JPS5884505A - Formed beam antenna - Google Patents

Abstract

PURPOSE:To obtain a formed beam antenna which can synthesize formed beams representing excellent characteristics for the radiation characteristics with a broad angle, by constituting one reflecting mirror through the combination of a torus mirror surface and a mirror surface of paraboloid of revolution and feeding power to the reflecting mirror with one primary radiator. CONSTITUTION:A main reflecting mirror 30 is constituted by combining partial reflecting mirrors 31-33 mainly. In the reflecting mirror 31, the negative side of the X axis is a part of a parabola taking a point F as a focus and having a directrix in parallel with the X axis and the positive side of the X axis is a torus being a part of a curve other than a parabola and turning a cut line 38 around the X axis by an angle of + or -theta0, in the cut line 38 of the X-Z plane. The reflecting mirrors 32, 33 consist of a part of the paraboloid of revolution turning a parabola taking the point F as a focus and having a directrix in parallel with the X axis around axes Z32, Z33. Thus, power is fed from a primary radiator 12 located at the point F and formed beams representing excellent characteristics for the radiation characteristics of a broad angle can be synthesized.

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Technical field to which the invention pertains The present invention relates to a reflector antenna for wireless communication, in which the shape of the radiation beam has a fan-shaped spread within a plane including the main axis of the reflector; The present invention relates to a so-called shaped beam antenna having a shaped beam that is not a perfect circle in orthogonal planes.

(2) Prior Art In normal radio communication, since radio stations communicate in direct pairs with each other, the antennas used are generally required to have high gain and low curve characteristics. However, for example, when communicating between multiple slave stations scattered within a certain area and one master station, the antenna of the master station must have a shaped beam that efficiently illuminates the area where the slave stations are scattered. is desired.

Fig. 1 is a plan view showing the arrangement of a master station and a slave station that perform wireless communication, and Figs. 2 and 3 are side views thereof, both of which are diagrams for explaining the effect of beam forming described above. be. In other words, when station A is the master station and stations B, 0, ・D, and B are slave stations, the beam shape of the antenna of the master station is as shown by the broken line 1 in Figure 1 in the horizontal plane. It is desirable to have a layered spread that covers the slave station.

On the other hand, in the vertical plane, depending on the difference in ground height where the slave station is located or the difference in distance from the master station, as shown in Figures 3 and 3, the normal pencil It is preferable to have a shaped beam as shown by the dashed line 3 in FIG. 3 rather than a shaped beam.

Conventionally, as a method of synthesizing this type of shaped beam, a method of synthesizing so-called cosecant two-can shaped beams has been considered for beam shaping in a vertical plane. (-Fuji, Yokotoba "Design Theory and Examples of Reflector Antenna for Search Radar" IEICE Antenna Propagation Study Group Material AP77-75
．． (November 21, 1977) However, this method alone cannot perform beam shaping in the horizontal plane. −
As a method of combining beams in a horizontal plane into a fan shape, as shown in the perspective view of a conventional fan beam antenna in FIG. An antenna configured by arranging the primary radiator 12 of a spherical wave source on the antenna 111 has been considered.

In Fig. 4, the coordinate system x-y-z is the focus of the parabolic tube reflector 10 at 1 m.
It is an orthogonal coordinate system centered on the center point y of 11, and the Y axis is on the focal line 11. Therefore, the cutting line of the parabolic tube reflector 10 in a plane parallel to the X-Z plane is a parabola having a single line parallel to the Y axis.

A side view of the antenna shown in FIG. 4 is shown in FIG. S, and a plan view thereof is shown in FIG. 6. The radio waves emitted from the primary radiator 12 installed at the center point F of the focal line 11 shown in FIG. It is radiated as a wave front that is constant in the traveling direction, as shown by propagation paths 14 and 15 in FIG. Therefore, the antenna as a whole has a maximum radiation direction in the Z-axis direction, as shown in FIG.
In the X-Z plane, the beam shows radiation characteristics with a narrowed beam width like the beam shown by real [19], and in the Y-Z plane, it shows radiation characteristics as shown by the broken line 20.
It shows radiation characteristics with a wide beam width as shown in the beam shown in .

However, in the antenna configured in this way, the reflected wave from the parabolic reflector 10 has a diverging wavefront in the Y-2 plane as shown in FIG. The presence of leakage radio waves from the radiated primary radiator 12 deteriorates the wide-angle radiation characteristics, resulting in the disadvantage that unnecessary radiated power cannot be ignored. This deterioration of the radiation characteristics at wide angles is a failure of Figure 1! In terms of I20, it is indicated by a large amplitude value at an angle of 36 degrees or more from the Z axis, and in particular, the amplitude value at an angle of 90 degrees or more from the KZ axis is due to the influence of leakage radio waves from the primary radiator 12. is large.

As a means of beam shaping on the vertical plane as well as on the horizontal plane, it is thought to combine the two methods described above and use a surface formed by arranging curves that synthesize the cosecant-square shaped pims on the vertical plane in a cylindrical shape. However, basically the fourth
Since there is no major difference in the configuration of the antenna shown in the figure, the aforementioned deterioration of the wide-angle radiation characteristics in the horizontal plane is unavoidable. Also,
In order to avoid this deterioration of the wide-angle directivity characteristic, it may be possible to combine two parabolic reflecting mirrors at both ends of the above-mentioned cylindrical mirror surface, but this is suggested in Japanese Patent Application No. 55-108087.

(3) Purpose of the present invention The present invention aims to eliminate the above-mentioned drawbacks by combining a toric mirror surface and a parabolic mirror to form a single reflecting mirror. It is an object of the present invention to provide a shaped beam antenna that can synthesize a shaped beam exhibiting good radiation characteristics even at wide angles by feeding power with a secondary radiator.

(4) Features of the present invention The present invention comprises a main reflecting mirror and a primary radiator that irradiates directly with the main reflecting mirror or via a sub-reflecting mirror, and the radio wave beam formed by the main reflecting mirror advances. Assuming the direction KZ-axis, the origin is assumed near the position of the primary radiator or sub-reflector that directly illuminates the main reflector, and the X-axis and Y-axis are assumed to be on a plane perpendicular to the above two axes including this origin. When considering the main reflecting mirror as a cut plane by a plane that includes the Y axis and forms a small angle with the two axes, a central partial reflecting mirror and two end partial reflecting mirrors adjacent to this central partial reflecting mirror. In the shaped beam antenna, the central partial reflector has a Y-Z
It is a circular arc when cut by a plane parallel to the plane, and X-z
At least a part of the plane cut surface is a curve other than a parabola, and the both-end partial reflecting mirror has a parabola that focuses on the origin and has a single line parallel to the X axis on the Y-Z plane. It is characterized in that it is a part of a rotating surface created by being rotated around a straight line included in the origin and passing through the origin.

(5) Examples of the present invention The embodiment drawings will be described in detail below.

FIG. 8 is a perspective view of an antenna according to a first embodiment of the present invention. In FIG. 8, the main reflecting mirror 30 is a partial reflecting mirror 31.32.
, and 33, and partially reflecting mirrors 35 and 36 are provided as necessary. The partial reflecting mirror 35 is a joining conversion section between partial reflection/reflection @31 and 32, and the partial reflecting mirror 36 is a joining conversion section between partial reflection f#, 31 and 33. Which main reflection @30 is fed by the primary radiator 12 of the spherical n-wave source in a plane that includes the X-axis and is orthogonal to the y-z plane? By synthesizing the shaped beams shown in I3, it is possible to synthesize a shaped beam having a fan-shaped spread as indicated by the broken line 1 in FIG. 1 in the Y-Z plane. This will be explained in more detail.

A cutaway view of the partial reflecting mirror 31 along the X-Z plane is shown in FIG. Cutting line (hereinafter referred to as "generating line of partial reflecting mirror 31-")
The curve 38 is determined by formula (1) by applying a normal mirror surface forming method within the two-dimensional X-Z plane. ;・p is the distance between point F and arbitrary 'AP on the mirror surface - I (φ) is the function H (θ) that indicates the electric sharp turn in the X-2 plane of the primary radiator 12, which is to be synthesized. FIG. 10 shows an example of a function indicating the radiation power characteristics in the X-Z plane.

The beam combining method can be qualitatively explained as follows. For example, when trying to synthesize 5 patterns in the X-2 plane as shown in Fig. 10, cut in the direction where the energy attenuation is steep, that is, at the angle θ! The reflected wave from 138' is made to travel in the direction of θ=o', that is, in the biaxial direction, as shown by break #39 in Figure 9, and in the direction of gradual energy attenuation, that is, to the angle θ side. is cutting line 3
As shown by the broken line 40 in FIG. 9, the reflected wave from 8 is θ=
If the cutting line 38 is formed so that it progresses between θ and θ, it will become .Therefore, the negative side of the X-axis of the cutting line 38 in FIG. It is a part of a parabola having a single line, and the positive side of the X-axis is a part of a curve other than the parabola.

Next, a method for configuring the main reflecting mirror 30 based on the generatrix of the partial reflecting mirror 31 determined by K as described above will be described.

FIG. 11 shows a cutaway view of the main reflecting mirror 30 on the Yz plane. The partial reflecting mirror 31 is angled upwardly from the above-mentioned generatrix around the X axis.
The 0-partial reflecting mirrors 32 and 33, each made of a torus rotated by 0 degrees, each have a point F as a focal point, and each rotates a parabola having a directrix parallel to the X-axis to the axis z, and axis Zll. The partial reflecting mirrors 35 and 36, which are part of the paraboloid of revolution, are not necessarily necessary, and can be provided as a joining conversion section when joining the partial reflecting mirror 31 and the partial reflecting mirror 32 or 33 is difficult. It is.

In such a configuration, first, the shape of the main beam radiated from this antenna will be explained. In FIG. 11, among the spherical waves emitted from the primary radiator 12 arranged at the point FIIC, the wave reflected by the partial reflecting mirror 31 is transmitted along the X axis, since the X axis is the rotation center axis of the torus. II! of FIG. 10 in a plane that includes II, exhibits radiation characteristics as shown in 42.

On the other hand, in a plane parallel to the y-z plane, the propagation path 43 in FIG.
And, as shown in 44, the technique is radiated in a circle centered on point F as a uniform technique. Part 1 - Broken diagram 1146
A radiation characteristic diagram of reflected waves in the Y-Z plane by the k-part mirror surface 31 ec is shown.

On the other hand, among the spherical waves emitted from the primary radiator 12, the waves reflected by the partial reflectors 32 and 33 have point F as the focal point of the partial reflectors 32 and 33, and the axis Zll and the axis z.
As is the axis of rotational symmetry, the wave reflected by the partial reflecting mirror 320 is emitted as a plane wave traveling in the direction of the axis z0, and the wave reflected by the partial reflecting mirror 33 is radiated as a plane wave traveling in the direction of the axis ZSS.

Broken lines 48 and 49 in FIG. 11 indicate the partial reflector 3, respectively.
Examples of propagation paths of 2 and 33 are shown. Therefore, the radiation characteristics have maximum radiation directions in the axis 2° and axis z0 directions, respectively,
The beam width becomes narrower. Two-point chain ll in Figure 12
y from partial reflecting mirrors 32 and 33 to l50 and 51
- Shows a radiation characteristic diagram in the z plane.

Note that, as described above, the partial reflecting mirrors 35 and 36 are not necessarily necessary, and their proportion to the entire main reflecting mirror 30 is small, so their influence on the overall radiation characteristics is negligible.

Furthermore, the radiation characteristics of the entire antenna are determined as the vector sum of the radiation waves of each partial reflector. First, in a plane that includes the X axis and is perpendicular to the yz plane, as is clear from the above explanation,
In the range where the angle in the z plane is ±0°, the solid line 42 in Figure 10
It exhibits the characteristic of having a shaped beam like this. On the other hand, Y-Z
In a plane parallel to the plane, for example, as shown in the radiation characteristic example in the y-z plane in FIG. At both ends, mushroom dot chains @SO and 51 showing the radiation characteristics of the partial reflecting mirrors 32 and 33, respectively, are the main components.
The overall radiation characteristic is as shown by a solid line 52. Therefore, the antenna of this embodiment has a shaped beam as shown by the solid line 42K in FIG. 10 in a plane that includes the It will have a shaped beam as shown in break 111.

Next, the wide angle number and durability characteristics in a plane parallel to the Y-Z plane will be explained. The wide-angle radiation characteristic becomes clear by comparing FIG. 6 and FIG. 11. That is, among the radio waves radiated from the primary radiator 12, the energy of the leakage radio waves traveling along the propagation paths 22 and 23 K shown by the broken lines in FIG. The radio waves are reflected by the beams and are concentratedly radiated near the axis Z□ and the axis ZSS as radio waves traveling along the propagation paths 43 and 44 shown by broken lines, and are effectively used for combining the main beam. Therefore, as shown by the solid line 54, the characteristic in the vicinity of 0-0 where the angle from the two axes in FIG. , and the amplitude value at an angle of more than SO degrees from the two axes also decreases by the amount that the leakage radio waves decrease.

Power is supplied to the main beam by an amount corresponding to the reduction in unnecessary radiation power at these wide angles.

FIG. 14 shows a partial reflecting mirror 31 of an antenna according to a second embodiment of the present invention.
FIG. 3 is a cross-sectional view taken on the X-2 plane of FIG. Cutting line 3
8 is composed of a plurality of partial parabolas. In the case of FIG. 14, the number of partial parabolas is three, namely partial parabolas -38-, , 38-, and 381, and each partial parabola has a point r as a common focal point. Partial paraboloids -38-, ,38-, and 3
The axes 81 are the Z axis, the zl axis, and the 2τ axis, respectively. Therefore, among the radio waves radiated in the X-Z plane from the primary radiator 12 of the spherical wave source placed at point r,
The reflected wave at the partial paraboloid @ 381 travels in the z-axis direction, and the reflected waves at the external paraboloid $ 38- and 3B-1 are 2', respectively.

The radiation propagates in the directions of the axis and the z'sa axis, and the radiation characteristic as a whole in the X-Z plane becomes K as shown in FIG. 1S, for example. Therefore, the generatrix of the partially reflecting mirror 31 shaped in this manner can also be applied to the present invention.

Figure 1s is a perspective view of the third practical example antenna of the heather invention.

This embodiment is a case in which the present invention is applied to a so-called offset antenna, in which a part of the main reflector 30 shown in FIG. 8 is used, and the primary radiator 12 is offset by an angle α from the negative two-axis direction. It is the composition. Therefore, the radiation characteristics are shown in Fig. 10 and xsv! It has properties similar to those shown in J. However, due to its configuration, it has the advantage that the reflected wave from the reflecting mirror is not blocked by the primary radiator 12, unlike the antenna of the embodiment shown in FIG.

In the above explanation, for convenience, each partial reflecting mirror 31, 32,
Although the focal points of 33 and 33 coincide with one point F, this is not necessarily a necessary condition, and the present invention can be applied even if the respective focal points are slightly deviated.

Further, in the above description, all antennas are described as transmitting antennas, but the present invention can also be applied to receiving antennas due to the reciprocity of antennas.

(6) Effects of the present invention As explained above, by using the present invention, it is possible to realize a shaped beam antenna that effectively irradiates an irradiation area and has good wide-angle radiation characteristics, and can be used in a certain area. Excellent effects can be obtained if the antenna of a master station that requires wireless communication with a plurality of scattered stations is used.

[Brief explanation of the drawing]

FIG. 1 is a plan view showing the arrangement of a master station and slave stations that perform wireless communication. FIGS. 2 and 3 are side views thereof. FIG. 4 is a perspective view of a conventional fan beam antenna. Figure 2 is its side view. Figure 6 is its plan view. FIG. 1 is a radiation characteristic diagram of the antenna shown in FIG. 4. FIG. 1 is a perspective view of an antenna according to a first embodiment of the present invention. FIG. 9 is a cross-sectional view of FIG. S taken along the X-Z plane. FIG. 10 is a radiation characteristic diagram of the partial reflecting mirror 31 in the X-Z plane. FIG. 11 is a cutaway view on the yz plane of FIG. 8. Figure 12 and Figure 13 are radiation characteristic diagrams of the antenna shown in Figure 8. Fig. 14 Partial reflecting mirror 31 of the antenna according to the second embodiment of the present invention
FIG. FIG. 16 is a radiation characteristic diagram in the X-Z plane. FIG. 16 is a perspective view of an antenna according to a third embodiment of the present invention. 10... Parabolic tube reflection cast, 11... Focal line of parabolic tube reflector, 12... Primary radiator, 14.15.16.17
, 22.23... Propagation path, 30... Main reflecting mirror, 31
, 32.33 , 35.36... partial reflecting mirror, 38
...cutting line, 43, 44, 48.49 pa° propagation path. Patent Applicant: NEC Corporation Representative Takashi Izunao Figure 1 Figure 2 Figure 3 Figure 6 Figure 7 Figure 8 Figure 11
(θ) Fig. 15 Fig. 16

Claims (1)

[Claims] (1) Main reflecting mirror (30) and 1. It is equipped with a primary radiator (12) that irradiates the main reflecting mirror directly or via a sub-reflecting mirror, and assumes two axes in the traveling direction of the radio beam formed by the main reflecting mirror, and directly irradiates the main reflecting mirror. When the origin is assumed to be near the position of the primary radiator or sub-reflector to irradiate, and the Y-axis and Y-axis are assumed to be in a plane perpendicular to the two axes that includes this origin, the main reflector (30) When considering a cut plane by a plane that includes the axis and makes a small angle with respect to the two axes, the central partial reflecting mirror (31) and the two end partial reflecting mirrors (32, 33) adjacent to this central partial reflecting mirror are In the shaped beam antenna including:
The cross section taken by a plane parallel to the Y-Z plane is a circular arc,
At least a part of the cross section taken by the
) is a part of a rotating surface created by rotating a parabola with a single line parallel to the Y-axis on the y-z plane, with the origin as the focal point, to a straight line that is included in the y-z plane and passes through the origin. A shaped beam antenna characterized by: