WO2008072415A1

WO2008072415A1 - Multiple frequency antenna

Info

Publication number: WO2008072415A1
Application number: PCT/JP2007/069816
Authority: WO
Inventors: Masashi Wakui
Original assignee: Nippon Antena Kabushiki Kaisha
Priority date: 2006-12-12
Filing date: 2007-10-11
Publication date: 2008-06-19

Abstract

A multiple frequency antenna that even in the operation in multiple frequency bands, allows minimizing of the whole length thereof. A helical element capable of operation in the frequency bands of FM broadcast is wound around the outer circumferential surface of stick-shaped support (10). Linear element (12) capable of operation in the frequency bands of terrestrial digital TV broadcast is disposed in first groove portion (10a) provided on the outer circumferential surface of the support (10) with a given length from its inferior end. Accordingly, there can be realized multiple frequency antenna (1) capable of operation in not only the frequency bands of FM broadcast but also the frequency bands of terrestrial digital TV broadcast, which multiple frequency antenna allows reduction of the whole length (L) of the helical element because of the effect of the linear element (12).

Description

Specification

Multi-frequency antenna

Technical field

TECHNICAL FIELD [0001] The present invention relates to a multifrequency antenna suitable for being mounted on a vehicle capable of receiving FM broadcast and terrestrial digital broadcast.

Background art

[0002] Conventional antenna devices attached to vehicles are generally antenna devices capable of receiving AM broadcasts and FM broadcasts. As this antenna device, a vehicle-mounted antenna device is known in which a helical antenna is wound around the rod portion of the antenna. FIG. 29 is a perspective view showing an example of the configuration of this antenna device. In the antenna device 100 shown in FIG. 29, the helical element 111 is wound around the outer peripheral surface of the rod-shaped insulating support 110 at a pitch p! /. A metal element fitting 113 is fitted to the lower end of the support 110. The lower part of the element fitting 113 is an attachment portion 114 for fixing the antenna device 100 to an antenna case attached to a vehicle roof or the like. The attachment portion 114 is formed with, for example, a male screw. Although not shown, the helical element 111 is wound! /, And is molded with resin from the tip of the support 110 to the element fitting 113.

[0003] The antenna device 100 with the diameter φ of the helical element 111 wound around the support 110 of about 6.8 mm, the pitch p of about 1.48 mm, and the length L of about 154 mm was attached to the antenna case. Figure 30 shows the frequency characteristics of the voltage standing wave ratio (VSWR) in the frequency band of FM broadcasting. The length L1 of the element fitting 113 is about 22.5 mm. Referring to the frequency characteristics shown in Fig. 30, it can be seen that it is almost resonating at 83 MHz, which is the center frequency of FM broadcasting. Also, the frequency band of FM broadcasting in Japan is 76 MHz to 90 MHz, and the antenna device 100 shown in FIG. 29 is almost operating in the frequency band of FM broadcasting. By the way, recently, it is desired to receive terrestrial digital TV broadcasts in vehicles. Terrestrial digital broadcasting The frequency band of TV broadcasting is the UHF band of 470 MHz to 710 MHz. The antenna device 100 shown in Fig. 29 is attached to the antenna case. Figure 31 shows the frequency characteristics of the UHF band. Referring to Fig. 31, the antenna device 100 is of course used for receiving SFM broadcasts. The force antenna device 100 is not operating in the UHF band, and the antenna device 100 receives terrestrial digital TV broadcasts. Power to do S Can't!

[0004] Therefore, FIG. 32 shows a configuration example of a conventional multi-frequency antenna configured to operate in a plurality of frequency bands.

The length of the parasitic coil unit 216 is adjusted so that the operating frequency band of the parasitic coil unit 216 having a large number of turns is the 800 MHz band in the mobile telephone network. The length of the second parasitic coil section 219 is adjusted so that the operating frequency band of the second parasitic coil section 219 with a slightly reduced number of turns is in the vicinity of the 800 MHz band in the mobile telephone network. Yes. As a result, a sufficiently wide frequency band can be secured even in the low frequency band of 800 MHz. In addition, by adjusting the length of the excitation coil section 217 so that the operating frequency band of the excitation coil section 217 having a reduced number of turns is 1.5 GHz in the mobile telephone network, the multi-frequency helical antenna is adjusted. The 200 can operate in the 800MHz band and 1.5GHz band in the mobile telephone network. The parasitic coil unit 216 and the second parasitic coil unit 219 are excited by the excitation coil unit 217.

Patent Document 1: JP 2000-295017 issued by the Japan Patent Office

Patent Document 2: JP 2003-37426 issued by the Japan Patent Office

Disclosure of the invention

Problems to be solved by the invention

[0005] The antenna device 100 described above has a problem that it cannot be operated in a plurality of frequency bands. Therefore, it is conceivable to apply a multi-frequency technique that operates in a plurality of frequency bands in the multi-frequency helical antenna 200 so that the antenna apparatus 100 operates in a plurality of frequency bands. That is, a non-powered helical element is further arranged between the pitches of the helical element 111. As a result, a multi-frequency antenna that operates in a plurality of frequency bands can be obtained. However, it is necessary to place an unpowered helical element between the pitches of the helical element 111. Therefore, it is necessary to increase the pitch of the helical element 111. As a result, the length L of the helical element 111 is too long! /, There is a problem in terms of design and handling.

[0006] Therefore, an object of the present invention is to provide a multi-frequency antenna capable of shortening the overall length as much as possible even when operated in a plurality of frequency bands.

Means for solving the problem

[0007] In order to achieve the above object, the present invention provides a helical element that operates in the first frequency band wound around the outer peripheral surface of the support, and a groove formed in the outer peripheral surface of the support. Or a linear element that operates in the second frequency band disposed in a storage hole formed in the support body.

The invention's effect

[0008] According to the present invention, the helical element that operates in the first frequency band wound around the outer peripheral surface of the support and the groove formed in the outer peripheral surface of the support or the support And a linear element that operates in the second frequency band disposed in the storage hole formed in FIG. In this case, since it is a linear element arranged in the groove or the accommodation hole that operates in the second frequency band, it is not necessary to increase the pitch of the helical element, and the overall length of the multi-frequency antenna is shortened. I can do it. In addition, the helical element is affected by the linear element, and the force S can be reduced to shorten the overall length of the multi-frequency antenna.

Brief Description of Drawings

FIG. 1 is a perspective view showing a configuration of a multi-frequency antenna that is effective in the first embodiment of the present invention.

FIG. 2 is a cross-sectional view taken along the line d-d showing the configuration of the multi-frequency antenna of the first embodiment according to the present invention.

FIG. 3 is a diagram showing the frequency characteristics of VSWR in the frequency band of FM broadcasting of the multi-frequency antenna of the first embodiment, which focuses on the present invention.

FIG. 4 is a diagram showing the frequency characteristics of the VSWR in the frequency band of the terrestrial digital TV broadcast of the multi-frequency antenna of the first embodiment according to the present invention.

[Fig. 5] The present invention is effective when the linear element of the multi-frequency antenna of the first embodiment is provided. It is a figure which shows the frequency characteristic of the VSWR of a helical element when not providing.

6] FIG. 6 is a block diagram showing a configuration of a receiving system when the multifrequency antenna of the first embodiment of the present invention is mounted on a vehicle or the like.

FIG. 7] An enlarged perspective view showing a configuration in which an element metal fitting is fitted to the lower portion of the support body, which is applied to the multi-frequency antenna of the first embodiment of the present invention.

FIG. 8 is a perspective view showing a configuration for comparing with a configuration in which an element metal fitting is fitted to the lower portion of the support, which is applied to the multi-frequency antenna of the first embodiment of the present invention.

FIG. 9] A perspective view showing the configuration of the multi-frequency antenna of the second embodiment according to the present invention. FIG. 10] A cross-sectional view taken along line ee showing the configuration of the multi-frequency antenna of the second embodiment, which focuses on the present invention.

11] An exploded perspective view showing the configuration of the multi-frequency antenna according to the third embodiment of the present invention. 12] A perspective view showing the configuration of the multi-frequency antenna according to the third embodiment of the present invention. is there. 13] A sectional view taken along line ff showing the configuration of the multi-frequency antenna of the third embodiment of the present invention.

14] FIG. 14 is a perspective view showing the structure of the element fitting in the multi-frequency antenna of the third embodiment which focuses on the present invention.

[15] FIG. 15 is a plan view showing the structure of the element fitting in the multi-frequency antenna of the third embodiment which focuses on the present invention.

16] A bottom view showing the structure of the element metal fitting in the multi-frequency antenna of the third embodiment which focuses on the present invention.

FIG. 17] A cross-sectional view taken along the central axis showing the configuration of the element fitting in the multi-frequency antenna of the third embodiment which focuses on the present invention.

18] A front view and a partially enlarged view showing the configuration of the linear element in the multi-frequency antenna of the third embodiment which is effective in the present invention.

19] FIG. 19 is a diagram showing the frequency characteristic of the voltage standing wave ratio (VSWR) in the frequency band of FM broadcasting of the multi-frequency antenna according to the third embodiment which focuses on the present invention.

20] The power of the present invention, the frequency of the terrestrial digital TV broadcasting of the multi-frequency antenna of the third embodiment It is a figure which shows the frequency characteristic of VSWR in several bands.

21] In the multi-frequency antenna of the third embodiment, which focuses on the present invention, the frequency characteristics of the VSWR in the FM broadcast frequency band when the diameter of the linear element is increased, It is a figure shown in contrast with the frequency characteristic of VSWR at the time of.

22] FIG. 22 is a diagram showing the frequency characteristics of VSWR in the frequency band of FM broadcasting when the distance between the helical element and the linear element is narrowed in the multi-frequency antenna of the third embodiment which focuses on the present invention.

23] In the multi-frequency antenna of the third embodiment, which focuses on the present invention, the VSWR of the frequency band of FM broadcasting when the diameter of the linear element is increased and the distance between the helical element and the linear element is increased. It is a figure which shows the frequency characteristic.

24] In the multi-frequency antenna according to the third embodiment, which is effective for the present invention, the impedance in the frequency band of FM broadcasting when the diameter of the linear element is increased and the distance between the helical element and the linear element is increased. It is a Smith chart which shows the frequency characteristic.

[Fig.25] The frequency characteristics of VSWR in the frequency band of FM broadcasting when the length of the helical element is increased and the length of the linear element is slightly shortened in the multi-frequency antenna of the third embodiment which is effective in the present invention. FIG.

[Fig.26] Impedance frequency in the frequency band of FM broadcasting when the length of the helical element is lengthened and the length of the linear element is slightly shortened in the multi-frequency antenna of the third embodiment which is effective in the present invention. It is a Smith chart which shows a characteristic.

[FIG. 27] In the multi-frequency antenna of the third embodiment of the present invention, the terrestrial digital of the multi-frequency antenna alone when the length of the helical element is lengthened and the length of the linear element is slightly shortened

It is a figure which shows the frequency characteristic of VSWR in the frequency band of TV broadcasting.

[Fig.28] In the multi-frequency antenna according to the third embodiment, which is effective in the present invention, the length of the helical element is increased and the length of the linear element is slightly shortened. It is a figure which shows a frequency characteristic.

FIG. 29 is a perspective view showing an example of a configuration of a conventional antenna device.

FIG. 30 is a diagram showing the frequency characteristics of VSWR in the frequency band of FM broadcasting of a conventional antenna device. FIG. 31 is a diagram showing the frequency characteristics of VSWR in the UHF band of a conventional antenna device.

FIG. 32 is a diagram showing a configuration example of a conventional multi-frequency antenna configured to operate in a plurality of frequency bands.

Explanation of symbols

[0010] 1 multi-frequency antenna, 2 multi-frequency antenna, 10 support, 10a 1st groove, 10b 2nd groove, 10c 3rd groove, 10d 4th groove, 11 helical element, 11a connection, 12-wire element , 13 Element bracket, 14 Mounting part, 15 Feeding part, 16 Splitter, 17a FM amplifier, 17b Terrestrial digital TV amplifier, 18a Radio receiver, 18b Terrestrial digital TV tuner, 20 Support, 20a 1st groove, 20b No. 1 2 groove part, 20c 3rd groove part, 20d 4th 21 ^ 21 Helicopter element, 22a spring element, 22b spring element, 22d spring element, 23 element bracket, 24 mounting part, 30 support, 30a storage Hole, 31 Helical element, 31a Connection part, 32 Linear element, 32a Flat hammered part, 33 Element bracket, 33a Cylindrical part, 33b Projecting piece, 33c Lower cylindrical part, 33d Fitting hole, 33e Through hole, 3 4 Mounting part, 35 Antenna cover, 100 Antenna device, 110 support, 111 Heli force Honoré element 113 element metal, 114 attachment portion, 200 multi-frequency to helical antennas, 2 16 passive coil section, 217 excitation coil section, 219 passive coil section

BEST MODE FOR CARRYING OUT THE INVENTION

FIG. 1 is a perspective view showing the configuration of the multi-frequency antenna according to the first embodiment of the present invention, and FIG. 2 is a cross-sectional view taken along the line d-d showing the configuration of the multi-frequency antenna of the first embodiment. Shown in In the multi-frequency antenna 1 shown in these drawings, a helical element 11 is wound at a pitch p on the outer peripheral surface of an insulating support 10 having a rod shape having a substantially circular cross section. A metal element fitting 13 that is electrically connected to the lower end of the helical element 11 is fitted to the lower end of the support 10. The lower part of the element metal fitting 13 has a mounting portion 14 with a reduced diameter for fixing the multi-frequency antenna 1 to an antenna case or the like. The mounting portion 14 is screwed to, for example, an antenna case mounted on the roof of a vehicle. A male screw is formed. The support 10 is formed by resin molding and has flexibility. A helical groove is formed on the outer peripheral surface, and a lead wire is wound around the helical groove so that the support 10 is pinched. H Helical element 11 of p is formed. Although not shown in the drawing, the tip force of the support 10 around which the helical element 11 is wound is also applied to the element fitting 13 and is molded with resin so as to cover the helical element 11.

Furthermore, four groove portions of a first groove portion 10a, a second groove portion 10b, a third groove portion 10c, and a fourth groove portion 10d are formed substantially parallel to the central axis of the support body 10 from the lower end to the upper side. Yes. The first groove portion 10a to the fourth groove portion 10d have substantially the same shape, a taper shape that narrows toward the tip, and the tip portion is formed in a semicircular shape. A linear element 12 having a length a slightly shorter than the length b is disposed in the first groove portion 10a having a length b with a distance from the helical element 11. In this case, the linear element 12 is disposed at the semicircular portion at the tip of the first groove portion 10a, and the distance from the helical element 11 can be at least about 1 mm. The linear element 12 is covered with an insulating film such as polyurethane, so that even if it comes into contact with the helical element 11 with a space therebetween, it is insulated from the direct current. The lower end of the linear element 12 is electrically connected to the element fitting 13, and the helical element 11 and the linear element 12 are supplied with power from the element fitting 13. The first groove portion 10a to the fourth groove portion 10d are formed at equal intervals, and when the bending stress is applied to the support body 10, the stress is evenly distributed, so that the support body 10 can be formed even if a groove is formed. It is prevented from being broken by bending stress.

Here, the helical element 11 has a length L that resonates in the frequency band of FM broadcasting, and the length a of the linear element 12 has a length that resonates in the frequency band of terrestrial digital TV broadcasting. . In this case, the diameter φ of the helical element 11 wound around the support 10 is about 6.8 mm, the pitch p is about 1 · 76 mm, the length L of the helical element 11 is about 139 mm, The length a of the linear element 12 is about 80 mm. The length b of the first groove portion 10a is about 85 mm, and the length L1 of the element metal fitting 13 is about 22.5 mm. The distance between the helical element 11 and the linear element 12 is at least about lmm. Figures 3 and 4 show the frequency characteristics of the voltage standing wave ratio (VSWR) when the multi-frequency antenna 1 with this size is attached to the antenna case.

The frequency characteristics shown in Fig. 3 are the frequency characteristics of VSW R in the FM broadcast frequency band of the multi-frequency antenna 1. Referring to Fig. 3, the frequency characteristic is 83 MHz, which is the center frequency of FM broadcast. Almost has resonance, multi-frequency antenna 1 is that the force ^s' s forces are almost operating in the frequency band of FM broadcast, Ru.

Further, the frequency characteristics shown in FIG. 4 are the frequency characteristics of VSWR in the frequency band of terrestrial digital TV broadcasting in the multi-frequency antenna 1 of the first embodiment of the present invention. Referring to FIG. It is considered to be a broadband frequency characteristic that resonates in the vicinity of 590 MHz, which is the center frequency of broadcasting, and the multi-frequency antenna 1 operates almost in the frequency band of terrestrial digital TV broadcasting from 470 MHz to 710 MHz! ! /, The power of S

In the conventional antenna device 100 shown in FIG. 29 having a helical element, when the pitch p is set to about 1.48 mm and the length L is set to 154 mm, the center frequency of FM broadcasting is almost 83 MHz. Resonates. On the other hand, in the multi-frequency antenna 1 according to the present invention, although the pitch p is increased to about 1.76 mm, the center frequency of FM broadcasting is assumed even if the length is shortened to 139 mm. It almost resonates at 83MHz.

[0015] This is considered that the electrical length of the helical element 11 is equivalently increased under the influence of the linear element 12. Therefore, Fig. 5 shows the frequency characteristics of VS WR in the FM broadcast frequency band for the helical element 11 with and without the linear element 12 as described above. Referring to FIG. 5, if the linear element 12 is not provided, the helical element 11 resonates at about 103 MHz and cannot cover the frequency band of FM broadcasting. However, if the linear element 12 is provided, the helical element 11 will resonate at about 83 MHz, and the helical element 11 will be able to cover the FM broadcast frequency band under the influence of the linear element 12. I know that. As described above, the multi-frequency antenna 1 which is the power of the present invention can reduce the posture even if it operates in a plurality of frequency bands. By using the helical element 11 as a voltage receiving element in the AM broadcast frequency band, the helical element 11 can also be used as an antenna for AM broadcast reception. In this way, the multi-frequency antenna 1 of the first embodiment of the present invention can be a multi-frequency antenna capable of receiving AM / FM broadcasting and terrestrial digital TV broadcasting.

[0016] The first embodiment of the present invention described above is equipped with a multi-frequency antenna 1 that can be applied to a vehicle or the like. Figure 6 shows a block diagram showing the configuration of the receiving system.

As shown in FIG. 6, the multi-frequency antenna 1 includes a helical element 11 and a linear element 12. The lower ends of the helical element 11 and the linear element 12 are connected, and power is supplied from the same power supply unit 15. The received signal derived from the power feeding unit 15 is demultiplexed by the demultiplexer 16 into an FM broadcast received signal and a terrestrial digital TV broadcast received signal. The demultiplexed FM broadcast reception signal is amplified by the FM amplifier 17a and supplied to the radio receiver 18a having the FM broadcast receiving unit. The demultiplexed terrestrial digital TV broadcast reception signal is amplified by the terrestrial digital TV amplifier 17b and supplied to the terrestrial digital TV tuner 18b. In this way, it is possible to receive at least FM broadcasts and terrestrial digital TV broadcasts simply by installing the multi-frequency antenna 1.

Further, in the multi-frequency antenna 1 which is the force according to the first embodiment of the present invention, the helical element 11 is wound! /, And the element metal fitting 13 is fitted to the lower part of the support 10! /, The Fig. 7 shows an enlarged perspective view of this fitting configuration. As shown in FIG. 7, the lower end of the helical element 11 is bent downward and connected to a connection portion 11 a that is tightly wound around the lower end portion of the support 10. Further, the lower end of the linear element 12 is stretched, and the insulating film is removed only at the stretched portion so as to be connected to the connection portion 11a. In this state, the element metal fitting 13 is fitted to the lower end portion of the support body 10 so as to cover the connection portion 11a and crimped. As a result, the helical element 11 and the linear element 12 are electrically connected to the element fitting 13. In this case, as shown in FIG. 8, it is possible to store the linear element 12 'in the storage hole formed substantially along the central axis of the support 10 as shown in FIG. When the linear element 12 ′ is stored in the storage hole formed along the axis, simply fitting the element metal fitting 13 to the lower end of the support 10 so as to cover the connecting portion 11a and caulking Although the helical element 11 is connected to the element fitting 13, it becomes difficult to securely connect the linear element 12 'to the element fitting 13, and another means for connecting the linear element 12' to the element fitting 13 is available. Necessary. In this way, by adopting a configuration in which the linear element 12 is disposed in the groove formed on the outer peripheral surface of the support 10, the configuration of the power feeding unit can be simplified. In addition, when a storage hole for storing the linear element 12 ′ is formed substantially along the center axis of the support 10, the support 10 is connected to the pipe. It becomes inferior in flexibility and becomes liable to break when bending stress is applied.

Next, FIG. 9 is a perspective view showing the configuration of the multi-frequency antenna according to the second embodiment of the present invention, and is cut along line ee showing the configuration of the multi-frequency antenna of the second embodiment. A cross-sectional view is shown in Fig. 10.

In the multi-frequency antenna 2 shown in these drawings, helical elements 21 are wound at a predetermined pitch on the outer peripheral surface of an insulating support 20 having a rod shape having a substantially circular cross section. At the lower end of the support 20, a metal element fitting 23 electrically connected to the lower end of the helical element 21 is fitted! /. The lower part of the element metal fitting 23 has a mounting portion 24 with a small diameter for fixing the multi-frequency antenna 2 to the antenna case or the like, and the mounting portion 24 is screwed to an antenna case mounted on a vehicle roof or the like, for example. A male screw is formed. The support 20 is formed by resin molding and has flexibility, and a helical groove is formed on the outer peripheral surface, and a conductive wire is wound in the helical groove to thereby form a predetermined pitch. Helical element 21 is formed. As shown in the figure, the helical element 21 is wound around the helical element 21! /, And the force is applied to the element fitting 23 from the tip of the support 20 to cover the helicity element 21. It is Monored.

[0019] Furthermore, the four predetermined lengths of the first groove portion 20a, the second groove portion 20b, the third groove portion 20c, and the fourth groove portion 20d are set to be upward from the lower end substantially parallel to the central axis of the support body 20. Grooves are formed. The first groove portion 20a to the fourth groove portion 20d have substantially the same shape, a tapered shape that narrows toward the front, and a tip portion that is semicircular. A linear element 22a is arranged in the first groove 20a, a linear element 22b force is arranged in the second groove 20b, and a linear element 22d is arranged in the fourth groove 20d at a distance from the helical element 21. In this case, the linear elements 22a, 22b, and 22d are arranged at the semicircular portions at the tip ends of the first flange portion 20a, the second flange portion 20b, and the fourth flange portion 20d. The distance from 21 can be at least about lm m. The linear elements 22a, 22b, and 22d are covered with an insulating film such as polyurethane, so that even if they are in contact with the spaced helical elements 21, they are insulated in a direct current manner. The lower ends of the linear elements 22a, 22b, and 22d are electrically connected to the element fitting 23, and the helical element 21 and the linear element are connected. The elements 22a, 22b, 22d are supplied with power from the element fitting 13. Note that the first groove portion 20a to the fourth groove portion 20d are formed at equal intervals, and even when a bending stress is applied to the support 20, the stress is evenly distributed, and the support 10 Is prevented from being broken by bending stress.

[0020] Here, the helical element 21 has a length that resonates in the frequency band of FM broadcasting, and the length of the linear element 22a has a length that resonates in the frequency band of terrestrial digital TV broadcasting. The length of the linear element 22b is the length that resonates in the frequency band of the 800MHz band mobile phone network, and the length of the linear element 22d is the length that resonates in the frequency band of the 1.8GHz band mobile phone network. It is said. As a result, the multi-frequency antenna 2 of the second embodiment can be a multi-frequency antenna that operates in four frequency bands. However, the frequency band in which the multi-frequency antenna 2 operates is not limited to the above-mentioned frequency band except for the frequency band of FM broadcasting, and is not limited to the above terrestrial digital radio, AMPS (Advanced Mobile Phone Service), GS M (Global System for mobile (communications), DCS (Digital Communication System), PCS (Personal communications Service), PD (Personal Digital Cellular) and other mobile phone network frequency bands, keyless systems, weather bands, DAB (Digital Audio Broadcast), etc. In this case, the lengths of the linear elements 22a, 22b, and 22d are respectively operated! /, And the length corresponding to the frequency band is! /.

In addition, in the multi-frequency antenna 2 of the second embodiment, the helical element 21 can be used as an antenna for AM broadcast reception by using the helical element 21 as a voltage receiving element in the frequency band of AM broadcasting. it can.

Also in the multi-frequency antenna 2 of the second embodiment, the lower end of the helical element 21 is bent downward and connected to a connection part tightly wound around the lower end part of the support 20. In addition, the lower ends of the linear elements 22a, 22b, and 22d are stretched, and the insulating film is removed only at the stretched portions so as to be connected to the connection portion. In this state, the element metal fitting 23 is fitted to the lower end portion of the support 20 so as to cover the connection portion, and is crimped. As a result, the helicoid element 21 and the spring-like elements 22a, 22b, 22d are electrically connected to the element fitting 23.

Next, an exploded perspective view showing the configuration of the multi-frequency antenna according to the third embodiment of the present invention is shown. 11 is a perspective view showing the configuration of the multi-frequency antenna according to the third embodiment of the present invention. FIG. 12 is a perspective view showing the configuration of the multi-frequency antenna according to the third embodiment of the present invention. Figure 13 shows the cross section.

The multi-frequency antenna 3 according to the third embodiment of the present invention shown in FIGS. 11 to 13 has a linear element 12 ′ in a housing hole formed along the substantially central axis of the support 10 shown in FIG. It is a multi-frequency antenna that embodies the multi-frequency antenna that is housed.

In the multi-frequency antenna 3 of the third embodiment, helical elements 31 are wound at a pitch p on the outer peripheral surface of an insulating support 30 whose outer shape, which has a substantially circular cross section, is a rod shape. At the lower end of the support 30, a metal element fitting 33 that is electrically connected to the lower end of the helical element 31 is fitted! The lower part of the element metal fitting 33 is provided with a mounting portion 34 having a small diameter for fixing the multi-frequency antenna 3 to the antenna case or the like, and the mounting portion 34 is screwed to an antenna case mounted on a vehicle roof or the like, for example. A male screw is formed. The support 30 is formed by resin molding and has flexibility, and a helical groove is formed on the outer peripheral surface, and a conductive wire is wound in the helical groove so that the pitch p is reduced. Helical element 31 is formed. In addition, as shown by the broken line in FIG. 12, the tip force of the support 30 around which the helical element 31 is wound is also applied to the element fitting 33, so that the resin antenna is covered so as to cover the helical element 31. Molded with cover 35.

Further, a storage hole 30a having a predetermined length is formed from the lower end upward along substantially the central axis of the support 30. A linear element 32 having a length a slightly shorter than the length of the storage hole 30a is stored in the storage hole 30a. In this case, the linear element 32 is passed through the through hole formed in the mounting portion 34 from below the lower mounting portion 34 of the element fitting 33, and the lower portion of the linear element 32 is press-fitted into the through hole. As a result, the linear element 32 is electrically connected to the element fitting 33 and mechanically fixed. The element fitting 33 in this state is positioned below the support body 30 around which the helical element 31 is wound, and the linear element 32 is passed through the storage hole 30a formed in the support body 30. The connecting portion 31a formed in the lower part of the support 30 from the upper side and having a slightly narrowed diameter is fitted into the element fitting 33, and the element fitting 33 is caulked. Connection Since the helical element 31 is tightly wound around the outer peripheral surface of the portion 31a, the lower end of the helical element 31 is electrically connected to the element fitting 33, and the helical element 31 and the linear element 32 are connected to the element fitting 33. It will be fed from.

The helical element 31 has a length L that resonates in the frequency band of FM broadcasting, and the length a of the linear element 32 has a length that resonates in the frequency band of terrestrial digital TV broadcasting. In this case, the diameter φ of the helical element 31 wound around the support 30 is about 6.8 mm, the pitch p is about 1 · 76 mm, the length L of the helical element 31 is about 139 mm, The length a of the linear element 32 is about 82 mm. The length L1 of the element bracket 33 is about 22.5 mm. Further, the storage hole 30a may be formed so as to penetrate the entire force support 30 whose length is about 85 mm. Further, the distance S between the helical element 31 and the fountain element 32 (see FIG. 13) is at least about lmm. In this case, if the frequency band of terrestrial digital TV broadcasting is 470 MHz to 710 MHz and the center frequency of the UHF band is 590 MHz, lmm is about 0.0002. In addition, the diameter D of the linear element 32 and the diameter C of the helical element 31 are about lmm (about 0 · 000 2 λ) or less.

[0025] Here, FIG. 14 is a perspective view showing the structure of the element metal fitting 33, FIG. 15 is a plan view showing the structure of the element metal fitting 33, and FIG. 16 is a bottom view showing the structure of the element metal fitting 33. A sectional view taken along the central axis showing the configuration of the metal fitting 33 is shown in FIG.

As shown in these drawings, the metal element fitting 33 is composed of a cylindrical portion 33a and a mounting portion 34 formed so as to protrude from the lower end of the cylindrical portion 33a. For example, a plurality of projecting pieces 33b, for example, six, are formed at substantially the center of the element metal fitting 33 so as to project from the outer peripheral surface of the cylindrical portion 33a at equal intervals. A lower cylindrical portion 33c is formed below the protruding piece 33b, and an attachment portion 34 having a screw formed on the outer peripheral surface is formed below the lower cylindrical portion 33c. A fitting hole 33d into which a connection part 31a formed at the lower part of the support 30 is fitted is formed in the upper part of the cylindrical part 33a, and the diameter of the lower part of the fitting hole 33d is slightly reduced. A through hole 33e having a reduced diameter communicating with the fitting hole 33d is formed through the mounting portion 34. The through hole 33e is formed substantially on the long axis of the element fitting 33, and the linear element 32 is passed through the through hole 33e. Note that the width of the plurality of protruding pieces 33b is increased as it goes outward. Thus, when the antenna cover 35 is molded, the antenna cover 35 is securely molded to the element fitting 33.

Next, FIG. 18 (a) shows a front view showing the configuration of the linear element 32, and FIG. 18 (b) shows a partially enlarged view thereof.

As shown in these drawings, the linear element 32 is composed of a linear metal wire, and a flat hitting portion 32a that is flattened and crushed is formed in the lower portion. The linear element 32 is passed through the through hole 33e from below the mounting portion 34 of the element fitting 33. When the flat hitting portion 32a comes into contact with the lower end of the through hole 33e, the flat hitting portion 32a is press-fitted into the through hole 33e using a tool. Thereby, the linear element 32 is fixed to the element fitting 33 and is electrically connected.

[0027] In the multi-frequency antenna 3 according to the third embodiment, which is effective in the present invention, the winding diameter Φ of the helical element 31 is about 6.8 mm, the wire diameter C of the helical element 31 is about 0.4 mm, and the pitch p is about 1 · 76 mm, length L is about 139 mm, length a of linear element 32 is about 82 mm, diameter D of linear element 32 is about 0.8 mm, and between helicity force element 31 and spring element 32図 Figure 19 shows the frequency characteristics of the VSWR in the FM broadcast frequency band when the multi-frequency antenna 3 with an S dimension of about 2.6 mm is attached to the antenna case, and the VS WR in the terrestrial digital TV broadcast frequency band. Figure 20 shows the frequency characteristics.

Referring to FIG. 19 and FIG. 20, the multi-frequency antenna 3 of the third embodiment having the above dimensions is set to a resonance frequency of about 83 MHz so that it can operate sufficiently in the frequency band of FM broadcasting, and 470 MHz to 710 MHz. It operates almost in the frequency band of terrestrial digital TV broadcasting.

[0028] Further, in the conventional antenna device 100 shown in Fig. 29 having a helical element, when the pitch p is about 1.48 mm and the length L is 154 mm, the center frequency of FM broadcasting is set. It almost resonates at 83MHz. On the other hand, in the multi-frequency antenna 3 which is effective in the third embodiment of the present invention, the length L is shortened to 139 mm even though the pitch p is increased to about 1.76 mm. However, it almost resonates at 83MHz, the center frequency of FM broadcasting. This is probably because the electrical length of the helical element 31 is equivalently increased under the influence of the linear element 32 as described above with reference to FIG. As described above, even if the multi-frequency antenna 3 of the third embodiment, which is effective in the present invention, operates in a plurality of frequency bands, the helical element 31 is affected by the linear element 32 and thus has a low profile. The ability to turn into S Further, by using the helical element 31 as a voltage receiving element in the AM broadcast frequency band, the helical element 31 can be used also as an AM broadcast receiving antenna. In this way, the multi-frequency antenna 3 of the third embodiment of the present invention can be a multi-frequency antenna capable of receiving AM / FM broadcasting and terrestrial digital TV broadcasting.

The configuration of the receiving system when the multi-frequency antenna 3 according to the third embodiment of the present invention is mounted on a vehicle or the like is the same as that shown in the block diagram of FIG.

[0029] Next, in the multi-frequency antenna 3 according to the third embodiment, which is useful for the present invention, the voltage standing wave ratio in the frequency band of FM broadcasting when the diameter D of the linear element 32 is increased to about lmm ( The frequency characteristics of VSWR) are shown in Fig. 21 in comparison with the frequency characteristics of VSWR when the diameter D of the linear element 32 is reduced to about 0.6 mm. The other dimensions of the multi-frequency antenna 3 are the dimensions when the electrical characteristics shown in FIGS. 19 and 20 are obtained!

Referring to FIG. 21, when the diameter D of the linear element 32 is increased to about lmm, the resonance frequency becomes about 78 MHz in the frequency band of FM broadcasting, and the resonance frequency moves to a low band. As described above, in the multi-frequency antenna 3 of the third embodiment, as the diameter D of the linear element 32 is increased, the influence on the helical element 31 is increased, and the resonance frequency moves to a lower range. . Therefore, the thickness of the linear element 32 cannot be increased too much.

[0030] Further, in the multi-frequency antenna 3 of the third embodiment which is effective in the present invention, the helical element

Figure 22 shows the frequency characteristics of the VSWR in the FM broadcast frequency band when a multi-frequency antenna 3 with a spacing S between 31 and the linear element 32 narrowed to about lmm is attached to the antenna case. The other dimensions of the multi-frequency antenna 3 are the dimensions when the electrical characteristics shown in FIGS. 19 and 20 are obtained.

Referring to FIG. 22, the distance S between the helical element 31 and the linear element 32 is reduced to about If lmm is set, the resonance frequency moves too low, and the resonance frequency does not appear in the frequency band of 70 MHz to 100 MHz, and almost does not operate in the frequency band of FM broadcasting. Thus, in the multi-frequency antenna 3 of the third embodiment, the effect on the helical element 31 increases as the distance S between the helical element 31 and the linear element 32 decreases, and the resonance frequency shifts to a lower range. Will come. Therefore, the distance S between the helical element 31 and the linear element 32 cannot be made too small.

[0031] Further, in the multi-frequency antenna 3 of the third embodiment which is effective in the present invention, the diameter D of the linear element 32 is set to about lmm, and the distance S between the helical element 31 and the linear element 32 is set to about 1. The frequency characteristics of the VSWR in the FM broadcast frequency band when the multi-frequency antenna 3 of 5 mm is attached to the antenna case is shown in Fig. 23, and the Smith chart showing the frequency characteristics of the impedance in the FM broadcast frequency band Shown in 24. The other dimensions of the multi-frequency antenna 3 are the dimensions when the electrical characteristics shown in FIGS. 19 and 20 are obtained.

Referring to Figs. 23 and 24, even if the diameter D of the linear element 32 is increased to about lmm, the distance S between the helical element 31 and the linear element 32 is increased from about lmm to about 1.5 mm. The resonance frequency moves from below 70MHz to about 78MHz. Thus, in the multi-frequency antenna 3 of the third embodiment, even if the diameter of the linear element 32 is increased, the helical element 31 is increased by increasing the distance S between the helical element 31 and the linear element 32. The resonance frequency shifts to a higher frequency as the effect on the frequency becomes smaller. In this case, if the pitch p is slightly roughened to about 1.89mm without changing the length L of the helical element 31, the electrical length of the helical element 31 will be shortened, and the resonance frequency will be the center frequency of FM broadcasting 83MHz Can be substantially resonated. However, although the VSWR characteristic is slightly degraded, it works well in the frequency band of FM broadcasting!

[0032] Even when the distance S between the helical element 31 and the linear element 32 is narrowed, the resonance frequency is set to 83 MHz, which is the center frequency of FM broadcasting, by reducing the diameter D of the linear element. It becomes possible to resonate. Thus, in the multi-frequency antenna 3 of the third embodiment according to the present invention, the diameter D of the linear element and the interval S between the helical element 31 and the linear element 32 are combined, and the helical element 31 is combined. By adjusting the electrical length, desired electrical characteristics can be obtained. In the multi-frequency antenna 3 according to the third embodiment, which is the force of the present invention, the diameter D of the linear element 32 is less than about 1 mm, and the distance S between the helicopter force element 31 and the linear element 32 is set as follows. It is preferable that the thickness is about lmm or more. In addition, if the wire diameter C of the helical element 31 is reduced, the desired electrical characteristics can be obtained in the frequency band of FM broadcasting and digital terrestrial TV broadcasting. lmm or less is preferred

[0033] Next, in the multi-frequency antenna 3 of the third embodiment, the length L of the helical element 31 of the helical element 31 is increased to about 152 mm, and the length a of the linear element 32 is slightly shortened to about 78 mm. Fig. 25 and Fig. 26 show the electrical characteristics in the FM broadcast frequency band and digital terrestrial TV broadcast frequency band when the multi-frequency antenna 3 is attached to the antenna case. The other dimensions of the multi-frequency antenna 3 are the dimensions when the electrical characteristics shown in FIGS. 19 and 20 are obtained.

The electrical characteristics shown in Fig. 25 are the frequency characteristics of the VSWR in the FM broadcast frequency band of the multi-frequency antenna 3 of the third embodiment, and the electrical characteristics shown in Fig. 26 are the frequency characteristics of the impedance in the FM broadcast frequency band. It is a Smith chart which shows. Referring to FIGS. 25 and 26, the multi-frequency antenna 3 of the third embodiment almost resonates at 83 MHz, which is the center frequency of FM broadcasting, and has a broader VSWR characteristic than the VSWR characteristic shown in FIG. It can be seen that it works well in the frequency band of FM broadcasting.

[0034] In addition, the electrical characteristics shown in FIG. 27 show the frequency of VSWR in the frequency band of a single terrestrial digital TV broadcast without attaching the multi-frequency antenna 3 of the third embodiment of the present invention having the above dimensions to the antenna case. The electrical characteristics shown in FIG. 28 are the VSWR frequency characteristics in the frequency band of terrestrial digital TV broadcasting when the multi-frequency antenna 3 of the third embodiment of the present invention having the above dimensions is attached to the antenna case. is there. Referring to FIG. 27, the multi-frequency antenna 3 alone has a broad frequency characteristic that resonates in the vicinity of 610 MHz, and the frequency characteristic deviates from the frequency band of terrestrial digital TV broadcasting to a high frequency range. However, referring to FIG. 28, it is considered to have a broad frequency characteristic that resonates in the vicinity of 590 MHz, which is the center frequency of terrestrial digital TV broadcasting. The multi-frequency antenna 3 of the third embodiment is a terrestrial digital of 470 MHz to 710 MHz. In the TV broadcast frequency band The power that is working In this way, by attaching the multi-frequency antenna 3 to the antenna case, it is considered that the frequency characteristics of the VSWR of the multi-frequency antenna 3 move to the whole low range due to the influence of the wiring in the antenna case. . The wavelength of FM broadcasting is very long compared to the wiring inside the antenna case, so there is almost no change in electrical characteristics depending on the presence or absence of the antenna case.

In this way, in the multi-frequency antenna 3 of the third embodiment, even if the length a of the linear element 32 is slightly shortened and the length L of the helical element 31 is increased, It works well in the frequency band of terrestrial digital TV broadcasting. In this case, the multi-frequency antenna 3 can be made a multi-frequency antenna capable of receiving AM / FM broadcasting and terrestrial digital TV broadcasting by using the helical element 31 as a voltage receiving element in the frequency band of AM broadcasting. .

[0036] In the multi-frequency antenna 3 according to the third embodiment, which is effective for the present invention described above, the representative value of the diameter D of the linear element 32 is about 0.8 mm. The linear element 32 is stored in the storage hole 30a. Accordingly, since the diameter of the storage hole 30a can be reduced (about 1 mm), the support 30 is sufficiently flexible even if it is in the shape of a pipe, and can be broken even if a bending stress is applied. I'm gonna get lost. Further, if the distance S between the helical element 31 and the linear element 32 is made smaller than about 2.6 mm, the diameter of the multi-frequency antenna 3 becomes smaller as the diameter of the support 30 becomes smaller. As a result, the multi-frequency antenna 3 becomes more flexible.

Industrial applicability

[0037] In order to obtain the above-described electrical characteristics in the multi-frequency antenna device according to the first and second embodiments of the present invention described above, the distance between the helical element and the linear element is at least about lmm or more. It is preferable that Therefore, by arranging the linear element in a tapered groove formed on the support by covering it with an insulating tube of about lmm thickness or more, the outer peripheral surface of the insulating tube is brought into contact with the tapered groove and the helical element is attached. The contact between the linear element and the helical element can be made constant. Thereby, the electrical characteristics of the multi-frequency antenna can be stabilized. In addition, the helical element and the linear element are arranged so that the distance between the helical element and the linear element is constant. An insulating material having a low dielectric constant may be disposed between the conductors.

In addition, in the multi-frequency antenna apparatus according to the first and second embodiments described above, the force in which four grooves are formed at equal intervals on the outer peripheral surface of the support is not limited to this. Only the same number of grooves as the number of linear elements may be formed. In this case, when a plurality of grooves are provided, it is preferable to provide them at equal intervals. In addition, the multi-frequency antenna, which is the power of the present invention, is intended for in-vehicle use attached to the roof or trunk of a vehicle, but is not limited to this, and any multi-frequency antenna that operates in two or more frequency bands can be applied. Can do.

Claims

The scope of the claims

[1] An insulating support having a predetermined length of a groove formed on the outer peripheral surface substantially parallel to the central axis from one end!

A helical element wound around the outer peripheral surface of the support and operating in a first frequency band fed from one end;

A linear element that is disposed in the groove formed in the support and operates in a second frequency band fed from an end; and

An element fitting that is fitted to the one end of the support and is electrically connected to the one end of the helical element and the end of the linear element, and has a mounting portion formed in the lower part;

A multi-frequency antenna, wherein power is supplied to the helical element and the linear element through the element fitting.

[2] The multiple support according to claim 1, wherein the support is made of a flexible resin, and a helical groove around which the helical element is wound is formed on an outer peripheral surface thereof. Frequency antenna.

[3] On the outer peripheral surface of the support body, a plurality of groove portions having a predetermined length are formed on the outer peripheral surface substantially parallel to the central axis from one end, and a plurality of grooves each operating in a different frequency band. Each of the linear elements is arranged, and the plurality of linear elements are connected to the element fitting, and are supplied with power to the helical element and the plurality of linear elements via the element fitting. The multi-frequency antenna according to claim 1.

[4] The line element according to any one of claims 1 to 3, wherein the linear element arranged in the groove is arranged in the groove so as to be spaced apart from the helical element by a predetermined distance. The multi-frequency antenna described in 1.

[5] The linear element disposed in the groove is covered with an insulating tube having a predetermined thickness so as to be spaced apart from the helical element by a predetermined distance. Item 4. The multi-frequency antenna according to any one of Items 1 to 3.

[6] A storage hole is formed almost along the central axis from one end, and the outer shape is formed in a rod shape. An insulating support,

A linear element that is disposed in the storage hole formed in the support and operates in a second frequency band that is fed from an end;

7. The multiple support according to claim 6, wherein the support is made of a flexible resin, and a helical groove around which the helical element is wound is formed on an outer peripheral surface thereof. Frequency antenna.