JPS63124606A - On-vehicle antenna system - Google Patents

Abstract

PURPOSE:To receive both FM/AM broadcast waves with excellent sensitivity by forming a slot to a metallic plate face arranged with an insulation gap to the outer face of the metal-made car body and connecting an outer sheath conductor grounded to the car body via a core conductor of a feeder and a middle wave band blocking capacitor to the middle of one side and the other side of the slot respectively. CONSTITUTION:An antenna 11 is arranged to a roof part 12a of a metal-made car body 12. The antenna 11 is provided with a T-shaped metallic flat plate 13 being an antenna element and slots 14a,14b are formed to the surface of the metallic flat plate 13 along each T-shaped side. In this antenna 11, the slots 14a,14b formed to the metallic flat plate 13 act like a slot antenna with respect to VHF, UHF bands, and the metallic flat plate 13 provided to the car body 12 with an insulation gap acts like a capacitive antenna to the middle wave band. Thus, a two-frequency band common use antenna is obtained to any of the AM and FM waves with excellent sensitivity.

Description

Detailed Description of the Invention [Technical Field of the Invention] The present invention relates to a vehicle antenna device that is mounted on a vehicle such as an automobile and receives AM broadcast waves (medium wave band) and FM broadcast waves (VHF, UHF band). Regarding.

[Prior art and its drawbacks] Generally, various shapes are used for private IUI antennas, but among these, antennas that do not have protruding parts from the vehicle body are more prone to problems such as damage and wind noise. There is no
Moreover, the appearance is also good.

Conventionally, window glass antennas and trunk antennas have been put into practical use as antennas of this type, but window glass antennas are directional for FM broadcast waves and are not suitable for vehicle antennas that move in any direction. Not only is it unsuitable, but it also has the disadvantage of lower reception sensitivity than the Rondo antenna. Further, trunk antennas have drawbacks such as not being able to obtain sufficient reception sensitivity for both FM and AM broadcast waves.

[Object of the Invention] The present invention was made in view of the above-mentioned drawbacks, and an object of the present invention is to provide an antenna device for a vehicle that does not have a protruding portion from the vehicle body and has good sensitivity to both FM and AM broadcast waves.

[Summary of the Invention] That is, the antenna device for a vehicle according to the present invention includes a metal plate disposed on the outer surface of a metal vehicle body with an insulating gap formed therein, a slot portion formed in the surface of the metal plate, and a slot portion formed in the surface of the metal plate. The core conductor of the power supply line and the jacket conductor of the car body grounding via the medium wave band blocking capacitor are connected to the center of one side and the center of the other side, respectively, and the FM waves are connected to the metal plate through the slot. It is configured to receive AM waves between the vehicle bodies.

[Embodiments of the invention] An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows its configuration as seen from the top side of the vehicle body.
IP-installed. This antenna 11 includes a T-shaped metal plate 13 that connects to the antenna element.
A slot portion 14a is provided on the surface of the
, 14b are formed.

FIG. 2 shows a cross-sectional configuration taken along the line II=II in FIG.
The recess 16 is formed in advance in the recess 2a, and is arranged with a predetermined gap G (for example, 3 to 6) with respect to the roof surface. Slit portions 14a and 14b of the metal flat plate 13 and the vehicle body 1
A core conductor 17a and a sheath conductor 17b of the power supply line 17 are connected to the power supply line 2, respectively, and the other end of the power supply line 1i117 is connected to the receiver 18.

FIG. 3 shows the power feeding configuration of this antenna 11. This antenna 11 has feeding points 19a, 19 at the center of slot portions 14a, 14b formed in a metal flat plate 13, respectively.
b, and slot 14a.

Each branch feed consisting of a coaxial cable is connected to the feed point 19a on one side of 14b. 1Iil17x, 17'y core conductor 17
a, and the outer conductor 17 is located at the other side power feeding point 19b.
b is connected via the medium wave band element capacitor 20.

Each branch power supply line 17x.

The jacket conductor 17y is further grounded to the vehicle body 12 near the feed point 198.19b. The received signals obtained via each branch feed line 17X, 17M are combined by a combiner 21 and given to the receiver 18 as an antenna output via a feed line $117.

That is, in the antenna 11 having the above configuration, the slot portion 14a is formed in the metal flat plate 13.

14k) acts as a slot antenna for VHF and UHF bands, and the metal flat plate 13 disposed with an insulating gap between it and the vehicle body 12 acts as a capacitive antenna for medium wave bands. Therefore, a dual frequency band antenna with good sensitivity to both AM waves and FM waves can be obtained. In addition, since the antenna 11 is installed in a planar manner on the external surface of the vehicle body 12 using a flat metal plate 13, there is no part that protrudes from the vehicle body surface, so there is no problem such as damage or wind noise. It never happens.

Furthermore, in the antenna 11 configured in this embodiment, the T-shaped metal flat plate 13 is used, and the two slot portions 14a and 14b are provided in different directions by 90'', so that, for example, each branch feeder line 17x.

By setting an appropriate phase difference for 17y (±180° or less: distance between two feeding points of 1/2 wavelength or less) and combining, it is possible to effectively create an omnidirectional antenna for FM waves. can. In this case, for AM waves, the phase difference is a negligible value, so it acts as a single capacitive antenna.

In addition, by constructing the T-shaped antenna 11 in the above embodiment with only one set on each side, and as shown in FIG. 4, by combining this antenna 11a with a window glass antenna 22 having different directivity, It is also possible to perform diversity reception.

[Effects of the Invention] As described above, according to the present invention, a metal plate is disposed on the outer surface of a metal car body with an insulating gap, a slot portion is formed on the surface of the metal plate, and the slot portion The core conductor of the power supply line and the outer sheath conductor of the car body grounding via the medium wave band blocking capacitor are connected to the center of one side and the center of the other side, respectively, and the FM wave is transmitted through the slot between the metal plate and the car body. Since the present invention is configured to receive AM waves, it is possible to provide a vehicle antenna device that is sensitive to both FM and AM broadcast waves without having a protruding portion from the vehicle body.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing a vehicle antenna device according to an embodiment of the present invention viewed from the top of the vehicle body, Section 2 is a sectional view taken along line II-n showing the vehicle antenna device of FIG. 1, and FIG. 4 is a diagram showing the power supply configuration of the antenna device of the vehicle, and FIG. 4 is a diagram showing another embodiment of the present invention. DESCRIPTION OF SYMBOLS 11... Antenna, 12... Vehicle body, 12a... Roof part surface, 13... Metal flat plate, 14a, 14b... Slot part, 15... Insulating material, 16... Concave part, 17
...Feeding line, 17a...Core conductor, 17b...Sheath conductor, 17X. 17y...branch feeder line, 18...reception area, 19a. 19b... Feeding point, 20... Medium wave band blocking capacitor, 21... Combiner, 22... Window glass antenna. Applicant's agent Patent attorney Takehiko Suzue Figure 1

Claims (1)

[Claims] A metal car body, a metal plate disposed on the outer surface of the car body with an insulating gap, a slot part formed in the metal plate surface, and a core conductor in the center of one side of the slot part. An antenna device for a vehicle, characterized in that it is equipped with a power supply line connected to a vehicle body grounding jacket conductor via a medium wave band blocking capacitor at the center of the side.