JPH0936632A - 3 frequency shared in-vehicle antenna - Google Patents

Abstract

(57) [Abstract] [Problem] To prevent an increase in diameter of a sleeve antenna,
It can be easily assembled and has good electrical characteristics. An outer conductor pipe (25) is located at the center of a connector joint (22), and a spell top (24) is fitted around the outer periphery thereof. The tip of the outer conductor pipe 25 is connected to the second radiator 28 by the embedding B, and the central core 26 of the outer conductor pipe 25 is connected to the first radiator 32 by the embedding A31. First radiator 32
And the second radiator 28 form a dipole antenna in the telephone frequency band. The upper end of the first radiator 32 is connected via a trap coil 33 to a joint B to which a whip antenna is attached. The whip antenna and the sleeve antenna unit 12 receive the AM frequency band and become an antenna that resonates in the FM frequency band.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a detachable vehicle-mounted antenna usable in the telephone frequency band, FM frequency band and AM frequency band.

[0002]

2. Description of the Related Art A conventional vehicle-mounted antenna has an AM band and an F band.
The antenna for receiving the M frequency band was mainly used, but with the recent spread of the mobile phone, an antenna for transmitting and receiving the mobile phone frequency band is further installed. The antenna for transmitting and receiving the car telephone frequency band is separately installed because the car telephone frequency band is 850 MHz to 950 MHz, which is significantly different from the AM frequency band and the FM frequency band.
This is because its radiation characteristics are also unique. However, in addition to the conventional AM / FM antenna, a transmission / reception antenna for the mobile phone frequency band is further installed on the vehicle body, which is not aesthetically pleasing, and the antenna installation work is complicated, resulting in an increase in cost. .

Therefore, in addition to the AM / FM antenna, a three-frequency common antenna that can be used as a transmitting / receiving antenna in the mobile phone frequency band has been proposed (Japanese Patent Laid-Open No. 64-5).
No. 104). In this three-frequency shared antenna, a whip antenna is provided above a sleeve antenna via a band separation coil. The band separation coil prevents the traveling wave of the sleeve antenna from being fed to the whip antenna, so that the sleeve antenna can be used for transmission / reception of an automobile telephone having a relatively high frequency.

Further, since the total length of the antenna is longer than 1 m, the whip antenna is housed inside the sleeve antenna for the purpose of preventing the antenna from being damaged during garage entry or car washing. It also has a waterproof structure.

[0005]

According to the conventional three-frequency shared antenna described above, in addition to the multi-layer structure unique to the sleeve antenna, a space for accommodating the whip antenna and a space for the drainage channel for waterproofing are provided. And are required. Furthermore, a space for arranging a coaxial cable for power supply is also required on the outer circumference of the drainage channel. For this reason, there is a problem in that the sleeve antenna portion is inevitably increased in diameter and complicated, and moreover, there is a wasteful space other than the upper and lower radiator portions of the sleeve antenna. Further, there is a problem that the electrical characteristics are deteriorated because the structure is not configured to prevent the radiation reduction due to the high frequency current flowing on the outer conductor side of the power feeding coaxial cable.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a vehicle-mounted three-frequency shared antenna having good electrical characteristics, which can prevent the sleeve antenna from having a large diameter and can be easily assembled.

[0007]

In order to achieve the above object, a three-frequency shared vehicle-mounted antenna according to the present invention comprises a tubular spell top, a coaxial line portion arranged in the spell top, and A tubular second radiator formed so that the outer conductor portion is folded back at the tip of the coaxial line portion; and a tubular first radiator formed so as to extend the core of the coaxial line portion, It comprises a sleeve antenna consisting of a joint connected to the first radiator via a trap coil, and a whip antenna part detachable from the joint, and the first radiator and the second radiator are of the telephone frequency band. When a dipole antenna is formed and the first radiator, the second radiator, the trap coil, and the whip antenna section resonate in the FM frequency band. In, FM / A to receive the AM frequency band
The M antenna is formed.

Further, in the above-mentioned three-frequency shared vehicle-mounted antenna, the sleeve antenna is assembled in the following steps (1) to (3). (1) The outer conductor portion is inserted into the spell top from one side and disposed substantially at the center thereof, and the outer conductor portion projecting from the other side of the spell top is inserted into the second radiator. Then, the step of integrating the spell top, the outer conductor portion and the second radiator into a first block (2) electrically fixing the core to the substantially central portion of the first radiator Step of forming second block (3) Insulating the core of the second block assembled in the step (2) in the outer conductor of the first block assembled in the step (1) Inserting the first block and the second block by interposing means.

Further, the sleeve antenna further comprises a power feeding portion fixed to the tip, and a waterproof cap mounted on the power feeding portion from which the sleeve antenna is removed and a tip end of the sleeve antenna from which the whip antenna is removed. A waterproof cap may be provided.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a schematic configuration of an embodiment of an on-vehicle antenna for three frequencies according to the present invention. In this figure, the three-frequency on-vehicle antenna has a total length of about 860 mm, and is attached to the vehicle body 18 so that the vehicle body 18 serves as a ground plane. The on-vehicle antenna for shared use of three frequencies includes an outer tube 1 and a whip antenna section 2 extending from the outer tube 1. The outer tube 1 is an insulating pipe made of synthetic resin, in which a sleeve antenna 12 and a spell top 11 are housed. In addition, a coaxial type power feeding means is provided at the center of the outer tube 1 up to about 3/4 from the lower end of the outer tube, and the sleeve antenna portion 12 is excited from this power feeding means or the sleeve antenna portion 12 The received signal is guided by the power feeding means. Further, the spell top 11 is arranged below the sleeve antenna section 12. This spell top 11 is connected to the outer conductor pipe of the power feeding means, and prevents standing wave current from flowing through the outer conductor pipe and canceling radiation in the front direction by the standing wave current.

A matching / branching device 15 is connected to the vehicle body 18 side of the power feeding means, and the matching / branching device 15 demultiplexes into a telephone frequency band (TEL) and an AM / FM frequency band. From the respective output terminals 16 and 17 to an automobile telephone and an AM / FM receiver. The sleeve antenna unit 12 connected to this power feeding means has a total length of about 15
It is a 0 mm dipole antenna, and it is 870-9
The operating frequency band is the mobile phone frequency band of 50 MHz band.

The core, which is the core wire of the power feeding means, extends further upward from the sleeve antenna portion 12 and is connected to the trap coil 13. The whip antenna section 2 is connected to the other end of the trap coil 13. The trap coil 13 is for electrically isolating the upper whip antenna section 2 and the sleeve antenna section 12 in the automobile telephone frequency band. The length from the lower end of the sleeve antenna unit 12 to the upper end of the whip antenna unit 2 is about 740 mm, and the whip antenna unit 2, the trap coil 13, and the sleeve antenna unit 12 form a resonant unipole antenna. It is designed to resonate in the FM frequency band. Although not resonant, the antenna part of the FM frequency band also receives the AM frequency band. Further, a wind noise reducing spiral wire 14 is wound around the whip antenna section 2 to prevent generation of wind noise.

Next, FIG. 2 is a sectional view showing an example of the detailed structure of the outer tube 1 of the on-vehicle antenna for shared use of three frequencies according to the present invention, and its enlarged view is shown in FIG. In these figures, a female screw to which the whip antenna section 2 is detachably fixed is formed on the upper end of the insulating outer tube 1, and the outer tube 1
A contactor 34 having a joint B35 arranged therein is screwed. This contactor 34 has a trap coil 3
3 is connected to one end, and the other end of the trap coil 33 is connected to the upper end of a pipe-shaped first radiator 32 forming one of the sleeve antenna parts 12. The first radiator 32 is arranged in the outer tube 1 so as to be in close contact with the inner surface of the outer tube 1.

Further, an embedding A31 is fitted into the lower end of the first radiator 32, and the core 26 is inserted in the embedding A31.
Are connected by soldering or the like. Furthermore, an embedding B29 is arranged in the first radiator 32 via an insulating washer 30. The embedded B29 is fitted and inserted into the upper end of the pipe-shaped second radiator 28. An outer conductor pipe 25 is arranged in the second radiator 28, an insulating cylinder is arranged in the outer conductor pipe 25, and a core 26 is arranged inside the insulating cylinder. This outer conductor pipe 25,
The insulating cylinder and the core 26 constitute a power feeding means.
The insulating washer 30 serves to insulate the outer conductor pipe 25 from the first radiator 32.

The above-mentioned power feeding means is used as the second radiator 28.
An insulator 27 that supports the outer conductor pipe 25 is disposed in the second radiator 28 so as to be located in the central portion of the. The second radiator 28 is also in close contact with the inner surface of the outer tube 1. The power supply means is the first radiator 32
The dipole antenna including the second radiator 28 is excited, and the excitation power is supplied from the connector 21 provided at the lower end of the outer tube 1. Further, the signal of the mobile phone frequency band received by the dipole antenna is output from the connector 21. This connector 2
1 is attached by being screwed to a connector joint 22 which is fitted into the lower end of the outer tube 1.

An outer conductor pipe 25 is fitted and inserted into the central portion of the connector joint 22, and is connected to the outer conductor pipe 25. A pipe-shaped spell top 24 is fitted and fitted around the outer periphery of the connector joint 22. There is. An outer conductor pipe 25 is arranged in the center of the spell top 24, and an insulator 23 is fitted in the spell top 24 for supporting the outer conductor pipe 25. The spell top 24 is in close contact with the inner surface of the outer tube 1. Explaining the operation of the spell top 24, the spell top 24 is assumed to have a wavelength of about 1/4 of a telephone band of a car.
Since its tip is open, its impedance is almost infinite in the mobile phone frequency band. That is, it is equivalent to a parallel resonance circuit connected to the open end of the spell top 24. As a result, the radiation due to the standing wave flowing through the spell top 24 has the same phase as the dipole antenna described above, and the radiation in the front direction is not canceled.

Thus, the sleeve antenna unit 1 of the present invention
2 is a pipe-shaped first radiator 32 and a pipe-shaped second radiator 32
It is configured as a dipole antenna including the radiator 28 of FIG. Then, when the excitation power of the automobile telephone frequency band is supplied from the connector 21, the outer conductor pipe 25
The first radiator 32 and the second radiator 28 are transmitted by the coaxial type power feeding means including the core and the core 26.
Will be excited. In addition, radiator 28, 32
Since the pipe has a thick pipe shape, the operating frequency band of the sleeve antenna unit 12 is widened.

Further, since the whip antenna unit 2 is detachably fixed to the joint B35 connected to the first radiator 32 via the trap coil 33, when the AM / FM antenna is not used, etc. The whip antenna 2 can be removed. In this case, waterproof measures can be taken by fitting a waterproof cap on the joint B35. The trap coil 33 prevents the traveling wave of the mobile phone frequency band of the sleeve antenna unit 12 from being transmitted to the whip antenna unit 12.

Next, a method of assembling the outer tube 1 having the sleeve antenna portion 12 built therein will be described with reference to FIG. First, as shown in FIG. 4A, the spell top 24 in which the insulator 23 is fitted is previously attached to the connector joint 22, and the outer conductor pipe 25 is fitted into such an assembly. Then, the second radiator 28 having the embedded B 29 and the insulator 27 fitted therein is fitted into the outer conductor pipe 25 protruding upward from this assembly. The assembly thus constructed is called a first block. Next, as shown in FIG. 3B, the connector 21 is screwed to the lower end of the connector joint 22 of the first block to form the third block.

Further, as shown in FIG.
After the embedding A31 is inserted into and soldered to, the first radiator 32 is inserted. This assembly is called the second block. Next, as shown in FIG. 3D, the insulating washer 30 is fitted into the core 26 of the second block, and then fitted into the third block from above. As a result, the core 26 is fitted into the outer conductor pipe 25 and reaches the connector 21, and the sleeve antenna unit 12 is assembled. After that, the trap coil 33 is connected to the upper end of the second radiator 28, and the outer tube 1 is fitted from above. Further, by mounting the contactor 34 on the upper end of the outer tube 1,
The outer tube 1 having the sleeve antenna portion 12 built therein can be assembled.

Next, a method of using the on-vehicle antenna for three frequencies according to the present invention will be described with reference to FIG. As shown in this figure, the whip antenna section 2 can be attached to the upper end of the sleeve antenna section 12 housed in the outer tube 1 by screwing. It is adapted to be attached to the upper end of by screwing. Therefore, when the three-frequency on-vehicle antenna is not used, the sleeve antenna should be removed from the power feeding unit 3 and the waterproof cap A should be attached to the upper end of the power feeding unit 3.
Make sure to wear 7. Thereby, waterproofing can be achieved when the on-vehicle antenna for three frequencies is removed from the power feeding unit 3.

In addition, the AM / F can be used only by using the car telephone.
When the M frequency band is not used, the whip antenna unit 2 is removed from the sleeve antenna unit 12. Then, a waterproof cap B8 is attached to the upper end of the sleeve antenna 12 so as to be waterproof. It should be noted that, from the power feeding unit 3, the reception signal in the AM / FM frequency band is output from the AM / FM terminal 4, and the signal in the mobile phone frequency band is TEL.
It is input / output via the cable 5 for. Further, a ground line 6 and a ground terminal for connecting the ground of the three-frequency on-vehicle antenna to the vehicle body are provided.

Next, FIG. 6 shows a cross section of the detailed structure of the power feeding section 3. As shown in this figure, a swelling portion made of an insulator A50 for holding the power feeding portion 3 on the vehicle body is provided at the upper end of the power feeding portion 3, and a lower portion of the insulator A50 is a die-cast cylinder. Fitted on top of 46. Also, an outer conductor 49 is provided at the center of the upper portion of the cylinder 46.
A coaxial type power feeding means constituted by a center contact 47 and a center contact 47 is fixed in the cylinder 46 by a fixing nut 45. An insulator B48 is arranged between the outer conductor 49 and the center contact 47.

In the middle of the cylinder 46, AM
The lid portion 44 having the / FM terminal 4 formed thereon is attached by a screw. A printed circuit board 43 in which a matching / branching device is incorporated is arranged inside the portion from which the lid portion 44 is removed, and the lower end portion of the center contact 47 is connected to the upper end of the printed circuit board 43 so that the center contact 47 is formed. The signal supplied from the
It is demultiplexed to the FM frequency band. The demultiplexed signal in the AM / FM frequency band is guided to the AM / FM terminal 4, and the demultiplexed signal in the mobile phone frequency band is taken out through the TEL cable 5. In this case, the impedance is matched by the matching means to be demultiplexed.

Next, a cross section of the detailed structure of the whip antenna section 2 is shown in FIG. As shown in this figure, the whip antenna section 2 is composed of a rod 53 and a spiral wire 54 wound spirally around the surface of the rod 53, and is covered with a jacket 55 from above the spiral wire 54. The spiral wire 54 adds irregularities to the surface of the rod 53 in order to prevent wind noise. The outer cover 55 is an insulating coating. Further, a cap B56 is fitted on the tip of the rod 53, and
A cap A57 is fitted over the outer cover 55.
The base end of the joint A51 is fitted into the lower end of the rod 53, and the cap C52 is attached to the lower part of the rod 53 from above the outer cover 55. This joint A
The sleeve antenna portion 12 is detachably attached to the power feeding portion 3 by screwing 51 onto the screw portion formed on the upper end of the outer conductor 49 of the power feeding portion 3.

As described above, the on-vehicle antenna for three frequencies according to the present invention is such that the whip antenna 2 is detachably attached to the tip of the upper radiator of the sleeve antenna portion 12 via the trap coil 33. Further, the high frequency current flowing through the outer conductor of the coaxial type power feeding means is blocked by the spell top, and further, when the sleeve antenna portion 12 is removed from the power feeding portion 3, the upper end of the power feeding portion 3 is waterproofed. A cap is attached and a waterproof cap is attached to the upper end of the sleeve antenna 12 when the whip antenna 2 cannot be attached.

[0027]

Since the present invention is configured as described above, the antenna portion can be removed as desired, and the degree of freedom in removal can be increased. Further, since the high-frequency current flowing through the outer conductor can be blocked by the spertop, radiation in the front direction is not canceled and good electrical characteristics can be obtained over a wide band. Furthermore, since the waterproof caps that can be attached to the upper end of the power feeding unit and the upper end of the sleeve antenna are provided, it is possible to use the waterproof caps according to the selection of removing each antenna.

[Brief description of drawings]

FIG. 1 is a diagram showing a schematic configuration of an embodiment of an in-vehicle antenna for three frequencies according to the present invention.

FIG. 2 is a diagram showing a detailed configuration of a sleeve antenna housed inside an outer tube in a three-frequency shared vehicle-mounted antenna of the present invention.

FIG. 3 is a diagram showing an enlarged view of the internal configuration of the outer tube shown in FIG.

FIG. 4 is a diagram showing an assembling method of a sleeve antenna housed in an outer tube of a three-frequency shared vehicle-mounted antenna of the present invention.

FIG. 5 is a diagram showing an assembling mode of each antenna in the three-frequency shared in-vehicle antenna of the present invention.

FIG. 6 is a diagram showing a detailed configuration of a power feeding unit in the three-frequency shared vehicle-mounted antenna of the present invention.

FIG. 7 is a diagram showing a detailed configuration of a whip antenna in a three-frequency shared vehicle-mounted antenna of the present invention.

[Explanation of symbols]

 1 Outer Tube 2 Whip Antenna 3 Feeding Part 4 AM / FM Terminal 5 TEL Cable 6 Earth Line 7 Waterproof Cap A 8 Waterproof Cap B 11,24 Spell Top 12 Sleeve Antenna Part 13,33 Trap Coil 14 Wind Noise Countermeasure Spiral Wire 15 Matching / Splitter 18 Vehicle body 21 Connector 22 Connector joint 23,27 Insulator 25 Outer conductor pipe 26 Core 28 Second radiator 29 Embedded B 30 Insulation washer 31 Embedded A 32 First radiator 34 Contact 35 Joint B 41 Shield tube 42 Joint C 43 Printed circuit board 44 Lid 45 Fixing nut 46 Cylinder 47 Center contact 48 Insulator B 49 Outer conductor 50 Insulator A 51 Joint A 52 Cap C 53 Rod 54 Spoiler Luwire 55 Outer jacket 56 Cap B 57 Cap A

Claims (3)

[Claims] 1. A tubular spell top, a coaxial line portion arranged in the spell top, and a cylindrical first portion formed so that its outer conductor portion is folded back at the tip of the coaxial line portion. A second radiator, a tubular first radiator formed to extend the core of the coaxial line portion, a sleeve antenna including a joint connected to the first radiator via a trap coil, and the joint A detachable whip antenna section, and a telephone band dipole antenna is formed by the first radiator and the second radiator, the first radiator, the second radiator, and the trap. FM with the coil and the whip antenna section
FM / that resonates in the frequency band and receives the AM frequency band
An on-vehicle antenna for shared use of three frequencies, which is formed with an AM antenna. 2. The sleeve antenna according to (1) to
The three-frequency shared vehicle-mounted antenna according to claim 1, which is assembled in the step (3). (1) The outer conductor portion is inserted into the spell top from one side and arranged at substantially the center thereof, and the outer conductor portion protruding from the other side of the spell top is inserted into the second radiator. Then, the step of integrating the spell top, the outer conductor portion and the second radiator into a first block (2) electrically fixing the core to the substantially central portion of the first radiator Step of forming a second block (3) Insulating the core of the second block assembled in the step (2) in the outer conductor of the first block assembled in the step (1) Inserting the first block and the second block by interposing means. 3. A waterproof cap to be attached to the power supply part from which the sleeve antenna is removed, and a power supply part to which the sleeve antenna is fixed to the end, and a waterproof cap to be attached to the end of the sleeve antenna from which the whip antenna is removed. The three-frequency shared vehicle-mounted antenna according to claim 1 or 2, further comprising a waterproof cap.