GB2523443A

GB2523443A - Composite antenna device

Info

Publication number: GB2523443A
Application number: GB1421673.3A
Authority: GB
Inventors: Yutaka Imamura
Original assignee: Harada Industry Co Ltd
Current assignee: Harada Industry Co Ltd
Priority date: 2013-12-11
Filing date: 2014-12-05
Publication date: 2015-08-26
Anticipated expiration: 2034-12-05
Also published as: JP6343230B2; GB201421673D0; GB2523443B; JP2015133692A

Abstract

A multiple frequency band antenna device comprises a first tuning coil 10 connected to a first power feeding source for a first frequency band and a second tuning coil 20 connected to a second power feeding source for a second frequency band. A common top loading capacity element 30 is connected to an end of the first and second tuning coils 10, 20, at the end which is opposite to the coil end which is connected to the respective power feeding sources. The said capacity element 30 functions as part of the antenna resonant elements involved in operating at the first and second frequency bands and also at a third frequency band. The tuning coils 10 and 20 may also operate as filters which attenuate frequencies other than that of the first and second frequency bands, respectively. The antenna may be arranged to operate at further frequency bands. Switches may be provided between the power feeding sources and the respective tuning coils 10, 20 to improve the isolation between the said sources. The antenna device may be disposed within a shark-fin cover 51 with at least one tuning coil 10, 20 located along an edge line of the said cover.

Description

COMPOSITE ANTENNA DEVICE

BACKGROUND OF THE INVENTION

Field of the Invention

[00011 The present invention relates to a composite antenna device, and more particularly to a composite antenna device that can receive signals in a plurality of frequency bands.

Description of the Related Art

[0002] Conventionally, there has existed a composite antenna that can receive signals in a plurality of frequency bands. A composite antenna can be designed freely to a certain extent as long as there is no problem with respect to space in which an antenna element is disposed However, there are a variety of restrictions, such as that, for a low profile antenna that can be mounted on a vehicle, there is a height limit, and the antenna needs to be contained in small space in a case. For this reason, sufficient antenna performance has been difficult to obtain. Mounting of a variety of pieces of information equipment on vehicles in recent years has been promoted in pursuit of safety and comfort. Along with the mounting of such information equipment, signals of a variety of frequency bands need to be used, and antenna elements suitable to the frequency bands need to be provided. However, when space in a case of a low profile antenna is small, there has been a problem that an excellent antenna characteristic cannot be obtained particularly in an AM frequency band, since antenna elements have influence on each other.

[0003] To solve the above problem, in a technique disclosed in Patent Document 1, a top capacity section is provided at a front end of a first antenna element of an AM/FM antenna to gain antenna capacity and lowering in performance is restricted in order to reduce lowering of performance of the first antenna element as compared to when a single one of an antenna element is used. A coil section is used to electrically disconnect the first antenna element and a second antenna element of Band hIlL-Band. The top capacity section, the first antenna element, and the coil section operate as a resonant antenna in an FM frequency band, and operate as a non-resonant antenna in an AM frequency band.

Citation List Patent Document [0004] [Patent Document 1] Japanese Patent Application Kokai Publication No. 20 12-199865 [0005] However, in the technique of Patent Document 1 described above, a clearance of 10 mm or larger has necessarily been provided between the first antenna element and the second antenna element in order to obtain isolation between the antenna elements. In relation to the isolation, a Band III antenna characteristic and an FM antenna characteristic have been in a relationship of trade-off. Accordingly, improvement in performance of both of the antenna characteristics has been desired. In recent years, further reduction in size of an antenna has been requested, and further reduction in installation space has been requested. In this case, isolation becomes even more difficult to obtain, and lowering in performance may have posed a problem. The top capacity section can also be considered to be increased in size. However, if the top capacity section becomes larger, there have been a problem concerning isolation between the top capacity section and the Band III antenna, and a problem of lowering in antenna performance of Band III.

SUMMARY OF THE INVENTION

[00061 Under the above-circumstances, the present invention provides a composite antenna device that can be reduced in size by sharing an antenna element in a plurality of frequency bands, can be reduced in cost since the number of elements can be reduced, and facilitates designing of an antenna.

[00071 In order to achieve the above object of the present invention, there is provided a composite antenna device according to the present invention that may comprise a first tuning coil section that is connected to a first power feeding section for a first frequency band and functions as a part of an element for the first frequency band; a second tuning coil section that is connected to a second power feeding section for a second frequency band that is higher than the first frequency hand, and functions as a part of an element for the second frequency band; and a common top capacity section that is connected to end sections of the first tuning coil section and the second tuning coil section on sides opposite to sides on which the first power feeding section and the second power feeding section are connected, respectively, functions as a part of elements for the first frequency hand and the second frequency band, and also functions as an element for a third frequency band that is lower than the first frequency band.

[00081 The first tuning coil section may function also as a filter that attenuates frequency bands other than the first frequency band.

[00091 The second tuning coil section may function also as a filter that attenuates frequency bands other than the second frequency band.

[00101 The composite antenna device may further comprise an element for 3.

a fourth frequency band that is higher than the second frequency band, the element being connected to a third power feeding section for the fourth frequency band.

[00111 A part of the first tuning coil section or the second tuning coil section niay function also as an element for the fourth frequency band that is higher than the second frequency band.

[00121 The first tuning coil section and/or the second tuning coil section may be made up of a series-connected circuit or a parallel-connected circuit of a coil and a capacitor.

[00131 An axial direction of the first tuning coil section andlor the second tuning coil section may be disposed along an edge line of a cover having a shark-fin shape [0014] The first tuning coil section and the second tuning coil section may also be connected to the common top capacity section through a predetermined coil.

[oois] The composite antenna device according to the present invention has advantages that size can be reduced by sharing an antenna element in a plurality of frequency bands, cost can be reduced since the number of elements can be reduced, and designing of an antenna is facilitated.

BRIEF DESCRIPTION OF DRAWINGS

[0016] FIG. 1 is an equivalent circuit diagram for explaining a configuration of a composite antenna device according to the present invention FIG. 2 is a partially cross-sectional schematic view for explaining a specific arrangement configuration of the composite antenna device according to the present invention; FIG. 3 is a schematic side view for explaining another specific arrangement configuration of the composite antenna device according to the present invention; FIG. 4 is an equivalent circuit diagram for explaining an another embodiment of the composite antenna device according to the present invention FIG. 5 is an equivalent circuit diagram for explaining a still another embodiment of the composite antenna device according to the present invention; FIG. 6 is an equivalent circuit diagTam for explaining an example in which a switch is attached to the composite antenna device according to the present invention; and FIG. 7 is an equivalent circuit diagram for explaining a variation of the composite antenna device according to the present invention shown in FIG. 6.

PREFERRED EMBODIMENTS OF THE INVENTION

[00171 Hereinaftei; embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is an equivalent circuit diagram for explaining a configuration of a composite antenna device according to the present invention. As illustrated, the composite antenna device according to the present invention mainly includes a first tuning coil section 10, a second tuning coil section 20, and a common top capacity section 30.

[00181 The first tuning coil section 10 functions as a part of an element for 5.

a first frequency band, for example, an FM frequency band. The FM frequency hand is, for example, a 76MHz to 90MHz band, or an 88MHz to 108MHz band. The first tuning coil section 10 is connected to a first power feeding section 1 for the first frequency band. The first tuning coil section 10 is made up of, for example, a wire rod that is helically wound physically Preferably, the wire rod of a coil of the first tuning coil section 10 is thick, and the coil diameter is large. The first tuning coil section 10 may be a coil pattern that is patterned in a spiral shape on a substrate by etching and the like. The coil only needs to be an inductor that can adjust a resonant frequency of an antenna, such as a distributed parameter element of a meander type, a fractal type, a spiral type, or the like, or a lumped parameter element such as a chip coil. The first power feeding section 1 is a power feeding section for the first frequency band, and is connected to a tuner and the like for the first frequency hand.

[00191 The second tuning coil section 20 functions as a part of an element for the second frequency band that is higher than the first frequency band, for example, for Band III for digital audio broadcasting (DAB). A frequency hand of Band III is, for example, a 174MHz to 240MHz band. The second tuning coil section 20 is connected to a second power feeding section 2 for the second frequency band. The second tuning coil section 20 is also made up of, for example, a wire rod that is helically wound physically.

Preferably, the wire rod of a coil of the second tuning coil section 20 is thick, and the coil diameter is large. The second tuning coil section 20 may be a coil pattern that is patterned in a spiral shape on a substrate by etching and the like. The coil only needs to be an inductor that can adjust a resonant frequency of an antenna, such as a distributed parameter element of a meander type, a fractal type, a spiral type, or the like, or a lumped parameter element such as a chip coil. The second power feeding section 2 is a power feeding section for the second frequency band, and is connected to a tuner and the like for the second frequency band. As described above, in the composite antenna device according to the present invention, the first tuning coil section 10 and the second tuning coil section 20 are connected separately, in a manner that the first tuning coil section 10 is connected to the first power feeding section 1 and the second tuning coil section 20 is connected to the second power feeding section 2.

[00201 In the example described above, description has been made by exemplifying a frequency band for DAB as the second frequency band.

However, the present invention is not limited to the above, and the second frequency band may also be a frequency band for, for example, digital television broadcasting (DTV, that is, a 470MHz to 710MHz band. As described above, the composite antenna device according to the present invention can be applied not only to a DAB composite antenna device, but also to a DTV composite antenna device and the lika [0021] The common top capacity section 30 functions as a part of elements for the first frequency band and the second frequency band, and also functions as an element for the third frequency band that is lower than the first frequency band, for example, an AM frequency band. The AM frequency band is, for example, a 526.5kHz to 1606.5kHz band. The common top capacity section 30 is connected to end sections of the first tuning coil section 10 and the second tuning coil section 20 on sides opposite to sides on which the first power feeding section 1 and the second power feeding section 2 are connected, respectively. That is, the common top capacity section 30 functions as a capacity loaded antenna. By having capacitance in the common top capacity section 30, the element for the first frequency band and the element for the second frequency band are shortened.

[0022] 7.

That is, in the composite antenna device according to the present invention, the common top capacity section 30 is used in common for the elements for the first frequency and the second frequency band. The first tuning coil section 10 and the second tuning coil section 20 are connected to the common top capacity section 30 in parallel, and are connected to the first power feeding section 1 and the second power feeding section 2, respectively.

[00231 In the composite antenna device having the above configuration, the common top capacity section 30 is shared as antennas in three frequency bands. That is, the first tuning coil section 10 and the common top capacity section 30 receive the FM frequency band as a resonant antenna. The second tuning coil section 20 and the common top capacity section 30 receive the frequency band of Band III as a resonant antenna. The common top capacity section 30 receives the AM frequency band as a capacity antenna [0024] The first tuning coil section 10 functions also as a filter that attenuates frequency bands other than the first frequency band. That is, the first tuning coil section 10 only allows the FM frequency band to pass through. The second tuning coil section 20 functions also as a filter that attenuates frequency bands other than the second frequency band. That is, the second tuning coil section 20 allows only the frequency band of Band III to pass through. As described above, the first tuning coil section 10 and the second tuning coil section 20 only need to function as what is called a trap coil.

[0025] To further improve receiving performance of the FM frequency band of the first tuning coil section 10, the second tuning coil section 20 may also be used as a band-pass filter to prevent more signals from flowing to the second tuning coil section 20 side. In view of the above, the second tuning coil section 20 may also be configured as a band-pass filter made up of, for example, a series-connected circuit of a coil and a capacitor. A resonant frequency of the series-connected circuit is matched with a frequency band of Band III. In this manner, only signals at around the resonant frequency of the series-connected circuit flow to the second tuning coil section 20 side, and a signal in the FM frequency band efficiently flows to the first tuning coil section 10 side. The capacitor may be a lumped parameter element, such as a chip capacitor, as well as a capacitor pattern that is patterned in a parallel flat plate shape on a substrate by etching and the like, or a thstributed parameter element that is formed in a stub type, an inter thgital type, or the like.

110026] Similarly, to further improve receiving performance of Band III of the second tuning coil section 20, the first tuning coil section 10 may be used as a band-pass filter that prevents more signals from flowing to the first tuning coil section 10. In view of the above, the first tuning coil section 10 may be configured as a band-pass filter made up of, for example, a series-connected circuit of a coil and a capacitor, just as described above. A resonant frequency of the series-connected circuit is matched with the FM frequency band. In this manner, only signals at around the resonant frequency of the series-connected circuit flow to the first tuning coil section side, and a signal of Band III efficiently flows to the second tuning coil section 20 side.

[0027] The first tuning coil section 10 and the second tuning coil section 20 may also be configured as a parallel-connected circuit of a coil and a capacitor, instead of the series-connected circuit of a coil and a capacitor.

[0028] The composite antenna device according to the present invention can support a variety of transmitted polarized waves, since the entire antenna supports a vertical component, the first tuning coil section 10 supports an inclined component, and the common top capacity section 30 supports a horizontal component.

[00291 FIG. 2 is a partial cross-sectional schematic view for explaining a specific arrangement configuration of the composite antenna device according to the present invention. FIG. 2A shows a side view, and FIG. 2B shows a rear view. In the drawing, the same reference numerals as those in FIG. 1 denote the same parts as those in FIG. 1. The illustrated example shows an arrangement example where the composite antenna of the present invention is applied to what is called a shark fin antenna. As ifiustrated, the common top capacity section 30 only needs to be made up of an umbrella-like metal piece. More specifically, the common top capacity section 30 has a cross-sectional shape in a mountain shape, in which there are formed a top section 31 and side sections 32 as slopes extending from both sides of the top section 31. The first tuning coil section 10 and the second tuning coil section 20 are electrically connected adjacent to a front end of the top section 31. In the ifiustrated example, an axial direction of the first tuning coil section 10 and the second tuning coil section 20 faces a vertical direction with respect to a base section 50. When the first tuning coil section 10 and the second tuning coil section 20 are too close to the base section 50 side, invalid capacity may increase. Accordingly the first tuning coil section 10 and the second tuning coil section 20 only need to be arranged away from the base section 50, and not to enter the inside of an inner side of the common top capacity section 30. For example, the first tuning coil section 10 and the second tuning coil section 20 only need to be fixed by using the fixing section 52 on the base section 50. In the latter stage of the power feeding section 1, there is arranged an amplification substrate 53 on which an amplifier circuit, a branching filter, and the like are mounted.

These sections are covered with a cover 51 having a shark fin shape.

-10 -[00301 FIG. 3 is a schematic side view for explaining another specific arrangement configuration of the composite antenna device according to the present invention. In the drawing, the same reference numerals as those in FIG. 2 denote the same parts as those in FIG. 2. The illustrated example is another arrangement example where the composite antenna of the present invention is applied to what is called a shark fin antenna. As illustrated, in this example, an axial direction of the first tuning coil section and the second tuning coil section 20 is arranged along an edge line of the cover having a shark fin shape. The common top capacity section 30 is arranged adjacent to a top section in a rear side of the shark fin antenna.

By the above arrangement, an antenna characteristic can be improved more.

The configuration may also be such that an axial direction of any one of the first tuning coil section 10 and the second tuning coil section 20 is arranged along an edge line of the cover having a shark fin shape [0031] As shown in FIG. 4, other elements may also be disposed. FIG. 4 is an equivalent circuit diagram for explaining another embodiment of the composite antenna device according to the present invention. In the drawing, the same reference numerals as those in FIG. 1 denote the same parts as those in FIG. 1. FIG. 1 shows the example where signals in three frequency bands can be received. In the example shown in FIG. 3, a signal in a fourth frequency band that is higher than the second frequency band, for example, a frequency band of L-Band of DAB, can also be received. A frequency band of L-Band is, for example, a 1.4GHz band. By this, for example, a part of the first tuning coil section 10 functions as an element 40 for the fourth frequency band. That is, a line length of a wire connected from the first power feeding section ito a first coil H of the first tuning coil section 10 is extended, and this extended section is used as the element 40 for the fourth frequency band. L-Band as the fourth frequency band is at a high frequency, and has a short element length. Accordingly, a part of the first tuning coil section 10 can be used as the element 40 for the fourth frequency band. The configuration may also be such that a part of the second tuning coil section 20 functions as the element 40 for the fourth frequency hand. As described ahove, for a high frequency band, such as a frequency band of L-Band, sufficient performance can he obtained as an antenna characteristic even with the above configuration.

[00321 In the illustrated example described above, a part of the first tuning coil section and a part of the second tuning coil section are used as an element for the fourth frequency band. That is, the element for the fourth frequency hand is also connected to the first power feeding section and the second power feeding section. However, the present invention is not limited to the ahove, and the element for the fourth frequency band may be connected to a third power feeding section that is different from the first power feeding section and the second power feeding section. That is, for example, as shown in FIG. 2, the element 40 for L-Band may be connected to the third power feeding section 3, and disposed in empty space, for example, empty space on a front end side having a shark fin shape or the like. The element for the fourth frequency band may be disposed in any place as long as the element is not in contact with the common top capacity section.

[00331 In the illustrated example described above, the first tuning coil section 10 is used and allowed to function as a filter that attenuates frequency bands other than the first frequency hand. The second tuning coil 20 is used and allowed to function as a filter that attenuates frequency hands other than the second frequency band. However, the present invention is not limited to the above, and higher degree of freedom can be ensured in designing by further using a predetermined coil. FIG. 5 is an equivalent circuit diagram for explaining a still another embodiment of the composite antenna device according to the present invention. In the drawing, the same reference numerals as those in FIG. 1 denote the same parts as those in FIG. 1. In the illustrated example, the first tuning coil section 10 and the second tuning coil section 20 are connected to the common top capacity section 30 through a third coil 60. That is, the third coil 60 is connected immediately below the common top capacity section 30, and the first tuning coil section 10 and the second tuning coil section 20 are connected in parallel through the third coil 60. As an example, there is shown an example where the second tuning coil section 20 side is made up of a series-connected circuit of a second coil 21 and a capacitor 61 by using the capacitor 61.

[00341 By the above configuration, the first tuning coil section 10 and the second tuning coil section 20 can he easily designed in a manner that adjustment of a resonant frequency and adjustment of a frequency band to be filtered are satisfied at the same time. That is, in the illustrated example, for the first frequency band, adjustment of a resonant frequency may be designed so that the first coil 11 and the third coil 60 combined together have a predetermined inductance while a filter is designed so that the first tuning coil section 10 has a predetermined inductance. For the second frequency band, adjustment of a resonant frequency may be designed so that the second coil 21 and the third coil 60 combined together have a predetermined inductance while a filter is designed so that the capacitor 61 and the second coil 21 have a predetermined inductance.

[00351 The configuration may be such that the third coil 60 is designed to be used as a part of the second tuning coil section 20, and only the capacitor 61 is disposed at a position of the second tuning coil section 20. That is, a resonant frequency and a ifiter need to be designed for each frequency band -13 -between the common top capacity section 30 and each power feethng section.

[00361 Next, description will be made on the composite antenna device with higher isolation with reference to FIG. 6. FIG. 6 is an equivalent circuit diagram for explaining an example where a switch is attached to the composite antenna device according to the present invention. In the drawing, the same reference numerals as those in FIG. 1 denote the same parts as those in FIG. 1. In the example shown in FIG. 6, a switch is provided between a tuning coil section and a power feeding section, so that frequency bands other than a selected frequency band are blocked, and performance of the selected frequency band is improved. As ifiustrated, in this example, a first switch 71 is provided between the first tuning coil section 10 and the first power feeding section 1. A second switch 72 is provided between the second tuning coil section 20 and the second power feeding section 2 The first switch 71 and the second switch 72 are controlled to be switched on and off. That is, when the first switch 71 is switched on, the second switch 72 is controlled to be switched off. When the first switch 71 is switched off, the second switch 72 is controlled to be switched on. In this manner, isolation between each antenna element is enhanced.

[00371 FIG. 7 is an equivalent circuit diagram for explaining a variation of the composite antenna device according to the present invention shown in FIG. 6. In the drawing, the same reference numerals as those in FIG. 6 denote the same parts as those in FIG. 6. In this example, the first tuning coil section 10 is connected to the common top capacity section 30 through the third coil 60. The second tuning coil section 20 is connected to the common top capacity section 30 through the first tuning coil section 10 and the third coil 60. A third tuning coil section 23 is connected to the common top capacity section 30 through the second tuning coil section 20, the first tuning coil section 10, and the third coil 60. A fourth tuning coil section 24 is connected to the common top capacity section 30 through the third tuning coil section 23, the second tuning coil section 20, the first tuning coil section 10, and the third coil 60. The first switch 7lis provided between the first tuning coil section 10 and the first power feeding section 1. Similarly, the second switch 72 is provided between the second tuning coil section 20 and the second power feeding section 2. A third switch 73 is provided between the third tuning coil section 23 and the third power feeding section 3. A fourth switch 74 is provided between the fourth tuning coil section 24 and a fourth power feeding section 4.

[0038] As described above, the composite antenna device according to the present invention can be configured, so that, for example, the tuning coil sections share a larger number of elements as a frequency band is lower.

Like the example of FIG 6, the first switch 71, the second switch 72, the third switch 73, and the fourth switch 74 may be controlled to be switched on and off. The on and off control may be performed exclusively, or, for example, performed in a manner a plurality of specific switches are switched on. More specifically, for example, in an example of the composite antenna device for an AM/FM band (76MHz to 90MHz), a V-LOW band (99MHz to 108MHz), a V-HIGH band (207MHz to 222MHz), and a terrestrial digital TV broadcast band (470MHz to 710MHz), when data broadcast is received while VICS (registered trademark) broadcast of an FM-band signal is received, a plurality of switches for required bands may be controlled to be switched on.

[0039] If the configuration is made so that a plurality of switches can be switched on, a filter circuit may be provided between a tuning coil section and a switch as needed, so that isolation between antenna elements is enhanced.

[0040] -15 -The present invention is particularly effective when frequency hands are close to each other, such as the FM frequency band and the frequency band of Band III. In a conventional antenna device, there has heen a trade-off relationship between frequencies close to each other, where improvement in performance of one frequency causes lowering in performance of the other frequency, due to the problem of isolation. Since reduction in size has been requested, isolation has been difficult to obtain, and performance has been lowered for each frequency. However, in the composite antenna device according to the present invention, there is no problem of isolation. Accordingly, the antenna can be designed by ignoring isolation. Since isolation can be ignored, antenna elements can be arranged densely, and size can be reduced. A tuning coil for an antenna element and a trap coil are shared, by which the number of components can he reduced, and cost can be reduced. Since power is fed to antenna elements separately, a branching ifiter can be omitted when a signal is supplied to an amplification cfrcuit and the like for each frequency band.

Accorcthgly, losses due to a mutual interference and a branching filter can he reduced. Adjustment at the time of designing is also easy.

[00411 Other than the antenna descr bed above, a GPS antenna, a TEL antenna, and the like may be disposed separately. Since size can be reduced for the composite antenna device according to the present invention, space in a case is increased. Accordingly, the other antennas described above can be disposed efficiently.

[00421 The composite antenna device according to the present invention is not limited to the above illustrated embodiments, but various modifications maybe made without departing from the scope of the present invention.

[00431 1 First power feeding section 2 Second power feethng section 3 Third power feethng section 4 Fourth power feeding section First tuning coil section 11 First coil Second tuning coil section 21 Second coil 23 Third tuning coil section 24 Fourth tuning coil section 30 Common top capacity section 31 Top section 32 Side section Element for the fourth frequency band Base section 51 Cover 52 Fixing section 53 Amplification substrate GO Third coil 61 Capacitor 71 First switch 72 Second switch 73 Third switch 74 Fourth switch -17 -

Claims

CLAIMS: 1. A composite antenna device that can receive signals in a plurality of frequency bands, comprising: a first tuning coil section that is connected to a first power feeding section for a first frequency band and functions as a part of an element for the first frequency band; a second tuning coil section that is connected to a second power feeding section for a second frequency band that is higher than the first frequency band, and functions as a part of an element for the second frequency band; and a common top capacity section that is connected to end sections of the first tuning coil section and the second tuning coil section on sides opposite to sides on which the first power feeding section and the second power feeding section are connected, respectively, functions as a part of elements for the first frequency hand and the second frequency hand, and also functions as an element for a third frequency band that is lower than the first frequency band.
2. The composite antenna device according to claim 1, wherein the first tuning coil section functions also as a filter that attenuates frequency hands other than the first frequency band.
3. The composite antenna device according to claim 1, wherein the second tuning coil section functions also as a filter that attenuates frequency bands other than the second frequency band.
4. The composite antenna device according to any one of claims 1 to 3, which further comprises an element for a fourth frequency band that is higher than the second frequency band, the element being connected to a third power feeding section for the fourth frequency band.
5. The composite antenna device accorthng to any one of claims 1 to 3, wherein a part of the first tuning coil section or the second tuning coil section functions also as an element for the fourth frequency band that is higher than the second frequency hand.
6. The composite antenna device accorthng to any one of claims 1 to 5, wherein the first tuning coil section and/or the second tuning coil section is made up of a series-connected circuit or a parallel-connected circuit of a coil and a capacitor.
7. The composite antenna device according to any one of claims 1 to 6, wherein an axial direction of the first tuning coil section and/or the second tuning coil section is disposed along an edge line of a cover having a shark-fin shape
8. The composite antenna device according to any one of claims 1 to 7, wherein the first tuning coil section and the second tuning coil section are connected to the common top capacity section through a predetermined coil.
9. The composite antenna device according to any one of claims 1 to 8, which further comprises: a first switch provided between the first tuning coil section and the first power feeding section; and a second switch provided between the second tuning coil section and the second power feeding section, wherein the first switch and the second switch are controlled to be switched on and off.
10. The composite antenna device according to any one of claims 1 to 9, wherein the first tuning coil section and the second tuning coil section share a larger number of elements as a frequency band is iowa -20 -