JPH0251902A - Parabolic antenna system - Google Patents

Abstract

PURPOSE:To simplify the constitution and the adjustment, to reduce the power loss and blocking and to improve the mechanical strength by using a single wire type spiral antenna in a planer form as a primary radiator. CONSTITUTION:The single wire spiral antenna 7 as a primary radiator is arranged to a focus of a parabolic reflecting mirror 1 and a coaxial line 6 is connected to the feeding point in the center of the single wire spiral antenna 7. The single wire spiral antenna 7 consists of one spiral conductor 8 connecting one end of a center conductor 6A of a coaxial line 6 and a matching disk 9 connecting to an outer conductor 6B of the coaxial line. Since the feeding coaxial line is led in a short distance on the center axis of the reflecting mirror, the power loss and blocking by the coaxial line are less, the mechanical strength is improved and the structure and adjustment are simplified.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a circularly polarized parabolic antenna device used for microwave communications such as receiving satellite broadcasting.

(Summary of the Invention) The present invention uses a spiral antenna having a single-wire spiral conductor as a -order radiator in a circularly polarized parabolic antenna device used for microwave communication such as receiving satellite broadcasting. It is something.

(Prior art) Conventionally, as this type of SHF day polarized river channel bora antenna device, there has been one that uses an end 7-year helical antenna as a -order radiator, as shown in Japanese Patent Application Laid-Open No. 56-93402. there were. FIG. 6 shows an example of the configuration in this case. In this figure, an end-fire helical antenna 2 is placed at the focal point of a parabolic reflector 1, and power is supplied to this by a coaxial line 3.

In addition, in Japanese Patent Application Laid-Open No. 62-32707 by the present applicant,
- A parabolic antenna device using a backfire helical antenna as a secondary radiator has been proposed. An example of the configuration in this case is shown in FIG. 7. In this figure, a backfire helical antenna 5 is arranged at the focal point of the parabolic reflector 1, and power is supplied to it by a thin line 6. The directivity of the backfire and helical antenna 5, that is, the main rope MB is directed toward reflection [1].

(Problem to be Solved by the Invention) By the way, in the conventional example shown in FIG. As a result, the coaxial line 3 is led out across the front surface of the parabolic reflector 1. Therefore, blocking occurs due to the coaxial line 3, and since the coaxial line 3 becomes long, loss is also large.Furthermore, there are problems with the support strength of the end 7-ear helical antenna 2.

In addition, another conventional example shown in the pIS7 figure above attempts to solve the problems of the conventional example shown in FIG. 6 by using a backfire helical antenna 5 as a -order radiator, Because it has a helical-shaped conductor in which the conductor is wound, the overall length of the -order radiator is thick (it is bulky, and there is a problem that the antenna depth is considerably larger than the focal length when configured as a parabolic antenna device). there were.

In addition, two
A parabolic antenna device using a #I type spiral antenna has been proposed. In this case, the -order radiator can be made smaller than that of a backfire helical antenna, and the depth of the parabolic antenna device can be reduced, but since a matching box must be used, the number of parts increases and the cost and configuration become more complex. There was also the problem that adjustment was difficult.

In view of the above points, the present invention uses a single-wire spiral antenna configured in a planar shape with a -order radiator, which is easy to configure and adjust, has low power loss and pro-waking, and has high mechanical strength. An object of the present invention is to provide a parabolic antenna device with a small depth dimension that can improve the characteristics of the antenna.

(Means for Solving the Problems) The present invention has a configuration in which a spiral antenna having a single-wire spiral conductor is arranged on the side of a reflecting mirror where the focal point is present, and a coaxial line is connected to the spiral antenna. The above problem, α, is solved.

(Function) The spiral antenna used in the present invention has a reflector arrangement side (
It has directivity on the power supply side), that is, the main lobe faces toward the reflector arrangement side, and has a spiral shape.
The center-side end of the conductor can be used as a feeding point. Therefore, when the spiral antenna is disposed at the focal point of the reflector, the feeding parallel line can be drawn out over the shortest distance on the center axis of the reflector. Therefore, there is almost no blocking due to the thin lines, and power loss can also be reduced. Furthermore, since the spiral antenna is configured in a planar shape, the depth dimension when combined with a reflecting mirror can be reduced. Furthermore, structurally, it is easy to ensure the support strength of the spiral antenna.

(Example) Hereinafter, an example of a parabolic antenna device according to the present invention will be described with reference to the drawings.

A first embodiment, which is the basis of the present invention, will be explained with reference to FIGS. 1 to 3. In these figures, a single-wire spiral antenna 7 is arranged at the focal point of the parabolic reflector 1, and a thin line (for example, a semi-rigid cable) 6 is connected to the feeding point at the center of the single-wire spiral antenna 7. Ru.

Here, the single-wire spiral antenna 7 has a single spiral shape (spiral shape) connected to the center conductor 6A of the coaxial line 6 at its center end, as shown in FIGS. 2 and 3.
It consists of a conductor 8 and a matching disk 9 connected to the outer conductor 6B of the coaxial line.

The current flowing through the fine line 6 is guided by the matching disk 9 and travels to the spiral conductor 8. ! ! The current distribution in the area of a congruent disk-lined spiral conductor is
It behaves as a transmission line current distribution between two lines. However, the image current generated in this area suppresses the radiation of radio waves from this part. Radio emission occurs predominantly in the area of the spiral that is not lined by a matching disk.

The most preferable arrangement of the spiral antenna 7 and the coaxial line 6 is when the center of the spiral antenna 7 and the direction in which the coaxial line/path 6 is drawn out are located on the central axis of the reflecting mirror 1. The directivity of the spiral antenna 7, that is, the main rope MB is, for example, at point #i in FIG.
It is indicated by.

Next, the operation of the first embodiment will be explained in the case of reception.

Electromagnetic waves incident in the direction of arrow W in FIG.

At this time, since the spiral antenna 7 has the main rope MB on the reflector placement side (power feeding side), the electromagnetic waves reflected by the reflector 1 are efficiently transferred to the spiral antenna 7.
received at In this case, the spiral antenna 7 exhibits good characteristics when the received electromagnetic waves are circularly polarized waves, similar to the helical antenna.

The parabolic antenna device shown in the first embodiment uses the single-wire spiral antenna 7 with a planar structure as the primary radiator used in combination with the reflector 1, so a helical antenna is used as the primary radiator. The depth dimension of the device can be reduced compared to the conventional case. Further, the feeding point can be set at the center side end of the spiral conductor 8, and the coaxial line 6 for power feeding can be drawn out over the shortest distance.

Therefore, power loss can be reduced, the coaxial line 6 does not need to cross the front surface of the reflecting mirror 1, and blocking does not occur. Furthermore, by employing a 7mm gamma cable, rigid cable, etc. as the coaxial line 6, it can be used as a support for the spiral antenna 7, and the support structure becomes a simple cylinder, and it is easy to ensure sufficient mechanical strength. be. Furthermore, the structure is simple, suitable for mass production, and advantageous for miniaturization.

Figure PJ4 shows a second embodiment of the invention. In this case, the single-wire spiral antenna 7A as a dog radiator consists of one spiral-shaped conductor 8 connected to the center conductor 6A of the thin line 6 at the center side i part, and a coaxial line. A matching disk 9 is connected to the outer conductor 6B of the spiral conductor 8, and a radio wave absorber 10 is disposed on the front side of the spiral conductor 8.

The shape of the radio wave absorber 10 is, for example, a disk shape that is approximately the same as or slightly larger than the outer diameter of the spiral-shaped conductor 8.

This arrangement of the radio wave absorber 10 suppresses unnecessary beams from the spiral antenna facing away from the reflecting mirror. Although not shown in the drawings, the above-described single-wire spiral antenna 7A is disposed at the focal point of the parabolic reflector 1, as in the first embodiment.

FIG. 5 shows a third embodiment of the invention. In this case, the single-wire spiral antenna 7B as a -order radiator has one spiral-shaped (vortex-shaped) conductor 8 connected to the center conductor 6A of the coaxial line 6 at the center side ia, and the same thin line. It consists of a matching disk 9 connected to the outer conductor 6B and a radio wave reflector 11 placed on the front side of the spiral conductor 8.

The radio wave reflector 11 is, for example, a thick disc-shaped plate that is approximately the same as or slightly larger than the outer diameter of the spiral-shaped conductor 8.

This arrangement of the radio wave reflector 11 suppresses unnecessary beams from the spiral antenna facing away from the reflector.

(Effects of the Invention) As explained above, the parabolic antenna device c of the present invention
According to the above, a spiral antenna having a single-wire spiral conductor is placed on the focal point side of the reflector, a coaxial line is connected to the spiral antenna, and the spiral antenna is used as a primary radiator. Therefore, power loss and blocking can be reduced, mechanical strength can be improved, and the depth of the device can be reduced. There are also features that are easy to structure and adjust and are suitable for mass production.

[Brief explanation of the drawing]

FIG. 1 is a side sectional view showing a first embodiment of a parabolic 7 antenna device according to the present invention, FIG. 2 is a sectional view showing a spiral antenna used in the first embodiment, and FIG. 3 is a perspective view of the same. Fourth
Figure 5 is a side sectional view showing the second embodiment of the present invention, Figure @5 is a side sectional view showing the third embodiment of the invention, Figure 6 is a side sectional view of a conventional example of a parabolic antenna device, and Figure 7. 1 is a side sectional view of another conventional example of a parabolic antenna device. 1... Parabolic reflector, 6... Coaxial line, 7,7A,
7B... Spiral antenna, 8... Spiral-shaped conductor, 9... Matching disk, 10... Radio wave absorber,
11...Radio wave reflector.

Claims (4)

[Claims] (1) A parabolic antenna device characterized in that a spiral antenna having a single-wire spiral conductor is arranged on the side where the focal point of the reflecting mirror is present, and a coaxial line is connected to the spiral antenna. (2) The parabolic antenna device according to claim 1, wherein the single-wire spiral antenna has a matching plate at a feeding end and a radio wave absorber in front of the spiral conductor. (3) The parabolic antenna device according to claim 1, wherein the single-wire spiral antenna has a matching plate at a feeding end and a reflector in front of the spiral conductor. (4) The parabolic antenna device according to claim 1, wherein the single-wire spiral antenna is located at the focal point of the reflecting mirror, and the coaxial line is installed on the central axis of the reflecting mirror.