Antenna device

Abstract

Provided is an antenna device that is small and low-profile, can reduce parasitic capacitance, and can be mixed with other media antennas without obstacles. The AM / FM antenna (13) is constructed by fixing a pair of capacitor-loaded vibrators (131, 132) to a retaining frame (133) through a fixing hole (1321), and fixing a helical antenna (134) at the bottom of the retaining frame (134). The capacitor-loaded vibrators (131, 132) are centered on a plane perpendicular to the roof and are opposite to each other at a specified interval and a specified angle. In addition, connecting parts are provided at locations lower than the upper edge, and are connected to each other via each connecting part. The edges of the capacitor-loaded vibrators (131, 132) are of a size that does not interfere with, for example, the SDARS antenna (14) and the GNSS antenna (19).

Description

[0001] This application is a divisional application of the invention patent application with Chinese patent application number 201780073473.6, national phase entry date May 28, 2019, international application date October 13, 2017, PCT international application number PCT / JP2017 / 037195, and invention name “antenna device”. Technical Field

[0002] The present invention relates to a low-profile antenna device which is mounted on the top (roof) of a vehicle and is capable of receiving radio waves for various media. Background Art

[0003] As conventional antenna devices mounted on a vehicle roof or the like, the antenna devices disclosed in Patent Documents 1 to 3 are known. These antenna devices house an antenna unit in an antenna housing that protrudes from the vehicle roof by a length of 70 mm or less. The antenna unit is provided with an antenna element for receiving FM band radio waves and a metal plate provided in an umbrella shape near the top of the antenna element in order to increase the gain of the AM band.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Publication No. 2010-21856

[0007] Patent Document 2: Japanese Patent Application Publication No. 2015-84575

[0008] Patent Document 3: Japanese Patent Application Publication No. 2016-174368 Summary of the invention

[0009] In recent years, there has been a tendency to mix a variety of media antennas such as telephone antennas and GPS antennas in antenna housings in addition to AM and FM broadcasts. Therefore, in the case where the antenna vibrator is set as a large metal plate in order to achieve a small and low-profile antenna device such as the antenna device disclosed in Patent Documents 1 to 3, other media antennas will be arranged closely, and the parasitic capacitance will increase due to the close antennas. Parasitic capacitance is an invalid capacitance component that is not intended by the designer and is caused by the physical structure. The larger the parasitic capacitance, the lower the gain. In addition, even antennas that are not close to each other are easily affected by each other.

[0010] An object of the present invention is to provide an antenna device which can reduce parasitic capacitance even if it is small and low-profile, and can be mixed with other media antennas without any hindrance.

[0011] The antenna device provided by the present invention is an antenna device installed on a vehicle roof, characterized in that it comprises: a housing portion having radio wave permeability and a storage space formed therein, and an antenna portion stored in the storage space. The antenna portion is configured to include: a pair of capacitor-loaded vibrators, the pair of capacitor-loaded vibrators are respectively centered on a plane orthogonal to the vehicle roof and are opposite to each other at a predetermined interval and a predetermined angle, and are respectively provided with connecting portions at a position lower than the upper edge, and are mutually conductive via each connecting portion; and a spiral vibrator, the spiral vibrator being electrically connected to each connecting portion to receive FM broadcasting.

[0012] Effects of the Invention

[0013] Since the edges (upper edge, side edge, lower edge) of the capacitor-loaded vibrator are separated from each other, the surface parallel to the roof is open. Therefore, although the electrostatic capacitance to the ground is added to the helical vibrator by the capacitor-loaded vibrator, the parasitic capacitance is reduced. Therefore, the gain of AM broadcasting and FM broadcasting is improved. In addition, since the edges of the opposing capacitor-loaded vibrators are discontinuous, interference with radio waves received by antennas for other media can be suppressed. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 (a) to (c) are appearance diagrams of the antenna device according to the first embodiment.

[0015] Figure 2 It is a diagram for explaining the arrangement of components constituting the antenna device according to the first embodiment.

[0016] Figure 3 (a) to (c) are diagrams for explaining the structure of the retaining frame.

[0017] Figure 4 (a) to (d) are diagrams illustrating the structure of a capacitor-loaded oscillator.

[0018] Figure 5 (a) to (c) are diagrams illustrating the structure of a helical oscillator.

[0019] Figure 6 (a) to (d) are diagrams for explaining the structure of AM / FM antennas.

[0020] Figure 7 It is an external perspective view showing a state where the antenna unit is accommodated in the accommodation space.

[0021] Figure 8 This is a perspective view showing a structural example of an antenna device including an antenna unit in a storage space.

[0022] Fig. 9 (a) to (e) are diagrams showing examples of changes in the electrical characteristics of the SDARS antenna.

[0023] Fig.10 (a) to (c) are diagrams showing examples of connection portions between capacitively loaded transducers.

[0024] Fig.11 (a) to (c) are diagrams for explaining the structure of the antenna device according to the second embodiment.

[0025] Fig.12 (a) and (b) are diagrams for explaining the structure of the antenna device according to the third embodiment.

[0026] Fig.13 It is a diagram for explaining the arrangement of the antenna unit of the antenna device according to the fourth embodiment.

[0027] Fig.14 (a) to (c) are diagrams for explaining the structure of the AM / FM antenna in the fourth embodiment.

[0028] Fig.15 (a) is a perspective view of the appearance of the antenna device according to the fifth embodiment. Fig.15 (b) is the local removal map in (a).

[0029] Fig.16 It is a diagram for explaining the arrangement of parts constituting the antenna device according to the fifth embodiment.

[0030] Fig.17 It is a perspective view of the appearance of a capacitively loaded vibrator according to the fifth embodiment.

[0031] Fig.18 (a) to (e) are diagrams illustrating the shapes of capacitor-loaded oscillators.

[0032] Fig.19 This is a graph showing average gain-frequency characteristics of the telephone antennas according to the first and fifth embodiments.

[0033] Fig. 20 This is a graph showing the average gain-frequency characteristics of an antenna for a keyless entry system.

[0034] Fig.21 This is a perspective view of the appearance of the SDARS antenna according to the fifth embodiment.

[0035] Fig. 22 It is composed Fig.21 Illustration of the configuration of the parts of the SDARS antenna.

[0036] Fig.23 yes Fig.21 AA′ cross-sectional view.

[0037] Fig.24 This is a diagram showing the positional relationship between the passive element for SDARS and the antenna body.

[0038] Fig.25 This is a simulation diagram showing the gain change caused by the direction of the SDARS antenna.

[0039] Fig.26 This is the gain-frequency characteristic diagram of the SDARS antenna.

[0040] Fig. 27 It is a perspective view of the appearance of the antenna portion of the antenna device according to the sixth embodiment.

[0041] Fig.28 (a) and (b) are diagrams illustrating the structure of a capacitor-loaded oscillator.

[0042] Fig.29 The drawings are explanatory diagrams of the assembly procedure of the spiral coil to the vibrator holder, wherein (a) shows the state before assembly and (b) shows the state after assembly. DETAILED DESCRIPTION

[0043] Hereinafter, an embodiment example of the present invention applied to a low-profile antenna device mounted on a vehicle roof will be described. This antenna device includes a plurality of antennas for receiving or transmitting radio waves for a plurality of media.

[0044] It should be noted that, hereinafter, for the sake of convenience, the roof side is referred to as the lower direction, the direction vertically upward from the roof is referred to as the upper direction, the longitudinal direction of the present invention is referred to as the front-rear direction (the front side is the front, and the back side is the back), and the direction perpendicular to the longitudinal direction is referred to as the left-right direction. In addition, there are also cases where the upper and lower directions are respectively expressed as the front and back or similar expressions are used.

[0045] [First embodiment]

[0046] Figure 1 (a) is a top view of the antenna device according to the first embodiment, Figure 1 (b) is a side view, Figure 1 (c) is a rear view. The antenna device 1 of this embodiment includes: a shell portion made of synthetic resin, which has radio wave permeability and has a storage space formed therein; and an antenna portion, which is stored in the storage space. The shell portion is composed of an antenna shell 10 having an opening surface on the lower surface side and an inner shell not shown. The antenna device 1 also has a base portion 20 that blocks the opening surface of the antenna shell 10, and a capture unit 30 for mounting the antenna device 1 on the roof and grounding it.

[0047] The antenna housing 10 is formed into a streamlined shape, which is a curved surface that becomes thinner and lower toward the front (toward the front end), and the side surface is curved inward (toward the central axis in the longitudinal direction). The lower surface of the antenna housing 10 is formed into a shape corresponding to the shape of the mounting surface of the roof (the bottom surface of the part on the roof side where the antenna device 1 is mounted, the same below). The length of the antenna housing 10 in the longitudinal direction is about 230 mm, the width is about 75 mm, and the height is about 70 mm.

[0048] <Parts Configuration>

[0049] Figure 2 1 is a diagram for explaining the arrangement of parts of the antenna device 1. The antenna device 1 includes an inner housing 11, the outer wall of which is shaped in accordance with the inner wall of the antenna housing 10. The inner housing 11 is made of radio wave transparent synthetic resin, and its lower surface is open. In addition, a groove and a plurality of bosses for screwing and fixing to the base 20 are formed on the outer flange of the lower surface.

[0050] The storage space is formed inside the inner housing 11 to protect the antenna. When the inner housing 11 is screwed to the base 20, the O-ring 22 is sandwiched and fixed by the inner wall of the inner housing 11 and the outer wall of the inner rib of the insulating wall of the insulating base 23, thereby forming a structure capable of ensuring dustproof and waterproof properties inside the antenna device 1.

[0051] The antenna housing 10 is fixed to the insulating base 23 by aligning the resin snap-fitting piece provided on the inner rear side of the antenna housing 10 with the snap-fitting piece embedding portion of the insulating base 23 and using this portion as a fulcrum to engage the locking claws provided on the front and left and right sides of the antenna housing 10 and the insulating base 23 with each other.

[0052] In addition, fixing pieces are provided at the left and right parts of the antenna housing 10 in addition to the locking claws, and the fixing pieces are assembled by inserting the fixing piece holes provided in the insulating base 23. By providing the fixing pieces, the antenna housing 10 can be prevented from being deformed due to the external force applied to the antenna housing 10, and since the external force is dispersed to the fixing pieces, the external force transmitted to the locking claws can be reduced, thereby preventing the locking claws from being disengaged from each other.

[0053] A soft insulating gasket 12 is installed between the outer edge of the lower surface of the inner shell 11 and the open end of the antenna shell 10. The gasket 12 is sandwiched and fixed when the antenna shell 10 is fixed to the base 20. The gasket 12 blocks the gap between the roof and the antenna shell 10 and the inner shell 11, thereby improving the aesthetics and dustproof and waterproof properties. In particular, it prevents water from being directly sprayed onto the sealing material 34 due to water spraying from a car washing machine, thereby improving the waterproof property of the sealing material 34.

[0054] An AM / FM antenna 13, an SDARS (Satellite Digital Audio Radio Service) antenna 14, an LTE antenna 15, a GNSS antenna 16, and a telephone antenna 17 are installed in the storage space of the inner shell 11. The AM / FM antenna 13 receives AM broadcast waves of 522kHz to 1710kHz and FM broadcast waves of 76MHz to 108MHz. In addition, it can also receive LW broadcast waves of 153kHz to 279kHz. The SDARS antenna 14 that receives circularly polarized waves receives waves in the 2.3GHz band as a satellite digital audio broadcasting service. The LTE (Long Term Evolution) antenna 15 transmits and receives waves in the 700MHz to 2.7GHz band. GNSS (Global Navigation Satellite System) is a general term for satellite positioning systems such as GPS, GLONASS, Galileo, and Quasi-Zenith Satellite (QZSS). The circularly polarized GNSS antenna 16 receives GNSS radio waves in the 1.5 GHz band. The telephone antenna 17 transmits and receives radio waves in the 700 MHz to 2.7 GHz band. The telephone antenna 17 is actually a type of LTE antenna.

[0055] The AM / FM antenna 13 is screwed to the inner wall boss of the inner housing 11 and is elastically held by an M-shaped connecting piece 191 as an elastic conductive member formed on the substrate 19. The SDARS antenna 14 is screwed and held by the insulating base 23. The LTE antenna 15 and the GNSS antenna 16 are fixed to the conductive base 21 via the substrate 18. The telephone antenna 17 is fixed to the conductive base 21 via the substrate 19. The signals received and amplified by the antennas 13 to 17 are sent to the electronic circuit on the vehicle side through the signal cables C1, C2, and C3.

[0056] The AM / FM antenna 13 is configured to include a pair of capacitance-loaded vibrators 131 and 132, a synthetic resin holder 133 having radio wave permeability, and a helical vibrator 134. The capacitance-loaded vibrators 131 and 132 are vibrators of a composite shape, for example, formed in a meandering shape, each having an electrical delay portion in a substantially central portion, and do not resonate in the AM / FM band by themselves. However, the helical vibrator 134 functions as a capacitance-loaded plate that adds (loads) an electrostatic capacitance to the ground, thereby enhancing the function as a voltage receiving element in the AM band and resonating in the FM band. Moreover, at frequencies other than the AM band and the FM band, the helical vibrator 134 functions as an impedance converter described later. The helical vibrator 134 is inserted between the capacitance-loaded vibrators 131 and 132 and the AM / FM amplifier circuit, and acts as a helical antenna that cooperates with the capacitance-loaded vibrators 131 and 132 and resonates in the FM band. The helical vibrator 134 is formed by winding a linear conductor around a hollow coil frame, and has line end terminals (in the upper and lower ends) formed at the upper and lower ends thereof to be electrically connected to the ends of the linear conductor. Figure 2 In the example shown, the lower terminal 1341 is elastically held by the M-shaped connecting piece 191. The structure of the AM / FM antenna 13 will be described in detail later.

[0057] The SDARS antenna 14 is configured to include a passive element 141, a passive element holder 142, a planar antenna 143, an amplifier substrate 144 for SDARS, a shielding cover 145, and a grounding plate 146. The planar antenna 143 is a main antenna for SDARS, and the passive element 141 in the form of a metal sheet is provided on the upper side of the planar antenna 143 at a predetermined interval in order to improve the antenna gain of the planar antenna 143. The shielding cover 145 formed by forming a metal sheet in a box shape is a conductive component that electrically shields the amplifier substrate 144 for SDARS. The grounding plate 146 is a conductive component that serves as a ground line (grounding part, the same below) of the planar antenna 143. In addition, the shielding cover 145 and the grounding plate 146 can be integrated. Such an SDARS antenna 14 is arranged in a recessed portion of the insulating base 23 that exists in front of the conductive base 21. The grounding plate 146 is separated from the roof by a predetermined distance. In addition, it is electrically isolated from the ground lines of other antennas other than the SDARS antenna. The reason for this will be described later.

[0058] The LTE antenna 15 is erected on the substrate 18. The GNSS antenna 16 is a planar antenna and is mounted on the surface of the substrate 18. On the back side of the substrate 18, a GNSS amplifier circuit, an LTE antenna matching circuit, and a common (diplexer) circuit that makes the outputs of the two antennas 15 and 16 one output are installed. The GNSS antenna 16 is electrically connected to the input part of the GNSS amplifier circuit. In addition, the LTE antenna 15 is electrically connected to the input part of the LTE antenna matching circuit. The electrical connection is performed by soldering or the like. The above-mentioned telephone antenna 17 is erected on the surface of the substrate 19. On the back side of the substrate 19, a matching circuit for the telephone antenna 17 and an AM / FM amplifier circuit, etc., which are not shown in the figure, are installed.

[0059] The base portion 20 is configured to include a metal conductive base 21 that becomes the same potential as the roof after being mounted on the roof, an O-ring 22 that is a soft insulator, and a resin insulating base 23 whose outer circumference corresponds to the shape of the lower surface of the antenna housing 10. The insulating base 23 is a resin component that has strength for holding the conductive base 21, the antenna housing 10, the inner housing 11, and the SDARS antenna 14. The conductive base 21 is a component that is formed by die casting and has a predetermined strength. When mounted, it becomes the same potential as the roof and functions as a ground wire (ground).

[0060] The front side of the conductive base 21 is formed with recesses 211, 212 and a wall 213 that shields these recesses 211, 212. The recess 211 accommodates electronic components such as the AM / FM amplifier circuit mounted on the back of the substrate 19. The recess 212 accommodates electronic components such as the GNSS amplifier circuit mounted on the back of the substrate 18. The wall 213 shields these storage spaces. In other words, the recesses 211, 212 and the wall 213 position the substrates 18, 19 and form independent shielding areas. In other words, the conductive base 21 also serves as a shielding component for various electronic components.

[0061] Around the recesses 211 and 212, screw holes for screwing the substrates 18 and 19 are also formed. However, in order to prevent the leakage of radio waves of the desired frequency band, the interval between the screw holes is preferably less than 1 / 2 of the wavelength of the radio waves. In addition, portions of the signal output pattern of the substrates 18 and 19 may also be opened. On the other hand, on the back side of the conductive base 21, a boss for screwing the gripping portion 3 is formed protruding downward.

[0062] The outer periphery of the insulating base 23 is in a shape corresponding to the shape of the opening surface of the antenna housing 10, and a guide groove for inserting the O-ring 22 and a snap mechanism for snapping the inner housing 11 are formed at a position slightly inside the outer periphery. A flat component mounting surface 231 is formed inside the guide groove and the snap mechanism. A hole 232 for mechanically connecting the conductive base 21 and the gripping portion 30 is formed in the approximate center of the component mounting surface 231. In addition, a recess 233 is formed at a position close to the front of the insulating base 23. The SDARS antenna 14 is accommodated in the recess 233.

[0063] The gripping portion 30 includes a bolt 31, a vehicle fixing claw component 32, a pre-locking retainer 33, a sealing material 34, and a metal spring 35. The pre-locking retainer 33 temporarily fixes the antenna device 1 to the roof. The pre-locking retainer 33 is provided with a locking claw. When the antenna mounting boss portion is inserted and embedded in the mounting hole on the roof side, the locking claw is embedded with the periphery of the mounting hole on the roof side. As a result, the antenna device 1 can be temporarily fixed before the bolt 31 is tightened, thereby improving the operability of installing the antenna on the roof. By tightening the bolt 31 after temporary fixing, the claw of the vehicle fixing claw component 32 is opened. Then, the top end of the fixing claw component 32 scrapes off the painted surface of the roof, thereby electrically connecting the roof and the conductive base 21 to become approximately the same potential and mechanically fixed. In addition, by tightening the bolt 31, the sealing material 34 fixed to the back of the insulating base 23 with an adhesive or the like is compressed due to its elasticity. As a result, dust can be prevented from entering the vehicle through the roof and waterproofing can be achieved. In addition, the rust resistance and waterproofness of the conductive base 21 and the metal spring 35 can be ensured.

[0064] The curvature of the roof on which the antenna device 1 is mounted may differ depending on the type of vehicle. The metal spring 35 is a slidable member whose portion in contact with the roof is convex and deforms to follow the shape (curvature) of the roof. Its effects will be described later.

[0065] <AM / FM Antenna Structure>

[0066] Next, the structure of the AM / FM antenna 13 will be described in detail. The AM / FM antenna 13 has a holder 133 having a three-dimensional shape with a trapezoidal cross section. Figure 3 (a) is a top view of the retainer 133. Figure 3 (b) is the main view, Figure 3(c) is a side view. The retaining frame 133 is made of a radio wave transparent synthetic resin that is long in the front-to-back direction and short in the left-to-right direction, and the upper bottom surface 1331 is a substantially flat surface. In addition, a groove portion 1332 having a flat bottom surface of a specified width is formed in the upper bottom surface 1331 at a position slightly forward from the center of the length. A threaded hole 1333 is formed in a specified position of the groove portion 1332. The threaded hole 1333 is used to fasten the capacitor-loaded vibrators 131, 132 and the spiral vibrator 134 to the inner wall boss of the inner housing 11 with screws. There are multiple ribs 1334 of various widths on both sides of the retaining frame 133. A locking claw 1335 is formed on any rib 1334. The ribs 1334 and the locking claw 1335 not only limit the angle and position of the capacitor-loaded vibrators 131, 132, but also improve the strength of the retaining frame.

[0067] Figure 4 1 is an explanatory diagram showing the shape and arrangement example of the capacitor-loaded vibrators 131 and 132. Figure 4 (a) is a top view, Figure 4 (b) is the main view, Figure 4 (c) is a side view. In addition, Figure 4 (d) is a dimensional illustration of these capacitor-loaded vibrators 131 and 132. As shown in these figures, the capacitor-loaded vibrators 131 and 132 are vibrators composed of composite elements in which a front face portion that becomes the front when installed and a rear face portion that becomes the rear are connected by a strip-shaped winding portion. "Winding portion" refers to a surface formed by a thin conductor vibrator formed to have at least one winding shape. Both are vibrators with roughly symmetrical shapes, one of which is centered on a plane orthogonal to the roof and is opposite to each other at a specified interval and a specified angle. The interval and angle are determined by the shape of the internal space of the inner shell 11. In addition, the rear face is a high-height structure.

[0068] The capacitor-loaded vibrators 131 and 132 are also provided with connecting portions 1312 and 1322 at positions lower than the uppermost position (hereinafter referred to as the "top") when installed, and are mutually conductive through these connecting portions 1312 and 1322. Each connecting portion 1312 and 1322 can be realized by forming a slit in a part of the capacitor-loaded vibrators 131 and 132 and then bending it. The difference in length of each connecting portion 1312 and 1322 is to clarify the installation direction of the capacitor-loaded vibrator 131 and the capacitor-loaded vibrator 132, which are roughly symmetrical, but this is not always necessary.

[0069] Fixing holes 1311 and 1321 are formed on the front and rear surfaces of the capacitor-loaded vibrators 131 and 132. The fixing holes 1311 and 1321 are used to fit with the locking claws 1335 of the holder 133. Thus, since the capacitor-loaded vibrators 131 and 132 can be locked to the holder 133 without using an adhesive or the like, not only can the assembly process be simplified, but also the change in electrical characteristics caused by the use of an adhesive or the like can be suppressed.

[0070] Furthermore, it is also possible to achieve fixation not only at the locking claws but also by heating with heat or the like after temporary fixation with the locking claws to weld to the retainer.

[0071] In the example of this embodiment, Figure 4 The height a1 of the front face shown in (d) is about 26 mm, the lateral length a2 is about 23 mm, the lateral length a3 of the winding portion is about 14 mm, and the lateral length a4 of the rear face is about 23 mm. The winding portion also has a path length in the height direction.

[0072] The wavelength λ1 of SDARS is about 120 mm, the height a1, length a2, and a4 are about 1 / 4 or less of the wavelength λ1 of SDARS, and the path length of the meandering portion is about 1 / 2 of the wavelength λ1 of SDARS. Therefore, the impedance of the meandering portion (starting end) when viewed from the front face becomes high at the frequency of SDARS and is electrically isolated. In other words, the capacitor-loaded vibrators 131 and 132 function as impedance converters in the frequency band used by SDARS, for example. The impedance when the meandering portion (rear end) is viewed from the rear face is the same.

[0073] Therefore, for the SDARS antenna 14, the capacitor-loaded vibrators 131 and 132 become conductors of a size that will not affect their own operation (including directivity). For the capacitor-loaded vibrators 131 and 132, the impedance from the rear end to the winding part and from the front end to the winding part becomes high at the frequency band of SDARS, so they will not be affected by the radio waves of SDARS. In other words, there will be no mutual interference. In addition, the wavelength λ2 of GNSS is approximately 190 mm, and the electrical length of the capacitor-loaded vibrators 131 and 132 is set to a length that will not resonate in a manner that is not 1 / 2 of the wavelength λ2 of GNSS, so the capacitor-loaded vibrators 131 and 132 will not interfere with the GNSS antenna 16.

[0074] In contrast, in the case of a single-plane vibrator without a meandering portion as in the aforementioned patent documents 1 to 3, if the required electrostatic capacitance to the ground is to be loaded, the lateral length is about 60 mm, which is 1 / 2 of the wavelength λ1, so that at least for the SDARS antenna 14, the gain is easily reduced and the directivity is distorted. In addition, the height is about twice the height a1, which is still about 1 / 2 of the wavelength λ1, and for the SDARS antenna 14, the gain is easily reduced and the directivity is distorted.

[0075] According to the experiment of the inventor of the present application, if the plate thickness of the capacitance-loaded vibrators 131 and 132 is 1 to 2 mm or less (sufficiently small thickness for the wavelengths λ1 and λ2) for the wavelengths λ1 and λ2, the height a1 is about 1 / 4 of the wavelength λ1 of the radio wave received by the planar antenna 143 or less, and the path length of the meandering portion is about 1 / 2±1 / 8 relative to the wavelength λ1, then no interference is observed between the AM / FM antenna 13 and the SDARS antenna 14. In addition, if the capacitance-loaded vibrators 131 and 132 are of a length that does not resonate with respect to the radio wave received by the GNSS antenna 16, then no interference is observed between the AM / FM antenna 13 and the GNSS antenna 16. In addition, the length of the front face and the rear face electrically isolated by the meandering portion is preferably about 1 / 4 of the wavelength λ1 or less.

[0076] like Figure 4 As in (a) to (d) of FIG. 1 , the capacitor-loaded vibrators 131 and 132 with an open top structure also exhibit excellent effects in relation to the spiral vibrator 134. That is, by opening the tops of the capacitor-loaded vibrators 131 and 132, the projected area of ​​the spiral vibrator 134 and the top is reduced compared to the case where the capacitance is loaded on a single surface. Therefore, in the capacitor-loaded vibrators 131 and 132, the eddy current that acts in a manner to cancel out the high-frequency current generated by the spiral vibrator 134 is reduced. As a result, the deterioration in the efficiency of the AM / FM antenna 13 is reduced. In addition, based on such an effect, the degree of freedom of the configuration position of the spiral vibrator 134 relative to the top is improved. For example, the spiral vibrator 134 does not necessarily have to be configured at the center of the top of the capacitor-loaded vibrators 131 and 132.

[0077] Regarding the structure of the present embodiment in which the top of the capacitor-loaded vibrators 131 and 132 is open, since there is no need to bend or draw the capacitor-loaded vibrators 131 and 132, the processing steps are simplified, which helps to reduce manufacturing costs. In addition, in such a structure, the parasitic capacitance generated between the adjacent conductors, in this example, between the telephone antenna 17, is reduced compared to the case where a single surface is used as a capacitor-loaded plate. Parasitic capacitance is an invalid capacitance component that is not intended by the designer and is caused by the physical structure. As mentioned above, the larger the parasitic capacitance, the lower the gain.

[0078] The telephone antenna 17 is arranged approximately at the center between the side edges of the front faces of the opposing capacitance-loaded vibrators 131 and 132. This also reduces the parasitic capacitance, so that Figure 7 and Figure 8 As shown in the figure, the relative distance between the telephone antenna 17 and the capacitor-loaded vibrators 131 and 132 is shortened. In addition, in order to further reduce the parasitic capacitance with the telephone antenna 17, one or more holes and / or slits may be further formed in the capacitor-loaded vibrators 131 and 132. Thus, the parasitic capacitance between the main ground line on the lower surface side of the capacitor-loaded vibrators 131 and 132 can be further reduced, so that sufficient performance can be obtained even if the lower surface side is formed of a conductive base.

[0079] Next, the helical vibrator 134 will be described. Figure 5 (a) is a top view of the spiral vibrator 134. Figure 5 (b) is the main view, Figure 5 (c) is a side view. The helical oscillator 134 is formed by winding a conductive wire around a cylindrical coil frame formed of a radio wave transparent synthetic resin. On the surface of the coil frame, grooves that determine the diameter and spacing are formed in a manner that can form the desired shape of the helical antenna, and by winding a linear conductor with the necessary number of turns on the coil frame, it can act as a helical antenna. At the bottom of the coil frame, a lower wire end terminal 1341 electrically connected to one end of the conductive wire is formed. The lower wire end terminal 1341 is elastically retained by the above-mentioned M-shaped connecting piece 191, and is conductively connected to the input terminal of the AM / FM amplification circuit installed on the back of the substrate 19. The upper wire end terminal 1342 is electrically connected to the other end of the conductive wire. A metal screw is inserted upward from the coil frame, and the rod of the metal screw is inserted into the threaded hole 1333 of the holder 133 and the circular hole formed by the connecting parts 1312 and 1322 of the capacitor-loaded vibrators 131 and 132, and they are fastened together to the inner wall boss of the inner housing 11, thereby electrically connecting the upper wire terminal 1342 to the capacitor-loaded vibrators 131 and 132. The metal screw can also be a screw with a spring washer to strengthen the mechanical retention.

[0080] In addition, the upper wire end 1342 is structured so as to be able to be flipped 180 degrees and mounted on the coil frame. Although the parts are shared, the number of turns of the helical vibrator 134 can be adjusted every half turn, thereby adjusting the reception frequency and improving the degree of freedom in design.

[0081] Figure 6 The diagram shows a state in which the capacitively loaded vibrators 131 and 132 are fixed to a holder 133 , and a helical vibrator 134 is further mounted on the holder 133 . Figure 6 (a) is a top view, Figure 6 (b) is the main view, Figure 6 (c) is a side view, Figure 6 (d) is a bottom view. Compared with the case of a single-sided capacitor-loaded plate with the top blocked, as described above, the degree of freedom of the configuration position of the spiral vibrator 134 is improved. In the present embodiment, the lower line terminal 1341 is set to a position approximately in the middle of the capacitor-loaded vibrators 131 and 132, so that the spiral vibrator 134 itself is slightly eccentric to the capacitor-loaded vibrator 132 side. By eccentricity like this, the capacitor-loaded vibrator close to the spiral vibrator 134 becomes the capacitor-loaded vibrator 132. Therefore, electrical interference can be generated only with respect to the capacitor-loaded vibrator 132, and the interference can be reduced compared to when electrical interference is generated with respect to both the capacitor-loaded vibrators 131 and 132, and performance degradation can be suppressed. The spiral vibrator 134 can also be slightly eccentric to the capacitor-loaded vibrator 131 side.

[0082] in addition, Figure 7 The antenna unit is shown in a state accommodated in the accommodation space of the inner case 11 . Figure 7 It means according to Figure 2 The configuration shown is a perspective view of the appearance of the assembled antenna device 1 in a state where only the antenna housing 10, the inner housing 11 and the O-ring 22 are removed. Figure 8 This is an explanatory diagram showing a state in which the storage space is seen through in a state in which the antenna case 10 , the inner case 11 , and the O-ring 22 are also assembled.

[0083] As shown in these figures, in the antenna device 1 of the present embodiment, the edges of the capacitor-loaded vibrators 131 and 132 are separated from each other and open to the surface parallel to the roof. Therefore, although the electrostatic capacitance to the ground is added to the helical vibrator 134 by the capacitor-loaded vibrators 131 and 132, the parasitic capacitance is reduced. Therefore, the gain of AM broadcasting and FM broadcasting is improved. In addition, since the edges of the opposing capacitor-loaded vibrators 131 and 132 are discontinuous, interference with radio waves received by antennas for other media can be suppressed.

[0084] That is, it is possible to provide a low-profile antenna device 1 having a small storage space and having a length in the longitudinal direction of approximately 230 mm, a width in the horizontal direction of approximately 75 mm, and a height of approximately 70 mm, and the SDARS antenna 14, the LTE antenna 15, the GNSS antenna 16, the telephone antenna 17, and the AM / FM antenna 13 can be arranged in this order from the front without interfering with each other.

[0085] In addition, if Figure 7 and Figure 8As shown in FIG. 1 , the AM / FM antenna 13 and the telephone antenna 17 are arranged close to each other. Therefore, the AM / FM antenna 13, which receives a frequency lower than that of the telephone antenna 17, is easily affected by the telephone antenna 17. Therefore, in the matching circuit mounted on the back of the substrate 19, a capacitor of preferably about 20 pF is connected in series to the feeding point of the telephone antenna 17, and impedance matching is performed for reception signals of each frequency. For example, 20 pF is about 80 kΩ in 1 MHz of the AM band and about 80 Ω in 100 MHz of the FM band.

[0086] In this regard, in the frequency band received by the telephone antenna 17, for example, above 800 MHz, the impedance is below 10Ω, and the impedance becomes particularly low. In addition, since the impedance matching with the telephone antenna 17 is achieved in the matching circuit, the loss in the reception band of the telephone antenna 17 is smaller. If the reception bandwidth of the telephone antenna 17 is considered, it is expected to be around 2pF to 20pF. This has the effect of ensuring the gain of both the telephone antenna 17 and the AM / FM antenna 13. Alternatively, a BEF (Band Elimination Filter) composed of a parallel resonant circuit using an inductor and a capacitor can be formed to increase the impedance near the AM band or the FM band to obtain the same effect.

[0087] In addition, by connecting in series between the M-shaped connecting piece 191 that feeds the AM / FM antenna 13 and the AM / FM amplifier, a filter is provided to make the frequency of the telephone antenna 17 a high impedance, thereby further avoiding mutual interference. This filter is a filter that does not place a chip capacitor in the signal path and the ground line, and is configured so that the received signal of the AM band is not attenuated by the capacitor voltage division. The filter is configured to reflect or attenuate the desired frequency band of the telephone antenna 17 by using the parallel resonance of the inductor and the capacitor and the open stub.

[0088] <SDARS antenna installation structure>

[0089] In this embodiment, an amplifier substrate 144 for SDARS is mounted on the back side of the substrate of the planar antenna 143 for SDARS, and the planar antenna 143 and the amplifier substrate 144 for SDARS are sandwiched by a passive element holder 142 that houses a passive element 141 and a metal shielding cover 145. Ribs for positioning with the planar antenna 143 for SDARS are provided at least at two locations on the lower surface of the passive element holder 142. In addition, the thickness of the passive element holder 142 is set to a thickness that keeps the interval between the passive element 141 and the planar antenna 143 for SDARS fixed. At least one or more slits for positioning are provided on the conductive passive element 141, and the slits are positioned by fitting with the positioning ribs of the passive element holder 142. It may also be a structure in which a protrusion is provided on the passive element 141 and a recessed shape is formed on the passive element holder 142. And, they are fixed by fastening with screws together with holes provided in the SDARS amplifier substrate 144 and holes provided in the ground plate 146. The ground plate 146 is arranged in front of the insulating base 23, and is positioned by being inserted into the recess 233 provided inside the rib of the insulating base 23. The thickness of the insulating base 233 at the portion where the recess 233 is formed is thinner than the thickness of the portion where the recess 233 is not formed, but since the recess 233 is formed in a shape that partially follows the shape of the ground plate 146 at a position inside the rib of the insulating base 23, the strength of the insulating base 23 is sufficiently ensured.

[0090] In addition, the ground plate 146 is not connected to the conductive base 21 and is electrically isolated from the conductive base 21. This is to prevent the influence on the electrical characteristics of the LTE antenna 15 and / or the telephone antenna 17 and to prevent the influence on the directivity of the SDARS antenna 14.

[0091] That is, the conductive base 21 also functions as the ground wire of the LTE antenna 15, the GNSS antenna 16, the telephone antenna 17, and the AM / FM antenna 13, but depending on the distance between the roof and the conductive base 21 and the size of the conductive base 21, it may also cause useless resonance (resonance phenomenon). The larger the conductive base 21, the easier it is for useless resonance to occur. If useless resonance occurs, the gain of the antenna that receives the radio waves in the frequency band including the frequency is reduced. In addition, depending on the curvature of the roof on which the antenna device 1 is mounted, there is a situation where the capacitance component between the conductive base 21 and the roof changes, and the gain of each antenna 13 to 17 is reduced or changed due to useless resonance.

[0092] Here, the unwanted resonance is briefly explained. If the inductance of the portion between the conductive base 21 and the vehicle fixing claw part 32 of the gripping portion 30 is set to L, and the capacitance of the space between the conductive base 21 and the roof is set to C, the frequency f of the unwanted resonance is expressed by 1 / [2π√(LC)]. In addition, if the area between the conductive base 21 and the roof is set to S, the distance between the conductive base 21 and the roof is set to d, and the dielectric constant of the above space is set to ε, then the capacitance C becomes ε·S / d. Moreover, if the conductor loss is set to R, the Q value indicating the sensitivity of the unwanted resonance is obtained by [√(L / C)] / R=1 / (ωCR). Here, ω is the angular frequency of the unwanted resonance, expressed as ω=2πf. In addition, the smaller the Q value of the unwanted resonance, the smaller the impact on the gain. If the conductive base 21 becomes larger and the area S becomes larger, the capacitance C becomes larger and the frequency f of the unwanted resonance becomes lower. As a result, the frequency f of the useless resonance becomes a frequency included in the frequency band (standard frequency band) used in transmission or reception, and there is a case where the gain of the antenna receiving the radio waves in the frequency band including this frequency is reduced. In addition, there are various types of roofs, and their respective curvatures vary. In the absence of the metal spring 35, if the curvature of the roof is large, the capacitance C becomes smaller. Moreover, the frequency f of the useless resonance becomes higher, and the Q value becomes larger, and the gain of each antenna 13 to 17 decreases. On the other hand, if the curvature of the roof is small, the capacitance C becomes larger, the frequency f of the useless resonance decreases, and the Q value becomes smaller. In this way, depending on the curvature of the roof, the capacitance C varies greatly, and the frequency f of the useless resonance also varies greatly.

[0093] Therefore, in this embodiment, by making the convex portion of the metal spring 35 contact the vehicle roof, firstly, the variation of the frequency f of the unnecessary resonance can be suppressed, and the antenna device 5 can be mounted on vehicle roofs having various curvatures.

[0094] When the metal spring 35 is present, the convex portion in contact deforms following the curvature of the roof because the metal spring 35 has sliding properties. Therefore, the variation of the capacitance C is reduced, and the variation of the frequency f of the unnecessary resonance is also reduced, so that the device can be mounted on roofs of various curvatures.

[0095] In this embodiment, by making the convex part of the metal spring 35 contact the roof, the capacitance C is increased and the frequency f of the unnecessary resonance is shifted to a lower range. Therefore, the frequency of the unnecessary resonance can be shifted outside the standard frequency band.

[0096] In this embodiment, in order to reduce the size of the conductive base 21 to a size that does not cause unnecessary resonance, the SDARS antenna 14 is not arranged on the conductive base 21 but on the insulating base 23. In addition, the ground line of the planar antenna 143 of the SDARS uses a ground plate 146 that is electrically isolated from the conductive base 21. Since the reception frequency band of the planar antenna 143 is a high frequency band such as the 2.3 GHz band, even if the ground plate 146 is a separate body, as long as it is slightly larger than the planar antenna 143, a ground line size sufficient for ensuring antenna gain can be obtained.

[0097] The structure in which the ground plate 146 is formed separately from the conductive base 21 also has the effect of increasing the freedom of the size and structure of the ground plate 146. The size and arrangement structure of the conductive base 21 are determined to a certain extent according to the requirements of the antenna device 1, but if, for example, the electrical length between the roof and the conductive base 21 is approximately 1 / 4 of the wavelength λ1 of the SDARS, the electrical characteristics of the SDARS may be degraded. In this embodiment, since the ground plate 146 is formed separately from the conductive base 21, the shape and size of the ground plate 146 can be arbitrarily set to obtain the desired electrical characteristics of the SDARS antenna 14, the directivity can be improved, and the freedom of design can be increased.

[0098] Fig. 9 1 is a diagram showing an example of changes in electrical characteristics caused by changes in the structure of the SDARS antenna 14. As described above, the SDARS antenna 14 is housed in the recess 233 of the insulating base 23. The recess 233 facilitates the positioning of the ground plate 146 during assembly and improves workability. In addition, the depth (thickness) of the recess 233 becomes a factor that determines the distance between the ground plate 146 and the roof. As described above, the size of the ground plate 146 is slightly larger than that of the flat antenna 143. Now, as Fig. 9 As shown in (a), if the distance between the roof and the ground plate 146 (the depth of the recess 233) is set to t, the directivity of the planar antenna 143 in the vertical direction is as follows: Fig. 9 As shown in (b) to (e), the larger the distance t is, the larger the skew is. The skewness of directivity will lead to a reduction in the gain of the planar antenna 143. Therefore, the distance t is less than 10 mm, preferably 2 mm to 10 mm, thereby achieving a low posture of less than 70 mm and achieving sufficient electrical characteristics of the SDARS for practical use.

[0099] The shielding property of the SDARS amplifier substrate 144 is ensured by soldering or welding the periphery of the shield case 145 to the SDARS amplifier substrate 144. The shield case 145 is electrically connected to the ground plate 146 and therefore has the same potential as the ground plate 146.

[0100] In addition, in this embodiment, an example is shown in which a portion corresponding to the threaded hole 1333 is set as a circular hole when the connecting portions 1312 and 1322 of the capacitor-loaded vibrators 131 and 132 are connected. Such a circular hole can be formed by Fig.10 As in (a), when forming each connecting portion 1312, 1322, each opposite end is cut into a semicircular shape and can be easily formed. Alternatively, it can also be formed as Fig.10 As in (b) and (c), the opposite ends of each connecting portion 1312 and 1322 are set to be R-shaped or rectangular and circular holes are formed near their top ends. In any case, these circular holes play a positioning role, so the operation when fixing to the retaining frame 133 becomes easy.

[0101] In addition, the meandering shape is also set in the up-down direction, but the same effect can be obtained even in the front-back direction.

[0102] [Second embodiment]

[0103] Next, the second embodiment of the present invention is described. The antenna device of the second embodiment has the same basic components and their arrangement, such as the antenna housing, inner housing, base portion, multiple antennas, substrate, gripping portion, etc., as the antenna device 1 of the first embodiment, but the shape of the capacitor-loaded vibrator constituting the AM / FM antenna and the structure of the retaining frame are different from those of the antenna device 1 of the first embodiment. Fig.11 (a) is a side view of a capacitance-loaded vibrator included in the antenna device according to the second embodiment. Fig.11 (b) is a top view. Fig.11 (c) is an assembly illustration diagram showing a portion of the inner housing cut away for ease of explanation. The antenna device 2 of this embodiment includes a pair of capacitor-loaded vibrators 131b and 132b and a portion of the pair of capacitor-loaded vibrators 131b and 132b is set as a connecting portion 1312b and 1322b, which is the same as the capacitor-loaded vibrators 131 and 132 of the first embodiment, but the meandering shape and the mounting structure to the holder 133b are different. The top ends of the connecting portions 1312b and 1322b extend downward, and the two are connected by metal screws and through a conductive relay component.

[0104] In the antenna device 2 of the second embodiment, the upper edges and lower edges of the capacitor-loaded vibrators 131b and 132b are separated from each other and open to a surface parallel to the roof. Therefore, although the electrostatic capacitance to the ground is added to the helical vibrator by the capacitor-loaded vibrators 131b and 132b, the parasitic capacitance is reduced. Since the connecting portions 1312b and 1322b extend downward, the generation of parasitic capacitance can also be suppressed in the connecting portions 1312b and 1322b. Therefore, the gain of AM broadcasting and FM broadcasting is improved. In addition, since the edges of the opposing capacitor-loaded vibrators are discontinuous, interference with radio waves received by antennas for other media can be suppressed.

[0105] [Third Embodiment]

[0106] Next, the third embodiment of the present invention will be described. The antenna device of the third embodiment also has the same basic components and their arrangement such as the antenna housing, the inner housing, the base portion, the plurality of antennas, the substrate, the gripping portion, etc. as the antenna device 1 of the first embodiment, but the shape of the capacitor-loaded vibrator constituting the AM / FM antenna and the structure of the retaining frame are different from those of the antenna device 1 of the first embodiment. Fig.12 (a) is an exploded view of a capacitor-loaded vibrator included in the antenna device according to the third embodiment. Fig.12 (b) is a perspective view of the assembled antenna. The antenna device 3 of this embodiment includes a pair of capacitively loaded vibrators 131c and 132c and a part of the pair of capacitively loaded vibrators 131c and 132c is used as a connecting portion, which is the same as the capacitively loaded vibrators 131b and 132b of the second embodiment, but is different in that the meandering shape and the connecting portion are two each.

[0107] In the antenna device 3 of the third embodiment, the upper edges and lower edges of the capacitor-loaded vibrators 131c and 132c are separated from each other and open to the surface parallel to the roof. Therefore, although the electrostatic capacitance to the ground is added to the helical vibrator by the capacitor-loaded vibrators 131c and 132c, the parasitic capacitance is reduced. Therefore, the gain of AM broadcasting and FM broadcasting is improved. In addition, the edges of the capacitor-loaded vibrators facing each other are discontinuous, so that interference with radio waves received by other media antennas can be suppressed.

[0108] [Fourth embodiment]

[0109] Next, the fourth embodiment of the present invention will be described. The antenna device of the fourth embodiment also has the same basic components and their arrangement such as the antenna housing, the inner housing, the base, the plurality of antennas, the substrate, the gripping portion, etc. as the antenna device 1 of the first embodiment, but has a different structure of the AM / FM antenna from the antenna device 1 of the first embodiment. Fig.13 4 is a diagram for explaining the arrangement of the antenna unit of the antenna device 4 according to the fourth embodiment. Fig.14is a diagram for explaining the structure of an AM / FM antenna in a fourth embodiment. Fig.14 (a) is a top view, Fig.14 (b) is the main view, Fig.14 (c) is a side view.

[0110] The antenna device 4 of the fourth embodiment includes a pair of capacitor-loaded vibrators 131d and 132d, and a part of the pair of capacitor-loaded vibrators 131d and 132d is set as a connecting portion, and is fixed to the retaining frame 133d through the fixing hole 1321d. This is the same as the capacitor-loaded vibrators 131 and 132 of the first embodiment, but the winding shape is different. In the capacitor-loaded vibrators 131d and 132d of the fourth embodiment, the remaining part of the part that is bent to become the connecting portion is a wide surface, and the front becomes the first winding portion and the rear becomes the second winding portion. In addition, the components of the spiral vibrator 134 are the same as the spiral vibrator 134 described in the first embodiment, but it is different from the first embodiment in that it is arranged on the conductive base 21 outside the substrate 19. Therefore, the spiral vibrator 134 is eccentric in the direction of the capacitor-loaded vibrator 131d.

[0111] In the antenna device 4 of the fourth embodiment, the upper edges and lower edges of the capacitor-loaded vibrators 131d and 132d are separated from each other and open to the surface parallel to the roof. Therefore, although the electrostatic capacitance to the ground is added to the helical vibrator 134 by the capacitor-loaded vibrators 131d and 132d, the parasitic capacitance is reduced. Therefore, the gain of AM broadcasting and FM broadcasting is improved. In addition, since the edges of the opposing capacitor-loaded vibrators are discontinuous, interference with radio waves received by other media antennas can be suppressed.

[0112] The first to fourth embodiments are described above, but the embodiments of the present invention are not limited to these embodiments. For example, a pair of capacitor-loaded vibrators 131 (131b~131d), 132 (132b~132d) (hereinafter, abbreviated as "131, etc.") and the spiral vibrator 134 may be electrically connected via an elastic connecting piece. In addition, the capacitor-loaded vibrators 131, etc. may be connected to each other via LC elements (inductors and capacitors), filters formed with conductive patterns on a substrate, etc. to avoid the resonance frequency of the capacitor-loaded vibrators 131, etc. and the spiral vibrator 134 being near the desired frequency.

[0113] In addition, the capacitively loaded vibrator 131, etc., in addition to the serpentine shape, can also be at least one fold, sawtooth, zigzag, fractal shape, etc., as long as it functions as an electrical delay unit. In addition, in each embodiment, the upper edge and the lower edge of the capacitively loaded vibrator 131, etc. are not continuous with each other, but the leading edge and the trailing edge can also be a structure where the leading edge and the trailing edge are discontinuous. In addition, a pair of capacitively loaded vibrators 131, etc. do not necessarily have to be bilaterally symmetrical.

[0114] In addition, the arrangement of the planar antenna 143 of the SDARS and the GNSS antenna 16 may be reversed. In addition, the planar antenna 143 of the SDARS and the GNSS antenna 16 may be overlapped vertically. In addition, when the required performance requirements are not strict, when the ground plate 146 is not provided and the grounding dimension of the SDARS amplifier substrate 144 or the shield case 145 is sufficient, it is also expected that the electrical performance can be improved by recessing in a shape close to the shape.

[0115] Although the conductive base 21 is integrally formed by die casting or the like and the ground plate 146 is separately provided, the conductive base 21 may include a structure in which the conductive base 21 and the metal thin plate are electrically at the same potential by screwing or welding or the like.

[0116] [Fifth embodiment]

[0117] Next, a fifth embodiment of the present invention will be described. Fig.15 (a) is a perspective view of the appearance of the antenna device according to the fifth embodiment. Fig.15 (b) is Fig.15 (a) Local resection image observed from the A-A' direction. Fig.16 1 is a diagram illustrating the arrangement of parts constituting the antenna device of the fifth embodiment. The antenna device 5 of the fifth embodiment is an antenna device mounted on a vehicle roof as in the previous embodiments, and includes a radio wave transparent casing having a storage space formed therein, and an antenna portion stored in the storage space.

[0118] The housing portion includes an antenna housing 50 having an open surface on the lower surface side, and a base portion 60 that closes the open surface of the antenna housing 50 with a gasket 52 made of soft resin. The antenna housing 50 is formed into a streamlined shape, and is a curved surface that becomes thinner and lower toward the front (toward the front end), and the side surface is also curved inward (toward the central axis in the longitudinal direction). The material and size of the antenna housing 50 are substantially the same as those of the antenna housing 10 of the first embodiment.

[0119] The base portion 60 is configured to include a conductive base 61 and an insulating base 63 for fixing the conductive base 61. Holes 611 and 612 for allowing cables C51, C53, C54, and C57 to pass through are formed in front and rear of the conductive base 61. On the other hand, a mounting hole 631 for screwing the conductive base 61 from the roof side and holes 632 and 633 for allowing cables C51, C53, C54, and C57 to pass through are formed on the insulating base 63. Grooves for accommodating a metal spring 64 and a soft sealing material 65 are formed on the back of the insulating base 63. The metal spring 64 is deformed in a manner that follows the shape (curvature) of the roof. That is, similarly to the first embodiment, regarding the metal spring 64, firstly, since the variation of the capacitance C (the variation of the frequency f of the unnecessary resonance) can be suppressed, the antenna device 5 can be installed on the roof of various curvatures, and secondly, the frequency f of the unnecessary resonance can be moved outside the standard frequency band. Therefore, the applicable range of the vehicle roof where sufficient antenna gain can be obtained can be expanded. The base portion 60 is fastened with bolts from the vehicle roof side (not shown) and is locked with nuts 66 .

[0120] In the antenna section, the SDARS antenna 54, the telephone antenna 57, the AM / FM antenna 53, and the keyless entry system antenna 51 are arranged in this order from the front. The AM / FM antenna 53 is configured to include a pair of capacitor-loaded vibrators 531 and 532 electrically connected via a connecting portion 533, and a helical vibrator 535 capable of receiving FM broadcasts by being electrically connected to the connecting portion 533 at one end. The pair of capacitor-loaded vibrators 531 and 532 and the connecting portion 533 are fixed to a vibrator holder 534 as a hard insulating member, and are fixed to the inner wall of the antenna housing 50 by means of screws 5331. The helical vibrator 535 is fixed to the inner wall of the antenna housing 50 together with the vibrator holder 534 by means of screws 5341.

[0121] In front of the capacitively loaded transducers 531 and 532 , a telephone antenna 57 is disposed at a predetermined interval so as not to be electrically continuous with the capacitively loaded transducers 531 and 532 .

[0122] The telephone antenna 17 of the first embodiment is an antenna for receiving signals of a frequency in the 800 MHz band, but the telephone antenna 57 of the fifth embodiment is a planar conductor plate with a cross section that is approximately ρ-shaped and whose upper portion is folded back along the inner wall of the antenna housing 50, and the amplitude of the oscillator is larger than that of the telephone antenna 17. Therefore, a wideband can be achieved, and even frequencies in the 700 MHz band can be received and transmitted. The telephone antenna 57 is fixed to the inner wall of the antenna housing 50 by screws 571. In front of the telephone antenna 57, a substantially rectangular passive element 55 for SDARS is arranged. The passive element 55 is fixed to the inner wall of the antenna housing 50 by screws 551.

[0123] On the conductive base 61, a keyless entry system substrate 510, an AM / FM substrate 530, and a telephone substrate 570, each of which has electronic circuit components mounted on an insulating member, are screwed and fixed. The other end (feeding portion) of the spiral vibrator 535 is electrically connected to the loop contact of the AM / FM substrate 530 while being elastically held. The loop contact is electrically connected to electronic circuit components such as an amplifier mounted on the AM / FM substrate 530. The electronic circuit components of the AM / FM substrate 530 are electrically connected to the vehicle-side electronic equipment through a cable C53. The feeding portion of the telephone antenna 57 is electrically connected to the loop contact of the telephone substrate 570 while being elastically held. The loop contact is electrically connected to the electronic circuit components mounted on the telephone substrate 570, and other electronic circuit components are electrically connected to the vehicle-side electronic equipment through a cable C57.

[0124] A keyless entry system antenna 51 is erected on the keyless entry system substrate 510. The keyless entry system antenna 51 is an antenna formed by winding a linear conductor 512 on a cylindrical holder 511 made of an insulator, and receives a signal of a frequency in the 900MHz band. The power supply unit of the keyless entry system antenna 51 is electrically connected to the electronic circuit components of the keyless entry system substrate 510. The electronic circuit components of the keyless entry system substrate 510 are electrically connected to the vehicle-side electronic equipment through a cable C51.

[0125] The keyless entry system antenna 51 is positioned behind the helical oscillator 535 of the AM / FM antenna 53 in the longitudinal direction so as not to be electrically continuous with the pair of capacitor-loaded oscillators 531 and 532. Since it is arranged at the rear in the antenna portion of the antenna device 5, it is possible to well receive not only vertically polarized waves but also horizontally polarized waves, for example, at the rear side of the roof, and thus improve the gain in the horizontal direction.

[0126] In addition, the area of ​​the conductive base 61 is larger than the area of ​​the capacitively loaded vibrators 531 and 532 when viewed from above. In other words, the area of ​​the conductive base 61 is larger than the projected area of ​​the capacitively loaded vibrators 531 and 532. In addition, since the keyless entry system antenna 51 is arranged below the capacitively loaded vibrators 531 and 532, the keyless entry system antenna 51 can be reliably grounded. Moreover, since the gap between the capacitively loaded vibrators 531 and 532 and the conductive base 61 is fixed, the reception performance in the AM / FM band is not affected by the curvature of the roof.

[0127] A ground plate 56 serving as a ground line for the SDARS antenna 54 is fixed in front of the insulating base 63. The SDARS antenna 54 is electrically connected to the vehicle-side electronic device via a cable C54. The detailed shapes and positional relationships of the passive element 55, the SDARS antenna 54, and the ground plate 56 will be described later.

[0128] As described above, the usage frequencies of the telephone antenna 57 and the keyless entry system antenna 51 are close. Therefore, by placing the AM / FM antenna 53 between the two, the two are physically separated, thereby reducing interference. On the other hand, the frequency band of the AM / FM antenna 53 is separated from the frequency bands of the telephone antenna 57 and the keyless entry system antenna 51. Therefore, even if the AM / FM antenna 53 and the telephone antenna 57, and the AM / FM antenna 53 and the keyless entry system antenna 51 are physically close to each other, they can operate in each frequency band without interference. The keyless entry system antenna 51 is arranged behind and below the capacitor-loaded vibrators 531 and 532, but is not limited to this.

[0129] Next, the capacitance-loaded elements 531 and 532 constituting the AM / FM antenna 53 will be described in detail. Fig.17 : is a perspective view of the appearance of the capacitor-loaded vibrators 531 and 532. In addition, Fig.18 531 and 532 are diagrams for explaining the shapes of capacitor-loaded oscillators 531 and 532. Fig.18 (a) is its main view, Fig.18 (b) is its top view, Fig.18 (c) is its left view, Fig.18 (d) is its right side view, Fig.18 (e) is a bottom view thereof. The pair of upper edges of the capacitively loaded vibrators 531 and 532 are separated from each other, and the connection portion 530 including the lower edge is formed integrally. That is, the connection portion 530 also has an electrical delay portion.

[0130] A locking portion 5321 is formed at a part of the capacitively loaded vibrators 531 and 532 , for example, at a lower portion of the capacitively loaded vibrators 532 . The locking portion 5321 is formed to lock the capacitively loaded vibrators 531 and 532 to the vibrator holder 533 .

[0131] The capacitively loaded vibrators 531 and 532 include the connecting portion 530 and most of them are formed into a meandering shape. That is, the meandering shape of the capacitively loaded vibrators 531 and 532 is more than that of the capacitively loaded vibrators 131 and 132 of the first embodiment, so the electrical length of the capacitively loaded vibrators 531 and 532 is different from the electrical length of the capacitively loaded vibrators 131 and 132 of the first embodiment. The electrical length of the capacitively loaded vibrators 531 and 532 of the fifth embodiment is a length that does not resonate in the frequency band used by the telephone antenna 57 (approximately 700MHz to 800MHz) and the keyless entry system antenna 51, and is longer than the wavelength of the frequency band used by the SDARS antenna 54. That is, the electrical length of the capacitively loaded vibrators 531 and 532 is a length that does not resonate in the frequency band used by the SDARS antenna 54. As a result, the interference between the capacitively loaded vibrators 531 and 532 and the telephone antenna 57 and the keyless entry system antenna 51 can be reduced. In addition, it is possible to suppress degradation (ripple) of the horizontal plane directivity of the SDARS antenna 54 .

[0132] Fig.19 2 shows an example of the results of verifying the difference in characteristics between the telephone antenna 17 of the first embodiment and the telephone antenna 57 of the fifth embodiment. Fig.19 This is a simulation diagram showing the relationship between frequency (700MHz~800MHz) and average gain (dBi). Fig.19 The middle dashed line indicates the average gain G11 of the telephone antenna 17, and the solid line indicates the average gain G51 of the telephone antenna 57. As shown in the figure, the average gain of the telephone antenna 57 is higher from 700 MHz to about 780 MHz than that of the telephone antenna 17. It can be seen that the capacitance-loaded transducers 531 and 532 of the fifth embodiment reduce the interference with the telephone antenna 57 compared with the capacitance-loaded transducers 131 and 132 of the first embodiment.

[0133] Fig. 20 : is a simulation diagram showing the relationship between the frequency (915 MHz to 935 MHz) and the average gain (dBi) of the keyless entry system antenna 51. Fig. 20In the figure, the dotted line represents the average gain G12 of the keyless entry system antenna 51 when the capacitive loading vibrators 131 and 132 of the first embodiment are used instead of the capacitive loading vibrators 531 and 532, and the solid line represents the average gain G52 of the keyless entry system antenna 51 when the capacitive loading vibrators 531 and 532 are used. As shown in the figure, by using the capacitive loading vibrators 531 and 532, the average gain of the keyless entry system antenna 51 becomes higher. In other words, the keyless entry system antenna 51 is not easily affected by the interference caused by the capacitive loading vibrators 531 and 532. Since the frequency band of the keyless entry system antenna 51 is narrow, there is no problem even if it is low-profile. Therefore, in the fifth embodiment, by configuring the keyless entry system antenna 51 below the capacitive loading vibrators 531 and 532, even if the number of media (antennas) increases, the length of the antenna device 5 in the front-to-back direction will not be much longer than the antenna device 1 of the first embodiment.

[0134] Next, the SDARS antenna 54 in the fifth embodiment will be described in detail. Fig.21 It is a perspective view of the appearance of the SDARS antenna 54. Fig. 22 It is a diagram for explaining the arrangement of the parts constituting the SDARS antenna 54. Fig.23 yes Fig.21 AA′ cross-sectional view.

[0135] The SDARS antenna 54 uses a planar antenna 540 as a main antenna. The planar antenna 540 is fixed to the surface of the SDARS substrate 542 using a double-sided tape 541. Electronic circuit parts such as an amplifier are mounted on the back of the SDARS substrate 542 and are shielded by a shielding cover 543. The shielding cover 543 is screwed to a ground plate 56 having a hole 561 formed in the center. The ground wire of the SDARS antenna 54 is separated from the roof by a predetermined distance and is electrically isolated from the ground wires of other antennas that receive radio waves outside the frequency band of the SDARS antenna 54. This is the same as the antenna device 1 of the first embodiment.

[0136] Fig.24 2 shows the positional relationship between the SDARS passive element 55 and the SDARS antenna 54 (antenna main body 540 ) when the antenna case 50 is covered on the base portion 60 . Fig.24 In the figure, the direction away from the paper (Z) is the top direction of the antenna device 5, the direction below the paper (X) is the rear of the antenna device 5, and the left direction (Y) is the width direction of the antenna device 5. Fig.24 As shown, the passive element 55 is arranged to be offset backward (in the X direction) with respect to the SDARS antenna 54. Therefore, the influence of the antenna characteristics caused by the presence of the telephone antenna 57 and the like behind the SDARS antenna 54 can be suppressed.

[0137] Fig.25 is a simulation diagram showing the gain change of the SDARS antenna 54 depending on the direction. Fig.25 In FIG. 5 , the dotted line represents the gain when the passive element 55 is not offset, and the solid line represents the gain when the passive element 55 is offset. Fig.25 As shown, it can be seen that the directivity Gx of the SDARS antenna 54 when the passive element is shifted backward (X direction) does not change much compared to the directivity Go when it is not shifted, but the gain in the rear (X direction) becomes higher in the shifted direction (X direction).

[0138] The SDARS antenna 54 of the fifth embodiment is different from the SDARS antenna 14 of the first embodiment in that the passive element 55 is offset to the rear (X direction) and a hole 561 is formed in the center of the ground plate 56. That is, in the SDARS antenna 54, the shielding cover 543 and the ground plate 56 are difficult to be combined, and the distance between the planar antenna 540 and the roof can be made shorter than that of the planar antenna 143 of the first embodiment.

[0139] Fig.26 1 is a diagram showing the relationship between the frequency and gain in the 2.3 GHz band of the SDARS antenna 14 in the first embodiment and the SDARS antenna 54 in the fifth embodiment. Fig.26 In the figure, the dotted line is the gain G13 of the SDARS antenna 14, and the solid line is the gain G53 of the SDARS antenna 54. The average gain G13 of the SDARS antenna 14 at a frequency of 2320 MHz to 2345 MHz (for SDARS) is 28.7 dBi, and the average gain G53 of the SDARS antenna 54 is 31.0 dBi. As can be seen, the average gain of the SDARS antenna 54 is higher than that of the SDARS antenna 14 at a frequency in the 2.3 GHz band.

[0140] [Sixth embodiment]

[0141] Next, a sixth embodiment of the present invention will be described. In the sixth embodiment, a modified example of the mounting structure of the AM / FM antenna is shown. Fig. 27 It is an external perspective view of the antenna portion of the antenna device 6 according to the sixth embodiment. Fig.28 (a) and (b) are diagrams for explaining the structure of the capacitance-loaded oscillator in the antenna device 6. Fig.29 The figures are explanatory diagrams of the installation procedure of the vibrator holder and the spiral coil, wherein (a) shows the state before assembly and (b) shows the state after assembly.

[0142] The antenna device 6 of the sixth embodiment is provided with a buffer body 6321 at one or more locations in order to fill the gap between the pair of capacitor-loaded vibrators 631 and 632 and the inner wall of the antenna housing. The buffer body 6321 may be formed by, for example, pressing the capacitor-loaded vibrator 632 from the inside to make it protrude, or may be provided on the inner wall of the antenna housing. In addition, the connecting portions 6313 and 6323 extending from the capacitor-loaded vibrators 631 and 632 are formed so as to overlap in the vertical direction when they are respectively mounted on the vibrator holder 630. Moreover, the connecting portion overlapping the upper one of the connecting portions 6313 and 6323, in this example, the connecting portion 6323, is provided with a protrusion 6325.

[0143] In addition, Fig. 27 In FIG. 1 , only the buffer body 6321 of the capacitor-loaded vibrator 632 on one side is shown, but in FIG. Fig. 27 The other side of the capacitor-loaded vibrator 631 which is not visible in the figure is also provided with a buffer body similar to the buffer body 6321. These buffer bodies 6321 fill the gap between the antenna housing and the inner wall when the assembly is completed. In other words, they are in contact with the antenna housing. Therefore, it is possible to prevent the capacitor-loaded vibrators 631 and 632 from vibrating due to the vibration of the vehicle after the antenna device 6 is installed in the vehicle, thereby preventing the generation of noise.

[0144] The purpose of overlapping the connecting parts 6313 and 6323 in the vertical direction is to reliably electrically connect the pair of capacitor-loaded vibrators 631 and 632 to one spiral vibrator 634, and the protrusion 6325 is provided to prevent the error of overlapping direction. That is, if the connecting part 6323 is mistakenly overlapped below the connecting part 6313, the shapes of the capacitor-loaded vibrators 631 and 632 will be deformed, and the distances from one end of the spiral vibrator 634 to the ends of each capacitor-loaded vibrator 631 and 632 will be different. The protrusion 6325 is provided to prevent such a situation from occurring.

[0145] The vibrator holder 630 has a guide having two sides and a predetermined thickness formed at a predetermined position in the front, and a protrusion 6301 is provided on one side (left side in this example) of the guide. A guide having two sides and a predetermined thickness is also provided at the upper end of the cylindrical holder of the helical vibrator 634, and a groove 6341 of a size for the protrusion 6301 to fit is formed on one side (left side in this example) of the guide.

[0146] Before assembly, Fig.29 As shown in (a), the protrusion 6301 of the vibrator holder 630 is positioned above the groove 6341 of the helical vibrator 634. Then, as Fig.19As shown in (b), the protrusion 6301 is inserted into the groove 6341. By setting such an installation structure, the helical vibrator 134 will not be assembled in the wrong direction in the front-to-back direction. In addition, the helical vibrator 634 is difficult to rotate relative to the vibrator holder 630, and the other end (power supply part) of the helical vibrator is reliably held at the loop contact point of the AM / FM substrate 530.

Claims

1. An antenna device installed in a vehicle, characterized in that: have: Base portion; a housing portion that forms a storage space together with the base portion; and an antenna stored in the storage space, The base portion has a conductive base and is provided with a ground plate. The antenna includes a first antenna located above the conductive base and a second antenna located above the ground plate. The second antenna is a planar antenna, The conductive base is separated from the ground plate.

2. The antenna device according to claim 1, characterized in that The conductive base and the ground plate are formed of different components.

3. The antenna device according to claim 1, characterized in that The conductive base is electrically connected to the vehicle.

4. The antenna device according to claim 1, characterized in that: The distance between a portion of the vehicle where the antenna device is mounted and the ground plate is 10 mm or less.

5. The antenna device according to claim 1, characterized in that: The distance between the portion of the vehicle where the antenna device is mounted and the ground plate is not less than 2 mm and not more than 10 mm.

6. The antenna device according to claim 1, characterized in that: The base portion has an insulating base, The ground plate is located inside the ribs of the insulating base.

7. The antenna device according to claim 6, characterized in that: The insulating base has a recessed portion at a position inside the rib. At least a portion of the recess has a shape that follows the shape of the ground plate.

8. The antenna device according to claim 1, characterized in that A hole is formed in the ground plate.

9. The antenna device according to claim 8, characterized in that: A shield cover fixed to the hole is also provided.

10. The antenna device according to claim 1, characterized in that: The first antenna receives at least ground waves. The second antenna at least receives satellite waves.

11. The antenna device according to claim 1, characterized in that: The planar antenna corresponds to circularly polarized waves.

12. The antenna device according to claim 1, characterized in that The ground plate has a size larger than that of the second antenna, and has a function of improving a gain of the second antenna.

13. The antenna device according to claim 1, characterized in that: The second antenna has a shielding cover, The ground plate is integrated with the shielding case.

14. The antenna device according to claim 1, characterized in that The planar antenna corresponds to circularly polarized waves, further comprising a passive element located above the planar antenna at a predetermined distance, The passive element is arranged to be offset from the planar antenna toward a side where the first antenna is located.

15. The antenna device according to any one of claims 1 to 14, characterized in that: The first antenna is at least one of an AM antenna, an FM antenna, an LTE antenna, a telephone antenna, and a keyless entry system antenna.

Images