JPH0287807A - Antenna equipment - Google Patents

Abstract

PURPOSE:To direct the beam of an antenna at any azimuth and to miniaturize an equipment by forming a main reflection mirror to a ring torus shape and fixing this mirror and using a horn elliptic mirror as its primary radiator and rotating this mirror around a horn shaft. CONSTITUTION:This equipment consists of an offset parabolic torus mirror surface 11, an elliptic mirror surface 21 which can be rotated around the revolving shaft of the torus mirror surface 11 and has the focus of the offset parabola as one focus, and a horn 3 which has the other focus of the elliptic mirror surface 21 as the phase center. That is, the main reflection mirror is fixed, and an offset type antenna symmetrical with respect to the rotation axis is obtained, and only the elliptic mirror 21 is rotated around the revolving shaft. Thus, the equipment is miniaturized and a beam 5 can be directed to all azimuthal directions.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an antenna device, and particularly to an earth station antenna and a radar antenna for satellite communication.

[Conventional technology]

Figure 3 is an example of literature: Antenna Engineering Handbook Ohmsha, 1980 Edition Chapter 4 Aperture Antenna 4.2
It is an external view showing the conventional antenna device shown in the basic configuration of an aperture antenna (P160-P161),
FIG. 4 is a diagram showing its principle.

In the figure, 1 is the main reflecting mirror, an off-cent parabola with F as the focal point, 2 is an elliptical mirror, F is one focal point of the elliptical mirror that is shared with the focal point of the reflecting mirror, and Fo is the other focal point of the elliptical mirror 2. , they share the phase center of horn 3. 4 is the axis of the horn 3, and the reflecting mirror 1 and the elliptical mirror 2 can be coaxially centered around this axis. Therefore, the radiation beam 5 from the antenna is directed in a constant direction at an angle α with respect to the horizontal (elevation angle El
-α) allows the depression angle (Az) to be moved in any angular direction.

Next, the operation will be explained. The radio waves 6 emitted from the horn 3 are converged by the elliptical mirror 2, focused at F, directed toward the offset parabola 1 again, reflected by this, and then radiated into space as a radiation beam 5 at an elevation angle α. Ru. Furthermore, in order to change the azimuth angle Az, it is sufficient to fix the horn 3 and rotate both the offset parabola 1 and the elliptical mirror 2 around the Az axis 4.

[Problem to be solved by the invention]

Since the conventional antenna device is configured as described above, it is necessary to rotate both the offset parabola 1 and the elliptical mirror 2, and the rotation, especially the rotation of the offset parabola, requires a fairly large and expensive mechanism. The problem was that it was needed.

This invention was made in order to solve the above-mentioned problems, and aims to provide a small and economical offset type antenna device that can move the beam in all directions in the Az force direction. purpose.

[Means to solve the problem]

In the antenna device according to the present invention, the main reflecting mirror is a fixed structure and a rotationally symmetrical offset type antenna, and only the elliptical mirror is rotated around the rotation axis.
The beam can be moved in the Az force direction.

[Operation] In the antenna device of the present invention, the main reflecting mirror is a fixed structure and a rotationally symmetrical offset type antenna,
Since only the elliptical mirror is rotated around the rotation axis, it is possible to obtain a small and economical offset-type antenna device capable of beam movement in all directions in the Az force direction.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

1 and 2 show an antenna device according to an embodiment of the present invention, in which 11 is a torus-shaped offset parabola, F is its focal point, and 21 is an elliptical mirror having two focal points, F and another focal point F0. The elliptical mirror 21 is rotationally symmetrical about the horn axis 4. Here, the radio waves 6 emitted from the phase center 3 of the horn 3 are focused on a focal point F by an elliptical mirror 21.

Further, the radiation beam emitted from F is reflected by the offset parabola 11 and radiated into space as a radiation beam 5 at an angle α with respect to the horizontal plane. Furthermore offcent parabola 11
has a torus shape around the axis 4, and as shown in FIG. 1, it has a cone-shaped offset parabola and a mirror surface. Here, the focal point F of the parabola 11 is located on a circle 8 centered on point 0 on the axis 4 and having a radius of 1/2·r, which is half the rotation radius r of the torus, as shown in FIG. positioned. Therefore, this F is A
When the beam in the z-force direction is moved, circle 8 in FIG. 5 is the focal line. In other words, when changing the direction of the Az force on the beam, by rotating the elliptical mirror 21 around the axis 4 while keeping the horn 3 fixed and the main reflecting mirror 11 fixed, the beam can be changed to any direction in the Az plane. It can be changed in the direction.

In the above embodiment, the main reflecting mirror is a torus-shaped offset parabola, but as shown in another embodiment of the present invention shown in FIG. 6, the main reflecting mirror may be a torus-shaped offset spherical mirror. .

That is, reference numeral 12 is a circular arc surface having a constant angle centered on the center 0, and the main reflecting mirror 13 is obtained by rotating this circular arc surface 12 once around the axis 4.

〔Effect of the invention〕

As described above, according to the present invention, the main reflecting mirror is fixed as a ring torus-shaped parabola or a spherical surface,
Since a horn elliptical mirror is used as the secondary radiator and only the elliptical mirror is rotated around the horn axis, the antenna beam can be directed arbitrarily in the Az (depression angle) direction, making the device compact. It is possible to obtain effects such as being economical.

[Brief explanation of the drawing]

Fig. 1 is an external view of an antenna device according to an embodiment of the present invention, Fig. 2 is a diagram for explaining the principle of an embodiment of the present invention, Fig. 3 is an external view of a conventional antenna device, and Fig. 4 is an external view of an antenna device according to an embodiment of the present invention. 5 is an explanatory diagram of a torus according to an embodiment of the present invention, and FIG. 6 is an external view of an antenna device according to another embodiment of the present invention. 11 is a main reflecting mirror (offset parabola), 21 is an elliptical mirror, 3 is a horn, 4 is a shaft, 5 is a radiation beam, and 6 is a radio wave. Note that the same reference numerals in the figures indicate the same or equivalent parts. Figure 21゛ Kasumiμ6ρ Figure

Claims (1)

[Claims] (1) A ring-shaped offset parabola or a spherical torus mirror surface, an elliptical mirror surface that is rotatable around the rotation axis of the torus mirror surface and has one focal point as the focal point of the offset parabola or spherical surface, and the other elliptical mirror surface. An antenna device comprising: a horn whose phase center is one focal point of the horn;