JPH042002B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an automotive antenna used mainly for receiving radio broadcasts, transmitting and receiving radio signals, etc. on a vehicle.

(Prior art) In recent years, small in-vehicle radios called personal radios with a frequency band of 903 to 905 MHz have become popular, so cars equipped with personal radios have long Sa90~
In addition to an AM/FM radio antenna 14 made of a rod antenna of about 110 cm, a personal radio antenna 15 made of a Franklin antenna of about 70 cm in length, for example, is installed on the vehicle body. However, since such an antenna protrudes long from the vehicle body, it is necessary to store or remove it each time the antenna is washed in an automatic car wash or parked in a garage. For this reason, as the number of antennas increases, the effort described above increases.
There is a desire for an automotive antenna that can be applied to both AM/FM radio and personal radio.

Therefore, conventionally, a monopole such as a cone-shaped antenna is formed, in which a coaxial line is formed using the waveguide outer frame of a horn-shaped antenna as a coaxial inner conductor, and the opening outer frame of the horn-shaped antenna is used as a radiating element to be coupled to the coaxial line. By forming an antenna, two
An antenna (see Japanese Patent Application Laid-open No. 168506/1983) that can operate in two different frequency bands has been proposed. It is unsuitable for use in wireless transmission and reception due to operational characteristics such as frequency bands and structural problems.

(Problems to be solved by the invention) As mentioned above, the conventional automobile antenna has
An antenna for AM/FM radio and an antenna for personal radio are provided separately, and antennas that operate in two different frequency bands in an integrated configuration as previously proposed are not suitable as antennas for automobiles. Therefore, the present invention provides an automotive antenna that can operate in two different frequency bands, such as AM/FM radio and personal radio, with a single antenna.
The purpose is to prevent an increase in the number of automobile antennas due to the installation of personal radios, and to reduce the trouble of attaching and detaching antennas when washing the car or parking it in the garage.

(Means for Solving the Problems) In order to solve the above problems, the present invention provides a first antenna section that operates in a first frequency band at the tip of a coaxial line, and provides an antenna section outside the coaxial line. A second antenna operating in a second frequency band is connected between the outer conductor and the metal body of the vehicle by utilizing the conductor as an antenna element.
By constructing the antenna section, an automobile antenna is constructed in which two antenna sections each operating in different frequency bands are integrally provided.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 and FIG. 2 are diagrams showing the configuration of an embodiment of the present invention. In FIGS. 1 and 2, reference numeral 1 denotes a coaxial line installed such that one end thereof projects vertically upward from the metal body 2 of the automobile, and is insulated from the metal body 2. At the tip of the coaxial line 1 protruding onto the metal body 2, there is a central conductor 1a.
A metal rod 3 with a length of approximately 8 cm, which corresponds to approximately 1/4 wavelength of radio waves in the frequency band of 903 to 905 MHz, used by personal radios, is provided to protrude upward, and a metal rod 3 is provided on the outer periphery of the tip. A tube 4 having the same length of about 8 cm is provided by folding back the conductor 1b, and these metal rods 3 and the tube 4 constitute a personal radio antenna section 5. The coaxial line 1 is installed so that the length of the part protruding from the metal body 2 is approximately 90 cm, which corresponds to approximately 1/4 wavelength of radio waves in the 76 to 90 MHz frequency band used in FM radio broadcasting. The outer conductor 1b of this coaxial line constitutes an AM/FM radio antenna section 6 whose ground is the metal body 2 of the automobile. The personal radio antenna section 5 is connected to the personal radio device 7 via the center conductor 1a and the outer conductor 1b of the coaxial line 1, and the AM/FM radio antenna section 6 has a center conductor connected to the outer conductor 1b of the coaxial line 1. , an AM/FM radio receiver 9 via coaxial lines 8 whose outer conductors are respectively connected to the metal body 2.
It is connected to the.

In the above configuration, the personal radio antenna section 5 can maintain continuity and insulation between the outer conductor 1b of the coaxial line 1 and the metal body 2 if the lower end of the tube 4 is 10 cm or more away from the metal body 2 of the automobile. Regardless, it functions as an antenna, and in this example it is 80 cm.
Since it is far away from the metal body 2, it has excellent directivity in a circular horizontal plane without being influenced by the metal body 2. The tube 4 is provided to prevent wetting current from occurring in the outer conductor 1b of the coaxial line 1 and to match the input/output impedance (50Ω) of the personal radio 7.
Further, in the AM/FM radio antenna section 6, the length of the outer conductor 1b of the coaxial line 1 serving as the antenna element protruding from the metal body 2 is set based on the wavelength of the FM radio broadcast. Since the antenna for FM radio and the antenna for AM radio can be used together, both AM and FM radio broadcasts can be received well.

Furthermore, as an example of actually installing this embodiment in a car, as shown in FIGS. 3a and 3b, the part of the coaxial line 1 that constitutes the antenna is buried in a rod-shaped member 10 made of resin. A cylindrical conductive stay 11 having a threaded portion on the upper outer peripheral surface is fitted onto the lower end of the rod-shaped member 10 so that it can stand upright on a car, and is fixed to the lower end of the rod-shaped member 10. The rod-shaped member 10 is fixed to the mounting fitting 13 by a nut 12 that is threadedly engaged with the rod-shaped member 10. This mounting bracket 1
3 is a type that is attached to a commonly used trunk lid. Then, the coaxial line 1 is connected to the personal radio, and the center conductor of the coaxial line 8 is electrically connected to the outer conductor 1b of the coaxial line 1, and the outer conductor of the coaxial line 8 is electrically connected to the metal body 2 of the automobile via the mounting bracket 13. Each stay 11 is connected by soldering or the like, and this coaxial line 8 is connected to an AM/FM radio receiver.

In addition, as an example, personal radio and AM/
Although we have described an automotive antenna that operates on both FM radio frequency bands, other antennas that operate on two different frequency bands can be configured similarly, in which case both frequency bands are at least three times as large as the lower frequency band. The difference is necessary.

Further, in the above embodiment, the personal radio antenna unit 5 is configured with a coaxial antenna, but it may also be configured with a Brown antenna or the like.

(Effects of the Invention) As explained above, the present invention provides a first antenna part that operates in a first frequency band at the tip of a coaxial line, and uses the outer conductor of this coaxial line as an antenna element, By configuring the second antenna section that operates in the second frequency band using the metal body as a ground, it is possible to configure an automotive antenna that operates in two different frequency bands with one piece, making it possible to create a personal antenna that operates in two different frequency bands. This has effects such as being able to prevent an increase in the number of automobile antennas due to the installation of radio equipment.

[Brief explanation of drawings]

FIGS. 1 and 2 are diagrams showing the configuration of an embodiment of the present invention, and FIGS. 3a and 3 are diagrams illustrating how the embodiment of the present invention is attached to an automobile.
FIG. 4 is a diagram showing a conventional automobile antenna. 1: coaxial line, 1a: center conductor, 1b: outer conductor,
2: Metal body, 3: Metal rod, 4: Conduit,
5: Personal radio antenna section, 6: AM/
Antenna section for FM radio.

Claims (1)

[Claims] 1. A first antenna portion corresponding to a first frequency band, disposed at the tip of a coaxial line and configured between a center conductor and an outer conductor of the coaxial line; 1. An antenna for an automobile, comprising: a second antenna portion corresponding to a second frequency band configured between the outer conductor and a metal body of the automobile, using an outer conductor.