JPH0669716A - Wide band-two dipole antenna - Google Patents

Abstract

PURPOSE:To obtain a uniform beam where the fluctuation of horizontal surface directivity half breadth and a gain is small with respect to a frequency as to a sector zone. CONSTITUTION:A wide band two dipole antenna 11 consisting of two pairs of dipole elements 12 and 12 which are arranged in parallel 10 right and left and of a reflecter 14 arranged in a position detached from the dipole elements 12 and 12 by about a 0.2 wavelength (wavelength is that of used frequency) is provided with the two pairs of non-feeding elements 13 and 13 of trapezoidal plates which are symmetrically arranged in parallel to the dipole elements 12 and 12 between the two pairs of the dipole elements 12 and 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wideband two-dipole antenna with a reflector having improved directional characteristics in a horizontal plane, as an antenna for a base station for land mobile communications used in automobile phones and the like.

[0002]

2. Description of the Related Art Conventionally, a frequency of 800 MHz band has been used for land mobile communication such as car telephone, and it has been used in omni-zone and 3
Sector zones, or 6 sector zone configurations are used. However, the development of land mobile communications, especially car phones, has been remarkable in recent years, and it is expected that the present system will not be able to cope with the increase in mobile stations in large cities, and digital car phones are being considered in new frequency bands. .

This digital system is based on the current 860MH.
810MHz instead of the frequency band from z to 940MHz
Frequency bands in the ~ 960 MHz band are used. Since the conventional 9% bandwidth becomes a wide bandwidth of 17%, it is necessary to make the antenna's voltage standing wave ratio characteristic, gain characteristic, and horizontal plane directivity characteristic wide.

In the 6-sector zone structure, an antenna having a vertical polarization and a horizontal plane directional characteristic of 60 ° is used for a base station. As a radiating element for obtaining a 60 ° beam, a dipole antenna with a corner reflector 1 as shown in FIG. 7 is used.
Alternatively, a 2-dipole antenna 2 or the like in which dipole elements as shown in FIG. 8 are stacked in a horizontal plane and a reflector is attached thereto can be considered. On the other hand, considering the installation location of the base station antenna such as a steel tower or the rooftop of a building, an antenna that is small and lightweight and has a small wind receiving area is desired.

The dipole antenna 1 with a corner reflector shown in FIG. 7 comprises a dipole element 3 and a flat reflector 4 bent at a predetermined angle (in the figure, 5 is a power feeding connector).
The maximum aperture width of the reflection plate 4 is about 1.3 wavelengths (here, the wavelength refers to the wavelength of the frequency used). 2 of FIG.
The dipole antenna 2 includes two sets of dipole elements 6 and 6.
The reflector 7 has a width of about 0.8 wavelength, which is about 40% smaller in maximum width than the dipole antenna 1 with a corner reflector. Therefore, the two-dipole antenna 2 is advantageous in terms of small size, light weight, and wind receiving area.

The two dipole antennas 2 are, as shown in detail in FIG. 8, two sets of dipole elements 6 and 6, which are separated by about 0.6 wavelengths, a feed balun 8, support insulators 9 for the dipole elements 6 and 6. The feeder line 10, the reflector 7 having a width of about 0.8 wavelength, and the feeder connector 5 are included. The predetermined horizontal plane directivity is determined by the distance between the two dipole elements 6 and 6, the lateral width of the reflector 7, and the distance between the dipole elements 6 and 6 and the reflector 7. As an example, FIG. 9 shows the horizontal plane directivity of the two-dipole antenna 2, FIG. 10 shows the horizontal half-width characteristic, and FIG. 11 shows the gain characteristic.

[0007]

However, as shown in FIG.
As shown in FIGS. 10 and 11, the two-dipole antenna 2 has large fluctuations in the half-width of the horizontal plane directivity and the gain (frequency characteristics) with respect to the frequency, and is 810 MHz to 960.
In the MHz band, the half-width of the horizontal plane is as large as 40 ° to 65 °, and there is a problem that the sector zone cannot be sufficiently constructed.

The present invention has been made in view of the above points,
An object of the present invention is to solve the above-mentioned problems and to provide a wideband two-dipole antenna which can obtain a uniform beam with a small horizontal plane directivity half value width and a small gain variation with respect to a sector zone.

[0009]

The structure of the present invention for attaining the above-mentioned object is such that two sets of dipole elements arranged side by side and in parallel with each other and a distance of about 0.2 wavelength from the dipole elements. 2 consisting of a reflector arranged at a position
In the dipole antenna, it is as follows.

(1) Between the two sets of dipole elements, two sets of parasitic elements are arranged symmetrically with each other in parallel to the dipole elements.

(2) In the above (1), the two sets of parasitic elements are formed of trapezoidal metal plates having a short inner side and a long outer side.

[0012]

[Operation] Since the present invention is configured as described above,
At low frequencies, the current is mainly distributed only on the dipole element, whereas at high frequencies, the current is distributed on the parasitic element as well as the dipole element.

Therefore, the wideband two-dipole antenna of the present invention can improve the frequency characteristic of the horizontal plane half-width and can obtain a uniform beam over a wide frequency band within the sector zone.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be exemplarily described in detail below with reference to the drawings. 1 and 2 show an embodiment of a wideband two-dipole antenna of the present invention, FIG. 1 is a perspective view thereof, and FIG. 2 is a left side view thereof.

In FIG. 1 and FIG. 2, the wideband two-dipole antennas 11 are arranged on the left and right sides and in parallel with each other by about 0.6.
Two sets of dipole elements 12, 12 arranged at wavelengths apart from each other and each having a length of about 0.6 wavelength, and on the upper inside of the dipole elements 12, 12 in parallel with each other by about 0.
Two sets of unpaid elements 13 and 13 arranged at four wavelengths apart,
The dipole elements 12 and 12 are arranged in parallel with the dipole elements 12 and 12 at a distance of about 0.2 wavelength, and each of the dipole elements 12 and 12 has a 0.8-wavelength planar reflection plate 14.

The dipole elements 12 and 12 are separated from the reflecting plate 14 by about 0.2 wavelengths, and the supporting insulating members 15 and 15 are provided.
And the parasitic element 1
3 and 13 are feed lines 1 of the dipole elements 12 and 12.
6 and 16 are respectively supported by the supporting insulating members 17 and 17 so as to be arranged at about 0.03 wavelength upper part. In the figure, 18 is a power supply balun connected to the center of the power supply line 16, and 19 is a power supply connector.

The two sets of parasitic elements 13 and 13 which are arranged between the dipole elements 12 and 12 in parallel and symmetrically to each other are metal plates, and the inside thereof has a wavelength of about 0.3. The trapezoidal shape has an outside of about 0.4 wavelength.

FIG. 3 shows current distributions on the dipole elements 12 and 12 and the parasitic elements 13 and 13 when operated, at respective frequencies of low and high frequencies. At a low frequency, the current is mainly distributed only on the dipole elements 12, 12, but at a high frequency, the current is distributed on both the dipole elements 12, 12 and the parasitic elements 13, 13. There is.

Dipole element 1 in this high frequency range
Due to the current distribution on 2, 2 and parasitic elements 13, 13, a high frequency current between the dipole elements 12, 12 having a wavelength of 0.6 wavelength and the parasitic elements 13, 13 having a wavelength of 0.4 wavelength. The virtual center of the distribution exists and is located inside the low frequency range. This allows
The maximum values of the current distribution are located at equivalent wavelength intervals from the low frequency to the high frequency, and the horizontal half-width of the directional characteristic can be made equal.

FIG. 4 shows the horizontal plane directivity characteristics of the wideband two-dipole antenna 11 in this embodiment, FIG. 5 shows the horizontal plane half-width, and FIG. 6 shows the gain characteristics thereof. Figure 4,
As shown in FIGS. 5 and 6, the parasitic elements 13 and 1 are
It can be clearly seen from Fig. 3 that the half-width of the horizontal plane and the frequency characteristics of gain are improved.

FIG. 5 shows the half-width of the horizontal plane when the parasitic elements 13, 13 are formed from a trapezoidal shape to a rectangular shape. From FIG. 5, it can be seen that the trapezoidal shape has a smaller variation with respect to frequency. This is because there is a virtual center of the current distribution of the middle frequency outside the parasitic elements 13 and 13 due to the difference in length between the inside and outside of the parasitic elements 13 and 13, which improves the frequency characteristics. Is a factor of.

Note that the technique of the present invention is not limited to the technique in the above-described embodiment, and may be implemented by means of another aspect having the same function, and the technique of the present invention can be variously modified within the scope of the configuration. Can be changed or added.

[0023]

As is apparent from the above description, according to the wideband two-dipole antenna of the present invention, between two sets of dipole elements of the dipole antenna, two sets of non-power feeding are provided in parallel with the dipole elements. By arranging the elements symmetrically with respect to each other, it is possible to obtain a uniform beam having a small horizontal plane directional half-width with respect to frequency and a small gain variation in the sector zone.

For this reason, the deviation of the horizontal plane directional characteristic can be made constant over the 17% ratio band required in the 800 MHz band digital mobile phone.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of a wideband two-dipole antenna of the present invention.

FIG. 2 is a left side view of FIG. 1, showing an embodiment of the present invention.

FIG. 3 is a diagram showing a current distribution at a low frequency and a high frequency of the antenna of the present embodiment.

FIG. 4 is a horizontal plane directional characteristic diagram of the antenna of the present embodiment.

FIG. 5 is a frequency characteristic diagram of a horizontal plane half-value width in the antenna of the present embodiment.

FIG. 6 is a frequency characteristic diagram of gain in the antenna of the present embodiment.

FIG. 7 is a perspective view of a conventional dipole antenna with a corner reflector.

FIG. 8 is a perspective view of a conventional 2-dipole antenna.

FIG. 9 is a horizontal plane directional characteristic diagram of a conventional two-dipole antenna.

FIG. 10 is a frequency characteristic diagram of a horizontal plane half-width of a conventional two-dipole antenna.

FIG. 11 is a frequency characteristic diagram of gain of a conventional two-dipole antenna.

[Explanation of symbols]

 11 Broadband 2 dipole antenna 12 Dipole element 13 Parasitic element 14 Reflector

Claims (2)

[Claims] 1. Two arranged side by side and in parallel with each other
A set of dipole elements and about 0.2 from the dipole elements
A two-dipole antenna comprising a reflector disposed at a position separated by a wavelength (a wavelength is a wavelength of a frequency used), wherein two dipole elements are provided in parallel with the two dipole elements. A wideband two-dipole antenna in which a pair of parasitic elements are symmetrically arranged. 2. The wideband two-dipole antenna according to claim 1, wherein the two sets of parasitic elements are made of trapezoidal metal plates having a short inner side and a long outer side.