JPS59229902A - Shaped-beam antenna - Google Patents

Abstract

PURPOSE:To obtain a shaped-beam antenna containing a primary radiator having a large degree of freedom with a simple constitution by consituting a main reflector with the envelope surface of a line group formed in accordance with the section form of a shaped beam to be synthesized. CONSTITUTION:A main reflector is formed by a part of five types of parabolas 3-7. These parabolas use the phase center point P of a primary radiator 13 as a common focal point and axes Z3-Z7 having different directions with angles theta3-theta7 on the basis of a reference axis Z of the reflector 2. With an antenna of such a consitution, the radio waves of a spherical wave source radiated within a cut plane from the radiator 13 are reflected by parabolas 3-7 and then radiated within the same plane as the radio waves traveling toward each axis. The radiation characteristics within the cut plane are shown by a solid line 40 as mainly a synthetic wave. Thus it is possible to synthesize the desirable radiation characteristics by adjusting the number of parabolas forming cut lines, the size of each parabola, the focal distance and the axis direction respectively.

Description

[Detailed description of the invention] [Technical field in which the invention deceives] The present invention belongs to reflector antennas in wireless communication, and relates to a shaped beam antenna suitable for antennas mounted on satellites that communicate with ground stations in the area. .

[Description of prior art]

Conventionally, it is desirable for this type of antenna to have a radiation characteristic in which the cross-sectional shape of the radiation beam is shaped so that it can efficiently irradiate a 4-tea area where ground stations are scattered. As a shaped beam antenna, for example, the first
A parabolic antenna fed by a plurality of primary radiators, as shown in a vertical side view in the figure, has conventionally been used. In FIG. 1, 1 is a parabolic mirror of revolution having a focal point at point F and 2 as a reference axis, and 10 and 11 are primary radiators. The primary radiators 1o and 11 are supplied with power by a power divider 12 with appropriate excitation amplitude ratios and phase differences, respectively.

Since these primary radiators 10 and 11 are each arranged to be deviated from the focal point F, the radio waves emitted from each primary radiator 10 and 11 and reflected by the parabolic mirror l travel in the respective traveling directions. They are radiated as different plane wave radio waves, and are combined as a whole according to the amplitude ratio and phase difference supplied by the power divider 12. Although FIG. 1 shows an example in which the number of primary radiators is two, the method of combining is the same even if there are two or more primary radiators. Therefore, a shaped beam antenna can be realized by selecting the number and arrangement position of the primary radiators, excitation amplitude ratio, and phase difference in accordance with the desired shape of the shaped beam.

However, an antenna with this configuration generally has the disadvantage that the power divider becomes more complex and its loss increases in proportion to the increase in the number of primary radiators. Also, as the number of primary radiators increases, the size and weight of the primary radiators and power divider as a whole increases, and ? When mounted on an IS star, there were drawbacks such as the large effect it would have on the overall configuration of the satellite.

In addition, as a shaped beam antenna with other configuration,
As in the antenna described in 0-99060, the structure of the primary radiator system is simplified by using a main reflector made up of a combination of multiple partial mirror surfaces each formed by a part of a paraboloid of revolution. There is also an antenna, but since it is a combination of multiple partial mirror surfaces, it is not possible to freely select the rotational symmetry axis and focal length of each partial mirror surface, and the proportion of each partial mirror surface to the entire main reflecting mirror, so it is difficult to design. The disadvantage was that the degree of freedom was small.

[Purpose of the invention]

The present invention aims to improve the above drawbacks, and provides a shaped beam antenna that can communicate with multiple stations, has a simple configuration, and has a primary radiator with a high degree of freedom in design. do.

[Summary of the invention]

The present invention is characterized in that the main reflecting mirror is constructed using an envelope surface of a group of lines formed in accordance with the cross-sectional shape of a shaped beam to be synthesized.

That is, the present invention provides a shaped beam antenna comprising a main reflecting mirror and a primary radiator that irradiates the main reflecting mirror directly or via one or more sub-reflecting mirrors, in which the main reflecting mirror Consisting of an envelope surface of a group of cutting lines formed by each cutting line of a group of planes including a fixed point located on the reflecting mirror and the phase center point of the primary radiator or the equivalent phase center point via the sub-reflector. and each of the above cutting lines is formed by a combination of a plurality of parabolas with different axis directions,
Further, the axes of each of the parabolas are formed to be different in direction from the axes of the adjacent parabolas forming other cutting lines.

[Explanation based on examples]

Next, embodiments of the present invention will be described in detail based on the drawings.

FIG. 2 is a box-cut plan view of an antenna according to an embodiment of the present invention, and FIG. 6 is a front view of the main reflecting mirror of the antenna.

In Figures 2 and 3, the main reflection ψ, 20 points 0 is 1
Point P is the intersection point of the beam axis in the maximum radiation direction of the secondary radiator 13 and the main reflecting mirror 2, and the point P is the phase center point of the primary radiator 13,
is the main reflecting mirror 20 reference axis.

The main reflecting mirror 2 is constituted by an enclosing surface of a group of cutting lines formed by each cutting line of a group of planes including point 0 and point P. Solid lines 20, 21, and 22 in FIG. 3 are some of the cutting lines forming the group of cutting lines. Each of these cutting lines is determined by the method described below.

FIG. 4 is an example of an equal gain diagram on the observation sphere of the shaped beams that the antenna of this embodiment attempts to synthesize. In FIG. 4, the solid line 49 is a gain diagram on the observation sphere, and the solid lines 3o and 31.32 are the cutting planes including the cuts a20 and 21.22 shown in FIG. 3, respectively, and the observation plane. It is a line of intersection with the spherical surface, and point Q is the intersection of the z-axis shown in FIG. 2 and the observation spherical surface. Note that the equal gain diagram represented by the solid line 49 in FIG. 4 is shown with respect to the angle from this Z axis, and the solid line 3
° and 32 correspond to the vertical angular axis and the horizontal angular axis, respectively. Therefore, radiation characteristics within each cutting plane -1 For example, the cuts t v considered by the solid lines 30, 31, and 32 in FIG.
Corresponding to Tfj+, characteristics as shown by a solid line 40, a broken line 41, and a two-dot chain line 42 in FIG. 5 are desired, respectively. In FIG. 5, the vertical axis 5° is an axis indicating the power amplitude value, and the horizontal axis 51 is the glaze indicating the angle from the z-axis. How to determine the cutting line of the main reflecting mirror 2 in order to obtain desirable radiation characteristics within each cutting plane will be explained using, for example, the case of the solid line 40 in FIG. 5.

6 is a central vertical sectional view of FIG. 2, and FIG. 7 is a radiation characteristic diagram of the main reflecting mirror 2 shown in FIG. 6. Note that the real center 40 of the seventh factor is the same as that shown in FIG. Main reflecting mirror 2 F, Il, 5 Ij shown by the cutting line shown in Fig. 6
It is formed by a part of the Class I parabola 3.4.5.6.7. Each parabola 3.4.5.6.7 has a common focus at the phase center point P of the primary radiator 13, and has different directions z3 and z4.
．． Let z6, z6, and z7 each be the remainder 1. θ3.04
, θ6, θ7 are paraboloids from the reference axis 2 of the main reflecting mirror 23.
4.6.7 angles.

In such a +1'4 antenna, the primary radiator 13
Yorikiri 1 "Sphere radiated in a plane In1 wave wave monument 01 ↓
1. After Lυ is reflected by each parabola 3.4.5.6.7,
4 of each? 1rJ as a radio wave traveling in i1 direction
1 - radiated within 1 uj. The radiation characteristic within this cutting plane is mainly expressed as a composite wave of these waves. Therefore, desired radiation characteristics can be synthesized by adjusting the number of parabolas forming the cutting line, the dimensions of each h1 line, the focal weight resistance, and the direction of the axis. By synthesizing the radiation characteristics described above within one plane of each cut,
The antenna as a whole can be synthesized with equal-gain warabi pongee shown by the solid line 49 in FIG.

As explained above, since the composition of equal gain diagrams is performed individually within each cut and paste plane, the constituent elements of the cut I-E lines that match Vr are not all the same (constituent committee). One part or the entire element is different, and this difference is mainly due to the direction of the axis, and the dimensions and focal length of each parabola are mainly due to the gradual sharpening of the envelope surface of the group of cutting lines. are selected as follows.

The number of cut groups depends on the overall size of the main reflecting mirror,
The wave number used can be selected depending on the shape of the gain-i diagram to be synthesized, or it can be increased or decreased based on the results of analysis or actual measurements of radiation characteristics that also take into account wave effects.

FIG. 8 shows another embodiment of the antenna according to the present invention, with the center vertical I;
The plan view and FIG. 9 are radial inertia diagrams of the main reflection fa2' shown in FIG. As shown in FIG. 8, the main reflecting mirror 2' of this embodiment has cutting lines formed by parts of six types of parabolas 3', 4 (5'), and this cutting line is centered on the basic axis 2. Therefore, the radiation characteristics to be synthesized are also obtained by rotating the solid line 43 showing the radiation characteristics in FIG. 9 around the axis 50. Axes z3 and 2. The angle θ and θ from the thorn 1z are as follows:
θ3-0. Out. The method of synthesizing the so-called bimodal beams shown by 43 with the disturbing radiation characteristics in each cutting plane is the same as in FIGS. 6 and 7. Actual%
, the % characteristic of the main reflector 2' of the antenna in the example is that the central part of each cutting line is a parabola 4 with the same focal length and axis.
', and the paraboloids F, i! have the same focal length but different axis directions. It is located at 3' and 5'.

In the above explanation, the primary radiator exists in the ')j41 path of radio waves, and the antenna with so-called blocking is described.
It can also be applied to a so-called offset type antenna.

Also, for the sake of explanation, the antenna was treated as a transmitting antenna, but due to the reciprocity of antennas, it can also be applied to receiving antennas, and therefore the ``irradiation'' used in ξ light above
The words "radiating" and "radiating" do not limit the invention to transmitting antennas.

〔Effect of the invention〕

As explained above, the advantage of the present invention is to form a main reflecting mirror using the envelope surface of the cut beam formed in accordance with the cross-sectional shape of the shaped beam to be synthesized, and The structure of the 11th order radiator system can be changed to 4. It is possible to realize an excellent cross-beam antenna that is simplified and has a large degree of freedom in design. In particular, it is said that it will be very effective if used in a satellite invitation antenna that requires communication with a number of JLFZ upper stations and has many restrictions on the size, weight, etc. of the entire antenna.

[Brief explanation of drawings]

Fig. 1 is a vertical cross section of a conventional antenna (1iil 1iIi diagram). Fig. 2 is a vertical cross section of an antenna according to an embodiment of the present invention.
T! ! I view. Figure 3 is a front view of the main reflection rust on the antenna. Figure 4 is the Kasari; # line diagram. Figure 5 shows its radiation characteristics. Figure 6 is a cross-sectional view of the medium-fired cotton in Figure 2. No. 717i is its radiation characteristic diagram. No. 8121 is a central network 1i of an antenna according to another embodiment of the present invention.
, l + 1 Kawashijo Figure 9 is its radiation characteristic diagram. 2.2'...Main reflection 16 3~7.3'~5'...
・Parabola, 13...Primary radiator, 0...Fixed point on the main reflector, P...1? jζradial position i[' center point,
2...Reference axis of main reflector. Patent applicant's representative Patent attorney Nao Takashi IdeFigure 1Figure 2Figure 3Figure 4Figure 5Figure 6Figure 8Figure 9

Claims (1)

[Claims] <l+ In a shaped beam antenna equipped with a main reflecting mirror and a primary radiator that irradiates this main reflecting steel via a direct reflection chain, the main reflecting mirror has a fixed point located on this main reflecting mirror. and an envelope surface of the cutting light group formed by each cutting line of the plane group including the phase center point of the primary radiator, and each cutting line is formed by a combination of algebraic parabolas with different axis directions. 1. A shaped beam antenna characterized in that the directions of the axes of each of the paraboloids are different from the directions of the axes of the paraboloids forming other cutting lines in contact with the membrane.