JPH077887B2 - Antenna device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of use] The present invention relates to an antenna used as a base station antenna when performing radio communication on a vertically polarized signal for a plurality of fixed stations or mobile stations. Regarding the device.

[Prior Art] Recently, the number of radio stations performing mobile communication has increased, especially, and along with this, base station antennas having horizontal plane directivity are widely used.

It is desirable that the base station antenna is installed on the top of the antenna column as a matter of course, but it is necessary to install a plurality of antennas on one column due to restrictions on the antenna construction site. There is a case where it is installed in the middle position of the column without getting the result.

[Problems to be Solved by the Invention] However, if the base station antenna is installed at an intermediate position of the support pillar, there is a problem that the radiated radio wave is affected by the adjacent support pillar and the directional characteristic of the antenna is not omnidirectional. .

Further, even when the base station antenna is installed on the top of the support pillar, if there is a lightning rod or a support pillar for the lightning rod in the vicinity thereof, there is a problem in that it is not omnidirectional similarly to the above.

FIG. 4 shows a conventional installation state of an omnidirectional antenna. A brown antenna 22 is installed as an omnidirectional antenna in the middle of a column 21.

5 (a) to 5 (c) show horizontal plane directional characteristics in the above-described conventional antenna installation state when the distance between the support column 21 and the antenna 22 is changed to 0.25λ, 0.3λ, 0.5λ, respectively. As is clear from the figure, it can be seen that the signal level on the column 21 side is lowered due to the influence of the column 21, and the directional characteristics are greatly distorted from the non-directionality. This is prop 21
Is considered to act as a kind of reflector.

The present invention has been made in view of the above problems, and an object of the present invention is to provide an antenna device capable of obtaining substantially omnidirectional horizontal directional characteristics with a simple configuration even when an antenna is installed in the middle of a column. To aim.

[Means and Actions for Solving the Problems] That is, an antenna device according to the present invention is a radiation device that is supported in parallel with an antenna column and spaced apart from the antenna column by a quarter wavelength or less. An antenna and a reflecting element that is parallel-supported to the antenna support column at a distance of about one-quarter wavelength or less than that of the radiating element, and is supported in parallel. It is configured to be reduced. In other words, the antenna pillar acts as a kind of reflector,
By suppressing the reflection element, a substantially omnidirectional horizontal plane directional characteristic can be obtained.

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

FIG. 1 shows an external configuration of the antenna device. In the figure, 11 is a column, 12 is a radiating element, 13 is a reflecting element, 14 is a support arm, and the radiating element 12 is about 4 minutes from the column 11. Of the radiating element with respect to the pillar 11,
Further, they are supported and arranged in parallel at a distance of about 1/4 wavelength or less from 12. In other words, the radiating element 12 and the reflecting element 13 are sequentially about 1/4 of the pillar 11.
They are arranged in parallel at intervals of a wavelength or less. Then, the radiating element 12 is connected to a wireless device (not shown) via the power supply line 15.

That is, in the antenna device having the above configuration, the radiating element
When radio waves are radiated from 12, first, the radiated radio waves are generated by the support 11 acting as a kind of reflector.
Due to the interference with the re-radiated radio wave from 11, the directivity sensitivity becomes strong on the reflecting element 13 side,
Due to the suppression effect of the re-radiated radio wave from the radiating element, the directivity deviation generated on the support 11 side when viewed from the radiating element 12 can be suppressed to about 3 db. Therefore, it is possible to make the horizontal plane directional characteristic of this antenna device substantially omnidirectional.

FIG. 2 (a) shows a plane arrangement configuration of the antenna device, and FIG. 2 (b) shows a horizontal plane directivity characteristic of the antenna device in the plane arrangement configuration. That is, radiation is performed on a center line passing through the column 11. Each of the element 12 and the reflective element 13 has about 4
One-half wavelength or less (0.19λ in this case)
If they are spaced apart and arranged in parallel, the horizontal plane directional characteristics will drop by 3db or more at two directional angles, but the degree of that drop will be substantial.
It can be kept as low as 3,5db, and it is possible to obtain a nearly omnidirectional characteristic.

Therefore, according to the antenna device having the above-described configuration, the drop in the directional characteristics that occurs on the pillar 11 side as viewed from the radiating element 12 is suppressed by the reflection element 13 arranged in the direction opposite to the pillar 11 to suppress the re-reflected radio waves. Since the number of antennas is suppressed to be small, even if the installation position of the antenna device is at the intermediate position of the support column 11, a substantially omnidirectional horizontal plane directional characteristic can be obtained with a relatively simple configuration.

This makes it possible to provide an inexpensive antenna device having good directional characteristics, and even when the lightning rod is attached to the column 11 itself, the horizontal plane directional characteristics are not greatly distorted from omnidirectionality.

In the above embodiment, the radiating element 12 and the reflecting element 13 are separately arranged on the center line of the column 11, but, for example, as shown in FIG. You may arrange | position by parallel-moving by a fixed space | interval (0.02 (lambda) in this case). In this case, as shown in FIG. 3 (b), the drop range of 3db or more in the horizontal plane directional characteristic can be set to about 60 ° in succession, and the drop degree can be suppressed to about 6 to 8db. . Therefore, the remaining 3
The directional deviation in the 00 ° pointing range is within 3db,
It can be configured as a substantially omnidirectional antenna.

Further, in the above-described embodiment, when the pillar 11 is thick, the drop in gain generated in the pillar direction becomes large, and when the pillar 11 is thin, it becomes small. Further, when the distance between the support 11 and the radiating element 12 or the distance between the radiating element 12 and the reflecting element 13 in the above-described embodiment is changed, the drop in the gain is changed.

Further, by constructing the antenna device in the above-mentioned embodiment in a multi-stage in the vertical direction using the assembly type columns, it is possible to realize a portable collinear antenna with high gain.

[Advantages of the Invention] As described above, according to the present invention, an antenna support, a radiating element that is supported in parallel with the antenna support at a distance of about ¼ wavelength or less, and the antenna described above. A reflection element that is parallelly supported to the support pillar at a distance of about a quarter wavelength or less than that of the radiating element and is supported in parallel, and is configured to reduce the influence of the antenna support pillar on the horizontal plane directional characteristics. Therefore, even when the antenna is installed in the middle of the supporting column, it is possible to provide an antenna device that can obtain a substantially omnidirectional horizontal plane directional characteristic with a simple configuration.

[Brief description of drawings]

FIG. 1 is a diagram showing an external configuration of an antenna device according to an embodiment of the present invention, FIG. 2 (a) is a diagram showing a planar configuration of the antenna device, and FIG. 2 (b) is a horizontal plane of the antenna device. FIG. 3A is a diagram showing a directivity characteristic, FIG. 3A is a diagram showing another embodiment of the antenna device, and FIG. 3B is a diagram showing a horizontal plane directivity characteristic of the antenna device in the other embodiment.
FIG. 5 is a diagram showing an external configuration of a conventional antenna device, and FIGS. 5A to 5C are diagrams showing horizontal plane directional characteristics of the conventional antenna device. 11 …… Post, 12 …… Radiating element, 13 …… Reflecting element, 14 ……
Support arm, 15 ... Feed line.

Claims (1)

[Claims] 1. An antenna support, a radiating element that is supported in parallel with the antenna support at a distance of about ¼ wavelength or less, and the antenna support is more approximately than the radiating element. Four
A reflecting element that is parallelly supported with a spacing of one-half wavelength or less and is parallelly arranged, and a radiation element and a reflecting element are arranged in parallel to the antenna column in this order, and the antenna column acts as a reflector. Antenna device characterized by obtaining substantially omnidirectionality by suppressing noise