JPH0756503Y2 - Antenna device - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field of the Invention The present invention has a directional pattern in a horizontal plane that is approximate to a circle.
More specifically, the present invention relates to an antenna device having two antennas provided in a vertical direction.

2. Description of the Related Art The wireless communication device, which is widely used under the name of personal wireless, is an extremely convenient device for communication between employees who work outside and the company. Is a device that is installed in the car, so when employees are away from the car for business negotiations,
We cannot contact you in case of emergency. For this reason, the car is equipped with a transmitting device for calling, and an employee away from the car carries a pocket-type receiving device, and when there is a communication request to the wireless communication device, a call for returning the employee to the car The configuration of transmitting radio waves from a car is starting to show signs of widespread use.

This means that two devices, a communication device for personal radio and a transmission device for calling, are attached to the vehicle, and the antenna also supports them,
A total of two antennas, one for each device, are mounted at different locations on the vehicle.

Problems to be Solved by the Invention The antennas described above are non-directional antennas such as whip antennas in consideration of maintaining constant sensitivity regardless of the direction of the vehicle. In the case where two antennas are attached, because of the size of the car, the antennas cannot be attached while keeping a sufficient distance from each other, so that mutual interference occurs between the antennas and the directional characteristics are disturbed. Therefore, there is a problem in that the sensitivity is lowered depending on the direction of the car, which makes communication difficult.

The present invention was created to solve the above problems, and an object of the present invention is to provide an antenna device capable of preventing the disturbance of the directional characteristics caused by the mutual interference of two antennas.

Means for Solving the Problems An antenna device according to the present invention is a plurality of dipole antennas arranged around a shaft core, and the antennas are mounted around the shaft core in parallel with the axial direction. A first antenna, a whip antenna arranged on a coaxial line of the first antenna, and a second antenna attached to an upper portion of an axial core portion of the first antenna;
Is a hollow portion formed in the center of the shaft core of the antenna, and is provided with a feed line insertion hole for passing a feed line of the second antenna.

Action Since the second antenna is provided above the first antenna, the first antenna is provided in the radiation direction of the radio wave of the second antenna.
The second antenna has a similar relationship with respect to the radiation direction of the radio wave of the second antenna. The second
Since the power supply line for supplying power to the antenna is inserted through the power supply line insertion hole which is a hollow portion where radio waves radiated from the first antenna do not reach, the power supply line interferes with the directional characteristics of the first antenna. do not do.

Embodiment FIG. 1 is a perspective view of a partially crushed appearance showing an embodiment of the present invention.

As shown in the figure, the antenna device described here as an example is a first antenna 11 which is a total of four dipole antennas arranged around a central support cylinder 15 which is an axial core.
And a second antenna 12 which is a whip antenna arranged on the coaxial line of the first antenna 11, and a feed line 14 of the second antenna 12 is inserted into a feed line insertion hole 13 which is the center of the central support tube 15. It has a basic configuration that allows you to pass through. The details will be described below.

In the figure, a connector support member 19 made of a ring-shaped metal is provided on the upper part of a central support cylinder 15 which is a thin cylindrical metal cylinder.
Is fixed, and a connector to which a coaxial cable 14 that is a power supply line is connected is provided in the center of the connector support member 19.
123 is attached. Around the center support cylinder 15, at a 90-degree angle, is a rectangular metal plate, and a reflection plate 114 is formed whose length in the long side direction is slightly shorter than the length of the center support cylinder 15. The central support cylinder 15 is attached along the axial direction.

The antenna cover 16 produced by molding an insulating material such as plastic into a cylindrical shape is attached with its inner peripheral surface supported by the outer edge of the reflection plate 114. The length along the axial direction is formed sufficiently longer than the length of the reflection plate 114 in the long side direction so that the central support cylinder 15 and the reflection plate 114 can be shielded from the field of view.

Antenna cover 16 divided into four by reflector 114
A dipole antenna 1 including a pair of radiators 111, which are metal pipes, and a radiator support member 112 made of an insulating material that supports the radiators 111, is provided in each of the internal spaces.
15 is fixed to the central support shaft cylinder 15 by a support 113 made of an insulating material at an angle of 45 degrees with respect to the reflection plate 114. At the bottom of the center support tube 15, the center support tube 15
The antenna mounting bracket 17, which is a bracket for fixing the vehicle to the car, is attached.

In addition, the connector 123 mounted on the top of the center support tube 15
A connector 121 corresponding to this connector 121 is attached to the lower part of the connector 121, and a whip antenna having a circular directional characteristic in a horizontal plane is attached as the second antenna 12 and is connected to the connector 123. The coaxial cable 14 is inserted through the feed line insertion hole 13 which is a hollow portion of the central support cylinder 15 from its upper part to its lower part, and is drawn out to the outside at its lower part.

As described above, the four reflectors 114 and the four dipole antennas 115 are attached inside the antenna cover 16, and the first antenna 11 is configured by the reflectors 114 and the dipole antenna 115. It is configured. The power is fed to the four dipole antennas 115 by the coaxial cable 18 via the bidirectional four-way distributor provided in the feed line insertion hole 13. The four corner reflectors are It operates as two antennas, and its directional characteristics in the horizontal plane are similar to those of a circle.

The output from a personal wireless device (not shown) is connected to the coaxial cable 14 that supplies power to the second antenna 12, and the coaxial cable 18 that supplies power to the first antenna 11 includes When a call request is made by the personal wireless device, the output of a transmitter (not shown) for notifying that there is a call is connected to a receiver carried by a driver away from the vehicle. .

The operation of one embodiment of the present invention having the above configuration will be described below.

The second antenna 12 operates as an antenna of the personal wireless device when it is mounted on the roof of the car by the mounting bracket 17, but no other antenna is located in the radiation direction of the radio wave. It operates as an antenna that exhibits a circular directional characteristic that is the directional characteristic of, and always operates as an antenna that exhibits a constant sensitivity regardless of the direction of the vehicle. Further, the first antenna 11 is similar to the above in that the other antennas are not positioned in the radiation direction of the radio wave, and therefore, when the radio wave notifying the call is
It operates as an antenna that exhibits directional characteristics approximate to a circle, and radiates radio waves of approximately constant intensity over an angle of 360 degrees, regardless of the relationship between the position of the driver and the movement of the vehicle.

As described above, in this embodiment, since the first antenna 11 having a complicated shape is covered with the antenna cover 16, the appearance is neat and the antenna is less noticeable. ,
The risk of theft is reduced.

The present invention is not limited to the above-mentioned embodiment, but the first antenna
With respect to 11, the case has been described in which the antenna having the directional characteristics approximate to a circular shape is an antenna including four corner reflectors, but other configurations, for example, four antennas from the embodiment shown in FIG. Reflector 11
It is possible to remove 4 to form an antenna composed of four dipole antennas 115 attached at an angle of 90 degrees to each other.

Further, the length along the axial direction of the antenna cover 16 has been described as the length covering the first antenna 11, but other lengths such as the first antenna 11 may be used.
It is possible to set the length to cover 11 and the second antenna 12 so that the antenna does not appear to be attached.

Further, the transmitting device whose output is connected to the first antenna 11 has been described as being mounted at a position away from the first antenna 11, but by using the central support cylinder 15 as a metal cylinder having a large inner diameter, It is possible to have a structure in which the transmitter is incorporated.

Effects of the Invention As described above, in the antenna device according to the present invention, the antennas do not interfere with each other even though the directional characteristics of the first antenna and the second antenna are approximately circular in the horizontal direction. Since it is configured, it is possible to prevent the disturbance of the directional characteristics caused by the mutual interference of the antennas, and at the time of mounting the antenna, it is sufficient to mount the antenna only at one place of the car, It also has the effect of being easy to install.

[Brief description of drawings]

FIG. 1 is a partially crushed external perspective view showing an embodiment of the present invention. 11 …… First antenna 12 …… Second antenna 13 …… Feed line insertion hole 14 …… Feed line

Claims (1)

[Scope of utility model registration request] 1. A plurality of dipole antennas arranged centering on a shaft core portion, wherein the antennas are mounted around the shaft core portion in parallel with the axial direction, respectively. A whip antenna arranged on the coaxial line of the antenna, wherein a second antenna attached to an upper part of the shaft core of the first antenna and a hollow part formed at the center of the shaft core of the first antenna An antenna device comprising: a feed line insertion hole for passing a feed line of the second antenna.