JPH05267926A - Primary radiator for parabolic antenna - Google Patents

Abstract

PURPOSE:To obtain an optimal radiation pattern and to utilize almost the whole mirror surface of a reflection mirror by providing additionally a concentric circular aperture ratio auxiliary ring on the outer periphery of a horn of a primary radiator, moving it in the axial direction of the horn and varying the opening diameter of the horn. CONSTITUTION:When the aperture ratio auxiliary ring 5 of the outer periphery of the horn 4 of the primary radiator 2 is moved to the rear of a horn opening so as to obtain the optimal reception state of a parabolic antenna attached to the roof of each home, etc., the aperture ratio auxiliary ring 5 goes to have no relation to the incidence of a radio wave and as for the primary radiator 2, the opening diameter of the horn 4 becomes the diameter. In such a manner, a comparatively wide radiation pattern is obtained, becomes to conform with a reflecting mirror whose opening angle is wide and almost the whole of the mirror surface of the reflecting mirror can be used. Also, when the aperture ratio auxiliary ring 5 is moved to the front of the horn opening part, the opening diameter of the ring 5 protruded forward becomes the diameter of the primary radiator 2 and a comparatively narrow pattern is obtained and can conform satisfactorily with the reflecting mirror whose opening angle is narrow.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a primary radiator of a parabolic antenna for receiving microwaves from satellite broadcasting and communication satellites.

[0002]

2. Description of the Related Art Parapolar antennas are most often used for direct reception of microwaves by end users such as homes using broadcasting satellites or communication satellites.
In a parabolic antenna A shown in the simplified cross-sectional view of FIG. 1, a reflecting mirror 1 and a primary radiator 2 are provided so as to face each other, and radio waves from a broadcasting satellite are reflected by the rotating secondary parabolic reflecting mirror 1 to be focused on a focus. The radio wave is received by the horn 2a of the primary radiator 2, and is guided from the rear portion of the primary radiator 2 to a converter 3 having a high-frequency signal amplification and same-wave conversion function through a waveguide 2b. FIG. 7 is a simplified enlarged sectional view of the primary radiator 2.

The aperture diameter of the primary radiator 2 is an important factor that determines the performance of the para-polar antenna in combination with the reflecting mirror 1, and there is a difference in the intensity depending on the angle of the incident radio wave. Areas of strong and weak electric fields, that is, different radiation patterns a, b, c of the primary radiator 2 are formed. If the radiation pattern does not match the aperture angle of the reflecting mirror (opening angle in the diametrical direction of the reflecting mirror as seen from the focal point of the reflecting mirror), the sensitivity of the antenna device may decrease and the noise may increase. To explain, the radiation pattern a of the primary radiator shown in FIG.
The antenna's aperture efficiency is low because it cannot receive radio waves from the entire aperture surface by receiving only radio waves in the vicinity of the center of the antenna and cannot effectively use the reflector. On the contrary, the radiation pattern b of the primary radiator in FIG. 9 is a horizontally long ellipse and is too wide in the horizontal direction, and the electric wave received from the reflecting mirror 1 becomes weak overall. Become. The radiation pattern c of the primary radiator shown in FIG. 10 is ideal because the aperture angle of the reflecting mirror 1 and the radiation pattern c are almost in a circle and the radiation pattern c is ideally received by the reflecting mirror 1 efficiently. As a result, an electric field with a uniform electric field over the entire surface and high sensitivity and low noise will be an excellent antenna.

The radiation pattern of the primary radiator generally depends on the aperture diameter of the horn 2a in FIG. 6, and the radiation pattern becomes larger as the aperture diameter becomes larger for a reflecting mirror having a certain aperture angle. As shown in FIG. 8, the radiation pattern a is narrow and high, and the smaller the opening diameter, the wider the radiation pattern b as shown in FIG. That is, as shown in FIG. 7, if the radio wave incident on the primary radiator 2 has a certain angle θ, a difference 1 occurs in the distance reaching both ends of the primary radiator, and a phase difference occurs in the incident radio waves at the both ends. Becomes weak. Furthermore, the situation is such that as the opening diameter of the horn 2a of the primary radiator increases, the phase difference of the radio waves gradually increases, and the sensitivity weakens even if the incident angle is small. However, if the opening diameter is large, radio waves from the front, that is, the axial direction can be efficiently received, so that the sensitivity becomes high and the radiation pattern becomes elongated as described above. On the contrary, if the opening diameter of the horn 2a of the primary radiator is small, the arrival amount of the radio wave from the axial direction is relatively smaller than the attenuation amount due to the phase difference, and the radiation pattern c is obtained, resulting in high sensitivity.

[0005]

The problem to be solved by the invention is that the primary radiator of the parabolic antenna obtains a radiation pattern suitable for the aperture angle of the reflecting mirror to form a uniform electric field over the entire surface of the reflecting mirror. An antenna system with good aperture efficiency, high sensitivity, and low noise is required, but it is not easy for the installed parabolic antenna to support the ideal reception posture for each user. It is an object of the present invention to easily construct a primary radiator of a parabolic antenna that obtains a good antenna system.

[0006]

According to the present invention, a concentric circular diameter auxiliary ring is attached to the outer periphery of a horn of a primary radiator provided at the focal position of a parabolic reflector, and the auxiliary diameter ring is attached to the horn. It is characterized in that the opening diameter of the horn of the primary radiator is changed by making it movable in the axial direction, that is, back and forth.

[0007]

[Function] In order to obtain the optimum receiving condition of the parabolic antenna installed on the roof of each home so as to receive the microwave from the broadcasting satellite etc., the aperture auxiliary ring on the outer circumference of the horn of the primary radiator is moved to the rear of the horn opening. When moved, the aperture auxiliary ring has no relation to the incidence of radio waves, and the aperture diameter of the horn becomes the diameter as a primary radiator, and a relatively wide radiation pattern is obtained and it becomes compatible with a reflector with a wide aperture angle. , Almost the entire mirror surface of the reflecting mirror can be used.
In some cases, moving the aperture assist ring forward of the horn opening results in a relatively narrow radiation pattern with the opening diameter of the ring protruding forward being the diameter of the primary radiator,
Well suited for reflectors with narrow aperture angles.

[0008]

1 to 5 are simplified cross-sectional views showing an embodiment of a primary radiator of a parabolic antenna of the present invention, and FIG. 1 shows the outer periphery of a horn 4 at the front end of the primary radiator 2 as a vertical outer wall 4a. Then, a caliber auxiliary ring 5 having a diameter larger than the horn opening diameter is fitted to the outer periphery of the horn so as to be slidable in the axial direction of the primary radiator, that is, in the front-rear direction, and the caliber auxiliary ring 5 moves rearward from the opening of the horn 4. It is in the state of having done. FIG. 2 shows a state in which the aperture auxiliary ring 5 is moved and protruded forward from the opening of the horn 4.

FIGS. 3 and 4 show specific means for sliding the aperture auxiliary ring back and forth on the vertical outer wall of the horn 4, and FIG. 3 shows the outer peripheral surface of the vertical outer wall 4a of the horn 4 and the inner periphery of the aperture auxiliary ring 5. This is a structure in which a female screw and a male screw that are screwed together are provided on the surface and the caliber auxiliary ring 5 is rotated and moved in the front-rear direction. FIG. 4 shows a structure in which the caliber auxiliary ring 5 is externally fitted on the vertical outer wall of the horn 4 so as to be slidable back and forth and fixed by a mounting screw 6 at a predetermined position. FIG. 5 shows a plurality of aperture auxiliary rings 5 and 5'concentrically attached to the outer periphery of the horn 4, and the means and mechanisms for sliding and fixing the aperture auxiliary rings back and forth are shown in FIG. 3 and FIG. The structure is made by screwing or mounting screws, and an optimum radiation pattern is obtained according to the aperture angle of the reflecting mirror corresponding thereto. The diameter and depth of the diameter auxiliary ring 5 are set theoretically and experimentally based on the relative relationship with the opening angle of the reflecting mirror, the focal length with the primary radiator, and the horn diameter. is there.

[0010]

Since the structure and operation of the primary radiator of the parabolic antenna of the present invention are as described above, (1), the parabolic antenna of the present invention is placed on the roof of each home or the like which receives a microwave from a broadcasting satellite. Is attached, and the caliber auxiliary ring is attached to the outer circumference of the horn of the primary radiator, and the caliber auxiliary ring is slid back and forth according to the opening angle of the corresponding reflecting mirror to obtain an optimum radiator pattern. If fixed at a position, the radiation pattern of the primary radiator can be arbitrarily changed for a reflector having wide and narrow aperture angles to obtain an optimum radiation pattern, and almost all mirror surfaces of the reflector can be used. A parabolic antenna with excellent performance can be configured, and an antenna system with high sensitivity and low noise can be obtained. (2) A high-performance antenna system can be created by manufacturing and attaching a small-scale aperture auxiliary ring without operating or replacing a precise and expensive reflector.

[Brief description of drawings]

FIG. 1 is a simplified cross-sectional view of a state in which a caliber auxiliary ring on the outer circumference of a horn of a primary radiator is located rearward.

FIG. 2 is a simplified cross-sectional view showing a state in which the diameter auxiliary ring is located in front of the outer periphery of the horn.

FIG. 3 is a schematic cross-sectional view showing a state in which the aperture auxiliary ring is fixed at a position slightly ahead of the horn by screwing female and male screws.

FIG. 4 is a cross-sectional view of a state in which the aperture auxiliary ring is fixed by a mounting screw.

FIG. 5 is a cross-sectional view of a horn fitted with a plurality of rings.

FIG. 6 is a simplified cross-sectional view of a parabolic antenna.

FIG. 7 is a simplified cross-sectional view showing the phase difference of the radio wave incident angle of the primary radiator.

FIG. 8 is a schematic diagram showing a vertically long radiation pattern of a primary radiator in a parabolic antenna.

FIG. 9 is a schematic diagram showing a horizontally long radiation pattern of a primary radiator in a parabolic antenna.

FIG. 10 is a schematic diagram showing an ideal radiation pattern of a primary radiator in a parabolic antenna.

[Explanation of symbols]

 2 Primary radiator 4 Horn 5 Auxiliary ring 6 Mounting screw

Claims (2)

[Claims] 1. A primary radiator of a parabolic antenna for receiving a microwave, which has a diameter larger than an opening diameter of the horn so as to be slidable on an outer periphery of a horn of the primary radiator in an axial direction (back and forth) of the primary radiator. A primary radiator of a parabolic antenna characterized in that the aperture auxiliary ring is attached to the horn so that the aperture of the horn can be varied so that the entire surface of the aperture of the reflector has a uniform electric field. 2. The primary radiator of the parabolic antenna according to claim 1, wherein a plurality of aperture auxiliary rings are concentrically attached to the outer periphery of the horn so as to be slidable in the axial direction of the primary radiator. .