JPS59194513A - Parabolic antenna for circular polarized wave - Google Patents

Abstract

PURPOSE:To omit a circular/angular converter, to obtain an economical antenna and to reduce the quantity of reflected waves from a glid type circular polarized wave generator to a pyramid horn by constituting a parabolic antenna by a parabola, a pyramid horn by constituting a parabolic antenna by a parabola, a pyramid corn, a down converter, an apex matching plate and the glid type circular polarized wave generator. CONSTITUTION:The circular polarized wave parabolic antenna is constituted by the parabola 1, the pyramid horn 14, the down converter 6, the elliptical cone type apex matching plate, and the glid type circular polarized wave generator 10 The terminal of the converter 6 is formed like a square and directly connected to the pyramid horn 14, so that the circular/angular converter can be omitted. Straightly polarized radio waves are radiated from the pyramid horn 14 and converted into circularly polarized waves by the glid type circular polarized wave generator 10 and the converted circular polarized waves are reflected, irradiated to the parabola 1 and then radiated to the space. The center axis of the pyramid horn 14 is made coincide with that of the apex matching plate 15 and the longitudinal direction of an opening of the pyramid horn 14 is made coincide with the apse line direction of the ellipse of the apex matching plate 15. Thus, the quantity of reflected waves from the circular polarized wave generator 10 to the pyramid horn 14 can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement of a circularly polarized parabolic antenna consisting of a primary radiation system and a parabola.

A conventional antenna of this type is shown in Figure 1.

Parabola (1) 9-conical horn (2), circularly polarized wave generator (3)
), a round-angle converter (4), a rectangular waveguide (5), and a down-converter (6). Furthermore, people are the central axis of parabola. Here, the nine circularly polarized wave generator (3) is generally one in which a quarter wavelength plate is inserted into a circular waveguide.

Further, the round angle converter (4) smoothly converts the rectangular aperture of the rectangular waveguide (5) and the circular aperture of the circularly polarized wave generator (3). Further, the down converter (6) has a built-in local oscillator and converts it to an intermediate frequency. The operation of this antenna will be explained in the case of transmission. The high frequency of the TEso mode from the rectangular waveguide (5) is converted to the TEs1 mode of the circular waveguide constituting the 9 circularly polarized wave generator (3),
After passing through the quarter-wave plate, it becomes a circularly polarized wave, which is guided to the conical horn (2), irradiates the parabola (1), and is radiated into space. In this irradiation.

Since the rectangular waveguide (5) is in the direction of propagation of radio waves, blocking occurs. Furthermore, this rectangular waveguide (5) also causes blocking when it is reflected by the parabola (1) and goes into space. In addition, when heading towards this space, use the conical horn (2).

The circularly polarized wave generator (3) and the round angle converter (4) also experience blocking, but since the position of this blocking is at the center of the parabola, the amount of blocking is smaller than in the case of the rectangular waveguide (5). There aren't many. Therefore, blocking due to the rectangular waveguide (5)K becomes a problem, which causes performance deterioration such as a decrease in gain and an increase in sidelobe level.

Therefore, the configuration is such that the nine rectangular waveguides (5) can be omitted.

There is an antenna shown in FIG. A conical horn (2), a nine-circularly polarized wave generator (3), and a round angle converter (4), which constitute the -order radiation system, are supported by a stay (7). in this case.

The blocking by the rectangular waveguide (5) in FIG. 1 is replaced by blocking by the stay (7).

In order to reduce performance deterioration due to fluctuations in the primary radiation system during strong winds, it is necessary to increase the width of the stay (7), which will increase blocking and cause performance deterioration as in the case of Figure 1. There was a drawback that caused

As a type with a small amount of blocking, there is a rear-feed type in which the position of the punching is placed at the center of the parabola. 'A conventional rear-feed antenna is shown in Figure 3.

Conical horn (2), 9 circularly polarized wave generator (3), round angle converter (
4).

Down converter (6), metal plate (8), vertex alignment plate 1
The radio wave emitted from the conical horn (2) is reflected by the metal plate (8), and the reflected wave is (1) and is radiated into space. Therefore.

The main cause of blocking in this case is the metal plate (8). Note that conventionally, a conical horn (2) is often used in such a circularly polarized antenna.

In this case, a 9-conical plate is used as the vertex matching plate (9). Here, to get a cheap antenna,
A format with as few parts as possible is required, and conventional equipment was not sufficient.

This invention uses a grid-type circularly polarized wave generator and a pyramidal horn to eliminate this drawback.

The present invention will be explained in detail below with reference to one drawing.

FIG. 4 shows an embodiment of the present invention, and the circularly polarized parabolic antenna of the present invention includes a parabola f1), a down converter (6) consisting of 70 pyramidal hoes, and an apex matching plate 119. and a grid-shaped circularly polarized wave generator 1101.

The terminal of the down converter (6) is rectangular and can be directly connected to the pyramidal horn circle, eliminating the need for round-corner conversion. A linearly polarized radio wave is radiated from a pyramidal horn circle, and is converted into a circularly polarized wave by a grid-shaped circularly polarized wave generator flQl.

It is reflected, irradiates the parabola (1), and is radiated into space.

FIG. 5 is an explanatory diagram of the principle of a grid-type circularly polarized wave generator.

This is a dielectric plate till with a thickness t, with a metal foil 02 stretched over the entire surface of one side, and a straight conductor U made of metal foil of a constant width on the other side.
□□□ are arranged repeatedly at regular intervals, and hereinafter, the former surface will be referred to as the metal foil surface and the latter surface as the grid surface. Assuming that the electric field pressure of a linearly polarized wave forming an angle of 45° with the straight conductor u3 is incident perpendicularly to the straight conductor u3, the component parallel to the straight conductor U3 will be reflected by the grid surface, and the perpendicular component will be reflected by the dielectric. It passes through the plate Ill, is reflected by the metal foil surface, passes through the dielectric plate t11J, and is finally radiated into space with a phase change of 2t(F-r>. Here, ε is the dielectric constant of the dielectric plate fill, and λ is the wavelength. Therefore, the values of ε and t are 4πF−−−′ −−−−−−−−−−−−−−−−
--+1) λ-2, circularly polarized waves can be obtained by the electric field reflected by the grid surface and the electric field reflected by the metal foil surface.

Therefore, in this case as well, the radio waves emitted from the pyramidal horn +141 are reflected by the grid-shaped circularly polarized wave generator (111I).
Therefore, a conical vertex matching plate 191 was used, but in this case, since it is a pyramidal horn (141), an elliptic conical vertex matching plate (15) is required.

FIG. 6 shows the relationship between the arrangement of the elliptical conical apex matching plate f151 and the square horn Q41. That is, the central axis of the pyramidal horn I and the central axis of the elliptical apex matching plate (15) are aligned, and the long side direction of the opening of the pyramidal horn Q41 is aligned with the long axis of the elliptic apex matching plate (19). The apex alignment plate is a pyramidal horn (14
1 circularly polarized wave generator (1[
It also contributes to controlling the radiation pattern from I.

Therefore, in some cases, the elliptical conical apex matching plate (151) shown in FIG. As described above, the circularly polarized parabolic antenna according to the present invention does not require a round angle converter, so an inexpensive antenna can be obtained, and by using an elliptical conical apex matching plate, a grid-shaped circularly polarized wave generator can be obtained. This has the advantage of reducing the amount of reflected waves from the horn to the pyramidal horn.

[Brief explanation of the drawing]

1 and 2 are schematic illustrations of a conventional circularly polarized parabolic antenna, FIG. 3 is a diagram showing a conventional rear-feed circularly polarized parabolic antenna, and FIG. 4 is a schematic diagram of an embodiment of the present invention. 5 is a diagram explaining the principle of a grid-type circularly polarized wave generator, and FIG. 6 is a partially enlarged view of FIG. 4. In the figure, (1) is a parabola, (2) is a conical horn, and (3)
is a circularly polarized wave generator, (4) is a round angle converter, and (5) is a rectangular waveguide. (6) is a down converter, (7) is a stay, and (8) is a metal plate. (9) is an apex matching plate, and 110+ is a grid-type circularly polarized wave generator. C11) is a dielectric plate; Agent Masuo Oiwa No. 2 Figure 3 Cause No. 4

Claims (1)

[Claims] A pyramidal horn is arranged along the central axis of the parabola. In this circularly polarized parabolic antenna with a reflective circularly polarized wave generator installed in the front, the central axis of the elliptical cone-shaped apex matching plate is aligned with the central axis of the parabola, and the ellipse of the apex matching plate is aligned with the central axis of the parabola. The apex matching plate is arranged on the surface of the reflective circularly polarized wave generator so that the long axis direction of the shape coincides with the long side direction or the short side direction of the opening of the pyramidal horn. Circularly polarized parabolic antenna.