JPS6320181Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a low sidelobe parabolic antenna that improves directivity by limiting specific directions.

Parabolic antennas used in microwave communication lines are desired to have low sidelobes from the viewpoint of effective use of frequencies in line networks with complex station placement and frequency allocation. Conventionally, in order to obtain good directional characteristics, as shown in the perspective view of FIG.
In some cases, a parabolic reflector 1 having a primary radiator 2 is provided with a shielding plate 3 around the periphery to suppress unnecessary radiation, and as shown in the perspective view of FIG. 2 and the enlarged view of FIG. There was one in which a leakage current blocker 4 (chiyoke) was provided in the opening of 2 to suppress unnecessary radiation. However, since the shielding plate 2 is attached to the parabolic reflector 1 itself, the former has the disadvantage that it is structurally large and increases the wind pressure load and self-weight, and as the opening diameter becomes larger, the manufacturing cost and the number of installation steps increase. There was a drawback. In addition, the latter has the disadvantage that by installing the leakage current blocker 4, the design must take into full consideration the reduction in gain due to the influence of radiation characteristics in the main direction and the frequency characteristics, and the dimensions and shape must be determined. . In addition, these conventional structures can suppress and improve the unnecessary radiation component of the primary radiator, which is the main factor that deteriorates the directivity characteristics of the antenna. There is a limit to how close the directional characteristics can be to the determined directional characteristics, and further improvement has been difficult.

The purpose of this invention is to provide a variable mechanism for the position or angle of a plate member made of a small metal or radio wave absorbing material with a simple structure, and to adjust the position or angle of the plate by attaching it around the opening of the primary radiator. An object of the present invention is to provide a low sidelobe antenna that suppresses unnecessary radiation of a device and at the same time compensates and improves radiation characteristics in a specific direction.

This idea is designed to suppress the unnecessary radiation of the primary radiator and compensate the radiation characteristics at the same time when the unnecessary radiation of the radiation characteristic of the primary radiator degrades the directivity characteristics of the parabolic antenna. A plate member made of metal and a radio wave absorbing material is provided around the area with a variable mechanism that can adjust the mounting position or angle, and the directivity characteristic in a certain specific direction is mainly improved.

This invention will be explained in detail below with reference to the drawings.

FIG. 4 is a perspective view of an embodiment of this invention, and FIGS. 5a, b, and c are partially enlarged top, side, and front views of FIG. 4. A small metal plate 5 is added to an antenna constituted by a parabolic reflector 1 and a primary radiator 2. This metal plate 51 is attached near the opening of the primary radiator, and the metal plate 51
is connected to an angle adjustment screw 53 by a hinge 54, and by adjusting the length of this angle adjustment screw 53, the opening angle of the metal plate 51 can be varied. Furthermore, they are attached to the waveguide section of the primary radiator main body 2 by a block 52, and by moving the position of this block along the tube axis, the position of the metal plate 51 relative to the primary radiator opening can be varied. is possible. Therefore, depending on the position and angle of this metal plate 51, unnecessary radiation on the sides and rear of the primary radiator can be suppressed, and a part of the radiated power can be canceled out to give a dip in the directivity characteristics. You can expect it.

FIG. 6 shows the actual data for improving the directivity characteristics of the 7 GHz 3 mφ antenna according to the present invention, where the solid line is the peak envelope value before improvement, and the dashed-dotted line and dotted line are the peak envelope values improved according to the present invention. The difference between the dashed line and the dotted line is that the opening angle of the metal plate 51 is the same, but the position in the axial direction with respect to the opening is slightly changed. As can be easily understood from now on, the angle that causes a 60 to 65 dB drop in the directional characteristics is changing. Therefore, by utilizing this characteristic, it is possible to further improve the directional characteristic compared to the generally obtained directional characteristic.

Note that the reduction in gain due to the attachment of the metal plate or the like according to this invention is of a level that does not cause any practical problems. In this example, we have explained the case where two metal plates are attached on both sides, but this can be done by attaching one metal plate to one side if it is in one direction, or if you want to improve all directions to a certain level and at the same time further improve a specific direction. is cylindrical,
It is easy to think that it would be effective to consider various shapes such as a conical shape or a pyramidal shape, and to attach a radio wave absorber at the same time. The embodiment of this invention has been described as a transmitting antenna, but due to its reversibility, radio wave interference can be similarly reduced when used as a receiving antenna.

From the above, when the present invention is applied to an antenna with a relatively small diameter or a small aperture angle, it can be expected to produce more effective results that are sufficiently improved compared to the directivity characteristics generally obtained in limited directions and frequencies. In addition, since the structure of the present invention is relatively simple and compact, it can be applied to antennas on existing lines, improving line quality and reducing wind pressure loads.
The influence on weight etc. can be ignored, and the cost is also very low.

[Brief explanation of the drawing]

Fig. 1 is a perspective view of an antenna with a conventional shielding plate attached, Fig. 2 is a perspective view of an antenna with a leakage current blocker attached to a conventional primary radiator, and Fig. 3 is an enlarged, partially broken view of Fig. 2. 4 is a perspective view of the embodiment of the present invention, FIGS. 5 a, b, and c are enlarged plan views, side views, and front views showing the vicinity of the primary radiator opening in FIG. It is the characteristic data of the Example of this invention. In the figure, 1... parabolic reflector, 2... primary radiator, 3... shielding plate, 4... leakage current blocking section, 5... metal plate according to the present invention, 51... metal plate, 52... mounting 53...Angle adjustment screw, 54...Hinge.

Claims (1)

[Scope of utility model registration request] A predetermined number of plate members made of metal or radio wave absorbing material are supported around the opening of the primary radiator by means for varying the front and rear positions and angles of the plate members with respect to the primary radiator opening. A low sidelobe parabolic antenna featuring