JPH0533053Y2 - - Google Patents

Description

[Detailed description of the invention] <Industrial application field> This invention relates to an antenna equipped with an improved feeder, and in particular improves directivity by arranging the radiator on the same plane as the arm of the antenna. ,
The present invention relates to an antenna in which a sleeve tube type balanced-unbalanced converter can be installed in the power feeding section as required.

<Prior art> In a conventional antenna, for example, as shown in FIG. 4, a radiator 1 is attached to a mounting fixture 5 that includes a feeding section above or below an antenna arm 4 to which a reflector 2 and a waveguide 3 are attached. It was installed via. A coaxial cable 6 connected to the fixture 5 was pulled out from the front of the antenna.

<Problems to be solved by the invention> In the conventional antenna as described above, the radiator 1 is located on a plane that is offset from the plane in which the reflector 2 and the waveguide 3 are lined up. At higher frequencies, the directivity characteristics of the antenna deteriorate, resulting in directivity that deviates from the intended direction, and the level of side lobes increases. Figure 5 shows the conventional antenna shown in Figure 4, for example 1.275G.
In the diagram showing the Hz directivity characteristics, the direction of the main lobe 7 is slightly tilted from the desired 0° direction, and the side lobes are also considerably larger than those of the antenna according to the present invention, which will be explained later.

<Means for solving the problem> The antenna according to this invention has a cylindrical radiator support terminal made of electrically insulating resin at one end of the antenna arm, with its central axis and the central axis of the arm. and each element of the radiator is attached to the terminal, and the core wire and braid of the coaxial cable inserted into the terminal are respectively connected to each element of the radiator.

Another feature of the antenna according to this invention is that a conductive sleeve tube, which acts as a balanced-unbalanced converter with a length longer than 1/4 wavelength of the operating frequency, is placed inside the cylindrical radiator support terminal coaxially with the terminal. The coaxial cable braid and the sleeve tube are electrically connected at a position approximately 1/4 wavelength in terms of electrical length within the sleeve tube from the power feeding point of the radiator.

<Function> According to the antenna of this invention, since the radiator element is placed on the central axis of the electrically stable antenna arm, the radiator element and the waveguide element are located on the same plane, and The radiator element can also take a symmetrical positional relationship with respect to the reflector element with the antenna arm as the center. For this reason, for example 1G
It exhibits excellent directivity characteristics even at high operating frequencies of Hz or higher, and the sidelobe level is extremely low. In addition, by using this invention in combination with a large number of stacked waveguides, it is possible to achieve extremely high gain and low sidelobes in a given direction.
You can get a level antenna.

<Description of Embodiments> This invention will be described in detail below with reference to illustrated embodiments.

1 and 2, 10 is an antenna arm, and 11 is an element holder 1 attached to the antenna arm 10.
The waveguide is attached via 2. A cylindrical terminal 13 made of insulating resin is connected to the end of the antenna arm 10, and both are fixed by rivets 14. Radiator elements 15, 15 are screwed and attached to the terminal 13. A conductive sleeve tube 16 that is longer than the operating frequency 1/4 wavelength and acts as a balanced-unbalanced converter is inserted into the terminal 13, and its tip ends slightly before the radiator elements 15, 15. There is. The conductive sleeve tube 16 is fixed to the terminal 13 by screws 17,17. A coaxial cable 18 is inserted into the sleeve tube 16, the core wire 19 of which is electrically connected to one radiator element, and the braided conducting wire 20 is electrically connected to the other radiator element. Connect the coaxial cable 18 at a position approximately 1/4 wavelength in terms of electrical length inside the tube from the tip of the sleeve tube 16.
The cover has been removed, and the metal screw 2
Sleeve pipe 16 at 1, 21 (4 locations every 90°)
The coaxial cable is electrically connected to the coaxial cable braid, and the coaxial cable is fixed. Further, a reflector 22 is attached to the sleeve tube 16 by a pedestal 23 at a position approximately 1/4 wavelength from the radiator elements 15, 15, and the reflector elements 24, 24 at the center of the reflector 22 is screwed into the sleeve tube 16 through the pedestal 23, thereby electrically connecting the reflector elements 24, 24 via the sleeve tube 16, and connecting the pedestal 23 and the sleeve tube 16.
are mechanically connected. 25 is an O-ring for keeping the coaxial cable 18 coaxial with the sleeve tube 16, and 26 is a waterproof tube for keeping the coaxial cable 18 coaxial with the sleeve tube 16 and preventing water from entering the sleeve tube. It is.

<Effects> According to the antenna feeding section having the above structure,
Since the radiator elements 15, 15 are arranged on the central axis of the arm 10, the radiator elements 15, 15, the waveguide element and reflector element located above the arm, and the radiator elements 15, 15, Waveguide element, reflector element and radiator element 1 located on the lower side of the arm
The positional relationship between 5 and 15 and the waveguide element and reflector element located below the arm is completely symmetrical about the arm. As a result, it is possible to obtain an antenna that has directivity characteristics that are accurately oriented in the desired direction and also has a low sidelobe level. Figure 3 is a diagram showing the 1.275GHz directivity characteristics of the antenna according to this invention.Compared to that of the conventional antenna shown in Figure 5, the direction of the main lobe is exactly 0°, and the side The level of the robe has also become much smaller. Well, according to this idea, the sleeve tube 16 is longer than 1/4 wavelength.
The sleeve tube 16 acts as a balanced-unbalanced converter, and the coaxial cable By directly connecting the 18 core wires 19 and the braid 20 to the radiator elements 15, 15, the adverse effects of the unbalanced current flowing therein can be prevented and stable operation can be obtained. Furthermore, since the coaxial cable 18 can be taken out from the rear of the antenna, there is no disturbance in the directivity characteristics caused by the coaxial cable.

According to this invention, it has excellent directional characteristics even at high frequencies of 1 GHz or higher, and its operation is stable.
In particular, in combination with a stacked waveguide, an antenna with high gain and stable operation can be constructed. In the above embodiment, the waveguide element and the reflector element were provided symmetrically above and below the arm 10, but the waveguide element was provided so as to pass through the arm, similar to the conventional one shown in FIG. , and only those indicated by reference numerals 24 and 24 may be provided as reflector elements.

[Brief explanation of the drawing]

Figure 1 is a partially omitted cross-sectional view of an embodiment of the antenna according to this invention, Figure 2 is a perspective view of the antenna in Figure 1, and Figure 3 shows the directivity characteristics of the antennas in Figures 1 and 2. 4 is a perspective view of a part of a conventional antenna, and FIG. 5 is a diagram showing the directivity characteristics of the antenna of FIG. 4. 10... antenna arm, 13... radiator support terminal, 15... radiator element, 16... sleeve tube, 18... coaxial cable, 19... core wire,
20... Braid, 21... Screw joining the sleeve tube and the braid, 22... Reflector, 24... Reflector element.

Claims (1)

[Claims for Utility Model Registration] (1) A cylindrical radiator support terminal made of electrically insulating resin at one end of the antenna arm;
Connect the arms so that their central axes match the central axes of the arms, attach each element of the radiator to the terminal, and connect the core wire and braid of the coaxial cable inserted into the terminal to each element of the radiator. Antenna that is connected. (2) A conductive sleeve tube with a length longer than 1/4 wavelength of the operating frequency that acts as a balanced-unbalanced converter is inserted coaxially with the above terminal into the inside of the above terminal, and the feed point of the radiator is inserted into the sleeve tube. 2. The antenna according to claim 1, wherein the coaxial cable braid and the sleeve tube are electrically connected at a position of about 1/4 wavelength with an electrical length of .