion via a filter portion that cuts off a frequency band of the first antenna.

[0015] The second antenna may include a first plate-shaped portion and a second plate-shaped portion, the first plate-shaped portion is located above the first antenna, and the second plate-shaped portion is electrically connected to the first plate-shaped portion via a fold line.

[0016] The first plate-shaped portion and the second plate-shaped portion may be arranged apart from each other in the front-rear direction.

[0017] At least a portion of the second antenna located above the first antenna may be divided in the left-right direction.

[0018] The antenna device may include a helical element electrically connected to the second antenna.

[0019] The spiral element may be spiral-shaped and rotate in an elliptical shape when viewed from the winding axis direction of the spiral element.

[0020] The antenna device may include a base that forms a housing space for the first antenna and the second antenna together with the housing.

[0021] The first antenna has a portion substantially perpendicular to the substrate.

[0022] Alternatively, the first antenna may be a TEL antenna, a TV antenna, a keyless entry antenna, an inter-vehicle communication antenna, or a WiFi antenna, and the second antenna may be an AM / FM antenna or a DAB receiving antenna.

[0023] The antenna device may include a helical element electrically connected to the second antenna, and the helical element may be arranged offset from a center in a left-right direction of a housing that holds the second antenna.

[0024] The winding axis of the spiral element may be inclined with respect to the up-down direction.

[0025] The helical element and the second antenna may not overlap in vertical direction.

[0026] The antenna device may include a holder that holds the helical element, and the holder may hold the helical element from an outer peripheral side or an inner peripheral side.

[0027] The stent may include a groove for holding the spiral element.

[0028] Alternatively, the base body may have a step on the lower surface.

[0029] The helical element may include: a first helical element; and a second helical element grounded via a filter unit that cuts off a frequency band of the first antenna.

[0030] The antenna device may include a conductor leaf spring that sandwiches the first antenna, and a portion of the first antenna sandwiched by the conductor leaf spring or the conductor leaf spring may have a protrusion.

[0031] The antenna device may include a third antenna provided in the housing, and an upper portion of the third antenna may be covered by a passive element.

[0032] The antenna device may include a second filter unit between the first helical element and an amplifier that amplifies a frequency of the second antenna, and the second filter unit may increase impedance of a TEL band.

[0033] One side and the other side of the second antenna divided in the left-right direction may be connected in the left-right direction.

[0034] The first antenna may extend upward from between one side and the other side of the second antenna divided in the left-right direction.

[0035] It should be noted that any combination of the above-described constituent elements and any configuration in which the expression of the present invention is converted into a method, a system, or the like are also effective as aspects of the present invention.

[0036] Effects of the Invention

[0037] According to the present invention, it is possible to provide an antenna device that includes a plurality of antennas in a common housing and can suppress a decrease in antenna gain and achieve miniaturization. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 It is a schematic diagram of the antenna device 1 according to the first embodiment of the present invention.

[0039] Figure 2 It is a characteristic diagram based on simulation showing the relationship between the frequency and the average gain of the TEL antenna 2 of the antenna device 1 (single-dot chain line) and the relationship between the frequency and the average gain of the TEL antenna 2 alone (without the capacitive load element 3) (solid line).

[0040] Figure 3 This is a characteristic diagram based on simulation showing the relationship between the total length (length L in the front-to-back direction) of the capacitive load element 3 and the average gain of the TEL antenna 2 at 1900 MHz when the TEL antenna 2 is arranged directly below the center position of the capacitive load element 3 in the front-to-back direction in the antenna device 1.

[0041] Figure 4 This is a characteristic diagram based on simulation, showing the relationship between the front-to-back distance x from the front end of the capacitive load element 3 to the front-to-back center position of the TEL antenna 2 and the average gain of the TEL antenna 2 at 1900 MHz when the front-to-back length L of the capacitive load element 3 in the antenna device 1 is set to λ / 2.

[0042] Figure 5 This is a characteristic diagram based on simulation, showing the relationship between the front-to-back distance x from the front end of the capacitive load element 3 to the front-to-back center position of the TEL antenna 2 and the average gain of the TEL antenna 2 at 1900 MHz when the front-to-back length L of the capacitive load element 3 in the antenna device 1 is set to λ.

[0043] Figure 6 It is a schematic diagram of an antenna device 1A according to a second embodiment of the present invention.

[0044] Figure 7 It is an exploded perspective view of the antenna device 1A.

[0045] Figure 8 Yes means Figure 7 An enlarged front cross-sectional view of the periphery of the fitting portion between the tongue portion 3 c of the capacitive load element 3 and the groove portion 6 a of the inner case 6 .

[0046] Fig. 9 This is an enlarged side cross-sectional view showing the periphery of the fitting portion when the tongue portion 3 c is provided at the rear end portion of the capacitive load element 3 and is fitted into the groove portion 6 a of the inner case 6 .

[0047] Fig.10 (A)~ Fig.10 (F) is a perspective view showing the assembly process of the spiral element 5, the bracket 7 and the TEL antenna substrate 4.

[0048] Fig.11 (A)~ Fig.11 (C) is a schematic plan view showing the relative positional relationship between the TEL antenna 2 and the helical element 5 in each case where the winding shape of the helical element 5 is a circle, an ellipse long in the left-right direction, and an ellipse long in the front-back direction.

[0049] Fig.12 It is an enlarged cross-sectional view showing a state where the conductor leaf springs 9 a and 9 b hold the TEL antenna substrate 4 .

[0050] Fig.13 It is a right side view of the antenna device 1A.

[0051] Fig.14 It is a right side cross-sectional view of the antenna device 1A.

[0052] Fig.15 yes Fig.14 Magnified front view.

[0053] Fig.16 1 is a connection circuit diagram of the antenna device 1A (part 1).

[0054] Fig.17 This is a connection circuit diagram of the antenna device 1A (part 2).

[0055] Fig.18 It is a schematic diagram of an antenna device 1B according to a third embodiment of the present invention.

[0056] Fig.19 This is a characteristic diagram based on simulation that shows the relationship between the frequency and the average gain of the TEL antenna 2 of the antenna device 1A according to embodiment 2 and the antenna device 1B according to embodiment 3 (dashed line and single-dash line) and the relationship between the frequency and the average gain of the TEL antenna 2 alone (when there is no capacitive load element 3) (solid line).

[0057] Fig. 20 This is a characteristic diagram based on actual measurement showing the relationship between the frequency and the average gain of the TEL antenna 2 in each case where the capacitance load element 3 is divided front and back into the first plate-shaped portion 3a and the second plate-shaped portion 3b and in each case where the capacitance load element 3 is not divided front and back.

[0058] Fig.21 3 is a schematic diagram of an antenna device according to Comparative Example 1.

[0059] Fig. 22 3 is a schematic diagram of an antenna device according to Comparative Example 2.

[0060] Fig.23 It is a characteristic diagram based on simulation that shows the relationship between the frequency and the average gain of the TEL antenna 2 of the antenna devices of Comparative Examples 1 and 2 (dashed line and single-dot chain line) and the relationship between the frequency and the average gain of the TEL antenna 2 alone (when there is no capacitive load element 3) (solid line).

[0061] Fig.24 This is a characteristic diagram based on simulation showing the relationship between the distance from the capacitive load element 3 (inter-antenna distance) and the average gain in the TEL antenna 2 of the comparative example.

[0062] Fig.25 It is a perspective view of an antenna device 1C according to a fourth embodiment of the present invention.

[0063] Fig.26 is Fig.25 The three-dimensional view of the inner shell 6 is omitted.

[0064] Fig. 27 3 is a characteristic diagram based on simulation showing the relationship between the frequency and the average gain in the FM band of the AM / FM antenna in each case where the capacitance load element 3 has the notch portion 3d and the notch portion 3d.

[0065] Fig.28 It is a front cross-sectional view of an antenna device 1D according to a fifth embodiment of the present invention.

[0066] Fig.29 The characteristic diagram based on simulation shows the relationship between the frequency and the average gain of the FM band of the AM / FM antenna in each case where the capacitive load element 3 is divided into the left plate-shaped portion 3e and the right plate-shaped portion 3f and when it is not divided into the left plate-shaped portion 3e and the right plate-shaped portion 3f. DETAILED DESCRIPTION

[0067] Hereinafter, with reference to the accompanying drawings, preferred embodiments of the present invention will be described in detail. It should be noted that the same or equivalent components, members, etc. shown in the various drawings are marked with the same symbols, and repeated descriptions are appropriately omitted. Moreover, the embodiments do not limit the invention but are illustrative, and all the features or their combinations described in the embodiments are not necessarily the essential features of the invention.

[0068] (Implementation Method 1)

[0069] Reference Figure 1 to Figure 5 , describing embodiment 1 of the present invention. Figure 1 Schematic diagram of the antenna device 1 according to Embodiment 1. Figure 1 , the front and rear, up and down, left and right directions of the antenna device 1 are defined. The direction perpendicular to the up and down direction is the horizontal direction. It should be noted that the front and rear direction is the length direction of the antenna device 1, and the left and right direction is the width direction of the antenna device 1. Moreover, the front is the forward direction when the antenna device 1 is installed on the vehicle, and the left and right directions are determined based on the state of observing the forward direction, that is, the front. The antenna device 1 is for vehicle-mounted use and is installed on the roof of the vehicle, etc. The antenna device 1 has an AM / FM antenna in a housing not shown in the figure, and the AM / FM antenna has a TEL antenna 2 as the first antenna, a capacitive load element 3 as the second antenna, and a helical element (AM / FM coil) 5. The capacitive load element 3 and the helical element 5 can receive AM / FM broadcasts.

[0070] The TEL (Telephone) antenna 2 is, for example, a conductor pattern on a substrate. The frequency band of the TEL antenna 2 is the PCS (Personal Communications Service) band. The frequency of the PCS band is in the range of 1850 to 1990 MHz, but the center frequency of the PCS band, i.e., 1900 MHz, is used as a representative value. The TEL antenna 2 exists in a plane parallel to the front-back and up-down directions. The TEL antenna 2 is preferably a wideband antenna capable of transmitting and receiving the AMPS band (Advanced Mobile Phone System) / PCS band. The frequency of the AMPS band is 824 to 894 MHz.

[0071] The capacitive load element 3 is a plate-shaped component formed by processing a metal plate (conductive plate) such as stainless steel. The capacitive load element 3 is located above the TEL antenna 2. When the TEL antenna 2 is located below a position that is an odd multiple of 1 / 4 of the wavelength λ from the end of the capacitive load element 3, the front-to-back length L of the capacitive load element 3 is preferably a natural number multiple of 1 / 2 of the wavelength λ. Here, the wavelength λ is the wavelength of the PCS band (TEL band). When the TEL antenna 2 is located below the central portion of the capacitive load element 3, the front-to-back length L of the capacitive load element 3 is preferably an odd multiple of 1 / 2 of the wavelength λ. Figure 1 In the example of , the length L of the capacitive load element 3 in the front-to-back direction is L=λ / 2. Figure 1 In FIG. 1 , the current distribution of the PCS frequency band generated by the capacitive load element 3 is represented by the dotted line. The position where the current distribution is the smallest, i.e. Figure 1 The front and rear ends of the capacitive load element 3 in the example are the points with the maximum voltage. Moreover, the position with the maximum current distribution, i.e. Figure 1 The center position of the capacitive load element 3 in the front-to-back direction in the example is the minimum voltage point. It should be noted that, when the TEL antenna 2 is a wideband antenna capable of transmitting and receiving the AMPS band / PCS band, the capacitive load element 3 becomes a non-resonant electrical length relative to the AMPS band. It should be noted that if the capacitive load element 3 has a non-resonant electrical length relative to the AMPS band (for example, approximately less than λ / 4 of the AMPS band), as long as the transmission and reception of the AMPS band is concerned, no matter where the TEL antenna 2 is configured below the capacitive load element 3, no adverse effects caused by electrical coupling with the capacitive load element 3 will occur.

[0072] The distance x in the front-to-back direction from the front end of the capacitive load element 3 to the center position of the TEL antenna 2 in the front-to-back direction is determined to avoid the maximum voltage point of the standing wave in the PCS frequency band generated by the capacitive load element 3. Preferably, the center position in the front-to-back direction of the TEL antenna 2 is located at the minimum voltage point of the capacitive load element 3 or within a range of λ / 8 from the minimum voltage point, or the TEL antenna 2 extends at the minimum voltage point of the capacitive load element 3 or within a range of λ / 8 from the minimum voltage point.

[0073] Figure 2 It is a characteristic diagram based on simulation showing the relationship between the frequency and the average gain of the TEL antenna 2 of the antenna device 1 (single-dot chain line) and the relationship between the frequency and the average gain of the TEL antenna 2 alone (without the capacitive load element 3) (solid line). Figure 2 The characteristic of the single-dot chain line shown is the characteristic when the TEL antenna 2 is arranged so that its center position in the front-back direction is located directly below the voltage minimum point of the capacitive load element 3. Figure 2 As shown, although the TEL antenna 2 of the antenna device 1 is located below the capacitive load element 3, substantially the same antenna gain characteristics as those in the case of the TEL antenna 2 alone can be obtained.

[0074] Figure 3 This is a characteristic diagram based on simulation showing the relationship between the total length (length L in the front-to-back direction) of the capacitive load element 3 and the average gain of the TEL antenna 2 at 1900 MHz when the TEL antenna 2 is arranged directly below the center position of the capacitive load element 3 in the front-to-back direction in the antenna device 1. Figure 3 The reason why the average gain drops significantly near the front-to-back length L of the capacitive load element 3 is that when the front-to-back length L of the capacitive load element 3 is λ and 2λ, the front-to-back center of the TEL antenna 2 is directly below the maximum voltage point of the capacitive load element 3. Figure 5 As described later, when the front-to-back length L of the capacitive load element 3 is λ / 2 and 3λ / 2, the front-to-back center position of the TEL antenna 2 is placed at the minimum voltage point of the capacitive load element 3 or within λ / 8 of the minimum voltage point, thereby achieving good gain.

[0075] Figure 4 This is a characteristic diagram based on simulation showing the relationship between the front-to-back distance x from the front end of the capacitive load element 3 to the front-to-back center of the TEL antenna 2 and the average gain of the TEL antenna 2 at 1900 MHz when the front-to-back length L of the capacitive load element 3 in the antenna device 1 is set to λ / 2. Figure 4 In the figure, λ / 4 on the horizontal axis corresponds to the minimum voltage point of the capacitive load element 3. Figure 4By setting the front-to-back distance x from the front end of the capacitive load element 3 to the front-to-back center of the TEL antenna 2 to λ / 8≤x≤3λ / 8, a good antenna gain of 3 dBi or more can be achieved.

[0076] Figure 5 This is a characteristic diagram based on simulation showing the relationship between the front-to-back distance x from the front end of the capacitive loading element 3 to the front-to-back center of the TEL antenna 2 and the average gain of the TEL antenna 2 at 1900 MHz when the front-to-back length L of the capacitive loading element 3 in the antenna device 1 is set to λ. Figure 5 In the figure, λ / 4 and 3λ / 4 on the horizontal axis correspond to the minimum voltage point of the capacitive load element 3. Figure 5 By setting the front-to-back distance x from the front end of the capacitive load element 3 to the front-to-back center of the TEL antenna 2 to λ / 8≤x≤3λ / 8 or 5λ / 8≤x≤7λ / 8, a good antenna gain of approximately 3dBi or more can be achieved.

[0077] According to the present embodiment, in the antenna device 1, since the TEL antenna 2 is located below the capacitive load element 3, it is possible to achieve miniaturization compared to the case where the TEL antenna 2 avoids the bottom of the capacitive load element 3 and moves away from the bottom of the capacitive load element 3 in the front-back direction (Comparative Example 1 described later). In addition, since the front-back center position of the TEL antenna 2 moves away from the vicinity of the maximum voltage point of the capacitive load element 3 in the front-back direction, it is possible to suppress a decrease in antenna gain. In particular, when the front-back center position of the TEL antenna 2 is located near the minimum voltage point of the capacitive load element 3 (for example, within a range of λ / 8 from the minimum voltage point), an antenna gain comparable to that of the TEL antenna 2 alone is achieved.

[0078] (Implementation Method 2)

[0079] Reference Figure 6 to Figure 17 , Fig.19 , Fig. 20 , describing embodiment 2 of the present invention. Figure 6 It is a schematic diagram of an antenna device 1A according to a second embodiment of the present invention. Figure 6 The structure of the antenna device 1A shown is similar to Figure 1 In contrast, the capacitive load element 3 includes the second plate-shaped portion 3b and the first plate-shaped portion 3a (equivalent to Figure 1 The capacitance load element 3 as a whole) and the second plate-shaped portion 3b are connected to each other through the filter 16, but are consistent in other points. Figure 6 The relative positional relationship between the TEL antenna 2 and the first plate-shaped portion 3a is shown in FIG. Figure 1The relative positional relationship between the TEL antenna 2 and the capacitive load element 3 is the same. The second plate-shaped portion 3b is located behind the first plate-shaped portion 3a. The filter 16 is a band elimination filter (BEF), and in this embodiment, it is a BEF that blocks the frequency band near the transmission and reception band of the TEL antenna 2. In this embodiment, by having the second plate-shaped portion 3b, the overall size of the capacitive load element 3 can be increased, and the performance of the AM / FM band can be improved.

[0080] Figure 7 It is an exploded perspective view of the antenna device 1A. Fig.13 It is a right side view of the antenna device 1A. Fig.14 1A is a right side cross-sectional view of the antenna device 1A. Figure 7 and Fig.14 middle, Fig.13 Illustration of the outer case 20 is omitted. The first plate-shaped portion 3a and the second plate-shaped portion 3b of the capacitance load element 3 are attached to the upper portion of the inner case 6 by screws 101 and 102, respectively (threaded fastening).

[0081] The capacitive load element 3 is made of SUS (stainless steel) for rust prevention, but a conductor sandwiched by an insulating film may be attached to the inner housing 6 as the capacitive load element 3. The capacitive load element 3 may also be a structure formed by printing on a flexible substrate as a conductive pattern. In addition, metal powder may be evaporated on the inner housing 6 to form the capacitive load element 3. The capacitive load element 3 is formed in a shape with a cross section convex upward, and is arranged with the longitudinal direction as the front-rear direction and approximately parallel to the top of the substrate 10 described later.

[0082] In order to prevent the capacitive load element 3 from expanding from the inner housing 6 in the left-right direction, the lower part of the capacitive load element 3 has a plurality of substantially vertical tongue pieces 3c (four on each side), such as Figure 8 As shown in the figure, each tongue portion 3c is inserted into the groove portion 6a provided in the inner case 6, thereby holding the capacitive load element 3 on the inner case 6. By providing the substantially vertical tongue portion 3c at the lower part of the capacitive load element 3, the opposing surface with respect to the ground can be reduced compared with a shape in which the tongue portion is provided in the left-right direction, so that the parasitic capacitance can be reduced, and the gain reduction of the AM / FM antenna can be prevented.

[0083] like Fig. 9As shown, the capacitive loading element 3 may be provided with a tongue portion 3c at the rear end of the upper portion and may be sandwiched in a groove portion 6a of the inner housing 6 provided at a position corresponding thereto. Moreover, although not shown in the figure, it may be provided with a tongue portion 3c at the front end of the upper portion of the capacitive loading element 3 and may also be sandwiched in the groove portion 6a of the inner housing 6. When the tongue portion 3c is provided at the front or rear end of the upper portion of the capacitive loading element 3, the upper portion of the capacitive loading element 3 is extended in the front-to-back direction by the length of the tongue portion 3c, and the effect as a capacitive load is further obtained without increasing the size of the inner housing 6, and the gain of the AM / FM antenna can be improved.

[0084] It should be noted that the capacitive load element 3 may be mounted on the inner housing 6 by welding or bonding. Furthermore, the capacitive load element 3 may have one of the first plate-shaped portion 3a and the second plate-shaped portion 3b screwed to the upper portion of the inner housing 6, and the other may be integrally formed to be held in the inner housing 6 without screwing. Alternatively, both the first plate-shaped portion 3a and the second plate-shaped portion 3b may be integrally formed to be held in the inner housing 6 without screwing.

[0085] The inner housing 6 is made of radio wave transparent synthetic resin (a molded product made of resin such as ABS resin). The inner housing 6 is mounted on the base 10 by six screws 103. Fig.13 As shown, the inner case 6 is covered by the outer case 20. That is, the antenna device 1A includes the TEL antenna 2 and the capacitive load element 3 in the common outer case 20.

[0086] The TEL antenna 2 is a conductor pattern provided on the TEL antenna substrate 4, and is capable of transmitting and receiving the AMPS band / PCS band. The TEL antenna substrate 4 is provided upright on the amplifier substrate 9 in a manner substantially perpendicular to the base 10 and substantially parallel to the longitudinal direction of the capacitive load element 3. That is, the TEL antenna 2 is substantially perpendicular to the base 10. The spiral element 5, the filter 16, and the terminal portions 17 and 18 are provided on the TEL antenna substrate 4. A pair of connecting plates 13 are respectively mounted on the inner housing 6 by screws 104, and the first plate-shaped portion 3a and the second plate-shaped portion 3b of the capacitive load element 3 are electrically connected to the pair of terminal portions 17. The pair of terminal portions 18 are clamped by a pair of conductor leaf springs (terminals) 9a provided on the amplifier substrate 9 and are electrically connected thereto. The lower end portion of the TEL antenna 2 is clamped by the conductor leaf spring 9b of the amplifier substrate 9 and is electrically connected thereto. The bracket 7 is mounted on the inner housing 6 by two screws 105 while holding the TEL antenna substrate 4. The TEL antenna 2 is located approximately at the center of the antenna device 1A in the left-right direction, which can suppress interference with the capacitive load element 3 and improve AM / FM performance. In addition, the upper portion of the outer shell 20 can be made thinner to improve the appearance design. Figure 7The spiral element 5 is offset (deviation) to the right, and the winding axis (central axis) of the spiral element 5 is substantially parallel to the up-down direction and substantially perpendicular to the left-right direction.

[0087] The amplifier substrate 9 is mounted on the base 10 by nine screws 106. Conductor leaf springs 9a, 9b, a GPS (Global Positioning System) antenna 21, an XM (satellite radio) antenna 22, and an AM / FM / XM / GPS amplifier and a TEL matching circuit (not shown) are provided on the amplifier substrate 9. The waterproof pad (water-tightening fastener) 8 is an annular elastic member such as an elastomer or rubber, and is provided on the base 10. The waterproof pad 8 is pressed against the base 10 all around by the lower end of the inner shell 6 fixed by screw fastening, etc., to watertighten the base 10 and the inner shell 6. The sealing member 15 is an annular elastic member such as an elastomer, polyurethane, or rubber, and is clamped between the lower surface of the base 10 and the vehicle body (e.g., the roof of a vehicle) where the antenna device 1A is installed, to watertighten the two. Bolts (vehicle body mounting screws) 11 are screwed to the base 10 via washers 12 and brackets 14 to fix the antenna device 1A to the roof of the vehicle or the like.

[0088] The connector 9c provided on the lower surface of the amplifier substrate 9 is connected through the connector hole 10b ( Figure 7 By exposing the connector 9c from the connector hole 10b of the base body 10, it is not necessary to prepare various cables according to the shape of the vehicle, and cost reduction can be achieved.

[0089] The base 10 has a structure with a step downward near the catch portion (gasket 12) of the base 10 for obtaining a compression connection with the vehicle (near the left-right center of the base 10 in this embodiment). Fig.14As shown, in the lower surface of the substrate 10, the inner side of the sealing member 15 becomes a convex portion 10a that protrudes downward compared to the outer side. Through this structure, near the capture portion of the substrate 10, the gap between the substrate 10 and the vehicle can be reduced and the capacitive coupling can be increased. Therefore, the occurrence of unnecessary resonance caused by the size of the substrate 10 can be suppressed (the amplitude of the unnecessary resonance frequency is reduced), and the decrease in the gain of the TEL antenna 2 can be suppressed. Moreover, in the high frequency band, near the capture portion of the substrate 10, the gap between the substrate 10 and the vehicle is small, so when the compression connection between the capture portion and the vehicle is obtained, the path length of the capture portion can be ignored, and the gain decrease of the TEL antenna 2 can be further suppressed. Moreover, by the structure of the lower surface of the substrate 10 becoming a convex portion 10a, the gap between the substrate 10 and the vehicle can be increased outside the capture portion, and the capacitive coupling between the substrate 10 and the vehicle can be reduced. Therefore, it is possible to cope with vehicle roofs of various curvatures. The reason is explained below. Outside the vicinity of the capture portion, when the curvature of the roof of the vehicle changes, it is far from the fastening connection base point, so the change in the gap between the vehicle roof and the base 10 increases and the change in capacitive coupling also increases. If the gap between the base 10 and the vehicle is reduced in the same manner as in the vicinity of the capture portion, the capacitive coupling increases, and the change in capacitive coupling is also large, so the change in the frequency of occurrence of unnecessary resonance increases, which sometimes has an adverse effect on the required frequency band. Due to the structure of the convex portion 10a, outside the vicinity of the capture portion, the gap between the base 10 and the vehicle is large, so the capacitive coupling is reduced, and even if the change in capacitive coupling is large, the change in the frequency of occurrence of unnecessary resonance is not too large. Therefore, it is possible to cope with vehicle roofs of various curvatures. It should be noted that the convex portion 10a can extend to the outside of the sealing member 15. It is preferred to have a structure that can avoid unnecessary resonance from occurring in the band of 700MHz to 960MHz.

[0090] In the antenna device 1A, the reason why the XM antenna 22, the GPS antenna 21, the TEL antenna 2, and the helical element 5 (a part of the AM / FM antenna) are arranged in order from the front to the back is explained. Regarding the bandwidth of each antenna, the XM antenna 22 is in the 2.3 GHz band, the GPS antenna 21 is in the 1.5 GHz band, the TEL antenna 2 is in the 700 MHz to 900 MHz band, the 1.7 GHz to 2.1 GHz band, and the 2.5 GHz to 2.6 GHz band, and the helical element 5 is in the 522 kHz to 1710 kHz (for AM) and the 76 MHz to 108 MHz (for FM). Here,

[0091] 1. The bandwidths of the GPS antenna 21 and the XM antenna 22 are close to the bandwidth of the TEL antenna 2. Therefore, in order to obtain mutual insulation, the distance between the GPS antenna 21 and the XM antenna 22 and the TEL antenna 2 needs to be increased. Therefore, by arranging the connector 9c between the arrangement space of the GPS antenna 21 and the XM antenna 22 and the arrangement space of the TEL antenna 2, mutual insulation can be ensured and the arrangement space can be reduced. Here, the XM antenna 22 is arranged in front of the GPS antenna 21 in order to arrange it in sequence in the order of the higher the frequency, the closer to the front, so as to suppress the interference between the antennas arranged nearby. This is because, for example, when the XM antenna 22 with a higher frequency than the GPS antenna 21 is arranged near the TEL antenna 2, the wavelength of the XM antenna 22 is smaller than that of the GPS antenna 21, so the size of the TEL antenna 2 cannot be ignored, and the interference becomes larger than when the GPS antenna 21 is arranged near the TEL antenna 2.

[0092] 2. In order to fix the antenna device 1A in a manner that avoids an increase in the gap between the antenna device 1A and the roof of the vehicle, the bolt 11 is screwed with the base 10 near the center of the front-back direction and the left-right direction of the antenna device 1A so that the front end of the claw of the washer (capture portion) 12 is connected to the vehicle in a voltage-tight manner. The TEL antenna 2 is connected to the vehicle equipment via the connector 9c directly exposed from the hole of the base 10 close to the bolt 11 and a cable not shown. When the distance between the TEL antenna 2 and the bolt 11 increases, the path between the TEL antenna 2 and the bolt 11 has an electrical length, and the current generated in the base 10 and the current generated in the roof of the vehicle are offset (the current to be excited in the TEL antenna 2 flows toward the vehicle), and the gain of the TEL antenna 2 may decrease. Therefore, the power supply position of the TEL antenna 2 is preferably located near the center of the front-back direction and the left-right direction of the antenna device 1A.

[0093] 3. When considering the aerodynamic force of the vehicle where the antenna device 1A is installed, the antenna device 1A is preferably raised in the vertical direction from the front direction to the rear direction. Therefore, it is preferable to place the XM antenna 22 and the GPS antenna 21, which are low in the vertical direction, in the front. The reason why the XM antenna 22 and the GPS antenna 21 are low in the vertical direction is that the required frequency is high and the wavelength is short, so they can be miniaturized.

[0094] For the above three reasons, the XM antenna 22, the GPS antenna 21, the TEL antenna 2, and the helical element 5 are arranged in this order from the front direction.

[0095] Fig.11 (A)~ Fig.11(C) is a schematic top view showing the relative positional relationship between the TEL antenna 2 and the helical element 5 in each case where the winding shape of the helical element 5 is a circle, an ellipse that is long in the left-right direction, and an ellipse that is long in the front-back direction. The helical element 5 is wound in a spiral shape, and when viewed from the top and bottom direction (winding axis direction), Figure 7 In the example, it is roughly circular ( Fig.11 (A)) but can also be Fig.11 (B) and Fig.11 (C) shows an elliptical shape and rotates. The effects of the elliptical shape are as follows.

[0096] 1. When the distance between the TEL antenna 2 and the helical element 5 is short, parasitic capacitance may occur between the two. In order to prevent this phenomenon, it is desirable to lengthen the distance between the TEL antenna 2 and the helical element 5, but it is difficult to lengthen the distance in the narrow inner housing 6. Therefore, Fig.11 As shown in (B), by making the helical element 5 rotate in an elliptical shape that is long in the left-right direction, the distance between the TEL antenna 2 and the helical element 5 becomes longer, thereby improving the insulation and suppressing the occurrence of parasitic capacitance between the two. Fig.11 When the helical element 5 is rotated in an elliptical shape that is long in the front-rear direction as shown in (C), the surface of the helical element 5 facing the TEL antenna 2 is reduced. Therefore, even if the TEL antenna 2 is spaced from the helical element 5 by a distance of 1 / 2 and 1 / 2, the helical element 5 can be rotated in an elliptical shape that is long in the front-rear direction. Fig.11 The TEL antenna 2 shown in (A) has the same separation distance from the helical element 5, and can also improve the insulation between the two, thereby suppressing the occurrence of parasitic capacitance between the two.

[0097] 2. By making the spiral element 5 rotate in an elliptical shape, when the minor diameter of the ellipse is equal to the diameter of a perfect circle, the projected area of ​​the spiral element 5 when viewed from above is larger than that of a perfect circle, and the electrical length can be further obtained compared with a perfect circle, so the degree of freedom of arrangement in the front-to-back direction in the inner housing 6 is improved. In addition, since the projected area of ​​the spiral element 5 when viewed from above is increased, high-frequency loss can be suppressed.

[0098] The above is the effect when the spiral element 5 is elliptical and rotates. It should be noted that the spiral element 5 can be in a polygonal shape such as a rectangle.

[0099] Helical element 5 Figure 7In the example, the spiral element 5 is offset (deviated) from the center of the left-right direction of the antenna device 1A in the right direction, but it can also be located in the center of the left-right direction. The winding axis (center axis) of the spiral element 5 can be inclined in the front-to-back direction (the winding axis of the spiral element 5 is not approximately parallel to the up-down direction). As a result, the distance between the spiral element 5 and the TEL antenna 2 can be extended, and the electrical length of the spiral element 5 can also be extended. Moreover, the winding axis of the spiral element 5 can also be inclined in the left-to-right direction (the winding axis of the spiral element 5 is not approximately perpendicular to the left-to-right direction). The effect produced by this is the same as the case of being inclined in the front-to-back direction. The spiral element 5 is configured to avoid overlapping the position in the up-down direction with the components on the capacitive load element 3 and the amplifier substrate 9. As a result, the occurrence of parasitic capacitance between the spiral element 5 and the capacitive load element 3 or between the spiral element 5 and the components on the amplifier substrate 9 can be suppressed.

[0100] Fig.10 (A)~ Fig.10 (F) is an exploded perspective view of the spiral element 5, the bracket 7, and the TEL antenna substrate 4. The spiral element 5 is held by the bracket 7 from the outside. Specifically, the bracket 7 has a spiral element holding portion 7a for accommodating the spiral element 5, and the spiral element holding portion 7a holds the spiral element 5 from the outside. The lead portions 5a of the spiral element 5 are respectively inserted into the spiral element connection holes 4a of the TEL antenna substrate 4. Since a high-frequency current flows more on the inner circumference side of the spiral element 5 than on the outer circumference side, high-frequency loss is less likely to occur when the spiral element 5 is held by the bracket 7 from the outside than when the spiral element 5 is held by the bracket 7 from the inside. In addition, since the spiral element 5 is held by the spiral element holding portion 7a from the outside, the maximum outer diameter of the spiral element 5 does not become larger than the inner diameter of the bracket 7, and the variation of the electrical length of the spiral element 5 can be suppressed. Moreover, a groove (not shown) can be dug on the inner surface of the spiral element holding portion 7a of the bracket 7, and the spiral element 5 can be arranged so as to be accommodated in the groove. In this case, the effect of suppressing the variation of the electrical length of the spiral element 5 and maintaining the interval between the conductors of the spiral element 5 is achieved. It should be noted that the spiral element 5 can also be held by the bracket 7 from the inside. That is, the spiral element 5 can be in a shape wound around the bracket 7. In addition, a groove can be dug on the bracket 7 and the spiral element 5 can be accommodated in the groove. The effect produced by this is the same as when it is accommodated in the groove on the inner surface of the spiral element holding portion 7a. The bracket 7 is mounted on the TEL antenna substrate 4. The bracket 7 holds the spiral element 5 and is mounted on the TEL antenna substrate 4, so the positional relationship between the TEL antenna 2 and the spiral element 5 is determined, and performance changes caused by mutual positional deviation can be avoided. It should be noted that the bracket 7 can also be absent if there is no adverse effect on use due to vibration, etc.

[0101] The position of the feeding point (terminal portion 18) of the helical element 5 is close to the helical element 5. As a result, the helical element 5 is located behind the antenna device 1A, so that the amplifier not shown in the figure can be set on the amplifier substrate 9. In addition, the conductor loss or the parasitic capacitance of the feeding line generated by the feeding line from the feeding point to the helical element 5 can be reduced. In addition, by making the length of the feeding line less than about 32 mm, which is 1 / 4 of the wavelength of the XM antenna 22, the gain reduction of the XM antenna 22 due to the length of the feeding line can be suppressed. In addition, since the position of the connection point (terminal portion 17) between the capacitance load element 3 and the helical element 5 is close to the helical element 5, the same effect as described above can be obtained.

[0102] like Fig.13 As shown, the front-to-back dimension of the first plate-shaped portion 3a of the capacitive load element 3 is about 50 mm, which is approximately 1 / 2 of the wavelength of the PCS band, and is an electrical length that does not resonate in the PCS band. Moreover, the front-to-back dimension of the second plate-shaped portion 3b of the capacitive load element 3 is about 23 mm, which is an electrical length that does not resonate in the PCS band. In addition, the total length of the first plate-shaped portion 3a and the second plate-shaped portion 3b of the capacitive load element 3 is about 80 mm, which is an electrical length that does not resonate in the AMPS band.

[0103] like Fig.14 and Fig.15 As shown, the passive element 25 covers the XM antenna 22 with a space left from above. The passive element 25 is mounted on the lower surface of the inner case 6 by, for example, welding. The XM antenna 22 is covered by the passive element 25, so that the gain in the vertex direction of the XM antenna 22 is increased. The GPS antenna 21 may also be covered by the passive element 25.

[0104] The filter 16 is a filter that electrically separates the first plate-shaped portion 3a and the second plate-shaped portion 3b of the capacitive load element 3 at high frequencies (above the frequency band of the TEL antenna 2) and electrically connects the first plate-shaped portion 3a and the second plate-shaped portion 3b of the capacitive load element 3 at low frequencies (below the frequency band of AM / FM). The filter 16 is provided between the first plate-shaped portion 3a close to the TEL antenna 2 and the spiral element 5, and is not provided between the second plate-shaped portion 3b not close to the TEL antenna 2 and the spiral element 5. Since the TEL antenna 2 is close to the first plate-shaped portion 3a, when the TEL antenna 2 transmits, there is a case where a high-frequency current is transmitted from the first plate-shaped portion 3a to the spiral element 5 and flows to the AM / FM amplifier. The filter 16 can cut off this current. Since the TEL antenna 2 is not close to the second plate-shaped portion 3b, such a current is difficult to flow, and the filter 16 is not provided in order to reduce costs. In the case where the attenuation of the filter 16 is insufficient, a filter can be added between the capacitive load element 3 and the spiral element 5.

[0105] The TEL antenna substrate 4 and the amplifier substrate 9 are electrically connected at the power supply point by the elasticity of the conductor leaf springs 9a and 9b as M-shaped springs ( Fig.12 ). When the number of power supply points increases, the shape of the conductor leaf springs 9a and 9b (M-shaped spring) often causes unstable fixation and unstable contact resistance. In addition, due to cross assembly, the contact resistance of the conductor leaf springs 9a and 9b may be different. Therefore, Fig.12 As shown, mutually facing projections 9d are provided on the inner sides of the conductor leaf springs 9a and 9b as M-shaped springs, and the TEL antenna substrate 4 is clamped by the projections 9d, thereby stabilizing the contact resistance of the conductor leaf springs 9a and 9b. It should be noted that the projections may be provided on the TEL antenna substrate 4 side instead of the conductor leaf springs 9a and 9b. In addition, projections may be provided on both. The same is true for the connection point between the capacitive load element 3 and the TEL antenna substrate 4 (the mutual connection portion between the connection plate 13 and the TEL antenna substrate 4).

[0106] Fig.16It is the connection circuit diagram (Part 1) of the antenna device 1A. The first plate-like portion 3a and the second plate-like portion 3b of the capacitive load element 3, and the helical element 5 form a vertex capacitive load type inverted F antenna. The AM / FM broadcast waves received by this inverted F antenna are transmitted to the amplifier substrate 9. One end of the helical element L1 among the helical elements 5 (L1 to L3) constituting the inverted F antenna is connected to the second plate-like portion 3b and is also connected to one end of the filter 16. The other end of the helical element L1 is connected to one ends of the helical elements L2 and L3. The other end of the helical element L2 is connected to the power supply point. The other end of the helical element L3 is connected to one end of the filter 19. The other end of the filter 19 is connected to the ground. It is possible to adjust the impedance and resonance frequency of the antenna by changing the relationship of the inductances of the helical elements 5 (L1 to L3) constituting the inverted F antenna. Specifically, the impedance of the antenna can be adjusted by the inductance of the helical element 5 (L3) connected to the ground. When the inductance is increased, the impedance decreases, and when the inductance is decreased, the impedance increases. Moreover, by adjusting the inductances of the other two helical elements 5 (L1, L2), the resonance frequency can be adjusted. Here, the inductances of the respective helical elements 5 have a relationship of L1 < L2 < L3. If an example of specific values is given, it is L1: 127 nH, L2: 425 nH, L3: 929 nH. The antenna mode for AM / FM can be an inverted L or a front-end short Braun, but by using an inverted F antenna, the impedance in the FM band can be increased, the impedance variation when adding the TEL antenna 2 can be reduced, and the influence of the TEL antenna 2 can be alleviated. The filter 19 is an FM band band-pass filter (BPF: Band Pass Filter). Since the AM band is no longer received when connected to the ground by using an inverted F antenna, the filter 19 that only allows the FM band to pass is loaded in order to reduce the degradation of the AM band.

[0107] Fig.17 It is the connection circuit diagram (Part 2) of the antenna device 1A. In the Fig.17 circuit, the different point from Fig.16 is that a filter 26 as a second filter is provided between the helical element 5 and the amplifier substrate 9. The filter 26 is provided on the TEL antenna substrate 4 side instead of on the amplifier substrate 9 side. As a result, the impedance of the TEL band on the helical element 5 side is increased compared to the power supply point of the helical element 5, the high-order harmonics of the FM resonance generated in the helical element 5 can be suppressed, and the gain reduction of the TEL antenna 2 can be suppressed. The filter 26 can be a parallel resonance circuit of a chip inductor and a chip capacitor, or can be a chip inductor whose self-resonance frequency is close to the required frequency band of the TEL antenna 2. Instead of chip components, the helical element 5 itself can also have this function. It should be noted that a structure that can avoid the occurrence of high-order harmonics in the frequency band of 700 MHz to 960 MHz is preferably used.

[0108] Fig.19 This is a characteristic diagram based on simulation showing the relationship between the frequency and the average gain of the TEL antenna 2 of the antenna device 1A of the second embodiment and the antenna device 1B of the third embodiment described later (dashed line and single-dot chain line) and the relationship between the frequency and the average gain of the TEL antenna 2 alone (without the capacitive load element 3) (solid line). Fig.19 The antenna gain of the TEL antenna 2 of the antenna device 1A of the present embodiment is also equal to the antenna gain of the TEL antenna 2 of the antenna device 1 of the first embodiment ( Figure 2 ) also achieves substantially the same good characteristics as when the TEL antenna 2 is used alone.

[0109] Fig. 20 This is a characteristic diagram based on actual measurement showing the relationship between the frequency and the average gain of the TEL antenna 2 when the capacitive load element 3 is divided into the first plate-shaped portion 3a and the second plate-shaped portion 3b and when it is not divided into the first plate-shaped portion 3a and the second plate-shaped portion 3b. Fig. 20 It can be seen that the capacitive load element 3 is divided into the first plate-shaped portion 3a and the second plate-shaped portion 3b in the front-to-back direction, thereby suppressing the interference between the capacitive load element 3 and the TEL antenna 2, and ensuring the average gain of the TEL antenna 2. The interference can be further suppressed by further dividing the capacitive load element 3 in the front-to-back direction, but the work efficiency during manufacturing deteriorates due to the division, the circuit becomes complicated, and the cost increases. Therefore, it is preferable to divide the capacitive load element 3 into two parts in the front-to-back direction as in the antenna device 1A.

[0110] (Implementation 3)

[0111] Fig.18 It is a schematic diagram of an antenna device 1B according to a third embodiment of the present invention. Fig.18 The antenna device 1B shown has a meander line 23 to replace the Figure 6 The filter 16 of the antenna device 1A shown in FIG. 2 is a filter 16 of the antenna device 1A shown in FIG. 2. The bending line 23 connects the first plate-shaped portion 3a and the second plate-shaped portion 3b of the capacitive load element 3 to each other. The other points of this embodiment are the same as those of the second embodiment. Fig.19 As shown, the antenna gain of the TEL antenna 2 of the antenna device 1B of the present embodiment is also similar to the antenna gain of the TEL antenna 2 of the antenna device 1A of the second embodiment, and has good characteristics substantially the same as those of the TEL antenna 2 alone.

[0112] (Comparative Example 1)

[0113] Fig.21 is a schematic diagram of an antenna device of Comparative Example 1. Figure 1Compared with the structure of the first embodiment shown, the TEL antenna 2 is different from the capacitive load element 3 in the front-back direction. Specifically, the front-back center position of the TEL antenna 2 is 30 mm away from the front end of the capacitive load element 3. The other points are the same.

[0114] Fig.23 This is a characteristic diagram based on simulation showing the relationship between the frequency and the average gain of the TEL antenna 2 of the antenna device of Comparative Example 1 and Comparative Example 2 described later (dashed line and single-dot chain line) and the relationship between the frequency and the average gain of the TEL antenna 2 alone (without the capacitive load element 3) (solid line). Fig.23 The antenna gain of the TEL antenna 2 of the antenna device of Comparative Example 1 is substantially the same as that of the TEL antenna 2 alone. However, since the TEL antenna 2 is separated forward from the capacitive load element 3, the antenna device becomes large.

[0115] (Comparative Example 2)

[0116] Fig. 22 is a schematic diagram of an antenna device of Comparative Example 2. Figure 1 Compared with the structure of the embodiment 1 shown in FIG. 1 , the center position of the TEL antenna 2 in the front-back direction is aligned with the front end of the capacitive load element 3, but the other points are aligned. Comparative Example 2 is an example in which the distance between the TEL antenna 2 and the front end of the capacitive load element 3 in the center position in the front-back direction is set to 0 mm in Comparative Example 1. In the case of Comparative Example 2, the TEL antenna 2 and the capacitive load element 3 are close to each other in the front-back direction, so the antenna device can be small, but due to the influence of the capacitive load element 3, as shown in FIG. Fig.23 As shown, the antenna gain of the TEL antenna 2 is significantly deteriorated compared with the case of the TEL antenna 2 alone.

[0117] Fig.24 This is a characteristic diagram based on simulation showing the relationship between the distance from the capacitive load element 3 (inter-antenna distance) and the average gain in the TEL antenna 2 of the comparative example. 30 mm on the horizontal axis corresponds to the comparative example 1, and 0 mm corresponds to the comparative example 2. Fig.24 In the technical concept of arranging the TEL antenna 2 away from the bottom of the capacitive load element 3 to avoid the influence of the capacitive load element 3, in order to improve the antenna gain of the TEL antenna 2, it is necessary to separate the TEL antenna 2 from the capacitive load element 3. In contrast, in the above-mentioned embodiments 1 to 3, the TEL antenna 2 can be arranged below the capacitive load element 3 and the antenna gain of the TEL antenna 2 can be improved, thereby suppressing the decrease in antenna gain and achieving miniaturization.

[0118] (Implementation 4)

[0119] Fig.25 It is a perspective view of an antenna device 1C according to a fourth embodiment of the present invention. Fig.26 is Fig.25 The three-dimensional diagram of the inner housing 6 is omitted in the figure. The antenna device 1C of the present embodiment is different from the antenna device 1A of the second embodiment in that the first plate-like portion 3a of the capacitive load element 3 is provided with a cutout portion 3d, but is consistent in other points. By having the cutout portion 3d, the first plate-like portion 3a is in a square shape with one side missing (a U-shape or a U-shape) when viewed from above, and is divided in the left-right direction except for the rear end. As a result, the first plate-like portion 3a has a pair of sides that are opposite to each other across the cutout portion 3d, and high-frequency currents tend to flow in opposite directions on each side of the pair of sides, and it is easy to cancel out higher harmonic components with frequencies higher than the FM band excited in the capacitive load element 3. Therefore, the distance between antennas with different resonance frequencies (capacitive load element 3 and TEL antenna 2) can be close.

[0120] Fig. 27 3 is a characteristic diagram based on simulation showing the relationship between the frequency and the average gain of the FM band of the AM / FM antenna in each case where the capacitive load element 3 has the notch portion 3d and the notch portion 3d. Fig. 27 By forming the first plate-shaped portion 3a of the capacitive load element 3 into a square shape with one side missing (U-shaped or U-shaped) as described above, the average gain of the TEL antenna 2 can be improved. This is because the parasitic capacitance can be reduced by increasing the distance between the capacitive load element 3 and the TEL antenna 2. In addition, by forming the first plate-shaped portion 3a into a square shape with one side missing (U-shaped or U-shaped), the working efficiency when the first plate-shaped portion 3a is mounted on the inner housing 6 can be improved compared to the case where the first plate-shaped portion 3a is composed of two plate-shaped portions separated from each other. In addition, the number of screws can be reduced, which can lead to cost reduction.

[0121] Fig.28 1 is a front cross-sectional view of an antenna device 1D according to a fifth embodiment of the present invention. The antenna device 1D of this embodiment is different from the antenna device 1A of the second embodiment in that the capacitive load element 3 is divided into a left plate-shaped portion 3e and a right plate-shaped portion 3f, and the TEL antenna substrate 4 and the TEL antenna provided on the TEL antenna substrate 4 protrude upward from between the left plate-shaped portion 3e and the right plate-shaped portion 3f, but is identical in other aspects. By dividing the capacitive load element 3 into left and right portions, it is possible to suppress the parasitic capacitance generated between the capacitive load element 3 and the TEL antenna 2, and to improve the performance of the AM / FM band. Furthermore, by the TEL antenna substrate 4 and the TEL antenna provided on the TEL antenna substrate 4 protruding upward from between the left plate-shaped portion 3e and the right plate-shaped portion 3f, it is possible to improve the performance of the TEL antenna. Fig.29The characteristic diagram based on simulation shows the relationship between the frequency and the average gain of the FM band of the AM / FM antenna in each case when the capacitive load element 3 is divided into the left plate-shaped portion 3e and the right plate-shaped portion 3f and when it is not divided into the left and right. Fig.29 In the case of the left-right split, the TEL antenna does not protrude upward from between the left plate upper portion 3e and the right plate upper portion 3f. Fig.29 By dividing the capacitive load element 3 into left and right parts, the average gain of the FM band of the AM / FM antenna can be improved.

[0122] The present invention has been described above by taking the embodiments as examples, but those skilled in the art will appreciate that various modifications may be made to the structural elements or processing steps of the embodiments within the scope of the technical claims of the invention.

[0123] The first antenna can replace the TEL antenna 2 with a TV antenna, a keyless entry antenna, an inter-vehicle communication antenna, or a WiFi antenna. The second antenna can replace the AM / FM antenna with a DAB (Digital Audio Broadcast) receiving antenna. The maximum voltage point of the capacitive load element 3 is Fig.18 In addition to the addition of the bending line 23 shown, the bending line 23 can be changed by adding a slit or forming a folded shape.

[0124] Description of Reference Numerals

[0125] 1, 1A to 1D antenna device, 2TEL antenna (first antenna), 3capacitive load element (second antenna), 3a first plate-shaped portion, 3b second plate-shaped portion, 3c tongue portion, 3d cutout portion, 3e left plate-shaped portion, 3f right plate-shaped portion, 4TEL antenna substrate, 4a spiral element connection hole, 5 spiral element (AM / FM coil), 5a lead-out portion, 6 inner housing, 6a groove portion, 7 bracket, 7a spiral element holding portion, 8 waterproof pad (water-tightening fastener), 9 amplifier substrate, 9a, 9 b conductor leaf spring (terminal), 9c connector, 9d protrusion, 10 base, 10a convex portion, 10b connector hole, 11 bolt (body mounting screw), 12 washer (catching portion), 13 connecting plate, 14 bracket, 15 sealing member, 16 filter (BEF), 17, 18 terminal portion, 19 filter (BPF), 20 outer shell (external shell), 21 GPS antenna, 22 XM antenna, 23 bending line, 25 passive component, 26 filter, 101 to 106 screws.

Claims

1. An antenna device, comprising: a first antenna; and a second antenna having a capacitive loading element located above the first antenna, The frequency of the frequency band corresponding to the first antenna is higher than the frequency of the frequency band corresponding to the second antenna. The first antenna and the second antenna are independent of each other, A power supply point of the first antenna and a power supply point of the second antenna are different from each other, An upper portion of the first antenna and a lower portion of the capacitive loading element overlap.

2. The antenna device according to claim 1, wherein: The capacitive loading element is divided in the front-rear direction.

3. The antenna device according to claim 1, wherein: At least one of the side surfaces of the capacitive load element has a slit.

4. The antenna device according to any one of claims 1 to 3, wherein: A notch portion is formed at an upper portion of the capacitance load element, and a pair of sides forming the notch portion are arranged to face each other.

5. The antenna device according to any one of claims 1 to 3, wherein: The antenna device further comprises an inner housing. The capacitive load element is screwed to the upper portion of the inner housing.

6. The antenna device according to any one of claims 1 to 3, wherein: The antenna device further includes an inner housing having a groove. The capacitive load element has a tongue portion at at least one of the upper portion and the lower portion, The tongue portion is inserted into the groove portion.

7. The antenna device according to any one of claims 1 to 3, wherein: The second antenna has a helical element, The antenna device further includes a holder that holds the helical element from the outside.

8. The antenna device according to any one of claims 1 to 3, wherein: The first antenna is a communication antenna, and the second antenna is a radio broadcasting antenna.

9. An antenna device comprising: First antenna; a second antenna having a capacitive loading element located above the first antenna; and Inner shell, The frequency of the frequency band corresponding to the first antenna is higher than the frequency of the frequency band corresponding to the second antenna. The first antenna and the second antenna are independent of each other, A power supply point of the first antenna and a power supply point of the second antenna are different from each other, The capacitive load element is screwed to the upper portion of the inner housing.

10. The antenna device according to claim 9, wherein: The capacitive loading element is divided in the front-rear direction.

11. The antenna device according to claim 9, wherein: At least one of the side surfaces of the capacitive load element has a slit.

12. The antenna device according to any one of claims 9 to 11, wherein: A notch portion is formed at an upper portion of the capacitance load element, and a pair of sides forming the notch portion are arranged to face each other.

13. The antenna device according to any one of claims 9 to 11, wherein: The second antenna has a helical element, The antenna device further includes a holder that holds the helical element from the outside.

14. The antenna device according to any one of claims 9 to 11, wherein: The first antenna is a communication antenna, and the second antenna is a radio broadcasting antenna.

15. An antenna device comprising: First antenna; A second antenna having a capacitive loading element located above the first antenna; and An inner housing having a groove portion, The frequency of the frequency band corresponding to the first antenna is higher than the frequency of the frequency band corresponding to the second antenna. The first antenna and the second antenna are independent of each other, A power supply point of the first antenna and a power supply point of the second antenna are different from each other, The capacitive load element has a tongue portion at at least one of the upper portion and the lower portion, The tongue portion is inserted into the groove portion.

16. The antenna device according to claim 15, wherein: The capacitive loading element is divided in the front-rear direction.

17. The antenna device according to claim 15, wherein: At least one of the side surfaces of the capacitive load element has a slit.

18. The antenna device according to any one of claims 15 to 17, wherein: A notch portion is formed at an upper portion of the capacitance load element, and a pair of sides forming the notch portion are arranged to face each other.

19. The antenna device according to any one of claims 15 to 17, wherein: The second antenna has a helical element, The antenna device further includes a holder that holds the helical element from the outside.

20. The antenna device according to any one of claims 15 to 17, wherein: The first antenna is a communication antenna, and the second antenna is a radio broadcasting antenna.

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