JPH0712123B2 - Antenna device - Google Patents

Description

TECHNICAL FIELD The present invention relates to a satellite-mounted antenna used for covering a wide service area such as communication / broadcasting using a satellite with a high gain. .

[Conventional technology]

FIG. 4 is an explanatory diagram showing an example of a service area in a conventional antenna device. In the figure, 21 is a circular service area centered on the point 0 and having a visual diameter of 2θ _o.
Numerals 23 and 23 are, for example, a pencil beam and a twin beam which form a rotationally symmetric radiation beam having a central axis in a direction from a satellite (not shown) to a point 0. It is well known that to maximize the lowest gain in the coverage area 21, it is better to cover with twin beams 23 than pencil beams 22.
Further, 24 is the outer circumference of the service area 21.

FIG. 5 is an explanatory diagram showing an example of an aperture distribution (electric field distribution) obtained by a dual beam radiation pattern in the antenna device of FIG. 4, and FIG. 5 (a) is a two-dimensional map of the amplitude distribution on the aperture. 5B shows a cross section of the two-dimensional map, and FIG. 5C shows a phase distribution corresponding to FIG. 5B. In these figures, 31 is the main beam, 32 and 33 are side lobes, and 34 and 35 are _Null . Further, in FIG. 5 (c), the + sign indicates the main beam 31.
Represents the same phase as the phase, and the-symbol represents the opposite phase to the above phase.

6 (a) and 6 (b) are a perspective view and a front view showing the configuration of a conventional antenna device of this type disclosed in, for example, Japanese Patent Publication No. 48-10257. In the figure, 40 is a horn antenna that radiates a main beam, and 41 to 48 are arranged adjacent to the periphery of the horn antenna 40.
Is a horn antenna excited in opposite phase. The + and − symbols shown in FIG. 6B indicate that the excitation phases of the horn antenna 40 and the horn antennas 41 to 48 are opposite phases. In the antenna device shown in FIGS. 6A and 6B, first, the horn antenna 40 excites the aperture distribution that contributes to the radiation of the main beam. Next, the horn antennas 41 to 48 adjacent to the periphery of the horn antenna 40.
The opposite phase of the horn antenna 40
An aperture distribution that is substantially rotationally symmetric with respect to the central axis of is excited. Twin beams are emitted due to the aperture distributions excited in the concentric and in-phase and anti-phase directions.

Since the service area of this twin beam is circular,
A circular beam that forms a twin beam in the service area 11 shown in the figure.
When covering with 12 to 15, some areas cannot be covered, as is apparent from FIG. Therefore, if the rectangular beams 16 to 19 are used instead of the circular beams 12 to 15, it is possible to eliminate the uncoverable area as described above.

[Problems to be solved by the invention]

Since the above-mentioned conventional antenna device of this type is configured as described above, for example, when the service area 11 as shown in FIG. 7 is covered by a plurality of circular beams 12 to 15 forming a twin beam, There was a problem that the minimum gain in area 11 was reduced.

The present invention has been made to solve the above problems, and an object thereof is to obtain an antenna device capable of covering a service area with a high gain and a simple configuration.

[Means for solving problems]

An antenna device according to the present invention includes a primary radiation system configured by a primary radiation radiator or a combination of a primary radiator and a reflecting mirror, and in one plane including a central axis of a beam radiated from the primary radiator. Illuminates the parabolic reflector with the main beam of the primary radiator, and in the plane that includes the central axis of the beam emitted from the primary radiator and is orthogonal to the above plane, the parabolic reflector with the main beam and the sublobe of the primary radiator. Is to be irradiated.

[Action]

In the antenna device of the present invention, the primary radiation system is configured by the primary radiator or a combination of the primary radiator and the reflecting mirror, and the aperture diameter of the primary radiator and the wavelength of the reflected beam of the radio wave emitted from the primary radiator. A rectangular beam forming a twin beam can be formed by providing a predetermined relationship between the angle and the angle at which the irradiation range of the radiation beam is viewed from the center of the opening of the primary radiator.

〔Example〕

1 (a) and 1 (b) are schematic views showing the configurations in the zx plane and the yz plane, respectively, in an antenna device according to an embodiment of the present invention. In FIG. 1, reference numeral 1 denotes a feed horn as a primary radiator, and for example, a rectangular horn whose opening diameter in the x direction is longer than that in the y direction is used. Reference numeral 2 is a radiation beam of the radio wave radiated by the feeding horn 1, of which 2a is a main beam area and 2b is a sub-beam area.

Reference numeral 3 denotes a reflecting mirror on which the radio wave radiated by the power feeding horn 1 is irradiated, and is a part of a paraboloid of revolution having the phase center F of the power feeding horn 1 as a focal point and having the k axis as a mirror axis. First
Figures (a) and (b) show the configurations in the zx plane and the yz plane, respectively. The reflection mirror 3 has a main portion of the radiation beam 2 of the radio wave radiated by the feed horn 1 in the yz plane. Beam area 2a
Only is illuminated. FIG. 2B is a diagram showing a calculation example of the aperture distribution (electric field distribution) obtained by the radiation beam in the antenna apparatus of FIG. Although not shown in the figure, the z'axis is an axis perpendicular to the paper surface. 31 is the main beam, 32 and 33 are side lobes, and 34 and 35 are _Null . Such an aperture distribution can be realized by appropriately selecting the aperture diameter of the rectangular horn forming the power feeding horn 1. FIG. 3 (c) is a diagram showing a calculation example of the radiation beam obtained by the aperture distribution shown in FIG. 2 (b).

The closed curve in FIG. 3 (c) shows the contour lines of the radiation level of the radiation beam. From the figure, it can be seen that a rectangular beam forming a twin beam is obtained in the x'-axis direction. It can be explained as follows that the radiation beam as shown in FIG. 3 (c) is obtained by the aperture distribution shown in FIG. 2 (b). The aperture distribution shown in FIG. 2 (b) is k in FIG. 1 (a).
The central axis of the beam parallel to the axis is the z'axis, and the electric field distribution perpendicular to the z'axis is shown. The axis that intersects the zx plane of this plane is the x'axis, and the axis that intersects the yz plane is the y'axis. zx
The in-plane aperture distribution is the same as the in-plane aperture distribution including the center of the aperture in the rotationally symmetric aperture distribution shown in FIG. Therefore, the radiation beam in this plane is
It becomes a twin beam 23 as shown in the figure. On the other hand, the aperture distribution in the y'z 'plane of FIG. 2 (b) is similar to the aperture distribution of the parabolic antenna which is normally used. Therefore,
The radiation beam in this plane becomes a pencil beam 22 as shown in FIG. As a result, by using the aperture distribution shown in FIG. 2 (b), a radiation beam that becomes a twin beam only in one plane (in the vertical direction of the drawing) as shown in FIG. 3 (c). Will be obtained.

In the above embodiment, when the power feeding horn 1 is rectangular,
Moreover, although the excitation mode is the TE ₀₁ mode, it may be used when the TE ₀₂ mode of a higher order mode or the like is generated to increase the sidelobe level. Furthermore, power supply mode 1
Even if is circular, a rectangular radiation beam can be formed, which is the TM ₁₁ mode, which is the higher mode at this time.

Further, although the reflecting mirror 3 is an offset parabola in the above embodiment, it may be a rotationally symmetric parabola.

〔The invention's effect〕

As described above, according to the present invention, in the antenna device, the primary radiator or the primary radiator configured by a combination of the primary radiator and the reflecting mirror is provided, and one of the primary axes including the central axis of the beam radiated from the primary radiator is provided. In the plane, the main beam of the primary radiator irradiates the parabolic reflector, and in the plane orthogonal to the plane including the central axis of the beam emitted from the primary radiator, the main beam and the side lobes of the primary radiator are used. Since the parabolic reflector is configured to irradiate, it is possible to obtain an excellent effect that an antenna device capable of covering a service area with high gain can be obtained with a simple configuration.

[Brief description of drawings]

FIGS. 1 (a) and 1 (b) are schematic views showing the configurations in the zx plane and the yz plane, respectively, in the antenna device according to the embodiment of the present invention, and FIG. 2 (a) is shown in FIG. ) And (b)
FIG. 2B is a diagram showing a calculation example of an electric field distribution of a radiation beam from a feed horn in the antenna device of FIG. 2, FIG. 2B is a diagram showing a calculation example of an aperture distribution in which a beam radiated from the feed horn is reflected by a reflecting mirror, 3 (a) and 3 (b) are explanatory views showing the intensity of the radiated electric field in the z'x 'plane and the y'z' plane, respectively, and FIG. 3 (c) is a dual view obtained by the antenna device of the invention. FIG. 4 is a diagram showing a calculation example of a rectangular beam forming a beam, FIG. 4 is an explanatory diagram showing an example of a service area in a conventional antenna device, and FIG. 5 is an aperture obtained by a dual beam radiation pattern in the antenna device of FIG. An explanatory view showing an example of the distribution (electric field distribution), FIGS. 6 (a) and 6 (b) are perspective views and front views showing the configuration of a conventional antenna device of this type, and FIG. 7 is a service in the conventional antenna device. Show other examples of areas It is an explanatory diagram. In the figure, 1 ... feed horn, 2 ... radiation beam from feed horn, 3 ... reflector, 4 ... central axis of feed horn 1, 11, 21 ... service area, 12-15 ... circular beam , 16 ~ 19 ... rectangular beam, 22 ... pencil beam, 23
...... Twin beam, 24 …… Outside of service area 21, 31 ……
Main beam, 32,33 …… Side lobe, _34,35 …… N _ull , 40-48
... It is a horn antenna. In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] 1. An antenna device comprising one reflecting mirror and a primary radiation system, wherein the primary radiation system is composed of a combination of a primary radiator and a reflecting mirror, and a beam emitted from the primary radiation system is abbreviated. One plane containing the central axis (eg yz
In the plane), the main beam of the primary radiation system is used to irradiate the reflecting mirror, and in the plane orthogonal to the plane including the substantially central axis of the beam emitted from the primary radiation system (for example, the zx plane), An antenna device configured to irradiate the reflecting mirror with a main beam and a sublobe of a primary radiation system.