JPS6212203A - Antenna system - Google Patents

Abstract

PURPOSE:To improve the wide angle directivity by providing a sub reflecting mirror supported by plural supports corresponding to a main reflecting mirror and forming a shadow image as a single strip shadow while using an optional single line as a base line at each support so as to suppress the caused sub lobe level. CONSTITUTION:The sub reflecting mirror 2 is arranged corresponding to a main reflecting mirror 1 and the sub reflecting mirror 2 is supported by supports 3-1-3-3. Not a single straight line support but a waving support is used for each support and the support 3-1 is formed corresponding to, e.g., a waving base line 101. Since the shape of equivalent aperture face of the supports 3-1-3-3 formed waving in this way shows waving form in the wide angle directivity within a plane perpendicular to a plane including the supports 3-1-3-3 and their antenna axes, the directivity of the equivalent aperture is scattered in terms of the angle and not deteriorated.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an antenna device, and relates to an I! ! In an aperture antenna including a main reflector used in a frequency band including a microwave band and a quasi-millimeter wave band in f.

The sub-reflector disposed corresponding to the main reflector relates to an antenna device that improves deterioration in wide-angle directivity characteristics that occurs through a support that supports a primary radiator.

[Conventional technology]

Due to its usefulness, an aperture antenna comprising a main reflector and a sub-reflector or primary radiator disposed corresponding to the main reflector is suitable for frequencies including the microwave band and quasi-millimeter wave band. Generally, it is widely used as an antenna for communication in the band. In particular, an axis-symmetric Cassegrain or Gregorian antenna with a sub-reflector has low noise characteristics and is therefore effectively used as an antenna for a satellite communications earth station. Figure 6 (al and (b)
6 is a diagram conceptually showing a front view and a side view of a conventionally widely used Cassegrain antenna.
A sub-reflector 2 is arranged corresponding to the main reflector 1, and the sub-reflector 2 is supported at a predetermined position by supports 3-1, 3-2 and 3-3 having a linear structure. .

[Problem that the invention seeks to solve]

In the conventionally widely used aperture antenna described above, as shown in FIG. The aperture formed through the main reflecting mirror 1 is affected by the shadows of the sub-reflecting mirror 2 and the pillars 3-1 to 3-3, which results in deterioration of the radiation directivity characteristics of the aperture antenna. 7th
What is shown in Figure (al) is a conceptual representation of the aperture surface corresponding to the aperture antenna shown in Figure 6 (al).
With respect to the circular opening surface 102 corresponding to the main reflecting mirror 1, the shadow 103 of the sub-reflecting mirror 2 and the shadows 104-
106, which deteriorates the radiation directivity characteristics as described above. Regarding the deterioration of the radiation directional characteristics, the influence on the main radiation direction of the aperture antenna is of course important, but the influence on the wide-angle directional characteristics corresponding to the sides is also extremely important.

This is particularly emphasized as a problem when the aperture antenna is used for satellite communications or the like.

As is well known, satellite communication lines are formed between multiple earth stations using communication satellites in geostationary orbit as relay stations, but this is a recent trend.

Including not only communication satellites, but also broadcast satellites, navigation satellites, etc.
The number of relay stations in geostationary orbit is increasing, and this trend is expected to increase further in the future. As the density of stations in geostationary orbit increases, interference and crosstalk between satellite communication lines, including those of earth stations, naturally come to the fore as a major problem. The recommendations of the Consultative Committee on Radiocommunications (CCIR) of the International Telecommunication Union also call for stricter level suppression of the radiation level in the wide-angle directional characteristics of aperture antennas.

Pillar 3- for the wide-angle directivity characteristic of the above-mentioned aperture antenna
The effects of the shadings 104 to 106 of Nos. 1 to 3 can be explained as follows with reference to FIG. 7 1al and Φ), FIG. 8 fa) and Φ)S, and FIG. 9.

FIG. 9 is an example of wide-angle directivity characteristics of a parabolic antenna as an aperture antenna in the 6 GHz band. 9th
What is shown in the upper right part of the figure is a view corresponding to the opening plane in FIG.

A reference line on the antenna scanning plane corresponding to the wide-angle directional characteristic 109 of the aperture antenna is shown, and B indicates a reference line on the antenna scanning plane corresponding to the wide-angle directional characteristic 110 of the aperture antenna. There is. As is clear with reference to FIG. 9, the radiation level of the wide-angle directional pattern 109 in the antenna scanning plane including the reference line A is clearly the same as the radiation level of the wide-angle directional pattern 110 in the antenna scanning plane including the reference line B. In comparison, it is at a relatively high level.

This factor can be easily understood by referring to FIG. 7 Φ). In FIG. 7(b),
What is shown as 107 is the equi-constrained aperture plane 1- corresponding to the shadow 104 of the pillar 3-1 in FIG. The main radiation direction of the aperture surface 107 coincides with the z-axis.The radiation directivity characteristics of this isovalue aperture surface 107 are shown in FIGS. 7 1al and (b) for the hYZ plane and the XZ plane, respectively. (In al, the presence of the shadow 104 is equivalent to superimposing the field distribution of the equivalent aperture surface 107 with a negative sign on the field distribution of the aperture surface 102. Therefore, the shadow 1
The influence on the radiation directivity characteristics due to the intervention of 04 is as follows:
The radiation directional characteristics of the equivalent aperture surface 107 appear in a form that is correlated with the radiation directional characteristics of the aperture surface 102 itself. This influence is.

With respect to the main radiation direction of the aperture surface 102 itself, the gain is relatively slight at a slightly lower range, but in the region of the secondary rope, which is a problem in wide-angle directional characteristics, the main radiation direction by the aperture surface 107 is 1 equivalent. The influence of the beam cannot be ignored. In particular, the radiation directivity characteristic 11 shown in FIG. 8(b)
The influence on the radiation directivity characteristics in the plane corresponding to the xz plane of No. 2 is significant. Of course.

This also affects the radiation directivity characteristic in the plane corresponding to the yz plane of the radiation directivity characteristic 111 in FIG. 7 1al.

As is clear from the comparison of the radiation directional characteristics 111 and 112, the difference in the width of the main beam of these radiation directional characteristics υ has little effect on the radiation directional characteristics 111, and therefore, on the talOyz plane in FIG. It can be seen that the influence on the radiation directivity characteristics within the corresponding plane is relatively small.

The coordinate system (x + y,
The xz plane and the yz plane in FIG. 9 correspond to the antenna scanning plane including the reference MA and the antenna scanning plane including the reference line Bi, respectively, in the diagram of the aperture plane shown in the upper right corner of FIG. Therefore, as described above, one equivalent frontage surface 107
It is concluded that the degree of correlation to the wide-angle directivity characteristic of is significant in the antenna scanning plane including the reference line At-. Due to the superimposition of the radiation directional characteristics 112 of the isolateral aperture surfaces 107, the wide-angle directional characteristics in the radiation directional characteristics 1 of the aperture surfaces 102 correspond to the superimposed portion, regardless of the presence or absence of its polarity. Bell goes up. Wide-angle directional characteristics 10 shown in Figure 9
The reason why the level of the directional characteristic 9 is higher than that of the wide-angle directional characteristic 110 is due to the above-mentioned phenomenon. In addition, in FIG. 9, the reference level line 108 is.

1 In the CCIR recommendation, the reference level line fully regulates the upper limit of the sublobe level in the wide-angle directional pattern, but clearly the sublobe level in the wide-angle directional pattern 110 is below the reference level line 108 f: It can be seen that the sub-rope level in the wide-angle directional characteristic 109 is above the reference level line 108.

Note that this cause of deterioration of wide-angle directivity characteristics is different from that caused by scattering of radio waves by the pillars, and is caused by attaching radio wave absorbers to the pillars, making irregularities on the surface of the pillars, or attaching the pillars to antennas. Even if a method of creating a structure in which the structure is undulated in a plane including the shaft and the support column is used, it cannot be a solution to this problem. That is, in the conventional antenna device, the sub-lobe level in the plane perpendicular to the plane including the antenna axis and the column supporting the primary radiator is increased due to the presence of the column, and It has the disadvantage of deteriorating wide-angle directional characteristics.

[Elaborate means to solve problems]

In order to solve the above-mentioned problems, the antenna device of the present invention includes a sub-reflector or a primary radiator supported by a plurality of supports, corresponding to a predetermined main reflector, and a In an antenna device that forms a predetermined aperture,
A shadow image of the opening surface by the plurality of pillars is provided for each pillar.

Each of them is formed as a single strip-shaped shadow using a single arbitrary line as a base line, or a composite strip-shaped shadow is formed using a composite line formed by a combination of a plurality of arbitrary lines as a base line. The plurality of supports are provided.

〔Example〕

Hereinafter, the present invention will be explained in detail with reference to the drawings.

FIG. 1+a) is a front view of a first embodiment of the present invention.

FIG. 1(b) is a partially enlarged view of the support column in the first embodiment.

In FIG. 1 fa), a sub-reflector 2 is arranged corresponding to the main reflection f#,1, and the sub-reflector 2 is located at the support column 3-1.3.
-2 and 3-3.

In this embodiment, unlike the conventional example shown in FIG. 6, each support is not a single straight support but a wave-shaped support. Fig. 1 Φ) shows a partially enlarged view of the support column 3-1.

A support 3-1 is formed corresponding to the wavy base line 101. By making the pillars 3-1.3-2 and 3-3 wavy in this way, the pillars 3-1.3-2 and 3-3
The wide-angle directional characteristics in a plane perpendicular to the plane containing the antenna axis and each of Dispersed and never degraded.

2, 3, 4 and 5 respectively represent the second embodiment of the present invention. Third. 4th j? and a fifth embodiment, and in each embodiment, a sub-reflector 2 is arranged corresponding to the main reflector 1, and the sub-reflector 2 is supported by supports 3-1, 3-2 and 3-3. Supported. In the second and third embodiments shown in FIGS. 2 and 3, the struts 3
-1.3-2 and 3-3 are each formed using a composite combination of a plurality of straight lines as a base line, and.

In the fourth and fifth embodiments shown in FIGS. 4 and 5, struts 3-1, 3-2 and 3-3 are each formed by a single linearly bent strut. .

No. 2 above. Third. In each of the fourth and fifth embodiments, as in the case of the first embodiment, consideration is given to the shape of each support so that the shadow on the opening surface does not form a single linear shape, and each The radiation directivity characteristics of the isolateral oral surface corresponding to the shadow are angularly distributed.

〔Effect of the invention〕

Having explained the above in detail, the present invention is applied to an antenna device including a primary radiator, in which a sub-reflector supported by a plurality of supports corresponds to a main reflector, and This has the effect of suppressing the secondary rope level and improving the wide-angle directional characteristics.

[Brief explanation of drawings]

FIG. 1 (al and Φ) are a front view of the first embodiment of the present invention, a partially enlarged view of the support column, and FIG. 2, respectively. 3, 4, and 5 respectively show the second embodiment of the present invention.
Third. FIG. 7 is a front view of the fourth and fifth embodiments. 6 (El and (b) are respectively a front view and a side view of the conventional antenna device, and FIG. 7 (al and Φ) are views showing the aperture surface and isolateral aperture surface of the conventional antenna device, respectively. Figure 8 (al and (b)) shows the radiation directional characteristics in the yz plane and the xz plane of the isolateral aperture plane, respectively. Figure 9 shows an example of the wide-angle directional characteristic of a conventional antenna device. In the figure, 1... ...Main reflector, 2...
Secondary reflector. 3-1~3... Support. Agent Patent Attorney Shinji Uchihara 703-101-4 Shadow (I7)
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Claims (1)

[Claims] An antenna device comprising a sub-reflector or a primary radiator supported by a plurality of supports corresponding to a predetermined main reflector, and forming a predetermined aperture through the main reflector, wherein The shaded image for the aperture surface is formed for each support as a single band-shaped shadow using a single arbitrary line as a base line, or a composite line formed by a combination of multiple arbitrary lines is formed as a base line. An antenna device comprising the plurality of pillars formed as strip-shaped shadows.